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Author name code: dreizler
ADS astronomy entries on 2022-09-14
author:"Dreizler, Stefan"
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Title: The CARMENES search for exoplanets around M dwarfs: Stable
radial-velocity variations at the rotation period of AD~Leonis --
A test case study of current limitations to treating stellar activity
Authors: Kossakowski, D.; Kürster, M.; Henning, Th.; Trifonov, T.;
Caballero, J. A.; Lafarga, M.; Bauer, F. F.; Stock, S.; Kemmer, J.;
Jeffers, S. V.; Amado, P. J.; Pérez-Torres, M.; Béjar, V. J. S.;
Cortés-Contreras, M.; Ribas, I.; Reiners, A.; Quirrenbach, A.;
Aceituno, J.; Baroch, D.; Cifuentes, C.; Dreizler, S.; Forcada,
J. S.; Hatzes, A.; Kaminski, A.; Montes, D.; Morales, J. C.; Pavlov,
A.; Peña, L.; Perdelwitz, V.; Reffert, S.; Revilla, D.; Rodríguez
López, C.; Rosich, A.; Sadegi, S.; Schöfer, P.; Schweitzer, A.;
Zechmeister, M.
2022arXiv220905814K Altcode:
Context: A challenge with radial-velocity (RV) data is disentangling
the origin of signals either due to a planetary companion or to
stellar activity. In fact, the existence of a planetary companion
has been proposed, as well as contested, around the relatively
bright, nearby M3.0V star AD Leo at the same period as the stellar
rotation of 2.23d. Aims: We further investigate the nature of this
signal. We introduce new CARMENES optical and near-IR RV data and an
analysis in combination with archival data taken by HIRES and HARPS,
along with more recent data from HARPS-N, GIANO-B, and HPF. Also,
we address the confusion concerning the binarity of AD Leo. Methods:
We consider possible correlations between the RVs and various stellar
activity indicators accessible with CARMENES. We applied models
within a Bayesian framework to determine whether a Keplerian model,
a red-noise quasi-periodic model using a Gaussian process, or a mixed
model would explain the observed data best. We also exclusively focus on
spectral lines potentially associated with stellar activity. Results:
The CARMENES RV data agree with the previously reported periodicity
of 2.23d, correlate with some activity indicators, and exhibit
chromaticity. However, when considering the entire RV data set,
we find that a mixed model composed of a stable and a variable
component performs best. Moreover, when recomputing the RVs using
only spectral lines insensitive to activity, there appears to be
some residual power at the period of interest. We therefore conclude
that it is not possible to determinedly prove that there is no planet
orbiting in synchronization with the stellar rotation given our data,
current tools, machinery, and knowledge of how stellar activity affects
RVs. We do rule out planets more massive than 27M_E (=0.084M_J). We
also exclude any binary companion around AD Leo with Msini > 3-6M_J
on orbital periods <14yr.
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Title: The BlueMUSE data reduction pipeline: lessons learned from
MUSE and first design choices
Authors: Weilbacher, Peter M.; Martens, Sven; Wendt, Martin; Roth,
Martin M.; Dreizler, Stefan; Kelz, Andreas; Bacon, Roland; Richard,
Johan
2022arXiv220906022W Altcode:
BlueMUSE is an integral field spectrograph in an early development
stage for the ESO VLT. For our design of the data reduction software for
this instrument, we are first reviewing capabilities and issues of the
pipeline of the existing MUSE instrument. MUSE has been in operation
at the VLT since 2014 and led to discoveries published in more than
600 refereed scientific papers. While BlueMUSE and MUSE have many
common properties we briefly point out a few key differences between
both instruments. We outline a first version of the flowchart for
the science reduction, and discuss the necessary changes due to the
blue wavelength range covered by BlueMUSE. We also detail specific
new features, for example, how the pipeline and subsequent analysis
will benefit from improved handling of the data covariance, and a more
integrated approach to the line-spread function, as well as improvements
regarding the wavelength calibration which is of extra importance in
the blue optical range. We finally discuss how simulations of BlueMUSE
datacubes are being implemented and how they will be used to prepare
the science of the instrument.
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Title: Precise mass determination for the keystone sub-Neptune planet
transiting the mid-type M dwarf G 9-40
Authors: Luque, R.; Nowak, G.; Hirano, T.; Kossakowski, D.; Pallé, E.;
Nixon, M. C.; Morello, G.; Amado, P. J.; Albrecht, S. H.; Caballero,
J. A.; Cifuentes, C.; Cochran, W. D.; Deeg, H. J.; Dreizler, S.;
Esparza-Borges, E.; Fukui, A.; Gandolfi, D.; Goffo, E.; Guenther,
E. W.; Hatzes, A. P.; Henning, T.; Kabath, P.; Kawauchi, K.; Korth,
J.; Kotani, T.; Kudo, T.; Kuzuhara, M.; Lafarga, M.; Lam, K. W. F.;
Livingston, J.; Morales, J. C.; Muresan, A.; Murgas, F.; Narita, N.;
Osborne, H. L. M.; Parviainen, H.; Passegger, V. M.; Persson, C. M.;
Quirrenbach, A.; Redfield, S.; Reffert, S.; Reiners, A.; Ribas, I.;
Serrano, L. M.; Tamura, M.; Van Eylen, V.; Watanabe, N.; Zapatero
Osorio, M. R.
2022arXiv220807287L Altcode:
Context. Despite being a prominent subset of the exoplanet population
discovered in the past three decades, the nature and provenance
of sub-Neptune-sized planets are still one of the open questions
in exoplanet science. Aims. For planets orbiting bright stars,
precisely measuring the orbital and planet parameters of the system
is the best approach to distinguish between competing theories
regarding their formation and evolution. Methods. We obtained 69
new radial velocity observations of the mid-M dwarf G 9-40 with the
CARMENES instrument to measure for the first time the mass of its
transiting sub-Neptune planet, G 9-40 b, discovered in data from the
K2 mission. Results. Combined with new observations from the TESS
mission during Sectors 44, 45, and 46, we are able to measure the
radius of the planet to an uncertainty of 3.4% (Rb = 1.900 +- 0.065
Re) and determine its mass with a precision of 16% (Mb = 4.00 +- 0.63
Me). The resulting bulk density of the planet is inconsistent with a
terrestrial composition and suggests the presence of either a water-rich
core or a significant hydrogen-rich envelope. Conclusions. G 9-40 b is
referred to as a keystone planet due to its location in period-radius
space within the radius valley. Several theories offer explanations
for the origin and properties of this population and this planet is a
valuable target for testing the dependence of those models on stellar
host mass. By virtue of its brightness and small size of the host, it
joins L 98-59 d as one of the two best warm (Teq ~ 400 K) sub-Neptunes
for atmospheric characterization with JWST, which will probe cloud
formation in sub-Neptune-sized planets and break the degeneracies of
internal composition models.
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Title: Detailed stellar activity analysis and modelling of GJ
832. Reassessment of the putative habitable zone planet GJ 832c
Authors: Gorrini, P.; Astudillo-Defru, N.; Dreizler, S.; Damasso,
M.; Díaz, R. F.; Bonfils, X.; Jeffers, S. V.; Barnes, J. R.; Del
Sordo, F.; Almenara, J. -M.; Artigau, E.; Bouchy, F.; Charbonneau,
D.; Delfosse, X.; Doyon, R.; Figueira, P.; Forveille, T.; Haswell,
C. A.; López-González, M. J.; Melo, C.; Mennickent, R. E.; Gaisné,
G.; Morales Morales, N.; Murgas, F.; Pepe, F.; Rodríguez, E.; Santos,
N. C.; Tal-Or, L.; Tsapras, Y.; Udry, S.
2022A&A...664A..64G Altcode: 2022arXiv220607552G
Context. Gliese-832 (GJ 832) is an M2V star hosting a massive planet on
a decade-long orbit, GJ 832b, discovered by radial velocity (RV). Later,
a super Earth or mini-Neptune orbiting within the stellar habitable zone
was reported (GJ 832c). The recently determined stellar rotation period
(45.7 ± 9.3 days) is close to the orbital period of putative planet
c (35.68 ± 0.03 days). <BR /> Aims: We aim to confirm or dismiss
the planetary nature of the RV signature attributed to GJ 832c, by
adding 119 new RV data points, new photometric data, and an analysis
of the spectroscopic stellar activity indicators. Additionally, we
update the orbital parameters of the planetary system and search
for additional signals. <BR /> Methods: We performed a frequency
content analysis of the RVs to search for periodic and stable
signals. Radial velocity time series were modelled with Keplerians
and Gaussian process (GP) regressions alongside activity indicators
to subsequently compare them within a Bayesian framework. <BR />
Results: We updated the stellar rotational period of GJ 832 from
activity indicators, obtaining 37.5<SUP>+1.4</SUP><SUB>-1.5</SUB>
days, improving the precision by a factor of 6. The new photometric
data are in agreement with this value. We detected an RV signal
near 18 days (FAP < 4.6%), which is half of the stellar rotation
period. Two Keplerians alone fail at modelling GJ 832b and a second
planet with a 35-day orbital period. Moreover, the Bayesian evidence
from the GP analysis of the RV data with simultaneous activity indices
prefers a model without a second Keplerian, therefore negating the
existence of planet c. <P />Activity indices, photometric and RV
time series are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">cdsarc.u-strasbg.fr</A>
(130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/664/A64">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/664/A64</A>
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Title: The HD 260655 system: Two rocky worlds transiting a bright
M dwarf at 10 pc
Authors: Luque, R.; Fulton, B. J.; Kunimoto, M.; Amado, P. J.; Gorrini,
P.; Dreizler, S.; Hellier, C.; Henry, G. W.; Molaverdikhani, K.;
Morello, G.; Peña-Moñino, L.; Pérez-Torres, M.; Pozuelos, F. J.;
Shan, Y.; Anglada-Escudé, G.; Béjar, V. J. S.; Bergond, G.; Boyle,
A. W.; Caballero, J. A.; Charbonneau, D.; Ciardi, D. R.; Dufoer, S.;
Espinoza, N.; Everett, M.; Fischer, D.; Hatzes, A. P.; Henning, Th.;
Hesse, K.; Howard, A. W.; Howell, S. B.; Isaacson, H.; Jeffers, S. V.;
Jenkins, J. M.; Kane, S. R.; Kemmer, J.; Khalafinejad, S.; Kidwell,
R. C.; Kossakowski, D.; Latham, D. W.; Lillo-Box, J.; Lissauer, J. J.;
Montes, D.; Orell-Miquel, J.; Pallé, E.; Pollacco, D.; Quirrenbach,
A.; Reffert, S.; Reiners, A.; Ribas, I.; Ricker, G. R.; Rogers, L. A.;
Sanz-Forcada, J.; Schlecker, M.; Schweitzer, A.; Seager, S.; Shporer,
A.; Stassun, K. G.; Stock, S.; Tal-Or, L.; Ting, E. B.; Trifonov,
T.; Vanaverbeke, S.; Vanderspek, R.; Villaseñor, J.; Winn, J. N.;
Winters, J. G.; Zapatero Osorio, M. R.
2022A&A...664A.199L Altcode: 2022arXiv220410261L
We report the discovery of a multiplanetary system transiting the
M0 V dwarf HD 260655 (GJ 239, TOI-4599). The system consists of at
least two transiting planets, namely HD 260655 b, with a period of
2.77 d, a radius of R<SUB>b</SUB> = 1.240 ± 0.023 R<SUB>⊕</SUB>,
a mass of M<SUB>b</SUB> = 2.14 ± 0.34 M<SUB>⊕</SUB>, and a bulk
density of ρ<SUB>b</SUB> = 6.2 ± 1.0 g cm<SUP>−3</SUP>, and HD
260655 c, with a period of 5.71 d, a radius of {R_c} = 1.533<SUB> -
0.046</SUB><SUP> + 0.051</SUP>{R_ \oplus }, a mass of M<SUB>c</SUB> =
3.09 ± 0.48 M<SUB>⊕</SUB>, and a bulk density of {ρ _c} = 4.7<SUB>
- 0.8</SUB><SUP> + 0.9</SUP>{{g}} g cm<SUP>−3</SUP>. The planets
have been detected in transit by the Transiting Exoplanet Survey
Satellite (TESS) mission and confirmed independently with archival
and new precise radial velocities obtained with the HIRES and CARMENES
instruments since 1998 and 2016, respectively. At a distance of 10 pc,
HD 260655 has become the fourth closest known multitransiting planet
system after HD 219134, LTT 1445 A, and AU Mic. Due to the apparent
brightness of the host star (J = 6.7 mag), both planets are among the
most suitable rocky worlds known today for atmospheric studies with
the James Webb Space Telescope, both in transmission and emission.
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Title: VizieR Online Data Catalog: GJ 832 stellar activity (Gorrini+,
2022)
Authors: Gorrini, P.; Astudillo-Defru, N.; Dreizler, S.; Damasso,
M.; Diaz, R. F.; Bonfils, X.; Jeffers, S. V.; Barnes, J. R.; Del
Sordo, F.; Almenara, J. -M.; Artigau, E.; Bouchy, F.; Charbonneau,
D.; Delfosse, X.; Doyon, R.; Figueira, P.; Forveille, T.; Haswell,
C. A.; Lopez-Gonzalez, M. J.; Melo, C.; Mennickent, R. E.; Gaisne,
G.; Morales, N.; Murgas, F.; Pepe, F.; Rodriguez, E.; Santos, N. C.;
Tal-Or, L.; Tsapras, Y.; Udry, S.
2022yCat..36640064G Altcode:
This work makes use of data from HARPS, the University College London
Echelle Spectrograph (UCLES) , and the Planet Finding Spectrograph
(PFS). HARPS data are available as raw images and reduced spectra,
while we accessed UCLES and PFS data only as RV time series. We used
a total of 227 RV data points for GJ 832. <P />(3 data files).
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Title: The CARMENES search for exoplanets around M dwarfs. Rotational
variation in activity indicators of Ross 318, YZ CMi, TYC 3529-1437-1,
and EV Lac
Authors: Schöfer, P.; Jeffers, S. V.; Reiners, A.; Zechmeister,
M.; Fuhrmeister, B.; Lafarga, M.; Ribas, I.; Quirrenbach, A.; Amado,
P. J.; Caballero, J. A.; Anglada-Escudé, G.; Bauer, F. F.; Béjar,
V. J. S.; Cortés-Contreras, M.; Alonso, E. Díez; Dreizler, S.;
Guenther, E. W.; Herbort, O.; Johnson, E. N.; Kaminski, A.; Kürster,
M.; Montes, D.; Morales, J. C.; Pedraz, S.; Tal-Or, L.
2022A&A...663A..68S Altcode: 2022arXiv220411685S
Context. The Calar Alto high-Resolution search for M dwarfs with
Exo-earths with Near-infrared and optical Échelle Spectrographs
(CARMENES) instrument is searching for periodic radial-velocity (RV)
variations of M dwarfs, which are induced by orbiting planets. However,
there are other potential sources of such variations, including
rotational modulation caused by stellar activity. <BR /> Aims: We
aim to investigate four M dwarfs (Ross 318, YZ CMi, TYC 3529-1437-1,
and EV Lac) with different activity levels and spectral sub-types. Our
goal is to compare the periodicities seen in 22 activity indicators
and the stellar RVs, and to examine their stability over time. <BR
/> Methods: For each star, we calculated generalised Lomb-Scargle
periodograms of pseudo-equivalent widths of chromospheric lines,
indices of photospheric bands, the differential line width as a measure
of the width of the average photospheric absorption line, the RV, the
chromatic index that describes the wavelength dependence of the RV,
and parameters of the cross-correlation function. We also calculated
periodograms for subsets of the data and compared our results to TESS
photometry. <BR /> Results: We find the rotation periods of all four
stars to manifest themselves in the RV and photospheric indicators,
particularly the TiO 7050 index, whereas the chromospheric lines
show clear signals only at lower activity levels. For EV Lac and
TYC 3529-1437-1, we find episodes during which indicators vary with
the rotation period, and episodes during which they vary with half
the rotation period, similarly to photometric light curves. <BR />
Conclusions: The changing periodicities reflect the evolution of stellar
activity features on the stellar surface. We therefore conclude that
our results not only emphasise the importance of carefully analysing
indicators complementary to the RV in RV surveys, but they also suggest
that it is also useful to search for signals in activity indicators
in subsets of the dataset, because an activity signal that is present
in the RV may not be visible in the activity indicators all the time,
in particular for the most active stars.
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Title: Transit Timing Variations for AU Microscopii b and c
Authors: Wittrock, Justin M.; Dreizler, Stefan; Reefe, Michael A.;
Morris, Brett M.; Plavchan, Peter P.; Lowrance, Patrick J.; Demory,
Brice-Olivier; Ingalls, James G.; Gilbert, Emily A.; Barclay, Thomas;
Cale, Bryson L.; Collins, Karen A.; Collins, Kevin I.; Crossfield,
Ian J. M.; Dragomir, Diana; Eastman, Jason D.; Mufti, Mohammed El;
Feliz, Dax; Gagné, Jonathan; Gaidos, Eric; Gao, Peter; Geneser,
Claire S.; Hebb, Leslie; Henze, Christopher E.; Horne, Keith D.;
Jenkins, Jon M.; Jensen, Eric L. N.; Kane, Stephen R.; Kaye, Laurel;
Martioli, Eder; Monsue, Teresa A.; Pallé, Enric; Quintana, Elisa
V.; Radford, Don J.; Roccatagliata, Veronica; Schlieder, Joshua E.;
Schwarz, Richard P.; Shporer, Avi; Stassun, Keivan G.; Stockdale,
Christopher; Tan, Thiam-Guan; Tanner, Angelle M.; Vanderburg, Andrew;
Vega, Laura D.; Wang, Songhu
2022AJ....164...27W Altcode: 2022arXiv220205813W
We explore the transit timing variations (TTVs) of the young (22 Myr)
nearby AU Mic planetary system. For AU Mic b, we introduce three Spitzer
(4.5 μm) transits, five TESS transits, 11 LCO transits, one PEST
transit, one Brierfield transit, and two transit timing measurements
from Rossiter-McLaughlin observations; for AU Mic c, we introduce
three TESS transits. We present two independent TTV analyses. First, we
use EXOFASTv2 to jointly model the Spitzer and ground-based transits
and obtain the midpoint transit times. We then construct an O -
C diagram and model the TTVs with Exo-Striker. Second, we reproduce
our results with an independent photodynamical analysis. We recover a
TTV mass for AU Mic c of ${10.8}_{-2.2}^{+2.3}$ M <SUB>⊕</SUB>. We
compare the TTV-derived constraints to a recent radial velocity
(RV) mass determination. We also observe excess TTVs that do not
appear to be consistent with the dynamical interactions of b and
c alone or due to spots or flares. Thus, we present a hypothetical
nontransiting "middle-d" candidate exoplanet that is consistent with
the observed TTVs and candidate RV signal and would establish the AU
Mic system as a compact resonant multiplanet chain in a 4:6:9 period
commensurability. These results demonstrate that the AU Mic planetary
system is dynamically interacting, producing detectable TTVs, and the
implied orbital dynamics may inform the formation mechanisms for this
young system. We recommend future RV and TTV observations of AU Mic
b and c to further constrain the masses and confirm the existence of
possible additional planet(s).
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Title: A detailed analysis of the Gl 486 planetary system
Authors: Caballero, J. A.; Gonzalez-Alvarez, E.; Brady, M.; Trifonov,
T.; Ellis, T. G.; Dorn, C.; Cifuentes, C.; Molaverdikhani, K.; Bean,
J. L.; Boyajian, T.; Rodriguez, E.; Sanz-Forcada, J.; Zapatero Osorio,
M. R.; Abia, C.; Amado, P. J.; Anugu, N.; Bejar, V. J. S.; Davies,
C. L.; Dreizler, S.; Dubois, F.; Ennis, J.; Espinoza, N.; Farrington,
C. D.; Garcia Lopez, A.; Gardner, T.; Hatzes, A. P.; Henning, Th.;
Herrero, E.; Herrero-Cisneros, E.; Kaminski, A.; Kasper, D.; Klement,
R.; Kraus, S.; Labdon, A.; Lanthermann, C.; Le Bouquin, J. -B.; Lopez
Gonzalez, M. J.; Luque, R.; Mann, A. W.; Marfil, E.; Monnier, J. D.;
Montes, D.; Morales, J. C.; Palle, E.; Pedraz, S.; Quirrenbach, A.;
Reffert, S.; Reiners, A.; Ribas, I.; Rodriguez-Lopez, C.; Schaefer, G.;
Schweitzer, A.; Seifahrt, A.; Setterholm, B. R.; Shan, Y.; Shulyak,
D.; Solano, E.; Sreenivas, K. R.; Stefansson, G.; Stuermer, J.;
Tabernero, H. M.; Tal-Or, L.; ten Brummelaar, T.; Vanaverbeke, S.;
von Braun, K.; Youngblood, A.; Zechmeister, M.
2022arXiv220609990C Altcode:
The Gl 486 system consists of a very nearby, relatively bright, weakly
active M3.5 V star at just 8 pc with a warm transiting rocky planet of
about 1.3 R_Terra and 3.0 M_Terra that is ideal for both transmission
and emission spectroscopy and for testing interior models of telluric
planets. To prepare for future studies, we collected light curves of
seven new transits observed with the CHEOPS space mission and new radial
velocities obtained with MAROON-X/Gemini North and CARMENES/Calar
Alto telescopes, together with previously published spectroscopic
and photometric data from the two spectrographs and TESS. We also
performed interferometric observations with the CHARA Array and
new photometric monitoring with a suite of smaller telescopes. From
interferometry, we measure a limb-darkened disc angular size of the
star Gl 486. Together with a corrected Gaia EDR3 parallax, we obtain
a stellar radius. We also measure a stellar rotation period at P_rot ~
49.9 d, an upper limit to its XUV (5-920 AA) flux with new Hubble/STIS
data, and, for the first time, a variety of element abundances (Fe,
Mg, Si, V, Sr, Zr, Rb) and C/O ratio. Besides, we impose restrictive
constraints on the presence of additional components, either stellar or
substellar, in the system. With the input stellar parameters and the
radial-velocity and transit data, we determine the radius and mass of
the planet Gl 486 b at R_p = 1.343+/0.063 R_Terra and M_p = 3.00+/-0.13
M_Terra. From the planet parameters and the stellar element abundances,
we infer the most probable models of planet internal structure and
composition, which are consistent with a relatively small metallic
core with respect to the Earth, a deep silicate mantle, and a thin
volatile upper layer. With all these ingredients, we outline prospects
for Gl 486 b atmospheric studies, especially with forthcoming James
Webb Space Telescope observations (abridged).
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Title: Transit Timing Variations for AU Microscopii b & c
Authors: Wittrock, Justin M.; Dreizler, Stefan; Reefe, Michael; Morris,
Brett; Plavchan, Peter; Lowrance, Patrick; Demory, Brice-Olivier;
Ingalls, James; Gilbert, Emily; Barclay, Thomas; Cale, Bryson; Collins,
Karen; Collins, Kevin; Crossfield, Ian; Dragomir, Diana; Eastman,
Jason; El Mufti, Mohammed; Feliz, Dax; Gagné, Jonathan; Gaidos, Eric;
Gao, Peter; Geneser, Claire; Hebb, Leslie; Henze, Chris; Horne, Keith;
Jenkins, Jon; Jensen, Eric; Kane, Stephen; Kaye, Laurel; Martioli,
Eder; Monsue, Teresa; Palle Bago, Enric; Quintana, Elisa; Radford,
Don; Roccatagliata, Veronica; Schlieder, Joshua; Schwarz, Richard;
Shporer, Avi; Stassun, Keivan; Stockdale, Christopher; Tan, Thiam-Guan;
Tanner, Angelle; Vanderburg, Andrew; Vega, Laura; Wang, Songhu
2022BAAS...54e.275W Altcode:
We explore the transit timing variations (TTVs) of the young (22 Myr)
nearby AU Mic planetary system. For AU Mic b, we introduce three
Spitzer (4.5 μm) transits, five TESS transits, 11 LCO transits,
one PEST transit, one Brierfield transit, and two transit timing
measurements from Rossiter-McLaughlin observations; for AU Mic c,
we introduce three TESS transits. We present two independent TTV
analyses. First, we use EXOFASTv2 to jointly model the Spitzer and
ground-based transits and to obtain the midpoint transit times. We then
construct an O-C diagram and model the TTVs with Exo-Striker. Second,
we reproduce our results with an independent photodynamical analysis. We
recover a TTV mass for AU Mic c of 10.8+2.3-2.2 M<SUB>⊕</SUB>. We
compare the TTV-derived constraints to a recent radial-velocity (RV)
mass determination. We also observe excess TTVs that do not appear to
be consistent with the dynamical interactions of b and c alone, and do
not appear to be due to spots or flares. Thus, we present a hypothetical
non-transiting "middle-d" candidate exoplanet that is consistent with
the observed TTVs, the candidate RV signal, and would establish the AU
Mic system as a compact resonant multi-planet chain in a 4:6:9 period
commensurability. These results demonstrate that the AU Mic planetary
system is dynamically interacting producing detectable TTVs, and the
implied orbital dynamics may inform the formation mechanisms for this
young system. We recommend future RV and TTV observations of AU Mic
b and c to further constrain the masses and to confirm the existence
of possible additional planet(s).
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Title: VizieR Online Data Catalog: Thorium in solar twins (Botelho+,
2019)
Authors: Botelho, R. B.; Milone, A. De C.; Melendez, J.; Bedell, M.;
Spina, L.; Asplund, M.; Dos Santos, L.; Bean, J. L.; Ramirez, I.;
Yong, D.; Dreizler, S.; Alves-Brito, A.; Yana Galarza, J.
2022yCat..74821690B Altcode:
The sample is composed of 67 solar twins (stars with effective
temperature, surface gravity, and metallicity around the solar values
within {+/-}100K in Teff and within {+/-}0.1dex in logg and [Fe/H]),
which were recently analysed by Spina et al. (2018MNRAS.474.2580S) and
Bedell et al. (2018ApJ...865...68B). Spina et al. (2018MNRAS.474.2580S)
derived their photospheric parameters by applying a line-by-line
differential spectroscopic analysis relative to the Sun through
equivalent width (EW) measurements of FeI and FeII lines. The estimated
typical errors in Teff, logg, [Fe/H], and {xi} (micro-turbulence
velocity) are, respectively, 4K, 0.012, 0.004dex and 0.011km/s. High
Accuracy Radial velocity Planet Searcher (HARPS) spectra are used
in this work to extract Th abundances. HARPS is an ultra-stable
echelle spectrograph installed on the 3.6m telescope of the European
Southern Observatory (ESO) at La Silla Observatory in Chile (Mayor
et al. 2003Msngr.114...20M). The HARPS spectra covers λ=3780-6910Å
under a resolving power R=115000. Each one-dimensional spectrum comes
from more than 50 stacked spectra that are previously Doppler-corrected
and carefully continuum normalized. <P />(3 data files).
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Title: VizieR Online Data Catalog: VRI photometry and radial velocity
of TOI-1759 (Espinoza+, 2022)
Authors: Espinoza, N.; Palle, E.; Kemmer, J.; Luque, R.; Caballero,
J. A.; Cifuentes, C.; Herrero, E.; Sanchez Bejar, V. J.; Stock, S.;
Molaverdikhani, K.; Morello, G.; Kossakowski, D.; Schlecker, M.; Amado,
P. J.; Bluhm, P.; Cortes-Contreras, M.; Henning, T.; Kreidberg, L.;
Kurster, M.; Lafarga, M.; Lodieu, N.; Morales, J. C.; Oshagh, M.;
Passegger, V. M.; Pavlov, A.; Quirrenbach, A.; Reffert, S.; Reiners,
A.; Ribas, I.; Rodriguez, E.; Lopez, C. R.; Schweitzer, A.; Trifonov,
T.; Chaturvedi, P.; Dreizler, S.; Jeffers, S. V.; Kaminski, A.;
Lopez-Gonzalez, M. J.; Lillo-Box, J.; Montes, D.; Nowak, G.; Pedraz,
S.; Vanaverbeke, S.; Zapatero Osorio, M. R.; Zechmeister, M.; Collins,
K. A.; Girardin, E.; Guerra, P.; Naves, R.; Crossfield, I. J. M.;
Matthews, E. C.; Howell, S. B.; Ciardi, D. R.; Gonzales, E.; Matson,
R. A.; Beichman, C. A.; Schlieder, J. E.; Barclay, T.; Vezie, M.;
Villasenor, J. N.; Daylan, T.; Mireies, I.; Dragomir, D.; Twicken,
J. D.; Jenkins, J.; Winn, J. N.; Latham, D.; Ricker, G.; Seager, S.
2022yCat..51630133E Altcode:
The 2 minutes cadence data were processed in the TESS Science Processing
Operations Center (SPOC) photometry and transit search pipelines at
NASA Ames Research Center, in Sectors 16 (2019 September to October),
17 (2019 October to November), and 24 (2020 April to May). <P />Among
the observations, a transit of TOI-1759b in 2020 May 21 was captured by
three independent telescopes/observatories: the OAA telescope of the
Observatori Astronomic Albanya (Spain; precision of 1140ppm; R-filter
observations), the RCO telescope of the Grand-Pra Observatory (Valais
Sion, Switzerland; precision of 1080ppm; ip-filter observations),
and the OMC telescope of the Montcabrer Observatory (Barcelona,
Spain; precision of 1500ppm; Ic-filter observations). <P />Long-term
photometric monitoring was also performed from the ground using the
0.8m Joan Oro telescope (TJO) at the Montsec Observatory in Lleida,
Spain and the 90cm telescope at the Sierra Nevada Observatory (SNO)
in R and V filter. <P />We monitored TOI-1759 with the CARMENES 38
instrument located on the 3.5m telescope at the Calar Alto Observatory
in Almeria, Spain, from 2020 July 24 to 2021 January 17 (R=94600). <P
/>(3 data files).
---------------------------------------------------------
Title: A black hole detected in the young massive LMC cluster NGC 1850
Authors: Saracino, S.; Kamann, S.; Guarcello, M. G.; Usher, C.;
Bastian, N.; Cabrera-Ziri, I.; Gieles, M.; Dreizler, S.; Da Costa,
G. S.; Husser, T. -O.; Hénault-Brunet, V.
2022MNRAS.511.2914S Altcode: 2021MNRAS.tmp.2924S; 2021arXiv211106506S
We report on the detection of a black hole (NGC 1850 BH1) in the
~100-Myr-old massive cluster NGC 1850 in the Large Magellanic Cloud. It
is in a binary system with a main-sequence turn-off star (4.9 ± 0.4
M<SUB>⊙</SUB>), which is starting to fill its Roche lobe and is
becoming distorted. Using 17 epochs of Very Large Telescope/Multi-Unit
Spectroscopic Explorer observations, we detected radial velocity
variations exceeding 300 km s<SUP>-1</SUP> associated with the target
star, linked to the ellipsoidal variations measured by the fourth
phase of the Optical Gravitational Lensing Experiment in the optical
bands. Under the assumption of a semidetached system, the simultaneous
modelling of radial velocity and light curves constrains the orbital
inclination of the binary to 38° ± 2°, resulting in a true mass of
the unseen companion of $11.1_{-2.4}^{+2.1}\,{\rm M}_{\odot }$. This
represents the first direct dynamical detection of a black hole in
a young massive cluster, opening up the possibility of studying the
initial mass function and the early dynamical evolution of such compact
objects in high-density environments.
---------------------------------------------------------
Title: The MAVERIC Survey: The first radio and X-ray limits on the
detached black holes in NGC 3201
Authors: Paduano, Alessandro; Bahramian, Arash; Miller-Jones,
James C. A.; Kawka, Adela; Göttgens, Fabian; Strader, Jay; Chomiuk,
Laura; Kamann, Sebastian; Dreizler, Stefan; Heinke, Craig O.; Husser,
Tim-Oliver; Maccarone, Thomas J.; Tremou, Evangelia; Zhao, Yue
2022MNRAS.510.3658P Altcode: 2021MNRAS.tmp.3428P; 2022arXiv220101418P
The Galactic globular cluster (GC) NGC 3201 is the first Galactic
GC observed to host dynamically confirmed stellar-mass black holes
(BHs), containing two confirmed and one candidate BH. This result
indicates that GCs can retain BHs, which has important implications
for GC evolution. NGC 3201 has been observed as part of the MAVERIC
survey of Galactic GCs. We use these data to confirm that there is
no radio or X-ray detection of the three BHs, and present the first
radio and X-ray limits on these sources. These limits indicate that
any accretion present is at an extremely low rate and may be extremely
inefficient. In particular, for the system ACS ID #21859, by assuming
the system is tidally locked and any accretion is through the capture
of the companion's winds, we constrain the radiative efficiency of
any accretion to ≲ 1.5 × 10<SUP>-5</SUP>. We also combine the
radio and X-ray source catalogues from the MAVERIC survey with the
existing MUSE spectroscopic surveys and the HUGS catalogue of NGC
3201 to provide a catalogue of 42 multiwavelength sources in this
cluster. We identify a new red straggler source with X-ray emission,
and investigate the multiwavelength properties of the sub-subgiant
population in the cluster.
---------------------------------------------------------
Title: A Transiting, Temperate Mini-Neptune Orbiting the M Dwarf
TOI-1759 Unveiled by TESS
Authors: Espinoza, Néstor; Pallé, Enric; Kemmer, Jonas; Luque,
Rafael; Caballero, José A.; Cifuentes, Carlos; Herrero, Enrique;
Sánchez Béjar, Víctor J.; Stock, Stephan; Molaverdikhani, Karan;
Morello, Giuseppe; Kossakowski, Diana; Schlecker, Martin; Amado,
Pedro J.; Bluhm, Paz; Cortés-Contreras, Miriam; Henning, Thomas;
Kreidberg, Laura; Kürster, Martin; Lafarga, Marina; Lodieu, Nicolas;
Morales, Juan Carlos; Oshagh, Mahmoudreza; Passegger, Vera M.; Pavlov,
Alexey; Quirrenbach, Andreas; Reffert, Sabine; Reiners, Ansgar; Ribas,
Ignasi; Rodríguez, Eloy; López, Cristina Rodríguez; Schweitzer,
Andreas; Trifonov, Trifon; Chaturvedi, Priyanka; Dreizler, Stefan;
Jeffers, Sandra V.; Kaminski, Adrian; López-González, María José;
Lillo-Box, Jorge; Montes, David; Nowak, Grzegorz; Pedraz, Santos;
Vanaverbeke, Siegfried; Zapatero Osorio, Maria R.; Zechmeister,
Mathias; Collins, Karen A.; Girardin, Eric; Guerra, Pere; Naves,
Ramon; Crossfield, Ian J. M.; Matthews, Elisabeth C.; Howell, Steve
B.; Ciardi, David R.; Gonzales, Erica; Matson, Rachel A.; Beichman,
Charles A.; Schlieder, Joshua E.; Barclay, Thomas; Vezie, Michael;
Villaseñor, Jesus Noel; Daylan, Tansu; Mireies, Ismael; Dragomir,
Diana; Twicken, Joseph D.; Jenkins, Jon; Winn, Joshua N.; Latham,
David; Ricker, George; Seager, Sara
2022AJ....163..133E Altcode: 2022arXiv220201240E
We report the discovery and characterization of TOI-1759 b, a temperate
(400 K) sub-Neptune-sized exoplanet orbiting the M dwarf TOI-1759
(TIC 408636441). TOI-1759 b was observed by TESS to transit in
Sectors 16, 17, and 24, with only one transit observed per sector,
creating an ambiguity regarding the orbital period of the planet
candidate. Ground-based photometric observations, combined with
radial-velocity measurements obtained with the CARMENES spectrograph,
confirm an actual period of 18.85019 ± 0.00014 days. A joint
analysis of all available photometry and radial velocities reveals a
radius of 3.17 ± 0.10 R <SUB>⊕</SUB> and a mass of 10.8 ± 1.5 M
<SUB>⊕</SUB>. Combining this with the stellar properties derived
for TOI-1759 (R <SUB>⋆</SUB> = 0.597 ± 0.015 R <SUB>⊙</SUB>;
M <SUB>⋆</SUB> = 0.606 ± 0.020 M <SUB>⊙</SUB>; T <SUB>eff</SUB>
= 4065 ± 51 K), we compute a transmission spectroscopic metric
(TSM) value of over 80 for the planet, making it a good target for
transmission spectroscopy studies. TOI-1759 b is among the top five
temperate, small exoplanets (T <SUB>eq</SUB> < 500 K, R <SUB>
p </SUB> < 4 R <SUB>⊕</SUB>) with the highest TSM discovered to
date. Two additional signals with periods of 80 days and >200 days
seem to be present in our radial velocities. While our data suggest
both could arise from stellar activity, the later signal's source and
periodicity are hard to pinpoint given the ~200 days baseline of our
radial-velocity campaign with CARMENES. Longer baseline radial-velocity
campaigns should be performed in order to unveil the true nature of
this long-period signal.
---------------------------------------------------------
Title: Discovery and mass measurement of the hot, transiting,
Earth-sized planet, GJ 3929 b
Authors: Kemmer, J.; Dreizler, S.; Kossakowski, D.; Stock,
S.; Quirrenbach, A.; Caballero, J. A.; Amado, P. J.; Collins,
K. A.; Espinoza, N.; Herrero, E.; Jenkins, J. M.; Latham, D. W.;
Lillo-Box, J.; Narita, N.; Pallé, E.; Reiners, A.; Ribas, I.;
Ricker, G.; Rodríguez, E.; Seager, S.; Vanderspek, R.; Wells, R.;
Winn, J.; Aceituno, F. J.; Béjar, V. J. S.; Barclay, T.; Bluhm, P.;
Chaturvedi, P.; Cifuentes, C.; Collins, K. I.; Cortés-Contreras, M.;
Demory, B. -O.; Fausnaugh, M. M.; Fukui, A.; Gómez Maqueo Chew, Y.;
Galadí-Enríquez, D.; Gan, T.; Gillon, M.; Golovin, A.; Hatzes, A. P.;
Henning, Th.; Huang, C.; Jeffers, S. V.; Kaminski, A.; Kunimoto,
M.; Kürster, M.; López-González, M. J.; Lafarga, M.; Luque,
R.; McCormac, J.; Molaverdikhani, K.; Montes, D.; Morales, J. C.;
Passegger, V. M.; Reffert, S.; Sabin, L.; Schöfer, P.; Schanche, N.;
Schlecker, M.; Schroffenegger, U.; Schwarz, R. P.; Schweitzer, A.;
Sota, A.; Tenenbaum, P.; Trifonov, T.; Vanaverbeke, S.; Zechmeister, M.
2022A&A...659A..17K Altcode: 2022arXiv220200970K
We report the discovery of GJ 3929 b, a hot Earth-sized planet orbiting
the nearby M3.5 V dwarf star, GJ 3929 (G 180-18, TOI-2013). Joint
modelling of photometric observations from TESS sectors 24 and 25
together with 73 spectroscopic observations from CARMENES and follow-up
transit observations from SAINT-EX, LCOGT, and OSN yields a planet
radius of R<SUB>b</SUB> = 1.150 ± 0.040 R<SUB>⊕</SUB>, a mass of
M<SUB>b</SUB> = 1.21 ± 0.42 M<SUB>⊕</SUB>, and an orbital period
of P<SUB>b</SUB> = 2.6162745 ± 0.0000030 d. The resulting density
of ρ<SUB>b</SUB> = 4.4 ± 1.6 g cm<SUP>−3</SUP> is compatible with
the Earth's mean density of about 5.5 g cm<SUP>−3</SUP>. Due to the
apparent brightness of the host star (J = 8.7 mag) and its small size,
GJ 3929 b is a promising target for atmospheric characterisation with
the JWST. Additionally, the radial velocity data show evidence for
another planet candidate with P<SUB>[c]</SUB> = 14.303 ± 0.035 d, which
is likely unrelated to the stellar rotation period, P<SUB>rot</SUB>
= 122 ± 13 d, which we determined from archival HATNet and ASAS-SN
photometry combined with newly obtained TJO data. <P />RV data and
stellar activity indices are only available at the CDS via anonymous ftp
to <A href="http://cdsarc.u-strasbg.fr">cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/659/A17">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/659/A17</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: GJ 3929 b RVs and activity
indicators (Kemmer+, 2022)
Authors: Kemmer, J.; Dreizler, S.; Kossakowski, D.; Stock, S.;
Quirrenbach, A.; Caballero, J. A.; Amado, P. J.; Collins, K. A.;
Espinoza, N.; Herrero, E.; Jenkins, J. M.; Latham, D. W.; Lillo-Box,
J.; Narita, N.; Palle, E.; Reiners, A.; Ribas, I.; Ricker, G.;
Rodriguez, E.; Seager, S.; Vanderspek, R.; Wells, R.; Winn, J.;
Aceituno, F. J.; Bejar, V. J. S.; Barclay, T.; Bluhm, P.; Chaturvedi,
P.; Cifuentes, C.; Collins, K. I.; Cortes-Contreras, M.; Demory, B. O.;
Fausnaugh, M. M.; Fukui, A.; Gomez Maqueo Chew, Y.; Galadi-Enriquez,
D.; Gan, T.; Gillon, M.; Golovin, A.; Hatzes, A. P.; Henning, T.;
Huang, C.; Jeffers, S. V.; Kaminski, A.; Kunimoto, M.; Kurster,
M.; Lopez-Gonzalez, M. J.; Lafarga, M.; Luque, R.; McCormac, J.;
Molaverdikhani, K.; Montes, D.; Morales, J. C.; Passegger, V. M.;
Reffert, S.; Sabin, L.; Schoefer, P.; Schanche, N.; Schlecker,
M.; Schroffenegger, U.; Schwarz, R. P.; Schweitzer, A.; Sota, A.;
Tenenbaum, P.; Trifonov, T.; Vanaverbeke, S.; Zechmeister, M.
2022yCat..36590017K Altcode:
Radial velocities and activity indices of GJ 3929 acquired with CARMENES
(Quirrenbach et al., 2014, in Proc. SPIE, Vol. 9147, Ground-based and
Airborne Instrumentation for Astronomy V, 91471F), a high-resolution
precise echelle spectrograph mounted at the 3.5m telescope at the
Calar Alto Observatory in Spain. <P />(1 data file).
---------------------------------------------------------
Title: A multi-planetary system orbiting the early-M dwarf TOI-1238
Authors: González-Álvarez, E.; Zapatero Osorio, M. R.; Sanz-Forcada,
J.; Caballero, J. A.; Reffert, S.; Béjar, V. J. S.; Hatzes, A. P.;
Herrero, E.; Jeffers, S. V.; Kemmer, J.; López-González, M. J.;
Luque, R.; Molaverdikhani, K.; Morello, G.; Nagel, E.; Quirrenbach,
A.; Rodríguez, E.; Rodríguez-López, C.; Schlecker, M.; Schweitzer,
A.; Stock, S.; Passegger, V. M.; Trifonov, T.; Amado, P. J.; Baker,
D.; Boyd, P. T.; Cadieux, C.; Charbonneau, D.; Collins, K. A.; Doyon,
R.; Dreizler, S.; Espinoza, N.; Fűrész, G.; Furlan, E.; Hesse, K.;
Howell, S. B.; Jenkins, J. M.; Kidwell, R. C.; Latham, D. W.; McLeod,
K. K.; Montes, D.; Morales, J. C.; O'Dwyer, T.; Pallé, E.; Pedraz,
S.; Reiners, A.; Ribas, I.; Quinn, S. N.; Schnaible, C.; Seager, S.;
Skinner, B.; Smith, J. C.; Schwarz, R. P.; Shporer, A.; Vanderspek,
R.; Winn, J. N.
2022A&A...658A.138G Altcode: 2021arXiv211114602G
Context. The number of super-Earth and Earth-mass planet discoveries has
increased significantly in the last two decades thanks to the Doppler
radial velocity and planetary transit observing techniques. Either
technique can detect planet candidates on its own, but the power
of a combined photometric and spectroscopic analysis is unique for
an insightful characterization of the planets, which in turn has
repercussions for our understanding of the architecture of planetary
systems and, therefore, their formation and evolution. <BR /> Aims: Two
transiting planet candidates with super-Earth radii around the nearby
(d = 70.64 ± 0.06 pc) K7-M0 dwarf star TOI-1238 were announced by
NASA's Transiting Exoplanet Survey Satellite (TESS), which observed
the field of TOI-1238 in four different sectors. We aim to validate
their planetary nature using precise radial velocities taken with
the CARMENES spectrograph. <BR /> Methods: We obtained 55 CARMENES
radial velocity measurements that span the 11 months between 9 May
2020 and 5 April 2021. For a better characterization of the parent
star's activity, we also collected contemporaneous optical photometric
observations at the Joan Oró and Sierra Nevada observatories and
retrieved archival photometry from the literature. We performed a
combined TESS+CARMENES photometric and spectroscopic analysis by
including Gaussian processes and Keplerian orbits to account for the
stellar activity and planetary signals simultaneously. <BR /> Results:
We estimate that TOI-1238 has a rotation period of 40 ± 5 d based on
photometric and spectroscopic data. The combined analysis confirms the
discovery of two transiting planets, TOI-1238 b and c, with orbital
periods of 0.764597<SUB>−0.000011</SUB><SUP>+0.000013</SUP>
d and 3.294736<SUB>−0.000036</SUB><SUP>+0.000034</SUP> d,
masses of 3.76<SUB>−1.07</SUB><SUP>+1.15</SUP> M<SUB>⊕</SUB>
and 8.32<SUB>−1.88</SUB><SUP>+1.90</SUP> M<SUB>⊕</SUB>, and
radii of 1.21<SUB>−0.10</SUB><SUP>+0.11</SUP> R<SUB>⊕</SUB> and
2.11<SUB>−0.14</SUB><SUP>+0.14</SUP> R<SUB>⊕</SUB>. They orbit
their parent star at semimajor axes of 0.0137 ± 0.0004 au and 0.036 ±
0.001 au, respectively.The two planets are placed on opposite sides of
the radius valley for M dwarfs and lie between the star and the inner
border of TOI-1238's habitable zone. The inner super-Earth TOI-1238
b is one of the densest ultra-short-period planets ever discovered
(ρ = 11.7<SUB>−3.4</SUB><SUP>+4.2</SUP> g cm<SUP>−3</SUP>). The
CARMENES data also reveal the presence of an outer, non-transiting,
more massive companion with an orbital period and radial velocity
amplitude of ≥600 d and ≥70 m s<SUP>−1</SUP>, which implies a
likely mass of M ≥ 2 √(1− e<SUP>2</SUP>) M<SUB>Jup</SUB> and a
separation ≥1.1 au from its parent star.
---------------------------------------------------------
Title: MUSE crowded field 3D spectroscopy in NGC 300. II. Quantitative
spectroscopy of BA-type supergiants
Authors: González-Torà, G.; Urbaneja, M. A.; Przybilla, N.; Dreizler,
S.; Roth, M. M.; Kamann, S.; Castro, N.
2022A&A...658A.117G Altcode: 2022arXiv220101311G
<BR /> Aims: A quantitative spectral analysis of BA-type supergiants
and bright giants in an inner spiral arm region of the nearby spiral
galaxy NGC 300 is presented, based on observations with the Multi Unit
Spectroscopic Explorer (MUSE) on the European Southern Obsevatory, Very
Large Telescope. The flux-weighted gravity-luminosity relationship
(FGLR), a stellar spectroscopic distance determination method for
galaxies, is extended towards stars at lower luminosities. <BR
/> Methods: Point spread function fitting 3D spectroscopy was
performed with PampelMUSE on the datacube. The 16 stars with the
highest signal-to-noise ratios are classified with regard to their
spectral type and luminosity class using Galactic templates. They
were analysed using hybrid non-local thermodynamic equilibrium
model spectra to fit the strongest observed hydrogen, helium, and
metal lines in the intermediate-resolution spectra. Supplemented by
photometric data, this facilitates fundamental stellar parameters
and interstellar reddening which have yet to be determined. <BR />
Results: Effective temperatures, surface gravities, reddening E(B−V),
bolometric magnitudes and luminosities, as well as radii and masses
are presented for the sample stars. The majority of the objects follow
the FGLR as established from more luminous BA-type supergiants in NGC
300. An increase in the scatter in the flux-weighted gravity-luminosity
plane is observed at these lower luminosities, which is in line with
predictions from population synthesis models.
---------------------------------------------------------
Title: TOI-1201 b: A mini-Neptune transiting a bright and moderately
young M dwarf
Authors: Kossakowski, D.; Kemmer, J.; Bluhm, P.; Stock, S.; Caballero,
J. A.; Béjar, V. J. S.; Guillén, C. Cardona; Lodieu, N.; Collins,
K. A.; Oshagh, M.; Schlecker, M.; Espinoza, N.; Pallé, E.; Henning,
Th.; Kreidberg, L.; Kürster, M.; Amado, P. J.; Anderson, D. R.;
Morales, J. C.; Cartwright, S.; Charbonneau, D.; Chaturvedi, P.;
Cifuentes, C.; Conti, D. M.; Cortés-Contreras, M.; Dreizler, S.;
Galadí-Enríquez, D.; Guerra, P.; Hart, R.; Hellier, C.; Henze,
C.; Herrero, E.; Jeffers, S. V.; Jenkins, J. M.; Jensen, E. L. N.;
Kaminski, A.; Kielkopf, J. F.; Kunimoto, M.; Lafarga, M.; Latham,
D. W.; Lillo-Box, J.; Luque, R.; Molaverdikhani, K.; Montes, D.;
Morello, G.; Morgan, E. H.; Nowak, G.; Pavlov, A.; Perger, M.;
Quintana, E. V.; Quirrenbach, A.; Reffert, S.; Reiners, A.; Ricker,
G.; Ribas, I.; López, C. Rodríguez; Osorio, M. R. Zapatero; Seager,
S.; Schöfer, P.; Schweitzer, A.; Trifonov, T.; Vanaverbeke, S.;
Vanderspek, R.; West, R.; Winn, J.; Zechmeister, M.
2021A&A...656A.124K Altcode: 2021arXiv210909346K
We present the discovery of a transiting mini-Neptune around TOI-1201,
a relatively bright and moderately young early M dwarf (J ≈ 9.5
mag, ~600-800 Myr) in an equal-mass ~8 arcsecond-wide binary system,
using data from the Transiting Exoplanet Survey Satellite, along with
follow-up transit observations. With an orbital period of 2.49 d,
TOI-1201 b is a warm mini-Neptune with a radius of R<SUB>b</SUB> =
2.415 ± 0.090 R<SUB>⊕</SUB>. This signal is also present in the
precise radial velocity measurements from CARMENES, confirming the
existence of the planet and providing a planetary mass of M<SUB>b</SUB>
= 6.28 ± 0.88 M<SUB>⊕</SUB> and, thus, an estimated bulk density
of 2.45<SUB>−0.42</SUB><SUP>+0.48</SUP> g cm<SUP>−3</SUP>. The
spectroscopic observations additionally show evidence of a signal
with a period of 19 d and a long periodic variation of undetermined
origin. In combination with ground-based photometric monitoring
from WASP-South and ASAS-SN, we attribute the 19 d signal to the
stellar rotation period (P<SUB>rot</SUB> = 19-23 d), although we
cannot rule out that the variation seen in photometry belongs to
the visually close binary companion. We calculate precise stellar
parameters for both TOI-1201 and its companion. The transiting
planet is anexcellent target for atmosphere characterization (the
transmission spectroscopy metric is 97<SUB>−16</SUB><SUP>+21</SUP>)
with the upcoming James Webb Space Telescope. It is also feasible to
measure its spin-orbit alignment via the Rossiter-McLaughlin effect
using current state-of-the-art spectrographs with submeter per second
radial velocity precision. <P />Additional data (i.e., stellar activity
indicators) are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/656/A124">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/656/A124</A>
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Stellar
atmospheric parameters of target stars with SteParSyn
Authors: Marfil, E.; Tabernero, H. M.; Montes, D.; Caballero, J. A.;
Lázaro, F. J.; González Hernández, J. I.; Nagel, E.; Passegger,
V. M.; Schweitzer, A.; Ribas, I.; Reiners, A.; Quirrenbach, A.;
Amado, P. J.; Cifuentes, C.; Cortés-Contreras, M.; Dreizler, S.;
Duque-Arribas, C.; Galadí-Enríquez, D.; Henning, Th.; Jeffers,
S. V.; Kaminski, A.; Kürster, M.; Lafarga, M.; López-Gallifa, Á.;
Morales, J. C.; Shan, Y.; Zechmeister, M.
2021A&A...656A.162M Altcode: 2021arXiv211007329M
We determined effective temperatures, surface gravities, and
metallicities for a sample of 343 M dwarfs observed with CARMENES,
the double-channel, high-resolution spectrograph installed at the
3.5 m telescope at Calar Alto Observatory. We employed SteParSyn,
a Bayesian spectral synthesis implementation particularly designed to
infer the stellar atmospheric parameters of late-type stars following
a Markov chain Monte Carlo approach. We made use of the BT-Settl model
atmospheres and the radiative transfer code turbospectrum to compute a
grid of synthetic spectra around 75 magnetically insensitive Fe I and Ti
I lines plus the TiO γ and ϵ bands. To avoid any potential degeneracy
in the parameter space, we imposed Bayesian priors on T<SUB>eff</SUB>
and logg based on the comprehensive, multi-band photometric data
available for the sample. We find that this methodology is suitable down
to M7.0 V, where refractory metals such as Ti are expected to condense
in the stellar photospheres. The derived T<SUB>eff</SUB>, logg, and
[Fe/H] range from 3000 to 4200 K, 4.5 to 5.3 dex, and −0.7 to 0.2
dex, respectively. Although our T<SUB>eff</SUB> scale is in good
agreement with the literature, we report large discrepancies in the
[Fe/H] scales, which might arise from the different methodologies and
sets of lines considered. However, our [Fe/H] is in agreement with the
metallicity distribution of FGK-type stars in the solar neighbourhood
and correlates well with the kinematic membership of the targets in the
Galactic populations. Lastly, excellent agreement in T<SUB>eff</SUB> is
found for M dwarfs with interferometric angular diameter measurements,
as well as in the [Fe/H] between the components in the wide physical
FGK+M and M+M systems included in our sample. <P />Full Tables
B.1-B.3 are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/656/A162">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/656/A162</A>
---------------------------------------------------------
Title: Diving Beneath the Sea of Stellar Activity: Chromatic Radial
Velocities of the Young AU Mic Planetary System
Authors: Cale, Bryson L.; Reefe, Michael; Plavchan, Peter; Tanner,
Angelle; Gaidos, Eric; Gagné, Jonathan; Gao, Peter; Kane, Stephen
R.; Béjar, Víctor J. S.; Lodieu, Nicolas; Anglada-Escudé, Guillem;
Ribas, Ignasi; Pallé, Enric; Quirrenbach, Andreas; Amado, Pedro J.;
Reiners, Ansgar; Caballero, José A.; Rosa Zapatero Osorio, María;
Dreizler, Stefan; Howard, Andrew W.; Fulton, Benjamin J.; Xuesong
Wang, Sharon; Collins, Kevin I.; El Mufti, Mohammed; Wittrock, Justin;
Gilbert, Emily A.; Barclay, Thomas; Klein, Baptiste; Martioli, Eder;
Wittenmyer, Robert; Wright, Duncan; Addison, Brett; Hirano, Teruyuki;
Tamura, Motohide; Kotani, Takayuki; Narita, Norio; Vermilion, David;
Lee, Rena A.; Geneser, Claire; Teske, Johanna; Quinn, Samuel N.;
Latham, David W.; Esquerdo, Gilbert A.; Calkins, Michael L.; Berlind,
Perry; Zohrabi, Farzaneh; Stibbards, Caitlin; Kotnana, Srihan; Jenkins,
Jon; Twicken, Joseph D.; Henze, Christopher; Kidwell, Richard; Burke,
Christopher; Villaseñor, Joel; Boyd, Patricia
2021AJ....162..295C Altcode: 2021arXiv210913996C
We present updated radial-velocity (RV) analyses of the AU
Mic system. AU Mic is a young (22 Myr) early-M dwarf known
to host two transiting planets-P <SUB> b </SUB> ~ 8.46 days,
${R}_{b}={4.38}_{-0.18}^{+0.18}\ {R}_{\oplus }$ , P <SUB> c </SUB>
~ 18.86 days, ${R}_{c}={3.51}_{-0.16}^{+0.16}\ {R}_{\oplus }$ . With
visible RVs from Calar Alto high-Resolution search for M dwarfs with
Exo-earths with Near-infrared and optical echelle Spectrographs
(CARMENES)-VIS, CHIRON, HARPS, HIRES, MINERVA-Australis, and
Tillinghast Reflector Echelle Spectrograph, as well as near-infrared
(NIR) RVs from CARMENES-NIR, CSHELL, IRD, iSHELL, NIRSPEC, and SPIRou,
we provide a 5σ upper limit to the mass of AU Mic c of M <SUB> c </SUB>
≤ 20.13 M <SUB>⊕</SUB> and present a refined mass of AU Mic b of
${M}_{b}={20.12}_{-1.57}^{+1.72}\ {M}_{\oplus }$ . Used in our analyses
is a new RV modeling toolkit to exploit the wavelength dependence of
stellar activity present in our RVs via wavelength-dependent Gaussian
processes. By obtaining near-simultaneous visible and near-infrared
RVs, we also compute the temporal evolution of RV "color" and
introduce a regressional method to aid in isolating Keplerian from
stellar activity signals when modeling RVs in future works. Using a
multiwavelength Gaussian process model, we demonstrate the ability
to recover injected planets at 5σ significance with semi-amplitudes
down to ≍10 m s<SUP>-1</SUP> with a known ephemeris, more than an
order of magnitude below the stellar activity amplitude. However,
we find that the accuracy of the recovered semi-amplitudes is ~50%
for such signals with our model.
---------------------------------------------------------
Title: Central kinematics of the Galactic globular cluster M80
Authors: Göttgens, Fabian; Kamann, Sebastian; Baumgardt, Holger;
Dreizler, Stefan; Giesers, Benjamin; Husser, Tim-Oliver; den Brok,
Mark; Fétick, Romain; Krajnovic, Davor; Weilbacher, Peter M.
2021MNRAS.507.4788G Altcode: 2021arXiv210811393G; 2021MNRAS.tmp.2212G
We use spectra observed with the integral-field spectrograph Multi
Unit Spectroscopic Explorer (MUSE) to reveal the central kinematics
of the Galactic globular cluster Messier 80 (M80, NGC 6093). Using
observations obtained with the recently commissioned narrow-field mode
of MUSE, we are able to analyse 932 stars in the central 7.5 arcsec
by 7.5 arcsec of the cluster for which no useful spectra previously
existed. Mean radial velocities of individual stars derived from the
spectra are compared to predictions from axisymmetric Jeans models,
resulting in radial profiles of the velocity dispersion, the rotation
amplitude, and the mass-to-light ratio. The new data allow us to
search for an intermediate-mass black hole (IMBH) in the centre of
the cluster. Our Jeans model finds two similarly probable solutions
around different dynamical cluster centres. The first solution has a
centre close to the photometric estimates available in the literature
and does not need an IMBH to fit the observed kinematics. The second
solution contains a location of the cluster centre that is offset
by about 2.4 arcsec from the first one and it needs an IMBH mass
of $4600^{+1700}_{-1400}~\text{M}_\odot {}$. N-body models support
the existence of an IMBH in this cluster with a mass of up to 6000
M<SUB>⊙</SUB> in this cluster, although models without an IMBH
provide a better fit to the observed surface brightness profile. They
further indicate that the cluster has lost nearly all stellar-mass black
holes. We further discuss the detection of two potential high-velocity
stars with radial velocities of 80-90 $\text{km}\, \text{s}^{-1}$
relative to the cluster mean.
---------------------------------------------------------
Title: VizieR Online Data Catalog: CARMENES stellar atmospheric
parameters (Marfil+, 2021)
Authors: Marfil, E.; Tabernero, H. M.; Montes, D.; Caballero, J. A.;
Lazaro, F. J.; Gonzalez Hernandez, J. I.; Nagel, E.; Passegger, V. M.;
Schweitzer, A.; Ribas, I.; Reiners, A.; Quirrenbach, A.; Amado, P. J.;
Cifuentes, C.; Cortes-Contreras, M.; Dreizler, S.; Duque-Arribas,
C.; Galadi-Enriquez, D.; Henning, T.; Jeffers, S. V.; Kaminski, A.;
Kurster, M.; Lafarga, M.; Lopez-Gallifa, A.; Morales, J. C.; Shan,
Y.; Zechmeister, M.
2021yCat..36560162M Altcode:
We present basic information of investigated M dwarfs, atomic data of
the selected TiI and FeI lines, wavelength ranges synthesised, and
the stellar atmospheric parameters (effective temperatures, surface
gravities, and metallicities) derived for the sample with SteParSyn. <P
/>(3 data files).
---------------------------------------------------------
Title: Mapping magnetic activity indicators across the M dwarf domain
Authors: Lafarga, Marina; Ribas, Ignasi; Reiners, Ansgar; Quirrenbach,
Andreas; Amado, Pedro J.; Caballero, Jose A.; Azzaro, Marco;
Béjar, Víctor J. S.; Cortés-Contreras, Miriam; Dreizler, Stefan;
Hatzes, Artie P.; Henning, Thomas; Jeffers, Sandra V.; Kaminski,
A.; Kürster, Martin; Montes, David; Morales, Juan Carlos; Oshagh,
Mahmoud; Rodríguez-López, Cristina; Schöfer, Patrick; Schweitzer,
Andreas; Zechmeister, Mathias
2021spc..confE...7L Altcode:
Stellar activity poses one of the main obstacles for the detection and
characterisation of exoplanets around cool stars, as it can induce
radial velocity (RV) signals that can hide or mimic the presence of
companions. Several activity indicators are routinely used to identify
activity-related signals in RV measurements, but not all indicators
trace exactly the same effects, nor are any of them always effective
in all stars. In this work, we evaluate the performance of a set of
common spectroscopic activity indicators for 98 M dwarfs observed
with CARMENES. We find that different indicators behave differently
depending on the mass and activity level of the target star. In
addition, we also observe that stars at the low-mass end of the
sample show the lowest RV scatter, which could potentially hint at
different manifestations of activity compared to higher-mass stars,
as well as being better candidates for planet searches. Overall, our
results show that when assessing the origin of an RV signal, it is
critical to take into account a large set of indicators, or at least
the most effective ones considering the characteristics of the star,
as failing to do so may lead to false planet claims.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Not-so-fine
hyperfine-split vanadium lines in cool star spectra
Authors: Shan, Y.; Reiners, A.; Fabbian, D.; Marfil, E.; Montes,
D.; Tabernero, H. M.; Ribas, I.; Caballero, J. A.; Quirrenbach, A.;
Amado, P. J.; Aceituno, J.; Béjar, V. J. S.; Cortés-Contreras, M.;
Dreizler, S.; Hatzes, A. P.; Henning, Th.; Jeffers, S. V.; Kaminski,
A.; Kürster, M.; Lafarga, M.; Morales, J. C.; Nagel, E.; Pallé, E.;
Passegger, V. M.; Rodriguez-López, C.; Schweitzer, A.; Zechmeister, M.
2021A&A...654A.118S Altcode: 2021arXiv210812442S
Context. M-dwarf spectra are complex and notoriously difficult to model,
posing challenges to understanding their photospheric properties and
compositions in depth. Vanadium (V) is an iron-group element whose
abundance supposedly closely tracks that of iron, but has origins that
are not completely understood. <BR /> Aims: Our aim is to characterize
a series of neutral vanadium atomic absorption lines in the 800-910
nm wavelength region of high signal-to-noise, high-resolution,
telluric-corrected M-dwarf spectra from the CARMENES survey. Many
of these lines are prominent and exhibit a distinctive broad and
flat-bottom shape, which is a result of hyperfine structure (HFS). We
investigate the potential and implications of these HFS split lines
for abundance analysis of cool stars. <BR /> Methods: With standard
spectral synthesis routines, as provided by the spectroscopy software
iSpec and the latest atomic data (including HFS) available from the
VALD3 database, we modeled these striking line profiles. We used them
to measure V abundances of cool dwarfs. <BR /> Results: We determined
V abundances for 135 early M dwarfs (M0.0 V to M3.5 V) in the CARMENES
guaranteed time observations sample. They exhibit a [V/Fe]-[Fe/H]
trend consistent with that derived from nearby FG dwarfs. The tight
(±0.1 dex) correlation between [V/H] and [Fe/H] suggests the potential
application of V as an alternative metallicity indicator in M dwarfs. We
also show hints that neglecting to model HFS could partially explain
the temperature correlation in V abundance measurements observed in
previous studies of samples involving dwarf stars with T<SUB>eff</SUB>
≲ 5300 K. <BR /> Conclusions: Our work suggests that HFS can impact
certain absorption lines in cool photospheres more severely than in
Sun-like ones. Therefore, we advocate that HFS should be carefully
treated in abundance studies in stars cooler than ~5000 K. On the other
hand, strong HFS split lines in high-resolution spectra present an
opportunity for precision chemical analyses of large samples of cool
stars. The V-to-Fe trends exhibited by the local M dwarfs continue
to challenge theoretical models of V production in the Galaxy. <P
/>Full Table A.1 is only available at the CDS via anonymous ftp to
<A href="http://cdsarc.u-strasbg.fr">cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/654/A118">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/654/A118</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: Metallicities on multiple MSs of
Omega Centauri (Latour+, 2021)
Authors: Latour, M.; Calamida, A.; Husser, T. -O.; Kamann, S.;
Dreizler, S.; Brinchmann, J.
2021yCat..36539008L Altcode:
We analyzed the MUSE spectra of selected stars on the MS of Omega
Centauri. We include the stars selected by us on the red- and blue-MS
as well as additional stars included in the 15 MSs identified by
Bellini et al., (2017, Cat. J/ApJ/844/164). We include only the stars
that have a spectrum with S/N>15. The effective temperatures and
metallicities are derived from a full spectral fit against grids
of model atmospheres computed with the PHEONIX code (Husser et al.,
2011A&A...533A...6B). We note that the model atmospheres used for
the fits are alpha-enhanced ([alpha/Fe]=0.3). Uncertainties on Teff and
M/H are calibrated as explained in the paper. Surface gravities are
derived from isochrones. Uncertainties on the log g are the standard
deviations of the log g values obtained from different isochrones
(see text in the paper for more details). <P />IDs and coordinates are
from Bellini (2017, Cat. J/ApJ/844/164) and the populations tags can
be retrieved from Bellini et al. (2017, Cat. J/ApJ/844/164). <P />(1
data file).
---------------------------------------------------------
Title: VizieR Online Data Catalog: TOI-1201 RV and activity index
(Kossakowski+, 2021)
Authors: Kossakowski, D.; Kemmer, J.; Bluhm, P.; Stock, S.; Caballero,
J. A.; Bejar, V. J. S.; Cardona Guillen, C.; Lodieu, N.; Collins,
K. A.; Oshagh, M.; Schlecker, M.; Espinoza, N.; Palle, E.; Henning,
Th.; Kreidberg, L.; Kuerster, M.; Amado, P. J.; Anderson, D. R.;
Morales, J. C.; Cartwright, S.; Charbonneau, D.; Chaturvedi, P.;
Cifuentes, C.; Conti, D. M.; Cortes-Contreras, M.; Dreizler, S.;
Galadi-Enriquez, D.; Guerra, P.; Hart, R.; Hellier, C.; Henze,
C.; Herrero, E.; Jeffers, S. V.; Jenkins, J. M.; Jensen, E. L. N.;
Kaminski, A.; Kielkopf, J. F.; Kunimoto, M.; Lafarga, M.; Latham,
D. W.; Lillo-Box, J.; Luque, R.; Molvaerdikhani, K.; Montes, D.;
Morello, G.; Morgan, E. H.; Nowak, G.; Pavlov, A.; Perger, M.;
Quintana, E. V.; Quirrenbach, A.; Reffert, S.; Reiners, A.; Ricker,
G.; Ribas, I.; Rodriguez Lopez, C.; Zapatero Osorio, M. R.; Seager,
S.; Schoefer, P.; Schweitzer, A.; Trifonov, T.; Vanaverbeke, S.;
Vanderspek, R.; West, R.; Winn, J.; Zechmeister, M.
2021yCat..36560124K Altcode:
High-resolution spectroscopy taken with the CARMENES VIS instrument
for the two M dwarfs in a binary system, TOI-1201 and its companion
(PM J02489-1432E). Likewise, the stellar activity indicators are output
from the SERVAL pipeline (Zechmeister et al. 2018A&A...609A..12Z),
namely, this entails the chromatic index (CRX), the differential line
width (dLW), the Halpha index, the Calcium triplet lines (CAIRT). The
photospheric TiO absorption band indices (at 7050Å, 8430Å, and 8860Å)
following Schoefer et al. (2019A&A...623A..44S, Cat. J/A+A/623/A44)
are included. Also, the cross-correlation function parameters,
as provided following Lafarga et al. (2020A&A...636A..36L,
Cat. J/A+A/636/A36), are included and these are: bisector velocity span
(BVS), contrast (CTR), and full width at half maximum (FWHM). <P />Most
observations are simultaneously, however there are 33 data points for
TOI-1201 (Nov. 2019 - Feb. 2020) and 23 for PM J02489-1432E (Nov. 2019 -
Jan. 2020). <P />(2 data files).
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M
dwarfs. Spectroscopic orbits of nine M-dwarf multiple systems,
including two triples, two brown dwarf candidates, and one close
M-dwarf-white dwarf binary
Authors: Baroch, D.; Morales, J. C.; Ribas, I.; Béjar, V. J. S.;
Reffert, S.; Cardona Guillén, C.; Reiners, A.; Caballero, J. A.;
Quirrenbach, A.; Amado, P. J.; Anglada-Escudé, G.; Colomé, J.;
Cortés-Contreras, M.; Dreizler, S.; Galadí-Enríquez, D.; Hatzes,
A. P.; Jeffers, S. V.; Henning, Th.; Herrero, E.; Kaminski, A.;
Kürster, M.; Lafarga, M.; Lodieu, N.; López-González, M. J.;
Montes, D.; Pallé, E.; Perger, M.; Pollacco, D.; Rodríguez-López,
C.; Rodríguez, E.; Rosich, A.; Schöfer, P.; Schweitzer, A.; Shan,
Y.; Tal-Or, L.; Zechmeister, M.
2021A&A...653A..49B Altcode: 2021arXiv210514770B
Context. M dwarfs are ideal targets for the search of Earth-size
planets in the habitable zone using the radial velocity method,
and are attracting the attention of many ongoing surveys. One of the
expected results of these surveys is that new multiple-star systems
have also been found. This is the case also for the CARMENES survey,
thanks to which nine new double-line spectroscopic binary systems have
already been announced. <BR /> Aims: Throughout the five years of
the survey the accumulation of new observations has resulted in the
detection of several new multiple-stellar systems with long periods
and low radial-velocity amplitudes. Here we newly characterise the
spectroscopic orbits and constrain the masses of eight systems and
update the properties of a system that we had reported earlier. <BR
/> Methods: We derived the radial velocities of the stars using
two-dimensional cross-correlation techniques and template matching. The
measurements were modelled to determine the orbital parameters of the
systems. We combined CARMENES spectroscopic observations with archival
high-resolution spectra from other instruments to increase the time
span of the observations and improve our analysis. When available,
we also added archival photometric, astrometric, and adaptive optics
imaging data to constrain the rotation periods and absolute masses
of the components. <BR /> Results: We determined the spectroscopic
orbits of nine multiple systems, eight of which are presented for
the first time. The sample is composed of five single-line binaries,
two double-line binaries, and two triple-line spectroscopic triple
systems. The companions of two of the single-line binaries, GJ 3626 and
GJ 912, have minimum masses below the stellar boundary, and thus could
be brown dwarfs. We found a new white dwarf in a close binary orbit
around the M star GJ 207.1, located at a distance of 15.79 pc. From a
global fit to radial velocities and astrometric measurements, we were
able to determine the absolute masses of the components of GJ 282 C,
which is one of the youngest systems with measured dynamical masses.
---------------------------------------------------------
Title: A stellar census in globular clusters with MUSE. A new
perspective on the multiple main sequences of ω Centauri
Authors: Latour, M.; Calamida, A.; Husser, T. -O.; Kamann, S.;
Dreizler, S.; Brinchmann, J.
2021A&A...653L...8L Altcode: 2021arXiv210901540L
Context. ω Cen is a rare example of a globular cluster where the iron
abundance of the stars spans more than one order of magnitude. Many
spectroscopic investigations of its red-giant and sub-giant branches
have revealed multiple peaks in the iron abundance distribution. The
metallicity distribution of main sequence (MS) stars is not well
characterized yet due to the faintness of the stars and lack of
data. So far, almost all studies of MS stars have been based on
photometric measurements. <BR /> Aims: Our goal is to investigate
the metallicity distribution of a statistically significant sample of
MS stars in ω Cen. In particular, we aim to revisit the metallicity
difference between the red and blue MS of the cluster. <BR /> Methods:
We used MUSE spectra obtained for the central region of ω Cen to
derive metallicities for ≈4200 MS stars. <BR /> Results: We find
that blue MS stars are, on average, ≈0.1 dex more metal-rich than
their red counterparts. On the basis of this new estimate, we find
that the two sequences can be fit on the Hubble Space Telescope
color-magnitude diagram with two isochrones having the same global
metallicity and age, but a higher helium abundance for the blue MS,
that is ΔY ≲ 0.1. Furthermore, we determined the average metallicity
of the five main populations along ω Cen MS and these estimates are
consistent with expectations from previous photometric studies. <P
/>Table B.1 is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr/">cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/653/L8">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/653/L8</A>
<P />Based on observations collected at the European Organisation
for Astronomical Research in the Southern Hemisphere, Chile (Program
IDs 094.D-0142(B), 095.D-0629(A), 096.D-0175(A), 097.D-0295(A),
098.D-0148(A), 099.D-0019(A), 0100.D-0161(A), 0101.D-0268(A),
0102.D-0270(A), 0103.D-0204(A), and 0104.D-0257(B)).
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Planet
occurrence rates from a subsample of 71 stars
Authors: Sabotta, S.; Schlecker, M.; Chaturvedi, P.; Guenther,
E. W.; Muñoz Rodríguez, I.; Muñoz Sánchez, J. C.; Caballero,
J. A.; Shan, Y.; Reffert, S.; Ribas, I.; Reiners, A.; Hatzes, A. P.;
Amado, P. J.; Klahr, H.; Morales, J. C.; Quirrenbach, A.; Henning,
Th.; Dreizler, S.; Pallé, E.; Perger, M.; Azzaro, M.; Jeffers, S. V.;
Kaminski, A.; Kürster, M.; Lafarga, M.; Montes, D.; Passegger, V. M.;
Zechmeister, M.
2021A&A...653A.114S Altcode: 2021arXiv210703802S
Context. The CARMENES exoplanet survey of M dwarfs has obtained more
than 18 000 spectra of 329 nearby M dwarfs over the past five years as
part of its guaranteed time observations (GTO) program. <BR /> Aims:
We determine planet occurrence rates with the 71 stars from the GTO
program for which we have more than 50 observations. <BR /> Methods:
We use injection-and-retrieval experiments on the radial-velocity
time series to measure detection probabilities. We include 27
planets in 21 planetary systems in our analysis. <BR /> Results:
We find 0.06<SUB>−0.03</SUB><SUP>+0.04</SUP> giant planets (100
M<SUB>⊕</SUB> < M<SUB>pl</SUB> sin i < 1000 M<SUB>⊕</SUB>)
per star in periods of up to 1000 d, but due to a selection bias this
number could be up to a factor of five lower in the whole 329-star
sample. The upper limit for hot Jupiters (orbital period of less than
10 d) is 0.03 planets per star, while the occurrence rate of planets
with intermediate masses (10 M<SUB>⊕</SUB> < M<SUB>pl</SUB> sin
i < 100 M<SUB>⊕</SUB>) is 0.18<SUB>−0.05</SUB><SUP>+0.07</SUP>
planets per star. Less massive planets with 1 M<SUB>⊕</SUB> <
M<SUB>pl</SUB> sin i < 10 M<SUB>⊕</SUB> are very abundant,
with an estimated rate of 1.32<SUB>−0.31</SUB><SUP>+0.33</SUP>
planets per star for periods of up to 100 d. When considering only
late M dwarfs with masses M<SUB>⋆</SUB> < 0.34 M<SUB>⊙</SUB>,
planets more massive than 10 M<SUB>⊕</SUB> become rare. Instead,
low-mass planets with periods shorter than 10 d are significantly
overabundant. <BR /> Conclusions: For orbital periods shorter than
100 d, our results confirm the known stellar mass dependences from
the Kepler survey: M dwarfs host fewer giant planets and at least two
times more planets with M<SUB>pl</SUB> sin i < 10 M<SUB>⊕</SUB>
than G-type stars. In contrast to previous results, planets around
our sample of very low-mass stars have a higher occurrence rate in
short-period orbits of less than 10 d. Our results demonstrate the
need to take into account host star masses in planet formation models.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Vanadium measurements for 135 M
dwarfs (Shan+, 2021)
Authors: Shan, Y.; Reiners, A.; Fabbian, D.; Marfil, E.; Montes,
D.; Tabernero, H. M.; Ribas, I.; Caballero, J. A.; Quirrenbach, A.;
Amado, P. J.; Aceituno, J.; Bejar, V. J. S.; Cortes-Contreras, M.;
Dreizler, S.; Hatzes, A. P.; Henning, T.; Jeffers, S. V.; Kaminski,
A.; Kuerster, M.; Lafarga, M.; Morales, J. C.; Nagel, E.; Palle, E.;
Passegger, V. M.; Rodriguez-Lopez, C.; Schweitzer, A.; Zechmeister, M.
2021yCat..36540118S Altcode:
Table A1 presents the measured V abundances ([V/H]) for 135
nearby early-M dwarfs from the CARMENES GTO sample. Two sets
of measurements are given, which are based on two independently
measured sets of fundamental stellar parameters for this sample
(Schweitzer et al., 2019A&A...625A..68S, Cat. J/A+A/625/A68 and
Marfil et al., submitted). Rotational velocities from Reiners et
al. (2018A&A...612A..49R, Cat. J/A+A/612/A49) and disk kinematic
membership designations (Cortes-Contreras+ in prep) are also
included. <P />(1 data file).
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Mapping
stellar activity indicators across the M dwarf domain
Authors: Lafarga, M.; Ribas, I.; Reiners, A.; Quirrenbach, A.;
Amado, P. J.; Caballero, J. A.; Azzaro, M.; Béjar, V. J. S.;
Cortés-Contreras, M.; Dreizler, S.; Hatzes, A. P.; Henning, Th.;
Jeffers, S. V.; Kaminski, A.; Kürster, M.; Montes, D.; Morales,
J. C.; Oshagh, M.; Rodríguez-López, C.; Schöfer, P.; Schweitzer,
A.; Zechmeister, M.
2021A&A...652A..28L Altcode: 2021arXiv210513467L
Context. Stellar activity poses one of the main obstacles for the
detection and characterisation of small exoplanets around cool stars,
as it can induce radial velocity (RV) signals that can hide or mimic
the presence of planetary companions. Several indicators of stellar
activity are routinely used to identify activity-related signals in
RVs, but not all indicators trace exactly the same activity effects,
nor are any of them always effective in all stars. <BR /> Aims:
We evaluate the performance of a set of spectroscopic activity
indicators for M dwarf stars with different masses and activity
levels with the aim of finding a relation between the indicators
and stellar properties. <BR /> Methods: In a sample of 98 M dwarfs
observed with CARMENES, we analyse the temporal behaviour of RVs and
nine spectroscopic activity indicators: cross-correlation function
(CCF) full-width-at-half-maximum (FWHM), CCF contrast, CCF bisector
inverse slope (BIS), RV chromatic index (CRX), differential line width
(dLW), and indices of the chromospheric lines Hα and calcium infrared
triplet. <BR /> Results: A total of 56 stars of the initial sample
show periodic signals related to activity in at least one of these
ten parameters. RV is the parameter for which most of the targets
show an activity-related signal. CRX and BIS are effective activity
tracers for the most active stars in the sample, especially stars with
a relatively high mass, while for less active stars, chromospheric
lines perform best. FWHM and dLW show a similar behaviour in all mass
and activity regimes, with the highest number of activity detections
in the low-mass, high-activity regime. Most of the targets for which
we cannot identify any activity-related signals are stars at the
low-mass end of the sample (i.e. with the latest spectral types). These
low-mass stars also show the lowest RV scatter, which indicates that
ultracool M dwarfs could be better candidates for planet searches
than earlier types, which show larger RV jitter. <BR /> Conclusions:
Our results show that the spectroscopic activity indicators analysed
behave differently, depending on the mass and activity level of the
target star. This underlines the importance of considering different
indicators of stellar activity when studying the variability of RV
measurements. Therefore, when assessing the origin of an RV signal,
it is critical to take into account a large set of indicators, or at
least the most effective ones considering the characteristics of the
star, as failing to do so may lead to false planet claims. <P />Full
Table A.1 is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/652/A28">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/652/A28</A>
---------------------------------------------------------
Title: Transit Timing Variations for AU Microscopii b & c
Authors: Wittrock, Justin M.; Dreizler, Stefan; Reefe, Michael;
Plavchan, Peter; Gilbert, Emily A.; Barclay, Thomas; Morris, Brett
M.; Demory, Brice-Olivier; Dragomir, Diana; Crossfield, Ian J. M.;
Ingalls, James; Lowrance, Patrick; Gao, Peter; Kaye, Laurel; Wang,
Songhu; Newton, Elisabeth R.; Gaidos, Eric; Cale, Bryson L.; El Mufti,
Mohammed; Collins, Kevin I.; Kane, Stephen R.; Tanner, Angelle; Gagné,
Jonathan; Quintana, Elisa V.; Vega, Laura D.; Schlieder, Joshua E.;
Monsue, Teresa; Hebb, Leslie; Stassun, Keivan G.; Roccatagliata,
Veronica; Schwarz, Richard P.; Tan, T. G.; Radford, Don J.; Stockdale,
Christopher
2021tsc2.confE...7W Altcode:
AU Mic is a relatively bright, nearby (9.7 pc), young (22 Myr) M1V
pre-main sequence star hosting two transiting exoplanets AU Mic b and c
and a spatially-resolved outer dusty debris disk. This research explores
the transit timing variations (TTVs) of AU Mic b and c. For AU Mic b,
we present three Spitzer/IRAC (4.5 μm) transits (two new), five TESS
Cycle 1 and 3 transits, 11 LCO transits, one PEST-0.30m transit,
one Brierfield-0.36m transit, and two transit timing measurements
from Rossiter-McLaughlin observations; for AU Mic c, we present three
TESS Cycle 1 and 3 transits. We use EXOFASTv2 to jointly model the
transits and to obtain the midpoint transit times. We then construct
an O-C diagram to map the TTVs. We model the TTVs for AU Mic b and c
with Exo-Striker to recover constraints on the mass for AU Mic c. We
compare the TTV-derived constraints to a recent radial-velocity mass
determination. The results demonstrate that the AU Mic planetary
system is dynamically interacting producing detectable TTVs, and the
implied orbital dynamics may inform future constraints on the formation
mechanisms for this young planetary system. However, stellar activity
from flares and rotational spot modulation complicate our analysis
of this young system. We recommend future TTV observations of AU Mic
b and c to further constrain the dynamical masses and to search for
additional planets in the system.
---------------------------------------------------------
Title: Small and rocky worlds orbiting M dwarfs: GJ 3473 b and GJ
3929 b
Authors: Kemmer, Jonas; Stock, Stephan; Kossakowski, Diana; Dreizler,
Stefan; Kaminski, Adrian; Molaverdikhani, Karan; Schlecker, Martin;
Caballero, Jose A.
2021tsc2.confE..67K Altcode:
We present two small transiting planets with mass measurements orbiting
bright mid M dwarfs (GJ 3473, GJ 3929). GJ 3473 b (Kemmer et al. 2020)
is a hot, presumably rocky, planet (P = 1.198 d, M<SUB>b</SUB> = 1.86
± 0.30 M<SUB>e</SUB>, and radius, R<SUB>b</SUB> = 1.264 ± 0.050
R<SUB>e</SUB>), which is due to its high temperature a particularly
attractive target for thermal emission spectroscopy. Further, it is
accompanied by another non-transiting planet (Pc = 15.509 ± 0.033
d) that has a minimum mass of M<SUB>c</SUB> sin i = 7.41 ± 0.91
M<SUB>e</SUB>. For GJ 3929 b (in prep.) we present a preliminary
analysis that yields a period of P = 2.616 d, mass M<SUB>b</SUB> =
2.03 ± 0.59 M<SUB>e</SUB>, and radius, R<SUB>b</SUB> = 1.155 ± 0.043
R<SUB>e</SUB>. The radial velocity data show evidence for another
signal, whose origin is, however, not yet clarified. Both systems
add to the TESS level-one science goal to measure the masses for 50
transiting planets with radii smaller than 4 R<SUB>e</SUB>.
---------------------------------------------------------
Title: Simultaneous photometric and CARMENES spectroscopic monitoring
of fast-rotating M dwarf GJ 3270. Discovery of a post-flare corotating
feature
Authors: Johnson, E. N.; Czesla, S.; Fuhrmeister, B.; Schöfer, P.;
Shan, Y.; Cardona Guillén, C.; Reiners, A.; Jeffers, S. V.; Lalitha,
S.; Luque, R.; Rodríguez, E.; Béjar, V. J. S.; Caballero, J. A.;
Tal-Or, L.; Zechmeister, M.; Ribas, I.; Amado, P. J.; Quirrenbach,
A.; Cortés-Contreras, M.; Dreizler, S.; Fukui, A.; López-González,
M. J.; Hatzes, A. P.; Henning, Th.; Kaminski, A.; Kürster, M.;
Lafarga, M.; Montes, D.; Morales, J. C.; Murgas, F.; Narita, N.;
Pallé, E.; Parviainen, H.; Pedraz, S.; Pollacco, D.; Sota, A.
2021A&A...651A.105J Altcode: 2021arXiv210407080J
Context. Active M dwarfs frequently exhibit large flares, which can
pose an existential threat to the habitability of any planet in orbit
in addition to making said planets more difficult to detect. M dwarfs
do not lose angular momentum as easily as earlier-type stars, which
maintain the high levels of stellar activity for far longer. Studying
young, fast-rotating M dwarfs is key to understanding their near
stellar environment and the evolution of activity. <BR /> Aims: We
study stellar activity on the fast-rotating M dwarf GJ 3270. <BR />
Methods: We analyzed dedicated high cadence, simultaneous, photometric
and high-resolution spectroscopic observations obtained with CARMENES of
GJ 3270 over 7.7 h, covering a total of eight flares of which two are
strong enough to facilitate a detailed analysis. We consult the TESS
data, obtained in the month prior to our own observations, to study
rotational modulation and to compare the TESS flares to those observed
in our campaign. <BR /> Results: The TESS data exhibit rotational
modulation with a period of 0.37 d. The strongest flare covered
by our observing campaign released a total energy of about 3.6 ×
10<SUP>32</SUP> erg, putting it close to the superflare regime. This
flare is visible in the B,V, r, i, and z photometric bands, which
allows us to determine a peak temperature of about 10 000 K. The flare
also leaves clear marks in the spectral time series. In particular,
we observe an evolving, mainly blue asymmetry in chromospheric lines,
which we attribute to a post-flare, corotating feature. To our knowledge
this is the first time such a feature has been seen on a star other
than our Sun. <BR /> Conclusions: Our photometric and spectroscopic
time series covers the eruption of a strong flare followed up by a
corotating feature analogous to a post-flare arcadal loop on the Sun
with a possible failed ejection of material.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Activity indicators across the
M dwarf domain (Lafarga+, 2021)
Authors: Lafarga, M.; Ribas, I.; Reiners, A.; Quirrenbach, A.; Amado,
P. J.; Caballero, J. A.; Azzaro, M.; Bejar, V. J. S.; Cortes-Contreras,
M.; Dreizler, S.; Hatzes, A. P.; Henning, T.; Jeffers, S. V.;
Kaminski, A.; Kuerster, M.; Montes, D.; Morales, J. C.; Oshagh, M.;
Rodriguez-Lopez, C.; Schoefer, P.; Schweitzer, A.; Zechmeister, M.
2021yCat..36520028L Altcode:
Properties of the 98 sample stars. Values taken from the latest
version of the Carmencita database available at the time. We also
show the number of CARMENES VIS observations (before performing any
sigma-clipping or discarding any observations due to low S/N), the
number of different nights covered by the observations, their time span,
and their RV scatter, measured as the standard deviation (std) of the
corrected serval RVs (instrumental drift and nightly average corrected,
averaged same-night observations, and linear trend removed). <P />(1
data file).
---------------------------------------------------------
Title: An ultra-short-period transiting super-Earth orbiting the M3
dwarf TOI-1685
Authors: Bluhm, P.; Pallé, E.; Molaverdikhani, K.; Kemmer, J.; Hatzes,
A. P.; Kossakowski, D.; Stock, S.; Caballero, J. A.; Lillo-Box, J.;
Béjar, V. J. S.; Soto, M. G.; Amado, P. J.; Brown, P.; Cadieux, C.;
Cloutier, R.; Collins, K. A.; Collins, K. I.; Cortés-Contreras, M.;
Doyon, R.; Dreizler, S.; Espinoza, N.; Fukui, A.; González-Álvarez,
E.; Henning, Th.; Horne, K.; Jeffers, S. V.; Jenkins, J. M.; Jensen,
E. L. N.; Kaminski, A.; Kielkopf, J. F.; Kusakabe, N.; Kürster, M.;
Lafrenière, D.; Luque, R.; Murgas, F.; Montes, D.; Morales, J. C.;
Narita, N.; Passegger, V. M.; Quirrenbach, A.; Schöfer, P.; Reffert,
S.; Reiners, A.; Ribas, I.; Ricker, G. R.; Seager, S.; Schweitzer,
A.; Schwarz, R. P.; Tamura, M.; Trifonov, T.; Vanderspek, R.; Winn,
J.; Zechmeister, M.; Zapatero Osorio, M. R.
2021A&A...650A..78B Altcode: 2021arXiv210301016B
Dynamical histories of planetary systems, as well as the atmospheric
evolution of highly irradiated planets, can be studied by characterizing
the ultra-short-period planet population, which the TESS mission is
particularly well suited to discover. Here, we report on the follow-up
of a transit signal detected in the TESS sector 19 photometric time
series of the M3.0 V star TOI-1685 (2MASS J04342248+4302148). We confirm
the planetary nature of the transit signal, which has a period of
P<SUB>b</SUB> = 0.6691403<SUB>−0.0000021</SUB><SUP>+0.0000023</SUP>
d, using precise radial velocity measurements taken with the CARMENES
spectrograph. From the joint photometry and radial velocity analysis,
we estimate the following parameters for TOI-1685 b: a mass of
M<SUB>b</SUB> = 3.78<SUB>−0.63</SUB><SUP>+0.63</SUP> M<SUB>⊕</SUB>,
a radius of R<SUB>b</SUB> = 1.70<SUB>−0.07</SUB><SUP>+0.07</SUP>
R<SUB>⊕</SUB>, which together result in a bulk density
of ρ<SUB>b</SUB> = 4.21<SUB>−0.82</SUB><SUP>+0.95</SUP> g
cm<SUP>−3</SUP>, and an equilibrium temperature of T<SUB>eq</SUB>
= 1069<SUB>−16</SUB><SUP>+16</SUP> K. TOI-1685 b is the least dense
ultra-short-period planet around an M dwarf known to date. TOI-1685 b
is also one of the hottest transiting super-Earth planets with accurate
dynamical mass measurements, which makes it a particularly attractive
target for thermal emission spectroscopy. Additionally, we report with
moderate evidence an additional non-transiting planet candidate in the
system, TOI-1685 [c], which has an orbital period of P<SUB>c</SUB> =
9.02<SUB>−0.12</SUB><SUP>+0.10</SUP> d.
---------------------------------------------------------
Title: Deciphering the Formation History of Omega Cen with a
Comprehensive Stellar Kinematic and Population Dataset
Authors: Seth, Anil C.; Alfaro Cuello, Mayte; Bellini, Andrea; Dotter,
Aaron L.; Dreizler, S.; Haeberle, Maximilian; Hannah, Christian;
Husser, Tim-Oliver; Kacharov, Nikolay; Kamann, Sebastian; Milone,
Antonino Paolo; Neumayer, Nadine; Nitschai, Maria Selina; Pechetti,
Renuka; Voggel, Karina; Weisz, Daniel R.; van de Ven, Glenn
2021hst..prop16777S Altcode:
Omega Centauri appears to be the stripped nucleus of one of the
largest satellite galaxies that has fallen into the Milky Way. Yet
the formation history of Omega Centauri is poorly understood due
to the complexity of its stellar populations. We propose to obtain
WFC3/UVIS imaging to measure proper motions and use UV photometry to
constrain stellar abundances and ages for hundreds of thousands of
stars within Omega Centauri's effective radius. In combination with a
MUSE spectral mosaic that will provide star-by-star metallicity and
radial velocity measurements, we will create and publicly release
an unprecedented catalog of 3-D stellar velocities, age estimates,
and abundance information. This combination of kinematic and stellar
population information will enable us to study the details of both how
and when Omega Centauri formed. These results will provide insight on
the galaxy in which Omega Centauri formed and its interaction with
the Milky Way, and will serve as a template for understanding the
formation and tidal stripping of nuclear star clusters.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Two
terrestrial planets orbiting G 264-012 and one terrestrial planet
orbiting Gl 393
Authors: Amado, P. J.; Bauer, F. F.; Rodríguez López, C.;
Rodríguez, E.; Cardona Guillén, C.; Perger, M.; Caballero, J. A.;
López-González, M. J.; Muñoz Rodríguez, I.; Pozuelos, F. J.;
Sánchez-Rivero, A.; Schlecker, M.; Quirrenbach, A.; Ribas, I.;
Reiners, A.; Almenara, J.; Astudillo-Defru, N.; Azzaro, M.; Béjar,
V. J. S.; Bohemann, R.; Bonfils, X.; Bouchy, F.; Cifuentes, C.;
Cortés-Contreras, M.; Delfosse, X.; Dreizler, S.; Forveille, T.;
Hatzes, A. P.; Henning, Th.; Jeffers, S. V.; Kaminski, A.; Kürster,
M.; Lafarga, M.; Lodieu, N.; Lovis, C.; Mayor, M.; Montes, D.;
Morales, J. C.; Morales, N.; Murgas, F.; Ortiz, J. L.; Pallé, E.;
Pepe, F.; Perdelwitz, V.; Pollaco, D.; Santos, N. C.; Schöfer, P.;
Schweitzer, A.; Ségransan, N. C.; Shan, Y.; Stock, S.; Tal-Or, L.;
Udry, S.; Zapatero Osorio, M. R.; Zechmeister, M.
2021A&A...650A.188A Altcode: 2021arXiv210513785A
We report the discovery of two planetary systems, namely G 264-012,
an M 4.0 dwarf with two terrestrial planets (M<SUB>b</SUB>
sin i=2.50<SUB>−0.30</SUB><SUP>+0.29</SUP> M<SUB>⊕</SUB>
and M<SUB>c</SUB> sin i=3.75<SUB>−0.47</SUB><SUP>+0.48</SUP>
M<SUB>⊕</SUB>), and Gl 393, a bright M 2.0 dwarf with one terrestrial
planet (M<SUB>b</SUB> sini = 1.71 ± 0.24M<SUB>⊕</SUB>). Although both
stars were proposed to belong to young stellar kinematic groups, we
estimate their ages to be older than about 700 Ma. The two planets
around G 264-012 were discovered using only radial-velocity (RV)
data from the CARMENES exoplanet survey, with estimated orbital
periods of 2.30 d and 8.05 d, respectively.Photometric monitoring and
analysis of activity indicators reveal a third signal present in the RV
measurements, at about 100 d,caused by stellar rotation. The planet
Gl 393 b was discovered in the RV data from the HARPS, CARMENES,
and HIRES instruments. Its identification was only possible after
modelling, with a Gaussian process (GP), the variability produced by
the magnetic activity of the star. For the earliest observations,
this variability produced a forest of peaks in the periodogram of
the RVs at around the 34 d rotation period determined from Kepler
data, which disappeared in the latestepochs. After correcting for
them with this GP model, a significant signal showed at a period
of 7.03 d. No significant signals in any of our spectral activity
indicators or contemporaneous photometry were found at any of the
planetary periods. Given the orbital and stellar properties, the
equilibrium temperatures of the three planets are all higher than that
for Earth. Current planet formation theories suggest that these two
systems represent a common type of architecture. This is consistent
with formation following the core accretion paradigm. <P />Full Tables
B.1 and B.2 are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/650/A188">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/650/A188</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: G 264-012 and Gl 393 radial
velocity curves (Amado+, 2021)
Authors: Amado, P. J.; Bauer, F. F.; Rodriguez Lopez, C.; Rodriguez,
E.; Cardona Guillen, C.; Perger, M.; Caballero, J. A.; Lopez-Gonzalez,
M. J.; Munoz-Rodriguez, I.; Pozuelos, F. J.; Sanchez-Rivero, A.;
Schlecker, M.; Quirrenbach, A.; Ribas, I.; Reiners, A.; Almenara,
J.; Astudillo-Defru, N.; Azzaro, M.; Bejar, V. J. S.; Bohemann, R.;
Bonfils, X.; Bouchy, F.; Cifuentes, C.; Cortes-Contreras, M.; Delfosse,
X.; Dreizler, S.; Forveille, T.; Hatzes, A. P.; Henning, T.; Jeffers,
S. V.; Kaminski, A.; Kuerster, M.; Lafarga, M.; Lodieu, N.; Lovis, C.;
Mayor, M.; Montes, D.; Morales, J. C.; Morales, N.; Murgas, F.; Ortiz,
J. L.; Palle, E.; Pepe, F.; Perdelwitz, V.; Pollaco, D.; Santos, N. C.;
Schoefer, P.; Schweitzer, A.; Segransan, N. C.; Shan, Y.; Stock, S.;
Tal-Or, L.; Udry, S.; Zapatero Osorio, M. R.; Zechmeister, M.
2021yCat..36500188A Altcode:
We tabulate the radial velocity (RV) time series (BJD) of the stars G
264-012 and Gl 393, the error of each RV measurement and the instrument
with which it was acquired. <P />(2 data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: GJ 1151 radial velocity curve
(Perger+, 2021)
Authors: Perger, M.; Ribas, I.; Anglada-Escude, G.; Morales, J. C.;
Amado, P. J.; Caballero, J. A.; Quirrenbach, A.; Reiners, A.; Bejar,
V. J. S.; Dreizler, S.; Galadi-Enriquez, D.; Hatzes, A. P.; Henning,
T.; Jeffers, S. V.; Kaminski, A.; Kuerster, M.; Lafarga, M.; Montes,
D.; Palle, E.; Rodriguez-Lopez, C.; Schweitzer, A.; Zapatero Osorio,
M. R.; Zechmeister, M.
2021yCat..36499012P Altcode:
CARMENES serval (CAR) and HARPS-N terra (HAN) radial velocities of GJ
1151. <P />(1 data file).
---------------------------------------------------------
Title: Mass and density of the transiting hot and rocky super-Earth
LHS 1478 b (TOI-1640 b)
Authors: Soto, M. G.; Anglada-Escudé, G.; Dreizler, S.;
Molaverdikhani, K.; Kemmer, J.; Rodríguez-López, C.; Lillo-Box, J.;
Pallé, E.; Espinoza, N.; Caballero, J. A.; Quirrenbach, A.; Ribas, I.;
Reiners, A.; Narita, N.; Hirano, T.; Amado, P. J.; Béjar, V. J. S.;
Bluhm, P.; Burke, C. J.; Caldwell, D. A.; Charbonneau, D.; Cloutier,
R.; Collins, K. A.; Cortés-Contreras, M.; Girardin, E.; Guerra, P.;
Harakawa, H.; Hatzes, A. P.; Irwin, J.; Jenkins, J. M.; Jensen, E.;
Kawauchi, K.; Kotani, T.; Kudo, T.; Kunimoto, M.; Kuzuhara, M.; Latham,
D. W.; Montes, D.; Morales, J. C.; Mori, M.; Nelson, R. P.; Omiya, M.;
Pedraz, S.; Passegger, V. M.; Rackham, B. V.; Rudat, A.; Schlieder,
J. E.; Schöfer, P.; Schweitzer, A.; Selezneva, A.; Stockdale, C.;
Tamura, M.; Trifonov, T.; Vanderspek, R.; Watanabe, D.
2021A&A...649A.144S Altcode: 2021arXiv210211640S
One of the main objectives of the Transiting Exoplanet Survey
Satellite (TESS) mission is the discovery of small rocky planets
around relatively bright nearby stars. Here, we report the discovery
and characterization of the transiting super-Earth planet orbiting
LHS 1478 (TOI-1640). The star is an inactive red dwarf (J ~ 9.6 mag
and spectral type m3 V) with mass and radius estimates of 0.20 ±
0.01M<SUB>⊙</SUB> and 0.25 ± 0.01R<SUB>⊙</SUB>, respectively, and
an effective temperature of 3381 ± 54 K. It was observed by TESS in
four sectors. These data revealed a transit-like feature with a period
of 1.949 days. We combined the TESS data with three ground-based transit
measurements, 57 radial velocity (RV) measurements from CARMENES, and
13 RV measurements from IRD, determining that the signal is produced
by a planet with a mass of 2.33<SUB>−0.20</SUB><SUP>+0.20</SUP>
M<SUB>⊕</SUB> and a radius of 1.24<SUB>−0.05</SUB><SUP>+0.05</SUP>
R<SUB>⊕</SUB>. The resulting bulk density of this planet is 6.67 g
cm<SUP>−3</SUP>, which is consistent with a rocky planet with an Fe-
and MgSiO<SUB>3</SUB>-dominated composition. Although the planet would
be too hot to sustain liquid water on its surface (its equilibrium
temperature is about ~595 K, suggesting aVenus-like atmosphere),
spectroscopic metrics based on the capabilities of the forthcoming
James Webb Space Telescope and the fact that the host star is rather
inactive indicate that this is one of the most favorable known rocky
exoplanets for atmospheric characterization.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. No evidence
for a super-Earth in a 2-day orbit around GJ 1151
Authors: Perger, M.; Ribas, I.; Anglada-Escudé, G.; Morales, J. C.;
Amado, P. J.; Caballero, J. A.; Quirrenbach, A.; Reiners, A.; Béjar,
V. J. S.; Dreizler, S.; Galadí-Enríquez, D.; Hatzes, A. P.; Henning,
Th.; Jeffers, S. V.; Kaminski, A.; Kürster, M.; Lafarga, M.; Montes,
D.; Pallé, E.; Rodríguez-López, C.; Schweitzer, A.; Zapatero Osorio,
M. R.; Zechmeister, M.
2021A&A...649L..12P Altcode: 2021arXiv210310216P
Context. The interaction between Earth-like exoplanets and the magnetic
field of low-mass host stars are considered to produce weak emission
signals at radio frequencies. A study using LOFAR data announced the
detection of radio emission from the mid M-type dwarf GJ 1151 that
could potentially arise from a close-in terrestrial planet. Recently,
the presence of a 2.5-M<SUB>⊕</SUB> planet orbiting GJ 1151 with a
2-day period has been claimed using 69 radial velocities (RVs) from
the HARPS-N and HPF instruments. <BR /> Aims: We have obtained 70 new
high-precision RV measurements in the framework of the CARMENES M-dwarf
survey and use these data to confirm the presence of the claimed planet
and to place limits on possible planetary companions in the GJ 1151
system. <BR /> Methods: We analysed the periodicities present in the
combined RV data sets from all three instruments and calculated the
detection limits for potential planets in short-period orbits. <BR
/> Results: We cannot confirm the recently announced candidate
planet and conclude that the 2-day signal in the HARPS-N and HPF
data sets is most probably produced by a long-term RV variability,
possibly arising from an outer planetary companion that has yet to
be constrained. We calculate a 99.9% significance detection limit of
1.50 m s<SUP>−1</SUP> in the RV semi-amplitude, which places upper
limits of 0.7 M<SUB>⊕</SUB> and 1.2 M<SUB>⊕</SUB> on the minimum
masses of potential exoplanets with orbital periods of 1 and 5 days,
respectively. <P />Table A.1 is only available at the CDS via anonymous
ftp to <A href="http://cdsarc.u-strasbg.fr/">cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/649/L12">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/649/L12</A>
---------------------------------------------------------
Title: Stellar atmospheric parameters of CARMENES GTO M dwarfs with
spectral synthesis and SteParSyn
Authors: Marfil, Emilio; Tabernero, Hugo M.; Montes, David; Caballero,
Jose Antonio; Lazaro-Barrasa, Francisco Javier; González Hernández,
Jonay I.; Nagel, Evangelos; Passegger, Vera M.; Schweitzer, Andreas;
Ribas, Ignasi; Reiners, Ansgar; Quirrenbach, Andreas; Amado, Pedro
J.; Cifuentes, Carlos; Cortés-Contreras, Miriam; Dreizler, Stefan;
Duque-Arribas, Christian; Galadí-Enríquez, David; Henning, Thomas;
Jeffers, Sandra V.; Kaminski, Adrian; Kürster, Martin; Lafarga,
Marina; López-Gallifa, Álvaro; Morales, Juan Carlos; Shan, Yutong;
Zechmeister, Matthias
2021csss.confE..19M Altcode: 2021csss.confE.298M
We aim to review the spectral synthesis technique to derive the stellar
atmospheric parameters (T<SUB>eff</SUB>, log g, and [Fe/H]) of 348 M
dwarfs in light of the optical and near-infrared spectra obtained with
CARMENES, the high-resolution, double-channel spectrograph installed at
the 3.5 m telescope at the Calar Alto observatory (Spain). The analysis
relies on the SteParSyn code as the preferred MCMC implementation of
the spectral synthesis technique, along with 75 carefully selected,
magnetically insensitive, Fe I and Ti I lines plus the γ- and ϵ-TiO
bands synthesised with a grid of BT-Settl model atmospheres and the
turbospectrum code. To avoid potential degeneracies in the parameter
space, we impose a Bayesian prior on T<SUB>eff</SUB> and log g based
on comprehensive, multi-band photometric data available for the
sample. As a benchmark test in T<SUB>eff</SUB>, log g, and [Fe/H]
we place special emphasis on three special subsets in our sample,
namely 14 M dwarfs with interferometric angular diameter measurements,
15 M+M systems, and 7 wide physical binaries harbouring an FGK-type
primary with known metallicity.
---------------------------------------------------------
Title: The Lines are Not Fine: Measuring Vanadium Abundances in M
dwarfs from Hyperfine-Split Lines
Authors: Shan, Yutong; Reiners, Ansgar; Fabbian, Damian; Marfil,
Emilio; Montes, David; Tabernero, Hugo M.; Ribas, Ignasi; Caballero,
Jose A.; Quirrenbach, Andreas; Amado, Pedro J.; Aceituno, J.; Bejar,
Victor J. S.; Cortes-Contreras, Miriam; Dreizler, Stefan; Hatzes,
Artie P.; Henning, Thomas; Jeffers, Sandra V.; Kaminski, Adrian;
Kürster, Martin; Lafarga, Marina; Morales, Juan Carlos; Nagel,
Evangelos; Rodriguez-Lopez, Cristina; Passegger, Vera M.; Schweitzer,
Andreas; Zechmeister, Mathias
2021csss.confE.160S Altcode:
Cool star atmospheres present challenges to chemical abundance
studies. To date, only a handful of elements have been quantified for
a handful of M dwarfs. In high-resolution spectra from the CARMENES
survey, we identify a series of dramatically hyperfine-split vanadium
features between 800 and 910 nm, which have strong and clean profiles
throughout the early M-dwarf range. These 'bucket-shaped' line regions
can be well-modeled with standard model atmospheres combined with
the latest atomic data from VALD. From these line regions, we measure
vanadium abundances for 140 nearby early M dwarfs in the CARMENES GTO
sample and confirm that they follow the same trend with metallicity
as the FG-type stars in the solar neighborhood, i.e., significantly
above predictions from galactic chemical evolution models. Exhibiting
a tight correlation with iron, vanadium abundances show promise
as a potential metallicity indicator for M dwarfs. We also present
evidence that several well-known chemical studies of K dwarfs have
systematically overestimated their vanadium abundances largely as a
result of neglecting to model hyperfine structure, a bias that worsens
with decreasing temperature. Our work highlights opportunities for
robust chemical analysis of cool stars afforded by high-quality spectra
redward of visible.
---------------------------------------------------------
Title: Mapping stellar activity indicators across the M dwarf domain
Authors: Lafarga, Marina; Ribas, Ignasi; Reiners, Ansgar; Quirrenbach,
Andreas; Amado, Pedro J.; Caballero, Jose A.; Azzaro, Marco;
Béjar, Víctor J. S.; Cortés-Contreras, Miriam; Dreizler, Stefan;
Hatzes, Artie P.; Henning, Thomas; Jeffers, Sandra V.; Kaminski,
A.; Kürster, Martin; Montes, David; Morales, Juan Carlos; Oshagh,
Mahmoud; Rodríguez-López, Cristina; Schöfer, Patrick; Schweitzer,
Andreas; Zechmeister, Mathias
2021csss.confE.184L Altcode:
Despite stellar magnetic activity being present in most cool
stars, its effects on spectroscopic observations are still not
well understood. Several activity indicators are routinely used to
identify activity-related signals in radial velocity (RV) measurements,
but not all indicators trace exactly the same effects, nor are any
of them always effective in all stars. This poses one of the main
obstacles for the detection and characterisation of small exoplanets,
as magnetic activity biases RV signals. In this work, we analyse
the temporal behaviour of RVs and a set of spectroscopic indicators
for 98 M dwarfs observed with CARMENES, with the aim of finding a
relation between indicator performance and stellar properties. We find
periodic signals related to activity for 56 sample stars. The activity
indicators behave differently depending on the mass and activity level
of the target star, e.g., cross-correlation function bisector inverse
slope and chromatic index are effective activity tracers for the most
active stars in the sample, especially stars with relatively high mass,
while for less active stars, chromospheric lines perform best. Most of
the targets for which we cannot identify any activity-related signal
are stars at the low-mass end of the sample, where stars are fully
convective, and also show the lowest RV scatter. This could potentially
hint at different manifestations of activity compared to higher-mass
stars. Moreover, ultracool M dwarfs could be better candidates for
planet searches than earlier types, which display higher levels of RV
variability. Our results show that none of the indicators are effective
activity tracers for all stars. Therefore, an analysis of a large set
of indicators seems necessary to obtain a complete picture of stellar
activity variability. This becomes critical when assessing the origin
of RV signals, as not using the most effective indicators considering
the characteristics of the star may lead to false planet claims.
---------------------------------------------------------
Title: A Deep Learning Approach to photospheric Parameters of CARMENES
Target Stars
Authors: Passegger, Vera Maria; Ordieres-Meré, Joaquin; Bello-García,
Antonio; Caballero, José Antonio; Schweitzer, Andreas; Amado, Pedro
J.; González-Marcos, Ana; Ribas, Ignasi; Reiners, Ansgar; Quirrenbach,
Andreas; Sarro, Luis M.; Solano, Enrique; Azzaro, Marco; Bauer, Florian
F.; Béjar, Victor J. S.; Cortés-Contreras, Miriam; Dreizler, Stefan;
Hatzes, Artie P.; Henning, Thomas; Jeffers, Sandra V.; Kaminski,
Adrian; Kürster, Martin; Lafarga, Marina; Marfil, Emilio; Montes,
David; Morales, Juan Carlos; Nagel, Evangelos; Tabernero, Hugo M.;
Zechmeister, Mathias
2021csss.confE..71P Altcode:
We construct an individual convolutional neural network architecture
for each of the four stellar parameters effective temperature (Teff),
surface gravity (log g), metallicity [M/H], and rotational velocity
(v sin i). The networks are trained on synthetic PHOENIX-ACES spectra,
showing small training and validation errors. We apply the trained
networks to the observed spectra of 283 M dwarfs observed with
CARMENES. Although the network models do very well on synthetic
spectra, we find large deviations from literature values especially
for metallicity, due to the synthetic gap.
---------------------------------------------------------
Title: A nearby transiting rocky exoplanet that is suitable for
atmospheric investigation
Authors: Trifonov, T.; Caballero, J. A.; Morales, J. C.; Seifahrt, A.;
Ribas, I.; Reiners, A.; Bean, J. L.; Luque, R.; Parviainen, H.; Pallé,
E.; Stock, S.; Zechmeister, M.; Amado, P. J.; Anglada-Escudé, G.;
Azzaro, M.; Barclay, T.; Béjar, V. J. S.; Bluhm, P.; Casasayas-Barris,
N.; Cifuentes, C.; Collins, K. A.; Collins, K. I.; Cortés-Contreras,
M.; de Leon, J.; Dreizler, S.; Dressing, C. D.; Esparza-Borges, E.;
Espinoza, N.; Fausnaugh, M.; Fukui, A.; Hatzes, A. P.; Hellier, C.;
Henning, Th.; Henze, C. E.; Herrero, E.; Jeffers, S. V.; Jenkins,
J. M.; Jensen, E. L. N.; Kaminski, A.; Kasper, D.; Kossakowski, D.;
Kürster, M.; Lafarga, M.; Latham, D. W.; Mann, A. W.; Molaverdikhani,
K.; Montes, D.; Montet, B. T.; Murgas, F.; Narita, N.; Oshagh,
M.; Passegger, V. M.; Pollacco, D.; Quinn, S. N.; Quirrenbach, A.;
Ricker, G. R.; Rodríguez López, C.; Sanz-Forcada, J.; Schwarz, R. P.;
Schweitzer, A.; Seager, S.; Shporer, A.; Stangret, M.; Stürmer, J.;
Tan, T. G.; Tenenbaum, P.; Twicken, J. D.; Vanderspek, R.; Winn, J. N.
2021Sci...371.1038T Altcode: 2021arXiv210304950T
Spectroscopy of transiting exoplanets can be used to investigate their
atmospheric properties and habitability. Combining radial velocity
(RV) and transit data provides additional information on exoplanet
physical properties. We detect a transiting rocky planet with an
orbital period of 1.467 days around the nearby red dwarf star Gliese
486. The planet Gliese 486 b is 2.81 Earth masses and 1.31 Earth radii,
with uncertainties of 5%, as determined from RV data and photometric
light curves. The host star is at a distance of ~8.1 parsecs, has
a J-band magnitude of ~7.2, and is observable from both hemispheres
of Earth. On the basis of these properties and the planet’s short
orbital period and high equilibrium temperature, we show that this
terrestrial planet is suitable for emission and transit spectroscopy.
---------------------------------------------------------
Title: A deep learning approach to photospheric parameters of CARMENES
target stars
Authors: Passegger, Vera Maria; Bello-García, Antonio; Ordieres-Meré,
Joaquin; Caballero, José Antonio; Schweitzer, Andreas; Amado, Pedro
J.; González-Marcos, Ana; Ribas, Ignasi; Reiners, Ansgar; Quirrenbach,
Andreas; Sarro, Luis M.; Solano, Enrique; Azzaro, Marco; Bauer, Florian
F.; Béjar, Victor J. S.; Cortés-Contreras, Miriam; Dreizler, Stefan;
Hatzes, Artie P.; Henning, Thomas; Jeffers, Sandra V.; Kaminski,
Adrian; Kürster, Martin; Lafarga, Marina; Marfil, Emilio; Montes,
David; Morales, Juan Carlos; Nagel, Evangelos; Tabernero, Hugo M.;
Zechmeister, Mathias
2021csss.confE.312P Altcode:
In the light of more and more new instrumentation to get a deeper
insight into the universe, tons of data are collected. While traditional
machine-learning methods have been used in processing stellar spectral
data, such large new datasets are better handled with Deep Learning (DL)
techniques. In this work, we present a Deep Convolutional Neural Network
(CNN) approach to derive fundamental stellar parameters (effective
temperature, surface gravity, metallicity and rotational velocity)
from high-resolution high signal-to-noise ratio spectra. We construct
an individual CNN architecture for each of the four parameters and
train them on synthetic PHOENIX-ACES spectra. After that, we apply
the trained networks to the observed spectra of 50 M dwarfs observed
with CARMENES. The CARMENES spectrograph, installed on the 3.5 m
telescope at the Calar Alto Observatory (Spain) has two channels,
covering the visible (0.52 to 0.96 µm, R = 96,400) and near-infrared
(0.96 to 1.71 µm, R = 80,600) spectral ranges. We compare our results
to literature values, and demonstrate that our method can be used
for stellar parameter determination without the need of having a huge
sample of stellar spectra with known parameters, because our networks
can be trained on synthetic spectra. Introducing Deep Transfer Learning
(DTL) in our approach allows us to transfer external knowledge about
the stellar parameters (e.g., from interferometry) to our training
set and therefore improve our results compared to literature.
---------------------------------------------------------
Title: Identification and Mitigation of a Vibrational Telescope
Systematic with Application to Spitzer
Authors: Challener, Ryan C.; Harrington, Joseph; Jenkins, James;
Kurtovic, Nicolás T.; Ramirez, Ricardo; McIntyre, Kathleen J.;
Himes, Michael D.; Rodríguez, Eloy; Anglada-Escudé, Guillem;
Dreizler, Stefan; Ofir, Aviv; Peña Rojas, Pablo A.; Ribas, Ignasi;
Rojo, Patricio; Kipping, David; Butler, R. Paul; Amado, Pedro J.;
Rodríguez-López, Cristina; Palle, Enric; Murgas, Felipe
2021PSJ.....2....9C Altcode: 2020arXiv201105270C
We observed Proxima Centauri with the Spitzer Space Telescope Infrared
Array Camera five times in 2016 and 2017 to search for transits of
Proxima Centauri b. Following standard analysis procedures, we found
three asymmetric, transit-like events that are now understood to be
vibrational systematics. This systematic is correlated with the width
of the point-response function (PRF), which we measure with rotated
and nonrotated-Gaussian fits with respect to the detector array. We
show that the systematic can be removed with a novel application of
an adaptive elliptical-aperture photometry technique, and compare the
performance of this technique with fixed and variable circular-aperture
photometry, using both BiLinearly Interpolated Subpixel Sensitivity
(BLISS) maps and nonbinned Pixel-Level Decorrelation (PLD). With BLISS
maps, elliptical photometry results in a lower standard deviation
of normalized residuals, and reduced or similar correlated noise
when compared to circular apertures. PLD prefers variable, circular
apertures, but generally results in more correlated noise than
BLISS. This vibrational effect is likely present in other telescopes
and Spitzer observations, where correction could improve results. Our
elliptical apertures can be applied to any photometry observations,
and may be even more effective when applied to more circular PRFs
than Spitzer's.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. LP 714-47 b
(TOI 442.01): populating the Neptune desert
Authors: Dreizler, S.; Crossfield, I. J. M.; Kossakowski, D.; Plavchan,
P.; Jeffers, S. V.; Kemmer, J.; Luque, R.; Espinoza, N.; Pallé, E.;
Stassun, K.; Matthews, E.; Cale, B.; Caballero, J. A.; Schlecker, M.;
Lillo-Box, J.; Zechmeister, M.; Lalitha, S.; Reiners, A.; Soubkiou,
A.; Bitsch, B.; Zapatero Osorio, M. R.; Chaturvedi, P.; Hatzes, A. P.;
Ricker, G.; Vanderspek, R.; Latham, D. W.; Seager, S.; Winn, J.;
Jenkins, J. M.; Aceituno, J.; Amado, P. J.; Barkaoui, K.; Barbieri, M.;
Batalha, N. M.; Bauer, F. F.; Benneke, B.; Benkhaldoun, Z.; Beichman,
C.; Berberian, J.; Burt, J.; Butler, R. P.; Caldwell, D. A.; Chintada,
A.; Chontos, A.; Christiansen, J. L.; Ciardi, D. R.; Cifuentes, C.;
Collins, K. A.; Collins, K. I.; Combs, D.; Cortés-Contreras, M.;
Crane, J. D.; Daylan, T.; Dragomir, D.; Esparza-Borges, E.; Evans, P.;
Feng, F.; Flowers, E. E.; Fukui, A.; Fulton, B.; Furlan, E.; Gaidos,
E.; Geneser, C.; Giacalone, S.; Gillon, M.; Gonzales, E.; Gorjian,
V.; Hellier, C.; Hidalgo, D.; Howard, A. W.; Howell, S.; Huber, D.;
Isaacson, H.; Jehin, E.; Jensen, E. L. N.; Kaminski, A.; Kane, S. R.;
Kawauchi, K.; Kielkopf, J. F.; Klahr, H.; Kosiarek, M. R.; Kreidberg,
L.; Kürster, M.; Lafarga, M.; Livingston, J.; Louie, D.; Mann, A.;
Madrigal-Aguado, A.; Matson, R. A.; Mocnik, T.; Morales, J. C.;
Muirhead, P. S.; Murgas, F.; Nandakumar, S.; Narita, N.; Nowak,
G.; Oshagh, M.; Parviainen, H.; Passegger, V. M.; Pollacco, D.;
Pozuelos, F. J.; Quirrenbach, A.; Reefe, M.; Ribas, I.; Robertson,
P.; Rodríguez-López, C.; Rose, M. E.; Roy, A.; Schweitzer, A.;
Schlieder, J.; Shectman, S.; Tanner, A.; Şenavcı, H. V.; Teske, J.;
Twicken, J. D.; Villasenor, J.; Wang, S. X.; Weiss, L. M.; Wittrock,
J.; Yılmaz, M.; Zohrabi, F.
2020A&A...644A.127D Altcode: 2020arXiv201101716D
We report the discovery of a Neptune-like planet (LP 714-47 b, P =
4.05204 d, m<SUB>b</SUB> = 30.8 ± 1.5M<SUB>⊕</SUB>, R<SUB>b</SUB>
= 4.7 ± 0.3 R<SUB>⊕</SUB>) located in the "hot Neptune
desert". Confirmation of the TESS Object of Interest (TOI 442.01)
was achieved with radial-velocity follow-up using CARMENES, ESPRESSO,
HIRES, iSHELL, and PFS, as well as from photometric data using TESS,
Spitzer, and ground-based photometry from MuSCAT2, TRAPPIST-South,
MONET-South, the George Mason University telescope, the Las Cumbres
Observatory Global Telescope network, the El Sauce telescope, the
TÜBİTAK National Observatory, the University of Louisville Manner
Telescope, and WASP-South. We also present high-spatial resolution
adaptive optics imaging with the Gemini Near-Infrared Imager. The low
uncertainties in the mass and radius determination place LP 714-47 b
among physically well-characterised planets, allowing for a meaningful
comparison with planet structure models. The host star LP 714-47 is
a slowly rotating early M dwarf (T<SUB>eff</SUB> = 3950 ± 51 K)
with a mass of 0.59 ± 0.02M<SUB>⊙</SUB> and a radius of 0.58
± 0.02R<SUB>⊙</SUB>. From long-term photometric monitoring and
spectroscopic activity indicators, we determine a stellar rotation
period of about 33 d. The stellar activity is also manifested as
correlated noise in the radial-velocity data. In the power spectrum
of the radial-velocity data, we detect a second signal with a period
of 16 days in addition to the four-day signal of the planet. This
could be shown to be a harmonic of the stellar rotation period or the
signal of a second planet. It may be possible to tell the difference
once more TESS data and radial-velocity data are obtained. <P
/>RV data are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/644/A127">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/644/A127</A>
<P />Based on observations carried out at the Centro Astronómico
Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Junta
de Andalucía and the Instituto de Astrofísica de Andalucía (CSIC),
on observations carried out at the European Southern Observatory
under ESO programme 0103.C-0152(A), and data collected with the 6.5
m Magellan Telescopes located at Las Campanas Observatory, Chile.
---------------------------------------------------------
Title: The CARMENES M-dwarf planet survey
Authors: Quirrenbach, Andreas; CARMENES Consortium; Amado, P. J.;
Ribas, I.; Reiners, A.; Caballero, J. A.; Aceituno, J.; Alacid, J. M.;
Alonso-Floriano, F. J.; Anglada-Escudé, G.; Azzaro, M.; Baroch,
D.; Bauer, F. F.; Becerril, S.; Béjar, V. J. S.; Bluhm, P.; Calvo
Ortega, R.; Cardona Guillén, C.; Casasayas-Barris, N.; Chaturvedi, P.;
Cifuentes, C.; Colomé, J.; Conte, D.; Cortés-Contreras, M.; Czesla,
S.; Díez-Alonso, E.; Domínguez Fernández, A. J.; Dreizler, S.;
Duque-Arribas, C.; Espinoza, N.; Fuhrmeister, B.; Galadí-Enríquez,
D.; Gar´a Quintana, E.; González-Alvare, E.; González Cuesta,
z. L.; González Hernández, J. I.; Guenther, E. W.; de Guindos,
E.; Hatzes, A. P.; Henning, T.; Herbort, O.; Herrero, E.; Hintz,
D.; Iglesias-Pára, J.; Jeffers, S. V.; Johnson, E. N.; de Juan, E.;
Kaminski, A.; Kemmer, J.; Khaimova, J.; Khalafinejad, S.; Klahr, H.;
Kossakowski, D.; Kreidberg, L.; Kürster, M.; Labarga, F.; Lafarga, M.;
Lampón, M.; Lara, L. M.; Lillo-Box, J.; Lodieu, N.; López Gallifa,
A.; López González, M. J.; López-Puertas, M.; Luque, R.; Marfil,
E.; Martín-Ruiz, S.; Matthé, C.; Molaverdikhani, K.; Montes, D.;
Morales, J. C.; Morales-Calderóon, M.; Nagel, E.; Nortmann, L.; Nowak,
G.; Ofir, A.; Oshaghi, M.; Pallé, E.; Passegger, V. M.; Pavlov,
A.; Pedraz, S.; Perdelwitz, V.; Perger, M.; Reffert, S.; Revilla,
D.; Rodríguez, E.; Rodríguez López, C.; Sabotta, S.; Sadegi, S.;
Sairam, L.; Salz, M.; Sánchez-López, A.; Sanz-Forcada, J.; Sarkis,
P.; Schäfer, S.; Schiller, J.; Schlecker, M.; Schmitt, J. H. M. M.;
Schöfer, P.; Schweitzer, A.; Seiferta, W.; Shan, Y.; Shulyak, D.;
Skrzypinski, S. L.; Solano, E.; Soto, M. G.; Stahl, O.; Stangret, M.;
Stock, S. A.; Strachan, J. B. P.; Stuber, T.; Stürmer, J.; Tabernero,
H. M.; Tal-Or, L.; Tala-Pinto, M.; Trifonov, T.; Vanaverbeke, S.;
Yan, F.; Zapatero Osorio, M. R.; Zechmeister, M.
2020SPIE11447E..3CQ Altcode:
The CARMENES instrument consists of two cross-dispersed Échelle
spectrographs, which together cover the wavelength range from 5,200
to 17,100 Å. During its first five years of operation at the 3.5 m
telescope on Calar Alto, Spain, it has been used for a radial-velocity
survey of 365 M dwarfs, for follow-up radial-velocity observations
of transiting exoplanets, and for spectroscopic studies of exoplanet
atmospheres during transits. The CARMENES data have also yielded a
wealth of information on the fundamental parameters and activity of
M dwarfs. We provide an overview of the scientific results from the
main CARMENES survey in the years 2016 to 2020.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Three
temperate-to-warm super-Earths
Authors: Stock, S.; Nagel, E.; Kemmer, J.; Passegger, V. M.; Reffert,
S.; Quirrenbach, A.; Caballero, J. A.; Czesla, S.; Béjar, V. J. S.;
Cardona, C.; Díez-Alonso, E.; Herrero, E.; Lalitha, S.; Schlecker,
M.; Tal-Or, L.; Rodríguez, E.; Rodríguez-López, C.; Ribas, I.;
Reiners, A.; Amado, P. J.; Bauer, F. F.; Bluhm, P.; Cortés-Contreras,
M.; González-Cuesta, L.; Dreizler, S.; Hatzes, A. P.; Henning,
Th.; Jeffers, S. V.; Kaminski, A.; Kürster, M.; Lafarga, M.;
López-González, M. J.; Montes, D.; Morales, J. C.; Pedraz, S.;
Schöfer, P.; Schweitzer, A.; Trifonov, T.; Zapatero Osorio, M. R.;
Zechmeister, M.
2020A&A...643A.112S Altcode: 2020arXiv201000474S
We announce the discovery of two planets orbiting the M dwarfs
GJ 251 (0.360 ± 0.015M<SUB>⊙</SUB>) and HD 238090 (0.578 ±
0.021M<SUB>⊙</SUB>) based on CARMENES radial velocity (RV) data. In
addition, we independently confirm with CARMENES data the existence
of Lalande 21185 b, a planet that has recently been discovered with
the SOPHIE spectrograph. All three planets belong to the class of
warm or temperate super-Earths and share similar properties. The
orbital periods are 14.24 d, 13.67 d, and 12.95 d and the minimum
masses are 4.0 ± 0.4 M<SUB>⊕</SUB>, 6.9 ± 0.9 M<SUB>⊕</SUB>,
and 2.7 ± 0.3 M<SUB>⊕</SUB> for GJ 251 b, HD 238090 b, and Lalande
21185 b, respectively. Based on the orbital and stellar properties,
we estimate equilibrium temperatures of 351.0 ± 1.4 K for GJ 251 b,
469.6 ± 2.6 K for HD 238090 b, and 370.1 ± 6.8 K for Lalande 21185
b. For the latter we resolve the daily aliases that were present in
the SOPHIE data and that hindered an unambiguous determination of the
orbital period. We find no significant signals in any of our spectral
activity indicators at the planetary periods. The RV observations
were accompanied by contemporaneous photometric observations. We
derive stellar rotation periods of 122.1 ± 2.2 d and 96.7 ± 3.7
d for GJ 251 and HD 238090, respectively. The RV data of all three
stars exhibit significant signals at the rotational period or its
first harmonic. For GJ 251 and Lalande 21185, we also find long-period
signals around 600 d, and 2900 d, respectively, which we tentatively
attribute to long-term magnetic cycles. We apply a Bayesian approach to
carefully model the Keplerian signals simultaneously with the stellar
activity using Gaussian process regression models and extensively
search for additional significant planetary signals hidden behind
the stellar activity. Current planet formation theories suggest
that the three systems represent a common architecture, consistent
with formation following the core accretion paradigm. <P />Tables
D.1-D.3 are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/643/A112">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/643/A112</A>
---------------------------------------------------------
Title: Leveraging HST with MUSE - I. Sodium abundance variations
within the 2-Gyr-old cluster NGC 1978
Authors: Saracino, S.; Kamann, S.; Usher, C.; Bastian, N.; Martocchia,
S.; Lardo, C.; Latour, M.; Cabrera-Ziri, I.; Dreizler, S.; Giesers,
B.; Husser, T. -O.; Kacharov, N.; Salaris, M.
2020MNRAS.498.4472S Altcode: 2020arXiv200903320S
Nearly all of the well-studied ancient globular clusters (GCs), in
the Milky Way and in nearby galaxies, show star-to-star variations in
specific elements (e.g. He, C, N, O, Na, and Al), known as 'multiple
populations' (MPs). However, MPs are not restricted to ancient clusters,
with massive clusters down to ~2 Gyr showing signs of chemical
variations. This suggests that young and old clusters share the same
formation mechanism but most of the work to date on younger clusters has
focused on N variations. Initial studies even suggested that younger
clusters may not host spreads in other elements beyond N (e.g. Na),
calling into question whether these abundance variations share the
same origin as in the older GCs. In this work, we combine Hubble Space
Telescope (HST) photometry with Very Large Telescope (VLT)/Multi-Unit
Spectroscopic Explorer (MUSE) spectroscopy of a large sample of red
giant branch (RGB) stars (338) in the Large Magellanic Cloud cluster
NGC 1978, the youngest globular to date with reported MPs in the form
of N spreads. By combining the spectra of individual RGB stars into
N-normal and N-enhanced samples, based on the 'chromosome map' derived
from HST, we search for mean abundance variations. Based on the NaD
line, we find a Na difference of Δ[Na/Fe] = 0.07 ± 0.01 between the
populations. While this difference is smaller than typically found in
ancient GCs (which may suggest a correlation with age), this result
further confirms that the MP phenomenon is the same, regardless of
cluster age and host galaxy. As such, these young clusters offer some
of the strictest tests for theories on the origin of MPs.
---------------------------------------------------------
Title: Leveraging HST with MUSE: II. Na-abundance variations in
intermediate age star clusters
Authors: Martocchia, S.; Kamann, S.; Saracino, S.; Usher, C.; Bastian,
N.; Rejkuba, M.; Latour, M.; Lardo, C.; Cabrera-Ziri, I.; Dreizler,
S.; Kacharov, N.; Kozhurina-Platais, V.; Larsen, S.; Mancino, S.;
Platais, I.; Salaris, M.
2020MNRAS.499.1200M Altcode: 2020arXiv200910023M; 2020MNRAS.tmp.2740M
Ancient (>10 Gyr) globular clusters (GCs) show chemical abundance
variations in the form of patterns among certain elements, e.g. N
correlates with Na and anticorrelates with O. Recently, N abundance
spreads have also been observed in massive star clusters that are
significantly younger than old GCs, down to an age of ~2 Gyr. However,
so far N has been the only element found to vary in such young
objects. We report here the presence of Na abundance variations in
the intermediate age massive star clusters NGC 416 (~6.5 Gyr old) and
Lindsay 1 (~7.5 Gyr old) in the Small Magellanic Cloud, by combining
Hubble Space Telescope (HST) and European Southern Observatory Very
Large Telescope MUSE observations. Using HST photometry, we were able to
construct 'chromosome maps' and separate subpopulations with different
N content, in the red giant branch of each cluster. MUSE spectra of
individual stars belonging to each population were combined, resulting
in high signal-to-noise spectra representative of each population,
which were compared to search for mean differences in Na. We find a mean
abundance variation of Δ[Na/Fe] = 0.18 ± 0.04 dex for NGC 416 and
Δ[Na/Fe] = 0.24 ± 0.05 dex for Lindsay 1. In both clusters, we find
that the population that is enhanced in N is also enhanced in Na, which
is the same pattern to the one observed in ancient GCs. Furthermore,
we detect a bimodal distribution of core-helium-burning red clump (RC)
giants in the UV colour-magnitude diagram of NGC 416. A comparison of
the stacked MUSE spectra of the two RCs shows the same mean Na abundance
difference between the two populations. The results reported in this
work are a crucial hint that star clusters of a large age range share
the same origin: they are the same types of objects, but only separated
in age.
---------------------------------------------------------
Title: VizieR Online Data Catalog: LP714-47 (TOI 442) radial velocity
curve (Dreizler+, 2020)
Authors: Dreizler, S.; Crossfield, I. J. M.; Kossakowski, D.; Plavchan,
P.; Jeffers, S. V.; Kemmer, J.; Luque, R.; Espinoza, N.; Palle, E.;
Stassun, K.; Matthews, E.; Cale, B.; Caballero, J. A.; Schlecker, M.;
Lillo-Box, J.; Zechmeister, M.; Lalitha, S.; Reiners, A.; Soubkiou,
A.; Bitsch, B.; Zapatero Osorio, M. R.; Chaturvedi, P.; Hatzes, A. P.;
Ricker, G.; Vanderspek, R.; Latham, D. W.; Seager, S.; Winn, J.;
Jenkins, J. M.; Aceituno, J.; Amado, P. J.; Barkaoui, K.; Barbieri, M.;
Batalha, N. M.; Bauer, F. F.; Benneke, B.; Benkhaldoun, Z.; Beichman,
C.; Berberian, J.; Burt, J.; Butler, R. P.; Caldwell, D. A.; Chintada,
A.; Chontos, A.; Christiansen, J. L.; Ciardi, D. R.; Cifuentes, C.;
Collins, K. A.; Collins, K. I.; Combs, D.; Cortes-Contreras, M.;
Crane, J. D.; Daylan, T.; Dragomir, D.; Esparza-Borges, E.; Evans,
P.; Feng, F.; Flowers, E. E.; Fukui, A.; Fulton, B.; Furlan, E.;
Gaidos, E.; Geneser, C.; Giacalone, S.; Gillon, M.; Gonzales, E.;
Gorjian, V.; Hellier, C.; Hidalgo, D.; Howard, A. W.; Howell, S.;
Huber, D.; Isaacson, H.; Jehin, E.; Jensen, E. L. N.; Kaminski, A.;
Kane, S. R.; Kawauchi, K.; Kielkopf, J. F.; Klahr, H.; Kosiarek,
M. R.; Kreidberg, L.; Kuerster, M.; Lafarga, M.; Livingston, J.;
Louie, D.; Mann, A.; Madrigal-Aguado, A.; Matson, R. A.; Mocnik,
T.; Morales, J. C.; Muirhead, P. S.; Murgas, F.; Nandakumar, S.;
Narita, N.; Nowak, G.; Oshagh, M.; Parviainen, H.; Passegger, V. M.;
Pollacco, D.; Pozuelos, F. J.; Quirrenbach, A.; Reefe, M.; Ribas, I.;
Robertson, P.; Rodriguez-Lopez, C.; Rose, M. E.; Roy, A.; Schweitzer,
A.; Schlieder, J.; Shectman, S.; Tanner, A.; Senavci, H. V.; Teske, J.;
Twicken, J. D.; Villasenor, J.; Wang, S. X.; Weiss, L. M.; Wittrock,
J.; Yilmaz, M.; Zohrabi, F.
2020yCat..36440127D Altcode:
High-resolution follow-up spectroscopy of the TESS planet candidates
is arranged by the TESS follow-up programme (TFOP), "Precise Radial
Velocities" SG4 subgroup. <P />We obtained High-resolution follow-up
spectroscopy for LP714-47 with CARMENES-VIS, CARMENES-NIR, ESPRESSO,
HIRES, iSHELL, and PFS. The observations began at mid February 2019,
just after the announcement of the transiting planet candidate, and
ended in January 2020. In this period, we collected 102 spectra. The
spectral resolution and the number of spectra obtained by the individual
instruments are listed in Table 1 of the paper. <P />The table contains
the time of observation as Barycentric Julian Date in units of days,
the measure radial velocities in unites of m/s, the measurement
uncertainties measured in m/s, and the instrument name. <P />(1
data file).
---------------------------------------------------------
Title: Discovery of a hot, transiting, Earth-sized planet and a second
temperate, non-transiting planet around the M4 dwarf GJ 3473 (TOI-488)
Authors: Kemmer, J.; Stock, S.; Kossakowski, D.; Kaminski, A.;
Molaverdikhani, K.; Schlecker, M.; Caballero, J. A.; Amado, P. J.;
Astudillo-Defru, N.; Bonfils, X.; Ciardi, D.; Collins, K. A.; Espinoza,
N.; Fukui, A.; Hirano, T.; Jenkins, J. M.; Latham, D. W.; Matthews,
E. C.; Narita, N.; Pallé, E.; Parviainen, H.; Quirrenbach, A.;
Reiners, A.; Ribas, I.; Ricker, G.; Schlieder, J. E.; Seager, S.;
Vanderspek, R.; Winn, J. N.; Almenara, J. M.; Béjar, V. J. S.;
Bluhm, P.; Bouchy, F.; Boyd, P.; Christiansen, J. L.; Cifuentes,
C.; Cloutier, R.; Collins, K. I.; Cortés-Contreras, M.; Crossfield,
I. J. M.; Crouzet, N.; de Leon, J. P.; Della-Rose, D. D.; Delfosse,
X.; Dreizler, S.; Esparza-Borges, E.; Essack, Z.; Forveille, Th.;
Figueira, P.; Galadí-Enríquez, D.; Gan, T.; Glidden, A.; Gonzales,
E. J.; Guerra, P.; Harakawa, H.; Hatzes, A. P.; Henning, Th.; Herrero,
E.; Hodapp, K.; Hori, Y.; Howell, S. B.; Ikoma, M.; Isogai, K.;
Jeffers, S. V.; Kürster, M.; Kawauchi, K.; Kimura, T.; Klagyivik,
P.; Kotani, T.; Kurokawa, T.; Kusakabe, N.; Kuzuhara, M.; Lafarga,
M.; Livingston, J. H.; Luque, R.; Matson, R.; Morales, J. C.; Mori,
M.; Muirhead, P. S.; Murgas, F.; Nishikawa, J.; Nishiumi, T.; Omiya,
M.; Reffert, S.; Rodríguez López, C.; Santos, N. C.; Schöfer, P.;
Schwarz, R. P.; Shiao, B.; Tamura, M.; Terada, Y.; Twicken, J. D.;
Ueda, A.; Vievard, S.; Watanabe, N.; Zechmeister, M.
2020A&A...642A.236K Altcode: 2020arXiv200910432K
We present the confirmation and characterisation of GJ 3473 b (G 50-16,
TOI-488.01), a hot Earth-sized planet orbiting an M4 dwarf star, whose
transiting signal (P = 1.1980035 ± 0.0000018 d) was first detected
by the Transiting Exoplanet Survey Satellite (TESS). Through a joint
modelling of follow-up radial velocity observations with CARMENES, IRD,
and HARPS together with extensive ground-based photometric follow-up
observations with LCOGT, MuSCAT, and MuSCAT2, we determined a precise
planetary mass, M<SUB>b</SUB> = 1.86 ± 0.30 M<SUB>⊕</SUB>, and
radius, R<SUB>b</SUB> = 1.264 ± 0.050 R<SUB>⊕</SUB>. Additionally,
we report the discovery of a second, temperate, non-transiting planet
in the system, GJ 3473 c, which has a minimum mass, M<SUB>c</SUB> sin
i = 7.41 ± 0.91 M<SUB>⊕</SUB>, and orbital period, P<SUB>c</SUB>
= 15.509 ± 0.033 d. The inner planet of the system, GJ 3473 b,
is one of the hottest transiting Earth-sized planets known thus
far, accompanied by a dynamical mass measurement, which makes it a
particularly attractive target for thermal emission spectroscopy. <P
/>RV data are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/642/A236">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/642/A236</A>
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Two
planets on opposite sides of the radius gap transiting the nearby
M dwarf LTT 3780
Authors: Nowak, G.; Luque, R.; Parviainen, H.; Pallé, E.;
Molaverdikhani, K.; Béjar, V. J. S.; Lillo-Box, J.; Rodríguez-López,
C.; Caballero, J. A.; Zechmeister, M.; Passegger, V. M.; Cifuentes,
C.; Schweitzer, A.; Narita, N.; Cale, B.; Espinoza, N.; Murgas, F.;
Hidalgo, D.; Zapatero Osorio, M. R.; Pozuelos, F. J.; Aceituno, F. J.;
Amado, P. J.; Barkaoui, K.; Barrado, D.; Bauer, F. F.; Benkhaldoun,
Z.; Caldwell, D. A.; Casasayas Barris, N.; Chaturvedi, P.; Chen, G.;
Collins, K. A.; Collins, K. I.; Cortés-Contreras, M.; Crossfield,
I. J. M.; de León, J. P.; Díez Alonso, E.; Dreizler, S.; El Mufti,
M.; Esparza-Borges, E.; Essack, Z.; Fukui, A.; Gaidos, E.; Gillon,
M.; Gonzales, E. J.; Guerra, P.; Hatzes, A.; Henning, Th.; Herrero,
E.; Hesse, K.; Hirano, T.; Howell, S. B.; Jeffers, S. V.; Jehin, E.;
Jenkins, J. M.; Kaminski, A.; Kemmer, J.; Kielkopf, J. F.; Kossakowski,
D.; Kotani, T.; Kürster, M.; Lafarga, M.; Latham, D. W.; Law, N.;
Lissauer, J. J.; Lodieu, N.; Madrigal-Aguado, A.; Mann, A. W.; Massey,
B.; Matson, R. A.; Matthews, E.; Montañés-Rodríguez, P.; Montes,
D.; Morales, J. C.; Mori, M.; Nagel, E.; Oshagh, M.; Pedraz, S.;
Plavchan, P.; Pollacco, D.; Quirrenbach, A.; Reffert, S.; Reiners,
A.; Ribas, I.; Ricker, G. R.; Rose, M. E.; Schlecker, M.; Schlieder,
J. E.; Seager, S.; Stangret, M.; Stock, S.; Tamura, M.; Tanner, A.;
Teske, J.; Trifonov, T.; Twicken, J. D.; Vanderspek, R.; Watanabe,
D.; Wittrock, J.; Ziegler, C.; Zohrabi, F.
2020A&A...642A.173N Altcode: 2020arXiv200301140N
We present the discovery and characterisation of two transiting
planets observed by the Transiting Exoplanet Survey Satellite
(TESS) orbiting the nearby (d<SUB>⋆</SUB> ≈ 22 pc), bright (J
≈ 9 mag) M3.5 dwarf LTT 3780 (TOI-732). We confirm both planets
and their association with LTT 3780 via ground-based photometry and
determine their masses using precise radial velocities measured with
the CARMENES spectrograph. Precise stellar parameters determined
from CARMENES high-resolution spectra confirm that LTT 3780 is a
mid-M dwarf with an effective temperature of T<SUB>eff</SUB> = 3360
± 51 K, a surface gravity of log g<SUB>⋆</SUB> = 4.81 ± 0.04
(cgs), and an iron abundance of [Fe/H] = 0.09 ± 0.16 dex, with an
inferred mass of M<SUB>⋆</SUB> = 0.379 ± 0.016M<SUB>⊙</SUB>
and a radius of R<SUB>⋆</SUB> = 0.382 ± 0.012R<SUB>⊙</SUB>. The
ultra-short-period planet LTT 3780 b (P<SUB>b</SUB> = 0.77 d) with
a radius of 1.35<SUB>-0.06</SUB><SUP>+0.06</SUP> R<SUB>⊕</SUB>,
a mass of 2.34<SUP>-0.23</SUP><SUB>+0.24</SUB> M<SUB>⊕</SUB>, and a
bulk density of 5.24<SUB>-0.81</SUB><SUP>+0.94</SUP> g cm<SUP>-3</SUP>
joins the population of Earth-size planets with rocky, terrestrial
composition. The outer planet, LTT 3780 c, with an orbital period of
12.25 d, radius of 2.42<SUB>-0.10</SUB><SUP>+0.10</SUP> R<SUB>⊕</SUB>,
mass of 6.29<SUB>-0.61</SUB><SUP>+0.63</SUP> M<SUB>⊕</SUB>, and
mean density of 2.45<SUB>-0.37</SUB><SUP>+0.44</SUP> g cm<SUP>-3</SUP>
belongs to the population of dense sub-Neptunes. With the two planets
located on opposite sides of the radius gap, this planetary system
is anexcellent target for testing planetary formation, evolution,
and atmospheric models. In particular, LTT 3780 c is an ideal object
for atmospheric studies with the James Webb Space Telescope (JWST).
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Rubidium
abundances in nearby cool stars
Authors: Abia, C.; Tabernero, H. M.; Korotin, S. A.; Montes, D.;
Marfil, E.; Caballero, J. A.; Straniero, O.; Prantzos, N.; Ribas,
I.; Reiners, A.; Quirrenbach, A.; Amado, P. J.; Béjar, V. J. S.;
Cortés-Contreras, M.; Dreizler, S.; Henning, Th.; Jeffers, S. V.;
Kaminski, A.; Kürster, M.; Lafarga, M.; López-Gallifa, Á.; Morales,
J. C.; Nagel, E.; Passegger, V. M.; Pedraz, S.; Rodríguez López,
C.; Schweitzer, A.; Zechmeister, M.
2020A&A...642A.227A Altcode: 2020arXiv200900876A
Due to their ubiquity and very long main-sequence lifetimes, abundance
determinations in M dwarfs provide a powerful and alternative tool to
GK dwarfs to study the formation and chemical enrichment history of our
Galaxy. In this study, abundances of the neutron-capture elements Rb,
Sr, and Zr are derived, for the first time, in a sample of nearby M
dwarfs. We focus on stars in the metallicity range - 0.5 ≲ [Fe/H]
≲ +0.3, an interval poorly explored for Rb abundances in previous
analyses. To do this we use high-resolution, high-signal-to-noise-ratio,
optical and near-infrared spectra of 57 M dwarfs observed with
CARMENES. The resulting [Sr/Fe] and [Zr/Fe] ratios for most M dwarfs
are almost constant at about the solar value, and are identical to
those found in GK dwarfs of the same metallicity. However, for Rb we
find systematic underabundances ([Rb/Fe] < 0.0) by a factor two on
average. Furthermore, a tendency is found for Rb - but not for other
heavy elements (Sr, Zr) - to increase with increasing metallicity
such that [Rb/Fe] ≳ 0.0 is attained at metallicities higher than
solar. These are surprising results, never seen for any other heavy
element, and are difficult to understand within the formulation of
the s- and r-processes, both contributing sources to the Galactic
Rb abundance. We discuss the reliability of these findings for
Rb in terms of non-LTE (local thermodynamic equilibrium) effects,
stellar activity, or an anomalous Rb abundance in the Solar System,
but no explanation is found. We then interpret the full observed [Rb/Fe]
versus [Fe/H] trend within the framework of theoretical predictions from
state-of-the-art chemical evolution models for heavy elements, but a
simple interpretation is not found either. In particular, the possible
secondary behaviour of the [Rb/Fe] ratio at super-solar metallicities
would require a much larger production of Rb than currently predicted
in AGB stars through the s-process without overproducing Sr and Zr.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. A deep
learning approach to determine fundamental parameters of target stars
Authors: Passegger, V. M.; Bello-García, A.; Ordieres-Meré, J.;
Caballero, J. A.; Schweitzer, A.; González-Marcos, A.; Ribas, I.;
Reiners, A.; Quirrenbach, A.; Amado, P. J.; Azzaro, M.; Bauer, F. F.;
Béjar, V. J. S.; Cortés-Contreras, M.; Dreizler, S.; Hatzes, A. P.;
Henning, Th.; Jeffers, S. V.; Kaminski, A.; Kürster, M.; Lafarga,
M.; Marfil, E.; Montes, D.; Morales, J. C.; Nagel, E.; Sarro, L. M.;
Solano, E.; Tabernero, H. M.; Zechmeister, M.
2020A&A...642A..22P Altcode: 2020arXiv200801186P
Existing and upcoming instrumentation is collecting large amounts
of astrophysical data, which require efficient and fast analysis
techniques. We present a deep neural network architecture to analyze
high-resolution stellar spectra and predict stellar parameters such as
effective temperature, surface gravity, metallicity, and rotational
velocity. With this study, we firstly demonstrate the capability of
deep neural networks to precisely recover stellar parameters from
a synthetic training set. Secondly, we analyze the application of
this method to observed spectra and the impact of the synthetic gap
(i.e., the difference between observed and synthetic spectra) on the
estimation of stellar parameters, their errors, and their precision. Our
convolutional network is trained on synthetic PHOENIX-ACES spectra
in different optical and near-infrared wavelength regions. For
each of the four stellar parameters, T<SUB>eff</SUB>, log g, [M/H],
and v sin i, we constructed a neural network model to estimate each
parameter independently. We then applied this method to 50 M dwarfs with
high-resolution spectra taken with CARMENES (Calar Alto high-Resolution
search for M dwarfs with Exo-earths with Near-infrared and optical
Échelle Spectrographs), which operates in the visible (520-960 nm)
and near-infrared wavelength range (960-1710 nm) simultaneously. Our
results are compared with literature values for these stars. They
show mostly good agreement within the errors, but also exhibit large
deviations in some cases, especially for [M/H], pointing out the
importance of a better understanding of the synthetic gap.
---------------------------------------------------------
Title: VizieR Online Data Catalog: CARMENES VIS RVs of 3 M dwarfs
(Stock+, 2020)
Authors: Stock, S.; Nagel, E.; Kemmer, J.; Passegger, V. M.; Reffert,
S.; Quirrenbach, A.; Caballero, J. A.; Czesla, S.; Bejar, V. J. S.;
Cardona, C.; Diez-Alonso, E.; Herrero, E.; Lalitha, S.; Schlecker, M.;
Tal-Or, L.; Rodriguez, E.; Rodriguez-Lopez, C.; Ribas, I.; Reiners,
A.; Amado, P. J.; Bauer, F. F.; Bluhm, P.; Cortes-Contreras, M.;
Gonzalez-Cuesta, L.; Dreizler, S.; Hatzes, A. P.; Henning, T.; Jeffers,
S. V.; Kaminski, A.; Kuerster, M.; Lafarga, M.; Lopez-Gonzalez, M. J.;
Montes, D.; Morales, J. C.; Pedraz, S.; Schoefer, P.; Schweitzer,
A.; Trifonov, T.; Zapatero Osorio, M. R.; Zechmeister, M.
2020yCat..36430112S Altcode:
We acquired spectra with CARMENES (Quirrenbach et al., 2014, in
Proc. SPIE, Vol. 9147, Ground-based and Airborne Instrumentation for
Astronomy V, 91471F), a high-resolution precise echelle spectrograph
mounted at the 3.5m telescope at the Calar Alto Observatory in Spain. <P
/>(3 data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: GJ 3473 (TOI-488) radial velocity
curve (Kemmer+, 2020)
Authors: Kemmer, J.; Stock, S.; Kossakowski, D.; Kaminski, A.;
Molaverdikhani, K.; Schlecker, M.; Caballero, J. A.; Amado, P. J.;
Astudillo-Defru, N.; Bonfils, X.; Ciardi, D.; Collins, K. A.; Espinoza,
N.; Fukui, A.; Hirano, T.; Jenkins, J. M.; Latham, D. W.; Matthews,
E. C.; Narita, N.; Palle, E.; Parviainen, H.; Quirrenbach, A.; Reiners,
A.; Ribas, I.; Ricker, G.; Schlieder, J. E.; Seager, S.; Vanderspek,
R.; Winn, J. N.; Almenara, J. M.; Bejar, V. J. S.; Bluhm, P.; Bouchy,
F.; Boyd, P.; Christiansen, J. L.; Cifuentes, C.; Cloutier, R.;
Collins, K. I.; Cortes-Contreras, M.; I. J. M., Crossfield; Crouzet,
N.; de, Leon J. P.; Della-Rose, D. D.; Delfosse, X.; Dreizler,
S.; Esparza-Borges, E.; Essack, Z.; Forveille, T.; Figueira, P.;
Galadi-Enriquez, D.; Gan, T.; Glidden, A.; Gonzales, E. J.; Guerra,
P.; Harakawa, H.; Hatzes, A. P.; Henning, T.; Herrero, E.; Hodapp,
K.; Hori, Y.; Howell, S. B.; Ikoma, M.; Isogai, K.; Jeffers, S. V.;
Kuerster, M.; Kawauchi, K.; Kimura, T.; Klagyivik, P.; Kotani, T.;
Kurokawa, T.; Kusakabe, N.; Kuzuhara, M.; Lafarga, M.; Livingston,
J. H.; Luqu!, E. R.; Mat Son, R.; Morales, J. C.; Mori, M.; Muirhead,
P. S.; Murgas, F.; Nishikawa, J.; Nishiumi, T.; Omiya, M.; Reffert,
S.; Rodriguez Lopez, C.; Santos, N. C.; Schoefer, P.; Schwarz, R. P.;
Shiao, B.; Tamura, M.; Terada, Y.; Twicken, J. D.; Ueda, A.; Vievard,
S.; Watanabe, N.; Zechmeister, M.
2020yCat..36420236K Altcode:
High-resolution follow-up spectroscopy of the TESS planet candidates
is arranged by the TESS follow-up programme (TFOP), "Precise Radial
Velocities" SG4 subgroup. <P />We observed GJ 3473 with CARMENES. The
observations began at the end of March 2019, just after the announcement
of the transiting planet candidate, and ended in January 2020. In this
period, we collected 67 pairs of VIS and NIR spectra with exposure
times of about 30 min each. <P />In the course of the Subaru IRD TESS
Intensive Follow-up Project (proposal S19A-069I), we observed GJ 3473
with the InfraRed Doppler spectrograph (IRD). A total of 56 frames were
acquired for GJ 3473 by IRD on 12 different nights between April 2019
and December 2019. <P />GJ 3473 was also observed by the High Accuracy
Radial velocity Planet Searcher (HARPS). The 32 observations presented
here were taken between May 2019 and March 2020. <P />(1 data file).
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Convective
shift and starspot constraints from chromatic radial velocities
Authors: Baroch, D.; Morales, J. C.; Ribas, I.; Herrero, E.;
Rosich, A.; Perger, M.; Anglada-Escudé, G.; Reiners, A.; Caballero,
J. A.; Quirrenbach, A.; Amado, P. J.; Jeffers, S. V.; Cifuentes,
C.; Passegger, V. M.; Schweitzer, A.; Lafarga, M.; Bauer, F. F.;
Béjar, V. J. S.; Colomé, J.; Cortés-Contreras, M.; Dreizler, S.;
Galadí-Enríquez, D.; Hatzes, A. P.; Henning, Th.; Kaminski, A.;
Kürster, M.; Montes, D.; Rodríguez-López, C.; Zechmeister, M.
2020A&A...641A..69B Altcode: 2020arXiv200616608B
Context. Variability caused by stellar activity represents a challenge
to the discovery and characterization of terrestrial exoplanets and
complicates the interpretation of atmospheric planetary signals. <BR
/> Aims: We aim to use a detailed modeling tool to reproduce the
effect of active regions on radial velocity measurements, which aids
the identification of the key parameters that have an impact on the
induced variability. <BR /> Methods: We analyzed the effect of stellar
activity on radial velocities as a function of wavelength by simulating
the impact of the properties of spots, shifts induced by convective
motions, and rotation. We focused our modeling effort on the active
star <ASTROBJ>YZ CMi</ASTROBJ> (GJ 285), which was photometrically
and spectroscopically monitored with CARMENES and the Telescopi Joan
Oró. <BR /> Results: We demonstrate that radial velocity curves
at different wavelengths yield determinations of key properties of
active regions, including spot-filling factor, temperature contrast,
and location, thus solving the degeneracy between them. Most notably,
our model is also sensitive to convective motions. Results indicate a
reduced convective shift for M dwarfs when compared to solar-type stars
(in agreement with theoretical extrapolations) and points to a small
global convective redshift instead of blueshift. <BR /> Conclusions:
Using a novel approach based on simultaneous chromatic radial velocities
and light curves, we can set strong constraints on stellar activity,
including an elusive parameter such as the net convective motion effect.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Variability
of the He I line at 10 830 Å
Authors: Fuhrmeister, B.; Czesla, S.; Hildebrandt, L.; Nagel, E.;
Schmitt, J. H. M. M.; Jeffers, S. V.; Caballero, J. A.; Hintz, D.;
Johnson, E. N.; Schöfer, P.; Zechmeister, M.; Reiners, A.; Ribas, I.;
Amado, P. J.; Quirrenbach, A.; Nortmann, L.; Bauer, F. F.; Béjar,
V. J. S.; Cortés-Contreras, M.; Dreizler, S.; Galadí-Enríquez,
D.; Hatzes, A. P.; Kaminski, A.; Kürster, M.; Lafarga, M.; Montes, D.
2020A&A...640A..52F Altcode: 2020arXiv200609372F
The He I infrared (IR) triplet at 10 830 Å is known as an activity
indicator in solar-type stars and has become a primary diagnostic in
exoplanetary transmission spectroscopy. He I IR lines are a tracer
of the stellar extreme-ultraviolet irradiation from the transition
region and corona. We study the variability of the He I triplet lines
in a spectral time series of 319 M dwarf stars that was obtained with
the CARMENES high-resolution optical and near-infrared spectrograph
at Calar Alto. We detect He I IR line variability in 18% of our
sample stars, all of which show Hα in emission. Therefore, we find
detectable He I variability in 78% of the sub-sample of stars with
Hα emission. Detectable variability is strongly concentrated in the
latest spectral sub-types, where the He I lines during quiescence
are typically weak. The fraction of stars with detectable He I
variation remains lower than 10% for stars earlier than M3.0 V,
while it exceeds 30% for the later spectral sub-types. Flares are
accompanied by particularly pronounced line variations, including
strongly broadened lines with red and blue asymmetries. However,
we also find evidence for enhanced He I absorption, which is
potentially associated with increased high-energy irradiation levels
at flare onset. Generally, He I and Hα line variations tend to be
correlated, with Hα being the most sensitive indicator in terms
of pseudo-equivalent width variation. This makes the He I triplet
a favourable target for planetary transmission spectroscopy. <P
/>Full Table 2 is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/640/A52">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/640/A52</A>
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Measuring
precise radial velocities in the near infrared: The example of the
super-Earth CD Cet b
Authors: Bauer, F. F.; Zechmeister, M.; Kaminski, A.; Rodríguez
López, C.; Caballero, J. A.; Azzaro, M.; Stahl, O.; Kossakowski,
D.; Quirrenbach, A.; Becerril Jarque, S.; Rodríguez, E.; Amado,
P. J.; Seifert, W.; Reiners, A.; Schäfer, S.; Ribas, I.; Béjar,
V. J. S.; Cortés-Contreras, M.; Dreizler, S.; Hatzes, A.; Henning,
T.; Jeffers, S. V.; Kürster, M.; Lafarga, M.; Montes, D.; Morales,
J. C.; Schmitt, J. H. M. M.; Schweitzer, A.; Solano, E.
2020A&A...640A..50B Altcode: 2020arXiv200601684B
The high-resolution, dual channel, visible and near-infrared
spectrograph CARMENES offers exciting opportunities for stellar
and exoplanetary research on M dwarfs. In this work we address the
challenge of reaching the highest radial velocity precision possible
with a complex, actively cooled, cryogenic instrument, such as the
near-infrared channel. We describe the performance of the instrument
and the work flow used to derive precise Doppler measurements from
the spectra. The capability of both CARMENES channels to detect
small exoplanets is demonstrated with the example of the nearby
M5.0 V star CD Cet (GJ 1057), around which we announce a super-Earth
(4.0 ± 0.4 M<SUB>⊕</SUB>) companion on a 2.29 d orbit. <P />Based
on observations collected at the Centro Astronómico Hispano Alemán
(CAHA) at Calar Alto, Almería, Spain, operated jointly by the Junta de
Andalucía and the Instituto de Astrofísica de Andalucía (CSIC). <P
/>Based on observations collected at the European Southern Observatory,
Paranal, Chile, under program 0103.C-0152(A), and La Silla, Chile,
under programs 072.C-0488(E) and 183.C-0437(A).
---------------------------------------------------------
Title: Stellar atmospheric parameters of FGK-type stars (EW method)
and M-type stars (spectral synthesis) from high-resolution optical
and near-infrared CARMENES spectra
Authors: Marfil, E.; Tabernero, H. M.; Montes, D.; Caballero, J. A.;
Lázaro-Barrasa, F. J.; González Hernández, J. I.; Soto, M. G.;
Nagel, E.; Kaminski, A.; Reiners, A.; Ribas, I.; Quirrenbach, A.;
Amado, P. J.; Bauer, F. F.; Cortés-Contreras, M.; Dreizler, S.;
Jeffers, S. V.; Kürster, M.; Lafarga, M.; Morales, J. C.; Passegger,
V. M.; Schweitzer, A.; Zechmeister, M.
2020sea..confE.156M Altcode:
We aim to review the equivalent width (EW) method and the spectral
synthesis technique to derive stellar atmospheric parameters of
FGKM-type stars in light of the optical and near-infrared spectra
obtained with CARMENES, the high-resolution, double-channel
spectrograph installed at the 3.5 m telescope at the Calar Alto
Observatory (Almería, Spain). On the one hand, we show the results
for 65 FGK-type stars observed with CARMENES and analysed with the
S TE P AR code, a Python implementation of the EW method, placing
special emphasis on the impact of the near-infrared wavelength region
on the parameter computations. On the other hand, we also highlight
the stellar atmospheric parameters obtained for the target M dwarfs in
the CARMENES Guaranteed Time Observations (GTO) programme by means of
the spectral synthesis technique as implemented in the SteParSyn code.
---------------------------------------------------------
Title: Precise mass and radius of a transiting super-Earth planet
orbiting the M dwarf TOI-1235: a planet in the radius gap?
Authors: Bluhm, P.; Luque, R.; Espinoza, N.; Pallé, E.; Caballero,
J. A.; Dreizler, S.; Livingston, J. H.; Mathur, S.; Quirrenbach,
A.; Stock, S.; Van Eylen, V.; Nowak, G.; López, E. D.; Csizmadia,
Sz.; Zapatero Osorio, M. R.; Schöfer, P.; Lillo-Box, J.; Oshagh, M.;
González-Álvarez, E.; Amado, P. J.; Barrado, D.; Béjar, V. J. S.;
Cale, B.; Chaturvedi, P.; Cifuentes, C.; Cochran, W. D.; Collins,
K. A.; Collins, K. I.; Cortés-Contreras, M.; Díez Alonso, E.; El
Mufti, M.; Ercolino, A.; Fridlund, M.; Gaidos, E.; García, R. A.;
Georgieva, I.; González-Cuesta, L.; Guerra, P.; Hatzes, A. P.;
Henning, Th.; Herrero, E.; Hidalgo, D.; Isopi, G.; Jeffers, S. V.;
Jenkins, J. M.; Jensen, E. L. N.; Kábath, P.; Kaminski, A.; Kemmer,
J.; Korth, J.; Kossakowski, D.; Kürster, M.; Lafarga, M.; Mallia,
F.; Montes, D.; Morales, J. C.; Morales-Calderón, M.; Murgas, F.;
Narita, N.; Passegger, V. M.; Pedraz, S.; Persson, C. M.; Plavchan,
P.; Rauer, H.; Redfield, S.; Reffert, S.; Reiners, A.; Ribas, I.;
Ricker, G. R.; Rodríguez-López, C.; Santos, A. R. G.; Seager, S.;
Schlecker, M.; Schweitzer, A.; Shan, Y.; Soto, M. G.; Subjak, J.;
Tal-Or, L.; Trifonov, T.; Vanaverbeke, S.; Vanderspek, R.; Wittrock,
J.; Zechmeister, M.; Zohrabi, F.
2020A&A...639A.132B Altcode: 2020arXiv200406218B
We report the confirmation of a transiting planet around the bright
weakly active M0.5 V star TOI-1235 (TYC 4384-1735-1, V ≈ 11.5 mag),
whose transit signal was detected in the photometric time series
of sectors 14, 20, and 21 of the TESS space mission. We confirm the
planetary nature of the transit signal, which has a period of 3.44
d, by using precise RV measurements with the CARMENES, HARPS-N,
and iSHELL spectrographs, supplemented by high-resolution imaging
and ground-based photometry. A comparison of the properties derived
for TOI-1235 b with theoretical models reveals that the planet has
a rocky composition, with a bulk density slightly higher than that
of Earth. In particular, we measure a mass of M<SUB>p</SUB> = 5.9
± 0.6 M<SUB>⊕</SUB> and a radius of R<SUB>p</SUB> = 1.69 ± 0.08
R<SUB>⊕</SUB>, which together result in a density of ρ<SUB>p</SUB>
= 6.7<SUB>- 1.1</SUB><SUP>+ 1.3</SUP> g cm<SUP>-3</SUP>. When compared
with other well-characterized exoplanetary systems, the particular
combination of planetary radius and mass places our discovery in the
radius gap, which is a transition region between rocky planets and
planets with significant atmospheric envelopes. A few examples of
planets occupying the radius gap are known to date. While the exact
location of the radius gap for M dwarfs is still a matter of debate,
our results constrain it to be located at around 1.7 R<SUB>⊕</SUB>
or larger at the insolation levels received by TOI-1235 b (~60
S<SUB>⊕</SUB>). This makes it an extremely interesting object for
further studies of planet formation and atmospheric evolution.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Dynamical
characterization of the multiple planet system GJ 1148 and prospects
of habitable exomoons around GJ 1148 b
Authors: Trifonov, T.; Lee, M. H.; Kürster, M.; Henning, Th.; Grishin,
E.; Stock, S.; Tjoa, J.; Caballero, J. A.; Wong, K. H.; Bauer, F. F.;
Quirrenbach, A.; Zechmeister, M.; Ribas, I.; Reffert, S.; Reiners,
A.; Amado, P. J.; Kossakowski, D.; Azzaro, M.; Béjar, V. J. S.;
Cortés-Contreras, M.; Dreizler, S.; Hatzes, A. P.; Jeffers, S. V.;
Kaminski, A.; Lafarga, M.; Montes, D.; Morales, J. C.; Pavlov, A.;
Rodríguez-López, C.; Schmitt, J. H. M. M.; Solano, E.; Barnes, R.
2020A&A...638A..16T Altcode: 2020arXiv200200906T
Context. GJ 1148 is an M-dwarf star hosting a planetary system composed
of two Saturn-mass planets in eccentric orbits with periods of 41.38
and 532.02 days. <BR /> Aims: We reanalyze the orbital configuration
and dynamics of the GJ 1148 multi-planetary system based on new precise
radial velocity measurements taken with CARMENES. <BR /> Methods: We
combined new and archival precise Doppler measurements from CARMENES
with those available from HIRES for GJ 1148 and modeled these data
with a self-consistent dynamical model. We studied the orbital
dynamics of the system using the secular theory and direct N-body
integrations. The prospects of potentially habitable moons around GJ
1148 b were examined. <BR /> Results: The refined dynamical analyses
show that the GJ 1148 system is long-term stable in a large phase-space
of orbital parameters with an orbital configuration suggesting apsidal
alignment, but not in any particular high-order mean-motion resonant
commensurability. GJ 1148 b orbits inside the optimistic habitable zone
(HZ). We find only a narrow stability region around the planet where
exomoons can exist. However, in this stable region exomoons exhibit
quick orbital decay due to tidal interaction with the planet. <BR />
Conclusions: The GJ 1148 planetary system is a very rare M-dwarf
planetary system consisting of a pair of gas giants, the inner of
which resides in the HZ. We conclude that habitable exomoons around
GJ 1148 b are very unlikely to exist.
---------------------------------------------------------
Title: VizieR Online Data Catalog: M dwarfs HeI infrared triplet
variability (Fuhrmeister+, 2020)
Authors: Fuhrmeister, B.; Czesla, S.; Hildebrandt, L.; Nagel, E.;
Schmitt, J. H. M. M.; Jeffers, S. V.; Caballero, J. A.; Hintz, D.;
Johnson, E. N.; Schoefer, P.; Zechmeister, M.; Reiners, A.; Ribas,
I.; Amado, P. J.; Quirrenbach, A.; Nortmann, L.; Bauer, F. F.; Bejar,
V. J. S.; Cortes-Contreras, M.; Dreizler, S.; Galadi-Enriquez, D.;
Hatzes, A. P.; Kaminski, A.; Kuerster, M.; Lafarga, M.; Montes, D.
2020yCat..36400052F Altcode:
The HeI infrared (IR) triplet at 10830Å is known as an activity
indicator and has become a primary diagnostic in exoplanetary
transmission spectroscopy. The HeI IR lines are a tracer of the
stellar extreme-ultraviolet irradiation from the transition region
and corona. We study the variability of the HeI IR triplet lines in
spectral time series of 319 M dwarf stars, obtained with the CARMENES
spectrograph. <P />We measure the pseudo-equivalent width (pEW) in each
stellar spectrum. The integration ranges for the line and the reference
bands are found in Table 1 of the paper. For comparison purposes
we also measure pEW values of Hα, the bluest CaII IR triplet line,
and the HeI D<SUB>3</SUB> line. From these measurements we compute the
mean pEW, the median absolute deviation (MAD) and Pearson's correlation
coefficients for the lines. <P />(1 data file).
---------------------------------------------------------
Title: A multiplanet system of super-Earths orbiting the brightest
red dwarf star GJ 887
Authors: Jeffers, S. V.; Dreizler, S.; Barnes, J. R.; Haswell, C. A.;
Nelson, R. P.; Rodríguez, E.; López-Gonz‧lez, M. J.; Morales, N.;
Luque, R.; Zechmeister, M.; Vogt, S. S.; Jenkins, J. S.; Palle, E.;
Berdi ñas, Z. M.; Coleman, G. A. L.; Díaz, M. R.; Ribas, I.; Jones,
H. R. A.; Butler, R. P.; Tinney, C. G.; Bailey, J.; Carter, B. D.;
O'Toole, S.; Wittenmyer, R. A.; Crane, J. D.; Feng, F.; Shectman,
S. A.; Teske, J.; Reiners, A.; Amado, P. J.; Anglada-Escudé, G.
2020Sci...368.1477J Altcode: 2020arXiv200616372J
The closet exoplanets to the Sun provide opportunities for detailed
characterization of planets outside the Solar System. We report
the discovery, using radial velocity measurements, of a compact
multiplanet system of super-Earth exoplanets orbiting the nearby red
dwarf star GJ 887. The two planets have orbital periods of 9.3 and
21.8 days. Assuming an Earth-like albedo, the equilibrium temperature
of the 21.8-day planet is ~350 kelvin. The planets are interior to,
but close to the inner edge of, the liquid-water habitable zone. We
also detect an unconfirmed signal with a period of ~50 days, which
could correspond to a third super-Earth in a more temperate orbit. Our
observations show that GJ 887 has photometric variability below 500
parts per million, which is unusually quiet for a red dwarf.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. The He
I infrared triplet lines in PHOENIX models of M 2-3 V stars
Authors: Hintz, D.; Fuhrmeister, B.; Czesla, S.; Schmitt,
J. H. M. M.; Schweitzer, A.; Nagel, E.; Johnson, E. N.; Caballero,
J. A.; Zechmeister, M.; Jeffers, S. V.; Reiners, A.; Ribas, I.; Amado,
P. J.; Quirrenbach, A.; Anglada-Escudé, G.; Bauer, F. F.; Béjar,
V. J. S.; Cortés-Contreras, M.; Dreizler, S.; Galadí-Enríquez,
D.; Guenther, E. W.; Hauschildt, P. H.; Kaminski, A.; Kürster, M.;
Lafarga, M.; López del Fresno, M.; Montes, D.; Morales, J. C.
2020A&A...638A.115H Altcode: 2020arXiv200506246H
The He I infrared (IR) line at a vacuum wavelength of 10 833 Å is a
diagnostic for the investigation of atmospheres of stars and planets
orbiting them. For the first time, we study the behavior of the He I
IR line in a set of chromospheric models for M-dwarf stars, whose much
denser chromospheres may favor collisions for the level population over
photoionization and recombination, which are believed to be dominant
in solar-type stars. For this purpose, we use published PHOENIX
models for stars of spectral types M2 V and M3 V and also compute new
series of models with different levels of activity following an ansatz
developed for the case of the Sun. We perform a detailed analysis of
the behavior of the He I IR line within these models. We evaluate the
line in relation to other chromospheric lines and also the influence
of the extreme ultraviolet (EUV) radiation field. The analysis of the
He I IR line strengths as a function of the respective EUV radiation
field strengths suggests that the mechanism of photoionization and
recombination is necessary to form the line for inactive models, while
collisions start to play a role in our most active models. Moreover,
the published model set, which is optimized in the ranges of the Na
I D<SUB>2</SUB>, Hα, and the bluest Ca II IR triplet line, gives an
adequate prediction of the He I IR line for most stars of the stellar
sample. Because especially the most inactive stars with weak He I IR
lines are fit worst by our models, it seems that our assumption of
a 100% filling factor of a single inactive component no longer holds
for these stars.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. A
super-Earth planet orbiting HD 79211 (GJ 338 B)
Authors: González-Álvarez, E.; Zapatero Osorio, M. R.; Caballero,
J. A.; Sanz-Forcada, J.; Béjar, V. J. S.; González-Cuesta, L.;
Dreizler, S.; Bauer, F. F.; Rodríguez, E.; Tal-Or, L.; Zechmeister,
M.; Montes, D.; López-González, M. J.; Ribas, I.; Reiners, A.;
Quirrenbach, A.; Amado, P. J.; Anglada-Escudé, G.; Azzaro, M.;
Cortés-Contreras, M.; Hatzes, A. P.; Henning, T.; Jeffers, S. V.;
Kaminski, A.; Kürster, M.; Lafarga, M.; Morales, J. C.; Pallé, E.;
Perger, M.; Schmitt, J. H. M. M.
2020A&A...637A..93G Altcode: 2020arXiv200313052G
<BR /> Aims: We report on radial velocity time series for two M0.0
V stars, GJ 338 B and GJ 338 A, using the CARMENES spectrograph,
complemented by ground-telescope photometry from Las Cumbres and
Sierra Nevada observatories. We aim to explore the presence of small
planets in tight orbits using the spectroscopic radial velocity
technique. <BR /> Methods: We obtained 159 and 70 radial velocity
measurements of GJ 338 B and A, respectively, with the CARMENES
visible channel between 2016 January and 2018 October. We also
compiled additional relative radial velocity measurements from the
literature and a collection of astrometric data that cover 200 a of
observations to solve for the binary orbit. <BR /> Results: We found
dynamical masses of 0.64 ± 0.07 M<SUB>⊙</SUB> for GJ 338 B and 0.69
± 0.07 M<SUB>⊙</SUB> for GJ 338 A. The CARMENES radial velocity
periodograms show significant peaks at 16.61 ± 0.04 d (GJ 338 B) and
16.3<SUB>-1.3</SUB><SUP>+3.5</SUP> d (GJ 338 A), which have counterparts
at the same frequencies in CARMENES activity indicators and photometric
light curves. We attribute these to stellar rotation. GJ 338 B shows
two additional, significant signals at 8.27 ± 0.01 and 24.45 ± 0.02
d, with no obvious counterparts in the stellar activity indices. The
former is likely the first harmonic of the star's rotation, while we
ascribe the latter to the existence of a super-Earth planet with a
minimum mass of 10.27<SUB>-1.38</SUB><SUP>+1.47</SUP> M<SUB>⊕</SUB>
orbiting GJ 338 B. We have not detected signals of likely planetary
origin around GJ 338 A. <BR /> Conclusions: GJ 338 Bb lies inside
the inner boundary of the habitable zone around its parent star. It
is one of the least massive planets ever found around any member
of stellar binaries. The masses, spectral types, brightnesses,
and even the rotational periods are very similar for both stars,
which are likely coeval and formed from the same molecular cloud, yet
they differ in the architecture of their planetary systems. <P />Full
Tables B.1-B.6 are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/637/A93">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/637/A93</A>
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M
dwarfs. Characterization of the nearby ultra-compact multiplanetary
system YZ Ceti
Authors: Stock, S.; Kemmer, J.; Reffert, S.; Trifonov, T.; Kaminski,
A.; Dreizler, S.; Quirrenbach, A.; Caballero, J. A.; Reiners,
A.; Jeffers, S. V.; Anglada-Escudé, G.; Ribas, I.; Amado, P. J.;
Barrado, D.; Barnes, J. R.; Bauer, F. F.; Berdiñas, Z. M.; Béjar,
V. J. S.; Coleman, G. A. L.; Cortés-Contreras, M.; Díez-Alonso, E.;
Domínguez-Fernández, A. J.; Espinoza, N.; Haswell, C. A.; Hatzes,
A.; Henning, T.; Jenkins, J. S.; Jones, H. R. A.; Kossakowski, D.;
Kürster, M.; Lafarga, M.; Lee, M. H.; López González, M. J.; Montes,
D.; Morales, J. C.; Morales, N.; Pallé, E.; Pedraz, S.; Rodríguez,
E.; Rodríguez-López, C.; Zechmeister, M.
2020A&A...636A.119S Altcode: 2020arXiv200201772S
Context. The nearby ultra-compact multiplanetary system YZ Ceti consists
of at least three planets, and a fourth tentative signal. The orbital
period of each planet is the subject of discussion in the literature
due to strong aliasing in the radial velocity data. The stellar
activity of this M dwarf also hampers significantly the derivation
of the planetary parameters. <BR /> Aims: With an additional 229
radial velocity measurements obtained since the discovery publication,
we reanalyze the YZ Ceti system and resolve the alias issues. <BR />
Methods: We use model comparison in the framework of Bayesian statistics
and periodogram simulations based on a method by Dawson and Fabrycky
to resolve the aliases. We discuss additional signals in the RV data,
and derive the planetary parameters by simultaneously modeling the
stellar activity with a Gaussian process regression model. To constrain
the planetary parameters further we apply a stability analysis on our
ensemble of Keplerian fits. <BR /> Results: We find no evidence for a
fourth possible companion. We resolve the aliases: the three planets
orbit the star with periods of 2.02 d, 3.06 d, and 4.66 d. We also
investigate an effect of the stellar rotational signal on the derivation
of the planetary parameters, in particular the eccentricity of the
innermost planet. Using photometry we determine the stellar rotational
period to be close to 68 d and we also detect this signal in the
residuals of a three-planet fit to the RV data and the spectral activity
indicators. From our stability analysis we derive a lower limit on the
inclination of the system with the assumption of coplanar orbits which
is i<SUB>min</SUB> = 0.9 deg. From the absence of a transit event with
TESS, we derive an upper limit of the inclination of i<SUB>max</SUB> =
87.43 deg. <BR /> Conclusions: YZ Ceti is a prime example of a system
where strong aliasing hindered the determination of the orbital
periods of exoplanets. Additionally, stellar activity influences
the derivation of planetary parameters and modeling them correctly
is important for the reliable estimation of the orbital parameters
in this specific compact system. Stability considerations then allow
additional constraints to be placed on the planetary parameters. <P
/>Table B.1 is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/636/A119">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/636/A119</A>.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Radial
velocities and activity indicators from cross-correlation functions
with weighted binary masks
Authors: Lafarga, M.; Ribas, I.; Lovis, C.; Perger, M.; Zechmeister,
M.; Bauer, F. F.; Kürster, M.; Cortés-Contreras, M.; Morales,
J. C.; Herrero, E.; Rosich, A.; Baroch, D.; Reiners, A.; Caballero,
J. A.; Quirrenbach, A.; Amado, P. J.; Alacid, J. M.; Béjar, V. J. S.;
Dreizler, S.; Hatzes, A. P.; Henning, T.; Jeffers, S. V.; Kaminski,
A.; Montes, D.; Pedraz, S.; Rodríguez-López, C.; Schmitt, J. H. M. M.
2020A&A...636A..36L Altcode: 2020arXiv200307471L
Context. For years, the standard procedure to measure radial velocities
(RVs) of spectral observations consisted in cross-correlating the
spectra with a binary mask, that is, a simple stellar template that
contains information on the position and strength of stellar absorption
lines. The cross-correlation function (CCF) profiles also provide
several indicators of stellar activity. <BR /> Aims: We present a
methodology to first build weighted binary masks and, second, to
compute the CCF of spectral observations with these masks from which
we derive radial velocities and activity indicators. These methods
are implemented in a python code that is publicly available. <BR />
Methods: To build the masks, we selected a large number of sharp
absorption lines based on the profile of the minima present in high
signal-to-noise ratio (S/N) spectrum templates built from observations
of reference stars. We computed the CCFs of observed spectra and
derived RVs and the following three standard activity indicators:
full-width-at-half-maximum as well as contrast and bisector inverse
slope. <BR /> Results: We applied our methodology to CARMENES
high-resolution spectra and obtain RV and activity indicator time
series of more than 300 M dwarf stars observed for the main CARMENES
survey. Compared with the standard CARMENES template matching pipeline,
in general we obtain more precise RVs in the cases where the template
used in the standard pipeline did not have enough S/N. We also show
the behaviour of the three activity indicators for the active star YZ
CMi and estimate the absolute RV of the M dwarfs analysed using the CCF
RVs. <P />Table A.1 is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/636/A36">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/636/A36</A>
---------------------------------------------------------
Title: Power spectra of solar brightness variations at various
inclinations
Authors: Nèmec, N. -E.; Shapiro, A. I.; Krivova, N. A.; Solanki,
S. K.; Tagirov, R. V.; Cameron, R. H.; Dreizler, S.
2020A&A...636A..43N Altcode: 2020arXiv200210895N
Context. Magnetic features on the surfaces of cool stars lead to
variations in their brightness. Such variations on the surface of
the Sun have been studied extensively. Recent planet-hunting space
telescopes have made it possible to measure brightness variations
in hundred thousands of other stars. The new data may undermine
the validity of setting the sun as a typical example of a variable
star. Putting solar variability into the stellar context suffers,
however, from a bias resulting from solar observations being carried
out from its near-equatorial plane, whereas stars are generally
observed at all possible inclinations. <BR /> Aims: We model solar
brightness variations at timescales from days to years as they would
be observed at different inclinations. In particular, we consider the
effect of the inclination on the power spectrum of solar brightness
variations. The variations are calculated in several passbands that are
routinely used for stellar measurements. <BR /> Methods: We employ the
surface flux transport model to simulate the time-dependent spatial
distribution of magnetic features on both the near and far sides of
the Sun. This distribution is then used to calculate solar brightness
variations following the Spectral And Total Irradiance REconstruction
approach. <BR /> Results: We have quantified the effect of the
inclination on solar brightness variability at timescales down to a
single day. Thus, our results allow for solar brightness records to
be made directly comparable to those obtained by planet-hunting space
telescopes. Furthermore, we decompose solar brightness variations into
components originating from the solar rotation and from the evolution
of magnetic features.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Absolute radial velocities of
CARMENES M dwarfs (Lafarga+, 2020)
Authors: Lafarga, M.; Ribas, I.; Lovis, C.; Perger, M.; Zechmeister,
M.; Bauer, F. F.; Kuerster, M.; Cortes-Contreras, M.; Morales,
J. C.; Herrero, E.; Rosich, A.; Baroch, D.; Reiners, A.; Caballero,
J. A.; Quirrenbach, A.; Amado, P. J.; Alacid, J. M.; Bejar, V. J. S.;
Dreizler, S.; Hatzes, A. P.; Henning, T.; Jeffers, S. V.; Kaminski,
A.; Montes, D.; Pedraz, S.; Rodriguez-Lopez, C.; Schmitt, J. H. M. M.
2020yCat..36360036L Altcode:
Absolute radial velocities (RVs) of 323 M dwarf stars observed with
CARMENES. The RVs were computed using the cross-correlation function
(CCF) method with binary masks on CARMENES visual observations. The
RV values and uncertainties also take into account the gravitational
redshift and the convective blueshift of the stars. The gravitational
redshift is computed using mass and radius values from Schweitzer
et al., 2019A&A...625A..68S, Cat. J/A+A/625/A68. We consider the
convective blueshift to be 0+/-100m/s for all stars. <P />(1 data file).
---------------------------------------------------------
Title: VizieR Online Data Catalog: HD 79211 CARMENES radial velocities
(Gonzalez-Alvarez+, 2020)
Authors: Gonzalez-Alvarez, E.; Zapatero Osorio, M. R.; Caballero,
J. A.; Sanz-Forcada, J.; Bejar, V. J. S.; Gonzalez-Cuesta, L.;
Dreizler, S.; Bauer, F. F.; Rodriguez, E.; Tal-Or, L.; Zechmeister, M.;
Montes, D.; Lopez-Gonzalez, M. J.; Ribas, I.; Reiners, A.; Quirrenbach,
A.; Amado, P. J.; Anglada-Escude, G.; Azzaro, M.; Cortes-Contreras, M.;
Hatzes, A. P.; Henning, T.; Jeffers, S. V.; Kaminski, A.; Kuerster,
M.; Lafarga, M.; Morales, J. C.; Palle, E.; Perger, M.; Schmitt,
J. H. M. M.
2020yCat..36370093G Altcode:
Detailed CARMENES RV analysis of the M0.0 V stars GJ 338 A (HD 79210)
and GJ 338 B (HD 79211), a wide binary system with similar mass stellar
components. <P />New RVs were obtained for each member of the stellar
binary using the CARMENES fibre-fed, echelle spectrograph. CARMENES
is installed at the 3.5m telescope of the Calar Alto Observatory in
Almeria (Spain). <P />(6 data files).
---------------------------------------------------------
Title: Stellar activity consequence on the retrieved transmission
spectra through chromatic Rossiter-McLaughlin observations
Authors: Boldt, S.; Oshagh, M.; Dreizler, S.; Mallonn, M.; Santos,
N. C.; Claret, A.; Reiners, A.; Sedaghati, E.
2020A&A...635A.123B Altcode: 2020arXiv200206373B
Mostly multiband photometric transit observations have been used so far
to retrieve broadband transmission spectra of transiting exoplanets
in order to study their atmosphere. An alternative method has been
proposed and has only been used once to recover transmission spectra
using chromatic Rossiter-McLaughlin observations. Stellar activity has
been shown to potentially imitate narrow and broadband features in the
transmission spectra retrieved from multiband photometric observations;
however, there has been no study regarding the influence of stellar
activity on the retrieved transmission spectra through chromatic
Rossiter-McLaughlin. In this study with the modified SOAP3.0 tool,
we consider different types of stellar activity features (spots and
plages), and we generated a large number of realistic chromatic
Rossiter-McLaughlin curves for different types of planets and
stars. We were then able to retrieve their transmission spectra
to evaluate the impact of stellar activity on them. We find that
chromatic Rossiter-McLaughlin observations are also not immune to
stellar activity, which can mimic broadband features, such as Rayleigh
scattering slope, in their retrieved transmission spectra. We also
find that the influence is independent of the planet radius, orbital
orientations, orbital period, and stellar rotation rate. However,
more general simulations demonstrate that the probability of mimicking
strong broadband features is lower than 25% and that can be mitigated
by combining several Rossiter-McLaughlin observations obtained during
several transits.
---------------------------------------------------------
Title: The binary content of multiple populations in NGC 3201
Authors: Kamann, S.; Giesers, B.; Bastian, N.; Brinchmann, J.;
Dreizler, S.; Göttgens, F.; Husser, T. -O.; Latour, M.; Weilbacher,
P. M.; Wisotzki, L.
2020A&A...635A..65K Altcode: 2019arXiv191201627K
We investigate the binary content of the two stellar populations that
coexist in the globular cluster NGC 3201. Previous studies of binary
stars in globular clusters have reported higher binary fractions in
their first populations (P1, having field-like abundances) compared
to their second populations (P2, having anomalous abundances). This
is interpreted as evidence for the latter forming more centrally
concentrated. In contrast to previous studies, our analysis focusses
on the cluster centre, where comparable binary fractions between the
populations are predicted because of short relaxation times. However,
we find that even in the centre of NGC 3201, the observed binary
fraction of P1 is higher (23.1 ± 6.2)% compared to (8.2 ± 3.5)%
in P2. Our results are difficult to reconcile with a scenario in
which the populations only differ in their initial concentrations,
but instead suggests that the populations also formed with different
fractions of binary stars.
---------------------------------------------------------
Title: The MUSE-Faint survey. I. Spectroscopic evidence for a star
cluster in Eridanus 2 and constraints on MACHOs as a constituent of
dark matter
Authors: Zoutendijk, Sebastiaan L.; Brinchmann, Jarle; Boogaard,
Leindert A.; Gunawardhana, Madusha L. P.; Husser, Tim-Oliver; Kamann,
Sebastian; Ramos Padilla, Andrés Felipe; Roth, Martin M.; Bacon,
Roland; den Brok, Mark; Dreizler, Stefan; Krajnović, Davor
2020A&A...635A.107Z Altcode: 2020arXiv200108790Z
<BR /> Aims: It has been shown that the ultra-faint dwarf galaxy
Eridanus 2 may host a stellar cluster in its centre. If this cluster
is shown to exist, it can be used to set constraints on the mass and
abundance of massive astrophysical compact halo objects (MACHOs) as a
form of dark matter. Previous research has shown promising expectations
in the mass range of 10-100 M<SUB>⊙</SUB>, but lacked spectroscopic
measurements of the cluster. We aim to provide spectroscopic evidence
regarding the nature of the putative star cluster in Eridanus 2 and to
place constraints on MACHOs as a constituent of dark matter. <BR />
Methods: We present spectroscopic observations of the central square
arcminute of Eridanus 2 from MUSE-Faint, a survey of ultra-faint dwarf
galaxies with the Multi Unit Spectroscopic Explorer on the Very Large
Telescope. We derived line-of-sight velocities for possible member stars
of the putative cluster and for stars in the centre of Eridanus 2. We
discuss the existence of the cluster and determine new constraints for
MACHOs using the Fokker-Planck diffusion approximation. <BR /> Results:
Out of 182 extracted spectra, we identify 26 member stars of Eridanus
2, seven of which are possible cluster members. We find intrinsic
mean line-of-sight velocities of 79.7<SUP>+3.1</SUP><SUB>-3.8</SUB> km
s<SUP>-1</SUP> and 76.0<SUP>+3.2</SUP><SUB>-3.7</SUB> km s<SUP>-1</SUP>
for the cluster and the bulk of Eridanus 2, respectively, as well
as intrinsic velocity dispersions of < 7.6 km s<SUP>-1</SUP>
(68% upper limit) and 10.3<SUP>+3.9</SUP><SUB>-3.2</SUB> km
s<SUP>-1</SUP>, respectively. This indicates that the cluster most
likely exists as a distinct dynamical population hosted by Eridanus 2
and that it does not have a surplus of dark matter over the background
distribution. Among the member stars in the bulk of Eridanus 2, we find
possible carbon stars, alluding to the existence of an intermediate-age
population. We derived constraints on the fraction of dark matter that
can consist of MACHOs with a given mass between 1 and 10<SUP>5</SUP>
M<SUB>⊙</SUB>. For dark matter consisting purely of MACHOs, the
mass of the MACHOs must be less than ∼7.6 M<SUB>⊙</SUB> and ∼44
M<SUB>⊙</SUB> at a 68- and 95% confidence level, respectively. <P
/>Table 2 is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/635/A107">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/635/A107</A>
<P />Based on observations made with ESO Telescopes at the La Silla
Paranal Observatory under programme ID 0100.D-0807.
---------------------------------------------------------
Title: A stellar census in globular clusters with MUSE. Extending
the CaT-metallicity relation below the horizontal branch and applying
it to multiple populations
Authors: Husser, Tim-Oliver; Latour, Marilyn; Brinchmann, Jarle;
Dreizler, Stefan; Giesers, Benjamin; Göttgens, Fabian; Kamann,
Sebastian; Roth, Martin M.; Weilbacher, Peter M.; Wendt, Martin
2020A&A...635A.114H Altcode: 2020arXiv200107725H
<BR /> Aims: We use the spectra of more than 30 000 red giant branch
(RGB) stars in 25 globular clusters (GC), obtained within the MUSE
survey of Galactic globular clusters, to calibrate the Ca II triplet
metallicity relation and derive metallicities for all individual
stars. We investigate the overall metallicity distributions as well
as those of the different populations within each cluster. <BR />
Methods: The Ca II triplet in the near-infrared at 8498, 8542, and 8662
Å is visible in stars with spectral types between F and M and can
be used to determine their metallicities. In this work, we calibrate
the relation using average cluster metallicities from literature and
MUSE spectra, and extend it below the horizontal branch - a cutoff
that has traditionally been made to avoid a non-linear relation -
using a quadratic function. In addition to the classic relation
based on V - V<SUB>HB</SUB>, we also present calibrations based on
absolute magnitude and luminosity. The obtained relations were used to
calculate metallicities for all the stars in the sample and to derive
metallicity distributions for different populations within a cluster,
which have been separated using so-called "chromosome maps" based on
HST photometry. <BR /> Results: We show that despite the relatively
low spectral resolution of MUSE (R = 1900 - 3700) we can derive single
star metallicities with a mean statistical intra-cluster uncertainty of
∼0.12 dex. We present metallicity distributions for the RGB stars in
25 GCs and investigate the different metallicities of the populations P3
(and higher) in so-called metal-complex or Type II clusters, finding
metallicity variations in all of them. We also detected unexpected
metallicity variations in the Type I cluster <ASTROBJ>NGC 2808</ASTROBJ>
and confirm the Type II status of <ASTROBJ>NGC 7078</ASTROBJ>. <P
/>Table 8 is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/635/A114">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/635/A114</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: GJ 3512 radial velocity and light
curves (Morales+, 2019)
Authors: Morales, J. C.; Mustill, A. J.; Ribas, I.; Davies, M. B.;
Reiners, A.; Bauer, F. F.; Kossakowski, D.; Herrero, E.; Rodriguez,
E.; Lopez-Gonzalez, M. J.; Rodriguez-Lopez, C.; Bejar, V. J. S.;
Gonzalez-Cuesta, L.; Luque, R.; Palle, E.; Perger, M.; Baroch,
D.; Johansen, A.; Klahr, H.; Mordasini, C.; Anglada-Escude, G.;
Caballero, J. A.; Cortes-Contreras, M.; Dreizler, S.; Lafarga, M.;
Nagel, E.; Passegger, V. M.; Reffert, S.; Rosich, A.; Schweitzer,
A.; Tal-Or, L.; Trifonov, T.; Zechmeister, M.; Quirrenbach, A.;
Amado, P. J.; Guenther, E. W.; Hagen, H. -J.; Henning, T.; Jeffers,
S. V.; Kaminski, A.; Kurster, M.; Montes, D.; Seifert, W.; Abellan,
F. J.; Abril, M.; Aceituno, J.; Aceituno, F. J.; Alonso-Floriano,
F. J.; Ammler-von Eiff, M.; Antona, R.; Arroyo-Torres, B.; Azzaro,
M.; Barrado, D.; Becerril-Jarque, S.; Benitez, D.; Berdinas, Z. M.;
Bergond, G.; Brinkmoller, M.; Del Burgo, C.; Burn, R.; Calvo-Ortega,
R.; Cano, J.; Cardenas, M. C.; Cardona Guillen, C.; Carro, J.; Casal,
E.; Casanova, V.; Casasayas-Barris, N.; Chaturvedi, P.; Cifuentes,
C.; Claret, A.; Colome, J.; Czesla, S.; Diez-Alonso, E.; Dorda, R.;
Emsenhuber, A.; Fernandez, M.; Fernandez-Martin, A.; Ferro, I. M.;
Fuhrmeister, B.; Galadi-Enriquez, D.; Gallardo Cava, I.; Garcia Vargas,
M. L.; Garcia-Piquer, A.; Gesa, L.; Gonzalez-Alvarez, E.; Gonzalez
Hernandez, J. I.; Gonzalez-Peinado, R.; Guardia, J.; Guijarro, A.;
de Guindos, E.; Hatzes, A. P.; Hauschildt, P. H.; Hedrosa, R. P.;
Hermelo, I.; Hernandez Arabi, R.; Hernandez, Otero F.; Hintz, D.;
Holgado, G.; Huber, A.; Huke, P.; Johnson, E. N.; de Juan, E.; Kehr,
M.; Kemmer, J.; Kim, M.; Kluter, J.; Klutsch, A.; Labarga, F.; Labiche,
N.; Lalitha, S.; Lampon, M.; Lara, L. M.; Launhardt, R.; Lazaro,
F. J.; Lizon, J. -L.; Llamas, M.; Lodieu, N.; Lopez Del Fresno, M.;
Lopez Salas, J. F.; Lopez-Santiago, J.; Magan Madinabeitia, H.; Mall,
U.; Mancini, L.; Mandel, H.; Marfil, E.; Marin Molina, J. A.; Martin,
E. L.; Martin-Fernandez, P.; Martin-Ruiz, S.; Martinez-Rodriguez,
H.; Marvin, C. J.; Mirabet, E.; Moya, A.; Naranjo, V.; Nelson, R. P.;
Nortmann, L.; Nowak, G.; Ofir, A.; Pascual, J.; Pavlov, A.; Pedraz,
S.; Perez Medialde, A. D.; Perez-Calpena, A.; Perryman, M. A. C.;
Rabaza, O.; Ramon Ballesta, A.; Rebolo, R.; Redondo, P.; Rix, H. -W.;
Rodler, F.; Rodriguez Trinidad, A.; Sabotta, S.; Sadegi, S.; Salz,
M.; Sanchez-Blanco, E.; Sanchez Carrasco, M. A.; Sanchez-Lopez, A.;
Sanz-Forcada, J.; Sarkis, P.; Sarmiento, L. F.; Schafer, S.; Schlecker,
M.; Schmitt, J. H. M. M.; Schofer, P.; Solano, E.; Sota, A.; Stahl, O.;
Stock, S.; Stuber, T.; Sturmer, J.; Suarez, J. C.; Tabernero, H. M.;
Tulloch, S. M.; Veredas, G.; Vico-Linares, J. I.; Vilardell, F.;
Wagner, K.; Winkler, J.; Wolthoff, V.; Yan, F.; Zapatero Osorio, M. R.
2020yCatp021036502M Altcode:
These tables list the radial velocities measured with the
visual (VIS) and near-infrared (NIR) channels of the CARMENES
spectrograph (Quirrenbach et al. 2018SPIE10702E..0WQ), and the
stellar activity indices computed with SERVAL (Zechmeister et
al. 2018A&A...609A..12Z). Photometry obtained from the Montsec,
Sierra Nevada, and las Cumbres observatories is also listed here as
used in the paper. <P />(4 data files).
---------------------------------------------------------
Title: RedDots: a temperate 1.5 Earth-mass planet candidate in a
compact multiterrestrial planet system around GJ 1061
Authors: Dreizler, S.; Jeffers, S. V.; Rodríguez, E.; Zechmeister, M.;
Barnes, J. R.; Haswell, C. A.; Coleman, G. A. L.; Lalitha, S.; Hidalgo
Soto, D.; Strachan, J. B. P.; Hambsch, F. -J.; López-González,
M. J.; Morales, N.; Rodríguez López, C.; Berdiñas, Z. M.; Ribas,
I.; Pallé, E.; Reiners, A.; Anglada-Escudé, G.
2020MNRAS.493..536D Altcode: 2019arXiv190804717D; 2020MNRAS.tmp..235D
Small low-mass stars are favourable targets for the detection
of rocky habitable planets. In particular, planetary systems in
the solar neighbourhood are interesting and suitable for precise
characterization. The RedDots campaigns seek to discover rocky planets
orbiting nearby low-mass stars. The 2018 campaign targeted GJ 1061,
which is the 20th nearest star to the Sun. For three consecutive months
we obtained nightly, high-precision radial velocity measurements with
the HARPS spectrograph. We analysed these data together with archival
HARPS data. We report the detection of three planet candidates with
periods of 3.204 ± 0.001, 6.689 ± 0.005, and 13.03 ± 0.03 d,
which are close to 1:2:4 period commensurability. After several
considerations related to the properties of the noise and sampling,
we conclude that a fourth signal is most likely explained by stellar
rotation, although it may be due to a planet. The proposed three-planet
system (and the potential four-planet solution) is long-term dynamically
stable. Planet-planet gravitational interactions are below our current
detection threshold. The minimum masses of the three planets range from
1.4 ± 0.2 to 1.8 ± 0.3 M<SUB>⊕</SUB>. Planet d, with msin I = 1.64
± 0.24 M<SUB>⊕</SUB>, receives a similar amount of energy as Earth
receives from the Sun. Consequently it lies within the liquid-water
habitable zone of the star and has a similar equilibrium temperature
to Earth. GJ 1061 has very similar properties to Proxima Centauri but
activity indices point to lower levels of stellar activity.
---------------------------------------------------------
Title: The peculiar kinematics of the multiple populations in the
globular cluster Messier 80 (NGC 6093)
Authors: Kamann, S.; Dalessandro, E.; Bastian, N.; Brinchmann, J.;
den Brok, M.; Dreizler, S.; Giesers, B.; Göttgens, F.; Husser,
T. -O.; Krajnović, D.; van de Ven, G.; Watkins, L. L.; Wisotzki, L.
2020MNRAS.492..966K Altcode: 2019arXiv191206158K; 2019MNRAS.tmp.3140K
We combine MUSE spectroscopy and Hubble Space Telescope ultraviolet
(UV) photometry to perform a study of the chemistry and dynamics of the
Galactic globular cluster Messier 80 (M80, NGC 6093). Previous studies
have revealed three stellar populations that vary not only in their
light-element abundances, but also in their radial distributions, with
the concentration decreasing with increasing nitrogen enrichment. This
remarkable trend, which sets M80 apart from other Galactic globular
clusters, points towards a complex formation and evolutionary
history. To better understand how M80 formed and evolved, revealing its
internal kinematics is key. We find that the most N-enriched population
rotates faster than the other two populations at a 2σ confidence
level. While our data further suggest that the intermediate population
shows the least amount of rotation, this trend is rather marginal
(1-2σ). Using axisymmetric Jeans models, we show that these findings
can be explained from the radial distributions of the populations if
they possess different angular momenta. Our findings suggest that the
populations formed with primordial kinematical differences.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M
dwarfs. Photospheric parameters of target stars from high-resolution
spectroscopy. II. Simultaneous multi-wavelength range modeling of
activity insensitive lines (Corrigendum)
Authors: Passegger, V. M.; Schweitzer, A.; Shulyak, D.; Nagel, E.;
Hauschildt, P. H.; Reiners, A.; Amado, P. J.; Caballero, J. A.;
Cortés-Contreras, M.; Domínguez-Fernández, A. J.; Quirrenbach,
A.; Ribas, I.; Azzaro, M.; Anglada-Escudé, G.; Bauer, F. F.; Béjar,
V. J. S.; Dreizler, S.; Guenther, E. W.; Henning, T.; Jeffers, S. V.;
Kaminski, A.; Kürster, M.; Lafarga, M.; Martín, E. L.; Montes, D.;
Morales, J. C.; Schmitt, J. H. M. M.; Zechmeister, M.
2020A&A...634C...2P Altcode:
No abstract at ADS
---------------------------------------------------------
Title: VizieR Online Data Catalog: EW and [Fe/H] for 30000 globular
cluster RGB stars (Husser+ 2020)
Authors: Husser, T. -O.; Latour, M.; Brinchmann, J.; Dreizler, S.;
Giesers, B.; Goettgens, F.; Kamann, S.; Roth, M. M.; Weilbacher,
P. M.; Wendt, M.
2020yCat..36350114H Altcode:
We measured equivalent widths of >30000 red giant branch stars in
25 globular clusters from our large MUSE survey and used mean cluster
metallicities to calibrate the CaT-metallicity relation, from which
reduced equivalent widths and metallicities were calculated for all
stars. Metallicities are given for four different calibrations,
based on the classical linear relation with only stars brighter
than the HB (1), all RGB stars and a quadratic relation (2), and
two calibrations based on absolute magnitude (3) and luminosity
(4). All metallicities are derived on the scale defined by Dias
et al. (2016A&A...590A...9D). The star IDs are taken from
the ACS Survey of Galactic Globular Clusters (Anderson et al.,
2008AJ....135.2055A), if they exist in that catalog. <P />(1 data file).
---------------------------------------------------------
Title: VizieR Online Data Catalog: Spectroscopy of the Eri 2 cluster
(Zoutendijk+, 2020)
Authors: Zoutendijk, S. L.; Brinchmann, J.; Boogaard, L. A.;
Gunawardhana, M. L. P.; Husser, T. -O.; Kamann, S.; Ramos Padilla,
A. F.; Roth, M. M.; Bacon, R.; den Brok, M.; Dreizler, S.; Krajnovic,
K.
2020yCat..36350107Z Altcode:
This table contains sources observed with the Multi Unit Spectroscopic
Explorer on the Very Large Telescope towards the centre of the
ultra-faint dwarf galaxy Eridanus 2 and its possible stellar
cluster. These measurements were used to determine the velocity
distributions of the putative cluster and the bulk of Eridanus 2,
to assess the nature of the cluster, and to derive constraints on
massive astrophysical compact halo objects. The sources in this table
were limited to those with a spectral signal to noise of at least 5,
a spectrum not showing galactic emission lines, and a measurement
of radial velocity; or those that we identified as potential carbon
stars. The positions have been calibrated against GAIA DR2. <P />(1
data file).
---------------------------------------------------------
Title: VizieR Online Data Catalog: YZ Ceti CARMENES and HARPS radial
velocity curve (Stock+, 2020)
Authors: Stock, S.; Kemmer, J.; Reffert, S.; Trifonov, T.; Kaminski,
A.; Dreizler, S.; Quirrenbach, A.; Caballero, J. A.; Reiners,
A.; Jeffers, S. V.; Anglada-Escude, G.; Ribas, I.; Amado, P. J.;
Barrado, D.; Barnes, J. R.; Bauer, F. F.; Berdinas, Z. M.; Bejar,
V. J. S.; Coleman, G. A. L.; Cortes-Contreras, M.; Diez-Alonso, E.;
Dominguez-Fernandez, A. J.; Espinoza, N.; Haswell, C. A.; Hatzes,
A.; Henning, T.; Jenkins, J. S.; Jones, H. R. A.; Kossakowski, D.;
Kuerster, M.; Lafarga, M.; Lee, M. H.; Lopez Gonzalez, M. J.; Montes,
D.; Morales, J. C.; Morales, N.; Palle, E.; Pedraz, S.; Rodriguez,
E.; Rodriguez-Lopez, C.; Zechmeister, M.
2020yCat..36360119S Altcode:
We acquired spectra with CARMENES (Quirrenbach et al., 2014, in
Proc. SPIE, Vol. 9147, Ground-based and Airborne Instrumentation for
Astronomy V, 91471F), a high-resolution precise echelle spectrograph
mounted at the 3.5m telescope at the Calar Alto Observatory in Spain. We
combined this data with 334 high-resolution spectra from HARPS, of which
59 were collected by the Red Dots program (Dreizler et al., 2019, arXiv
e-prints, arXiv:1908.04717) and the remaining by Astudillo-Defru et
al. (2017A&A...605L..11A, Cat. J/A+A/605/L11). <P />(1 data file).
---------------------------------------------------------
Title: A stellar census in globular clusters with MUSE: Binaries in
NGC 3201
Authors: Giesers, Benjamin; Kamann, Sebastian; Dreizler, Stefan;
Husser, Tim-Oliver; Askar, Abbas; Göttgens, Fabian; Brinchmann, Jarle;
Latour, Marilyn; Weilbacher, Peter M.; Wendt, Martin; Roth, Martin M.
2019A&A...632A...3G Altcode: 2019arXiv190904050G
We utilise multi-epoch MUSE spectroscopy to study binary stars in the
core of the Galactic globular cluster NGC 3201. Our sample consists of
3553 stars with 54 883 spectra in total comprising 3200 main-sequence
stars up to 4 magnitudes below the turn-off. Each star in our sample
has between 3 and 63 (with a median of 14) reliable radial velocity
measurements within five years of observations. We introduce a
statistical method to determine the probability of a star showing
radial velocity variations based on the whole inhomogeneous radial
velocity sample. Using HST photometry and an advanced dynamical MOCCA
simulation of this specific cluster we overcome observational biases
that previous spectroscopic studies had to deal with. This allows
us to infer a binary frequency in the MUSE field of view and enables
us to deduce the underlying true binary frequency of (6.75 ± 0.72)%
in NGC 3201. The comparison of the MUSE observations with the MOCCA
simulation suggests a large portion of primordial binaries. We can
also confirm a radial increase in the binary fraction towards the
cluster centre due to mass segregation. We discovered that in the core
of NGC 3201 at least (57.5 ± 7.9)% of blue straggler stars are in a
binary system. For the first time in a study of globular clusters,
we were able to fit Keplerian orbits to a significant sample of 95
binaries. We present the binary system properties of eleven blue
straggler stars and the connection to SX Phoenicis-type stars. We
show evidence that two blue straggler formation scenarios, the mass
transfer in binary (or triple) star systems and the coalescence
due to binary-binary interactions, are present in our data. We also
describe the binary and spectroscopic properties of four sub-subgiant
(or red straggler) stars. Furthermore, we discovered two new black
hole candidates with minimum masses (M sin i) of (7.68 ± 0.50)
M<SUB>⊙</SUB>, (4.4 ± 2.8) M<SUB>⊙</SUB>, and refine the minimum
mass estimate on the already published black hole to (4.53 ± 0.21)
M<SUB>⊙</SUB>. These black holes are consistent with an extensive
black hole subsystem hosted by NGC 3201. <P />The full radial velocity
sample (Table A.1) is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/632/A3">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/632/A3</A>
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. The He
I triplet at 10830 Å across the M dwarf sequence
Authors: Fuhrmeister, B.; Czesla, S.; Hildebrandt, L.; Nagel, E.;
Schmitt, J. H. M. M.; Hintz, D.; Johnson, E. N.; Sanz-Forcada, J.;
Schöfer, P.; Jeffers, S. V.; Caballero, J. A.; Zechmeister, M.;
Reiners, A.; Ribas, I.; Amado, P. J.; Quirrenbach, A.; Bauer, F. F.;
Béjar, V. J. S.; Cortés-Contreras, M.; Díez-Alonso, E.; Dreizler,
S.; Galadí-Enríquez, D.; Guenther, E. W.; Kaminski, A.; Kürster,
M.; Lafarga, M.; Montes, D.
2019A&A...632A..24F Altcode: 2019arXiv191100246F
The He I infrared (IR) triplet at 10 830 Å is an important activity
indicator for the Sun and in solar-type stars, however, it has rarely
been studied in relation to M dwarfs to date. In this study, we use the
time-averaged spectra of 319 single stars with spectral types ranging
from M0.0 V to M9.0 V obtained with the CARMENES high resolution
optical and near-infrared spectrograph at Calar Alto to study the
properties of the He I IR triplet lines. In quiescence, we find the
triplet in absorption with a decrease of the measured pseudo equivalent
width (pEW) towards later sub-types. For stars later than M5.0 V,
the He I triplet becomes undetectable in our study. This dependence
on effective temperature may be related to a change in chromospheric
conditions along the M dwarf sequence. When an emission in the triplet
is observed, we attribute it to flaring. The absence of emission during
quiescence is consistent with line formation by photo-ionisation
and recombination, while flare emission may be caused by collisions
within dense material. The He I triplet tends to increase in depth
according to increasing activity levels, ultimately becoming filled in;
however, we do not find a correlation between the pEW(He IR) and X-ray
properties. This behaviour may be attributed to the absence of very
inactive stars (L<SUB>X</SUB>/L<SUB>bol</SUB> < -5.5) in our sample
or to the complex behaviour with regard to increasing depth and filling
in. <P />Full Table 2 is only available at the CDS via anonymous ftp to
<A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/632/A24">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/632/A24</A>
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Title: VizieR Online Data Catalog: EREBOS project. I. (Schaffenroth+,
2019)
Authors: Schaffenroth, V.; Barlow, B. N.; Geier, S.; Vuckovic,
M.; Kilkenny, D.; Wolz, M.; Kupfer, T.; Heber, U.; Drechsel, H.;
Kimeswenger, S.; Marsh, T.; Wolf, M.; Pelisoli, I.; Freudenthal, J.;
Dreizler, S.; Kreuzer, S.; Ziegerer, E.
2019yCat..36300080S Altcode:
The EREBOS (Eclipsing Reflection Effect Binaries from Optical Surveys)
project aims to study a large sample of homogeneously selected HW
Vir systems (eclipsing binaries with cool stellar or substellar
companions), and in particular their orbital, atmospheric, and
fundamental parameters. <P />Two different photometric surveys
are used to search such systems: OGLE (a long-term, large-scale
photometric sky survey focused on variability, see Udalski et al.,
2015AcA....65....1U) and ATLAS (a high-cadence all-sky survey system
designed to find dangerous near-Earth asteroids, see Tonry et al.,
2018PASP..130f4505T). The number of known HW Vir systems results
increased by a factor of almost ten. <P />(6 data files).
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Title: A stellar census in globular clusters with MUSE: multiple
populations chemistry in NGC 2808
Authors: Latour, M.; Husser, T. -O.; Giesers, B.; Kamann, S.;
Göttgens, F.; Dreizler, S.; Brinchmann, J.; Bastian, N.; Wendt, M.;
Weilbacher, P. M.; Molinski, N. S.
2019A&A...631A..14L Altcode: 2019arXiv190904959L
Context. Galactic globular clusters (GCs) are now known to host
multiple populations displaying particular abundance variations. The
different populations within a GC can be well distinguished following
their position in the pseudo two-colors diagrams, also referred to as
"chromosome maps". These maps are constructed using optical and near-UV
photometry available from the Hubble Space Telescope (HST) UV survey
of GCs. However, the chemical tagging of the various populations in
the chromosome maps is hampered by the fact that HST photometry and
elemental abundances are both only available for a limited number
of stars. <BR /> Aims: The spectra collected as part of the MUSE
survey of globular clusters provide a spectroscopic counterpart to
the HST photometric catalogs covering the central regions of GCs. In
this paper, we use the MUSE spectra of 1115 red giant branch (RGB)
stars in NGC 2808 to characterize the abundance variations seen in
the multiple populations of this cluster. <BR /> Methods: We used
the chromosome map of NGC 2808 to divide the RGB stars into their
respective populations. We then combined the spectra of all stars
belonging to a given population, resulting in one high signal-to-noise
ratio spectrum representative of each population. <BR /> Results:
Variations in the spectral lines of O, Na, Mg, and Al are clearly
detected among four of the populations. In order to quantify these
variations, we measured equivalent width differences and created
synthetic populations spectra that were used to determine abundance
variations with respect to the primordial population of the cluster. Our
results are in good agreement with the values expected from previous
studies based on high-resolution spectroscopy. We do not see any
significant variations in the spectral lines of Ca, K, and Ba. We
also do not detect abundance variations among the stars belonging
to the primordial population of NGC 2808. <BR /> Conclusions: We
demonstrate that in spite of their low resolution, the MUSE spectra can
be used to investigate abundance variations in the context of multiple
populations. <P />The populations spectra and the list of stars included
in these spectra are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/631/A14">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/631/A14</A>Based
on observations collected at the European Organisation for Astronomical
Research in the Southern Hemisphere, Chile (proposal IDs 094.D-0142(B),
096.D-0175(A)).
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Title: A stellar census in globular clusters with MUSE: A spectral
catalogue of emission-line sources
Authors: Göttgens, Fabian; Husser, Tim-Oliver; Kamann, Sebastian;
Dreizler, Stefan; Giesers, Benjamin; Kollatschny, Wolfram; Weilbacher,
Peter M.; Roth, Martin M.; Wendt, Martin
2019A&A...631A.118G Altcode: 2019arXiv190905872G
<BR /> Aims: Globular clusters produce many exotic stars due to
a much higher frequency of dynamical interactions in their dense
stellar environments. Some of these objects were observed together
with several hundred thousand other stars in our MUSE survey of 26
Galactic globular clusters. Assuming that at least a few exotic stars
have exotic spectra (i.e. spectra that contain emission lines), we
can use this large spectroscopic data set of over a million stellar
spectra as a blind survey to detect stellar exotica in globular
clusters. <BR /> Methods: To detect emission lines in each spectrum,
we modelled the expected shape of an emission line as a Gaussian
curve. This template was used for matched filtering on the differences
between each observed 1D spectrum and its fitted spectral model. The
spectra with the most significant detections of Hα emission are
checked visually and cross-matched with published catalogues. <BR
/> Results: We find 156 stars with Hα emission, including several
known cataclysmic variables (CV) and two new CVs, pulsating variable
stars, eclipsing binary stars, the optical counterpart of a known
black hole, several probable sub-subgiants and red stragglers,
and 21 background emission-line galaxies. We find possible optical
counterparts to 39 X-ray sources, as we detected Hα emission in several
spectra of stars that are close to known positions of Chandra X-ray
sources. This spectral catalogue can be used to supplement existing
or future X-ray or radio observations with spectra of potential
optical counterparts to classify the sources. <P />Table A.2 and
spectra (FITS) are available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/631/A118">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/631/A118</A>
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Title: VizieR Online Data Catalog: NGC 6397 stars MUSE spectra
(Husser+, 2016)
Authors: Husser, T. -O.; Kamann, S.; Dreizler, S.; Wendt, M.; Wulff,
N.; Bacon, R.; Wisotzki, L.; Brinchmann, J.; Weilbacher, P. M.; Roth,
M. M.; Monreal-Ibero, A.
2019yCat..35880148H Altcode:
We observed the globular cluster NGC 6397 during MUSE commissioning,
lasting from July 26nd to August 3rd, 2014, to explore the capabilities
of MUSE in crowded stellar fields. <P />To obtain clean spectra in
a crowded region such as a globular cluster, sophisticated analysis
techniques are required. <P />Provided are all the obtained spectra
with a signal-to-noise ratio of five or larger, i.e. 14271 spectra in
total. <P />(3 data files).
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Title: VizieR Online Data Catalog: NGC 2808 stellar population spectra
(Latour+, 2019)
Authors: Latour, M.; Husser, T. -O.; Giesers, B.; Kamann, S.;
Goettgens, F.; Dreizler, S.; Brinchmann, J.; Bastian, N.; Wendt, M.;
Weilbacher, P. M.; Molinski, N. S.
2019yCat..36310014L Altcode:
We provide the summed spectra of population 1 to 4. The radial
velocities are corrected so that the spectrum are at rest
wavelength. The table includes the list of stars whose spectrum are
included in the combined spectra along with their population number. <P
/>(3 data files).
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Title: No evidence for intermediate-mass black holes in the globular
clusters ω Cen and NGC 6624
Authors: Baumgardt, H.; He, C.; Sweet, S. M.; Drinkwater, M.; Sollima,
A.; Hurley, J.; Usher, C.; Kamann, S.; Dalgleish, H.; Dreizler, S.;
Husser, T. -O.
2019MNRAS.488.5340B Altcode: 2019arXiv190710845B; 2019MNRAS.tmp.1999B
We compare the results of a large grid of N-body simulations with the
surface brightness and velocity dispersion profiles of the globular
clusters ω Cen and NGC 6624. Our models include clusters with varying
stellar-mass black hole retention fractions and varying masses of a
central intermediate-mass black hole (IMBH). We find that an ∼ 45
000 M<SUB>⊙</SUB> IMBH, whose presence has been suggested based
on the measured velocity dispersion profile of ω Cen, predicts
the existence of about 20 fast-moving, m > 0.5 M<SUB>⊙</SUB>,
main-sequence stars with a (1D) velocity v > 60 km s<SUP>-1</SUP>
in the central 20 arcsec of ω Cen. However, no such star is present
in the HST/ACS proper motion catalogue of Bellini et al. (2017),
strongly ruling out the presence of a massive IMBH in the core of
ω Cen. Instead, we find that all available data can be fitted by a
model that contains 4.6 per cent of the mass of ω Cen in a centrally
concentrated cluster of stellar-mass black holes. We show that this
mass fraction in stellar-mass BHs is compatible with the predictions of
stellar evolution models of massive stars. We also compare our grid of
N-body simulations with NGC 6624, a cluster recently claimed to harbour
a 20 000 M<SUB>⊙</SUB> black hole based on timing observations of
millisecond pulsars. However, we find that models with M<SUB>IMBH</SUB>
> 1000 M<SUB>⊙</SUB> IMBHs are incompatible with the observed
velocity dispersion and surface brightness profile of NGC 6624, ruling
out the presence of a massive IMBH in this cluster. Models without an
IMBH provide again an excellent fit to NGC 6624.
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Title: The EREBOS project: Investigating the effect of substellar
and low-mass stellar companions on late stellar evolution. Survey,
target selection, and atmospheric parameters
Authors: Schaffenroth, V.; Barlow, B. N.; Geier, S.; Vučković,
M.; Kilkenny, D.; Wolz, M.; Kupfer, T.; Heber, U.; Drechsel, H.;
Kimeswenger, S.; Marsh, T.; Wolf, M.; Pelisoli, I.; Freudenthal, J.;
Dreizler, S.; Kreuzer, S.; Ziegerer, E.
2019A&A...630A..80S Altcode: 2019arXiv190709892S
Eclipsing post-common-envelope binaries are highly important for
resolving the poorly understood, very short-lived common-envelope
phase of stellar evolution. Most hot subdwarfs (sdO/Bs) are the bare
helium-burning cores of red giants that have lost almost all of their
hydrogen envelope. This mass loss is often triggered by common-envelope
interactions with close stellar or even substellar companions. Cool
companions to hot subdwarf stars such as late-type stars and brown
dwarfs are detectable from characteristic light-curve variations -
reflection effects and often eclipses. In the recently published
catalog of eclipsing binaries in the Galactic Bulge and in the Asteroid
Terrestrial-impact Last Alert System (ATLAS) survey, we discovered
125 new eclipsing systems showing a reflection effect seen by visual
inspection of the light curves and using a machine-learning algorithm,
in addition to the 36 systems previously discovered by the Optical
Gravitational Lesing Experiment (OGLE) team. The Eclipsing Reflection
Effect Binaries from Optical Surveys (EREBOS) project aims at analyzing
all newly discovered eclipsing binaries of the HW Vir type (hot subdwarf
+ close, cool companion) based on a spectroscopic and photometric
follow up to derive the mass distribution of the companions, constrain
the fraction of substellar companions, and determine the minimum mass
needed to strip off the red-giant envelope. To constrain the nature of
the primary we derived the absolute magnitude and the reduced proper
motion of all our targets with the help of the parallaxes and proper
motions measured by the Gaia mission and compared those to the Gaia
white-dwarf candidate catalog. It was possible to derive the nature
of a subset of our targets, for which observed spectra are available,
by measuring the atmospheric parameter of the primary, confirming
that less than 10% of our systems are not sdO/Bs with cool companions
but are white dwarfs or central stars of planetary nebula. This large
sample of eclipsing hot subdwarfs with cool companions allowed us to
derive a significant period distribution for hot subdwarfs with cool
companions for the first time showing that the period distribution is
much broader than previously thought and is ideally suited to finding
the lowest-mass companions to hot subdwarf stars. The comparison
with related binary populations shows that the period distribution
of HW Vir systems is very similar to WD+dM systems and central stars
of planetary nebula with cool companions. In the future, several new
photometric surveys will be carried out, which will further increase
the sample of this project, providing the potential to test many
aspects of common-envelope theory and binary evolution.
---------------------------------------------------------
Title: VizieR Online Data Catalog: HeI IR triplet measurements for
M dwarfs (Fuhrmeister+, 2019)
Authors: Fuhrmeister, B.; Czesla, S.; Hildebrandt, L.; Nagel, E.;
Schmitt, J. H. M. M.; Hintz, D.; Johnson, E. N.; Sanz-Forcada, J.;
Schoefer, P.; Jeffers, S. V.; Caballero, J. A.; Zechmeister, M.;
Reiners, A.; Ribas, I.; Amado, P. J.; Quirrenbach, A.; Bauer, F. F.;
Bejar, V. J. S.; Cortes-Contreras, M.; Diez-Alonso, E.; Dreizler,
S.; Galadi-Enriquez, D.; Guenther, E. W.; Kaminski, A.; Kuerster,
M.; Lafarga, M.; Montes, D.
2019yCat..36320024F Altcode:
We measure the pseudo-equivalent width (pEW) in the averaged stellar
spectra using a Voigt fit with four Voigt components to account for
neighbouring lines. The fit does not account for the bluest HeI triplet
component and treats the two redder components as one component as they
are totally blended for the used resolution of 80400. For comparison
purposes we give also pEW values of Hα, the bluest CaII IR triplet
line, and the HeI D<SUB>3</SUB> line which were obtained by integration
over the line from the same spectra. As a further comparison for the
activity level of the star we give LX/Lbol values mostly taken from
the ROSAT all-sky survey. <P />(1 data file).
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Title: A giant exoplanet orbiting a very-low-mass star challenges
planet formation models
Authors: Morales, J. C.; Mustill, A. J.; Ribas, I.; Davies, M. B.;
Reiners, A.; Bauer, F. F.; Kossakowski, D.; Herrero, E.; Rodríguez,
E.; López-González, M. J.; Rodríguez-López, C.; Béjar, V. J. S.;
González-Cuesta, L.; Luque, R.; Pallé, E.; Perger, M.; Baroch,
D.; Johansen, A.; Klahr, H.; Mordasini, C.; Anglada-Escudé, G.;
Caballero, J. A.; Cortés-Contreras, M.; Dreizler, S.; Lafarga, M.;
Nagel, E.; Passegger, V. M.; Reffert, S.; Rosich, A.; Schweitzer,
A.; Tal-Or, L.; Trifonov, T.; Zechmeister, M.; Quirrenbach, A.;
Amado, P. J.; Guenther, E. W.; Hagen, H. -J.; Henning, T.; Jeffers,
S. V.; Kaminski, A.; Kürster, M.; Montes, D.; Seifert, W.; Abellán,
F. J.; Abril, M.; Aceituno, J.; Aceituno, F. J.; Alonso-Floriano,
F. J.; Ammler-von Eiff, M.; Antona, R.; Arroyo-Torres, B.; Azzaro,
M.; Barrado, D.; Becerril-Jarque, S.; Benítez, D.; Berdiñas, Z. M.;
Bergond, G.; Brinkmöller, M.; del Burgo, C.; Burn, R.; Calvo-Ortega,
R.; Cano, J.; Cárdenas, M. C.; Cardona Guillén, C.; Carro, J.; Casal,
E.; Casanova, V.; Casasayas-Barris, N.; Chaturvedi, P.; Cifuentes,
C.; Claret, A.; Colomé, J.; Czesla, S.; Díez-Alonso, E.; Dorda, R.;
Emsenhuber, A.; Fernández, M.; Fernández-Martín, A.; Ferro, I. M.;
Fuhrmeister, B.; Galadí-Enríquez, D.; Gallardo Cava, I.; García
Vargas, M. L.; Garcia-Piquer, A.; Gesa, L.; González-Álvarez,
E.; González Hernández, J. I.; González-Peinado, R.; Guàrdia,
J.; Guijarro, A.; de Guindos, E.; Hatzes, A. P.; Hauschildt, P. H.;
Hedrosa, R. P.; Hermelo, I.; Hernández Arabi, R.; Hernández Otero,
F.; Hintz, D.; Holgado, G.; Huber, A.; Huke, P.; Johnson, E. N.;
de Juan, E.; Kehr, M.; Kemmer, J.; Kim, M.; Klüter, J.; Klutsch,
A.; Labarga, F.; Labiche, N.; Lalitha, S.; Lampón, M.; Lara, L. M.;
Launhardt, R.; Lázaro, F. J.; Lizon, J. -L.; Llamas, M.; Lodieu,
N.; López del Fresno, M.; López Salas, J. F.; López-Santiago, J.;
Magán Madinabeitia, H.; Mall, U.; Mancini, L.; Mandel, H.; Marfil,
E.; Marín Molina, J. A.; Martín, E. L.; Martín-Fernández, P.;
Martín-Ruiz, S.; Martínez-Rodríguez, H.; Marvin, C. J.; Mirabet,
E.; Moya, A.; Naranjo, V.; Nelson, R. P.; Nortmann, L.; Nowak, G.;
Ofir, A.; Pascual, J.; Pavlov, A.; Pedraz, S.; Pérez Medialdea, D.;
Pérez-Calpena, A.; Perryman, M. A. C.; Rabaza, O.; Ramón Ballesta,
A.; Rebolo, R.; Redondo, P.; Rix, H. -W.; Rodler, F.; Rodríguez
Trinidad, A.; Sabotta, S.; Sadegi, S.; Salz, M.; Sánchez-Blanco,
E.; Sánchez Carrasco, M. A.; Sánchez-López, A.; Sanz-Forcada, J.;
Sarkis, P.; Sarmiento, L. F.; Schäfer, S.; Schlecker, M.; Schmitt,
J. H. M. M.; Schöfer, P.; Solano, E.; Sota, A.; Stahl, O.; Stock, S.;
Stuber, T.; Stürmer, J.; Suárez, J. C.; Tabernero, H. M.; Tulloch,
S. M.; Veredas, G.; Vico-Linares, J. I.; Vilardell, F.; Wagner, K.;
Winkler, J.; Wolthoff, V.; Yan, F.; Zapatero Osorio, M. R.
2019Sci...365.1441M Altcode: 2019arXiv190912174M
Surveys have shown that super-Earth and Neptune-mass exoplanets are more
frequent than gas giants around low-mass stars, as predicted by the core
accretion theory of planet formation. We report the discovery of a giant
planet around the very-low-mass star GJ 3512, as determined by optical
and near-infrared radial-velocity observations. The planet has a minimum
mass of 0.46 Jupiter masses, very high for such a small host star,
and an eccentric 204-day orbit. Dynamical models show that the high
eccentricity is most likely due to planet-planet interactions. We use
simulations to demonstrate that the GJ 3512 planetary system challenges
generally accepted formation theories, and that it puts constraints
on the planet accretion and migration rates. Disk instabilities may
be more efficient in forming planets than previously thought.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Emission-line sources MUSE spectral
catalogue (Goettgens+, 2019)
Authors: Goettgens, F.; Husser, T. -O.; Kamann, S.; Dreizler, S.;
Giesers, B.; Kollatschny, W.; Weilbacher, P. M.; Roth, M. M.; Wendt, M.
2019yCat..36310118G Altcode:
The spectra were extracted from datacubes taken with MUSE at the VLT. We
used matched filtering to search for emission-line objects (ELOs) in
globular clusters. The tables contain the properties of the detected
ELOs, including references to the literature. Please see the paper
for details about which filter was used for the reported V magnitude,
and which conventions are used for the cluster membership indicator
and the indicator for radial velocity variations. <P />(3 data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: MUSE binaries in NGC 3201
(Giesers+, 2019)
Authors: Giesers, B.; Kamann, S.; Dreizler, S.; Husser, T. -O.;
Askar, A.; Goettgens, F.; Brinchmann, J.; Latour, M.; Weilbacher,
P. M.; Wendt, M.; Roth, M. M.
2019yCat..36320003G Altcode:
Since 2014, 27 Galactic globular clusters were observed (PI: S. Kamann,
formerly S. Dreizler) with the integral field spectrograph Multi Unit
Spectroscopic Explorer (MUSE) at the Very Large Telescope (VLT; Kamann
et al. 2018MNRAS.473.5591K). In the wide field mode, MUSE covers a 1'x1'
field of view (FoV) with a spatial sampling of 0.2" and a spectral
sampling of 1.25Å (resolving power of 1770<R<3590) in the
wavelength range from 4750 to 9350Å. MUSE allows to extract spectra
of some thousand stars per exposure. For this paper, all observations
of NGC 3201 obtained before May 2019 were used. In addition to the
pointings listed in Kamann et al. (2018MNRAS.473.5591K), a deep
field was also implemented. Table 1 lists the number of visits and
total integration times for the different pointings. The data include
adaptive optics (AO) observations, the standard observing mode since
the AO system was commissioned in October 2017. The AO observations are
treated in the same way as our previous observations.The only difference
is that a wavelength window of each spectrum around the sodium lines
(5805Å-5965Å) has to be masked due to the AO laser emission. The
catalogue includes the full radial velocity sample obtained from 63
MUSE observations done for different pointings in NGC 3201 and the
orbital parameters of the 95 well constrained binaries in NGC 3201. <P
/>(5 data files).
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Title: First light of engineered diffusers at the Nordic Optical
Telescope reveal time variability of the optical eclipse depth
of WASP-12b
Authors: von Essen, C.; Stefansson, G.; Mallonn, M.; Pursimo,
T.; Djupvik, A. A.; Mahadevan, S.; Kjeldsen, H.; Freudenthal, J.;
Dreizler, S.
2019A&A...628A.115V Altcode: 2019arXiv190405362V
We present the characterization of two engineered diffusers mounted
on the 2.5-meter Nordic Optical Telescope, located at Roque de
Los Muchachos, Spain. To assess the reliability and the efficiency
of the diffusers, we carried out several test observations of two
photometric standard stars, along with observations of one primary
transit observation of TrES-3b in the red (R band), one of CoRoT-1b
in the blue (B band), and three secondary eclipses of WASP-12b (V
band). The achieved photometric precision is in all cases within the
submillimagnitude level for exposures between 25 and 180 s. Along
with a detailed analysis of the functionality of the diffusers,
we add a new transit depth measurement in the blue (B band) to the
already observed transmission spectrum of CoRoT-1b, disfavoring
a Rayleigh slope. We also report variability of the eclipse depth
of WASP-12b in the V band. For the WASP-12b secondary eclipses, we
observe a secondary depth deviation of about 5σ, and a difference of
6σ and 2.5σ when compared to the values reported by other authors
in a similar wavelength range determined from Hubble Space Telescope
data. We further speculate about the potential physical processes or
causes responsible for this observed variability. <P />The data of the
light curves are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/628/A115">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/628/A115</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: Abundances for 79 Sun-like stars
within 100pc (Bedell+, 2018)
Authors: Bedell, M.; Bean, J. L.; Melendez, J.; Spina, L.; Ramirez,
I.; Asplund, M.; Alves-Brito, A.; Dos Santos, L.; Dreizler, S.; Yong,
D.; Monroe, T.; Casagrande, L.
2019yCat..18650068B Altcode:
To achieve sufficient signal-to-noise for high-precision abundance
work, we stacked >=50 observations for each star. All spectra were
taken with the High Accuracy Radial velocity Planet Searcher (HARPS)
spectrograph on the 3.6m telescope of the European Southern Observatory
(ESO), located at La Silla Observatory in Chile; with resolving power
R=115000 and wavelength coverage between 378-691nm. A majority of
the selected sample were observed by us in the course of a large ESO
observing program on HARPS (Melendez+ 2015Msngr.161...28M). Other stars
had a sufficient number of publicly available spectra in the online
ESO Science Archive Facility. <P />The solar reference spectrum used
in this work was created by combining multiple exposures of sunlight
reflected from the asteroid Vesta. It was continuum-normalized in the
same manner as the target spectra and has S/N~1300/pix at 600nm. <P
/>Spectra previously obtained with the MIKE spectrograph and analyzed
in Ramirez+ (2014A&A...572A..48R) were also used in some parts
of this analysis. These spectra have S/N~400/pix at 600nm, resolution
R=83000-65000 (on blue/red CCDs), and wavelength coverage between 320
and 1000nm. <P />(2 data files).
---------------------------------------------------------
Title: Planetary system around the nearby M dwarf GJ 357 including
a transiting, hot, Earth-sized planet optimal for atmospheric
characterization
Authors: Luque, R.; Pallé, E.; Kossakowski, D.; Dreizler, S.; Kemmer,
J.; Espinoza, N.; Burt, J.; Anglada-Escudé, G.; Béjar, V. J. S.;
Caballero, J. A.; Collins, K. A.; Collins, K. I.; Cortés-Contreras,
M.; Díez-Alonso, E.; Feng, F.; Hatzes, A.; Hellier, C.; Henning,
T.; Jeffers, S. V.; Kaltenegger, L.; Kürster, M.; Madden, J.;
Molaverdikhani, K.; Montes, D.; Narita, N.; Nowak, G.; Ofir, A.;
Oshagh, M.; Parviainen, H.; Quirrenbach, A.; Reffert, S.; Reiners,
A.; Rodríguez-López, C.; Schlecker, M.; Stock, S.; Trifonov, T.;
Winn, J. N.; Zapatero Osorio, M. R.; Zechmeister, M.; Amado, P. J.;
Anderson, D. R.; Batalha, N. E.; Bauer, F. F.; Bluhm, P.; Burke, C. J.;
Butler, R. P.; Caldwell, D. A.; Chen, G.; Crane, J. D.; Dragomir,
D.; Dressing, C. D.; Dynes, S.; Jenkins, J. M.; Kaminski, A.; Klahr,
H.; Kotani, T.; Lafarga, M.; Latham, D. W.; Lewin, P.; McDermott,
S.; Montañés-Rodríguez, P.; Morales, J. C.; Murgas, F.; Nagel,
E.; Pedraz, S.; Ribas, I.; Ricker, G. R.; Rowden, P.; Seager, S.;
Shectman, S. A.; Tamura, M.; Teske, J.; Twicken, J. D.; Vanderspeck,
R.; Wang, S. X.; Wohler, B.
2019A&A...628A..39L Altcode: 2019arXiv190412818L
We report the detection of a transiting Earth-size planet around GJ
357, a nearby M2.5 V star, using data from the Transiting Exoplanet
Survey Satellite (TESS). GJ 357 b (TOI-562.01) is a transiting, hot,
Earth-sized planet (T<SUB>eq</SUB> = 525 ± 11 K) with a radius of
R<SUB>b</SUB> = 1.217 ± 0.084 R<SUB>⊕</SUB> and an orbital period
of P<SUB>b</SUB> = 3.93 d. Precise stellar radial velocities from
CARMENES and PFS, as well as archival data from HIRES, UVES, and
HARPS also display a 3.93-day periodicity, confirming the planetary
nature and leading to a planetary mass of M<SUB>b</SUB> = 1.84 ± 0.31
M<SUB>⊕</SUB>. In addition to the radial velocity signal for GJ 357
b, more periodicities are present in the data indicating the presence
of two further planets in the system: GJ 357 c, with a minimum mass
of M<SUB>c</SUB> = 3.40 ± 0.46 M<SUB>⊕</SUB> in a 9.12 d orbit,
and GJ 357 d, with a minimum mass of M<SUB>d</SUB> = 6.1 ± 1.0
M<SUB>⊕</SUB> in a 55.7 d orbit inside the habitable zone. The host
is relatively inactive and exhibits a photometric rotation period of
P<SUB>rot</SUB> = 78 ± 2 d. GJ 357 b isto date the second closest
transiting planet to the Sun, making it a prime target for further
investigations such as transmission spectroscopy. Therefore, GJ 357 b
represents one of the best terrestrial planets suitable for atmospheric
characterization with the upcoming JWST and ground-based ELTs. <P
/>RV data are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/628/A39">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/628/A39</A>
---------------------------------------------------------
Title: Rocky planets from the CARMENES Survey
Authors: Dreizler, Stefan
2019ESS.....410202D Altcode:
Since the first discovery, more than 800 exoplanets have been detected
through the radial velocity method, the majority orbiting solar-like
stars. Although M-stars are the most frequent stars, very few planets
have yet been found around M-stars of late spectral type. <P />CARMENES,
operated since 2016, is a high-resolution visible-near-IR spectrograph
dedicated to search for such low-mass planets around low-mass stars and
already doubled the number of known planets with host stars below 0.2
M<SUB>Sun</SUB>. Not surprisingly, also this stellar parameter range
has its surprises in terms of planetary system architectures. We will
give an overview of exoplanet detections (published and unpublished)
from the CARMENES survey and then concentrate on the low-mass planets,
including the very recent detection of two Earth-mass planets around
Teegarden's star highlighting the capability of CARMENES. The planetary
system is special since Teegarden's star is only one out of three
planet host stars with an effective temperature below 3000K. Its two
planets are within the optimistic and conservative habitable zone,
respectively. Notably, the Earth, as well as other Solar System planets
are currently or in near future in the transit visibility zone see
from Teegarden's star.
---------------------------------------------------------
Title: VizieR Online Data Catalog: WASP-12, CoRoT-1 and TrES-3 light
curves (von Essen+, 2019)
Authors: von Essen, C.; Stefansson, G.; Mallonn, M.; Pursimo,
T.; Djupvik, A. A.; Mahadevan, S.; Kjeldsen, H.; Freudenthal, J.;
Dreizler, S.
2019yCat..36280115V Altcode:
5 differential photometry time series of primary transit events (first
two) and secondary transit events (last three) of three different
extrasolar planets. <P />(1 data file).
---------------------------------------------------------
Title: Kepler Object of Interest Network. III. Kepler-82f: a new
non-transiting 21 M<SUB>⊕</SUB> planet from photodynamical modelling
Authors: Freudenthal, J.; von Essen, C.; Ofir, A.; Dreizler, S.; Agol,
E.; Wedemeyer, S.; Morris, B. M.; Becker, A. C.; Deeg, H. J.; Hoyer,
S.; Mallonn, M.; Poppenhaeger, K.; Herrero, E.; Ribas, I.; Boumis,
P.; Liakos, A.
2019A&A...628A.108F Altcode: 2019arXiv190706534F
Context. The Kepler Object of Interest Network (KOINet) is a
multi-site network of telescopes around the globe organised for
follow-up observations of transiting planet candidate Kepler objects of
interest with large transit timing variations (TTVs). The main goal of
KOINet is the completion of their TTV curves as the Kepler telescope
stopped observing the original Kepler field in 2013. <BR /> Aims: We
ensure a comprehensive characterisation of the investigated systems
by analysing Kepler data combined with new ground-based transit data
using a photodynamical model. This method is applied to the Kepler-82
system leading to its first dynamic analysis. <BR /> Methods: In order
to provide a coherent description of all observations simultaneously,
we combine the numerical integration of the gravitational dynamics of
a system over the time span of observations with a transit light curve
model. To explore the model parameter space, this photodynamical model
is coupled with a Markov chain Monte Carlo algorithm. <BR /> Results:
The Kepler-82b/c system shows sinusoidal TTVs due to their near 2:1
resonance dynamical interaction. An additional chopping effect in
the TTVs of Kepler-82c hints to a further planet near the 3:2 or 3:1
resonance. We photodynamically analysed Kepler long- and short-cadence
data and three new transit observations obtained by KOINet between 2014
and 2018. Our result reveals a non-transiting outer planet with a mass
of m<SUB>f</SUB> = 20.9 ± 1.0 M<SUB>⊕</SUB> near the 3:2 resonance to
the outermost known planet, Kepler-82c. Furthermore, we determined the
densities of planets b and c to the significantly more precise values
ρ<SUB>b</SUB> = 0.98<SUB>-0.14</SUB><SUP>+0.10</SUP> g cm<SUP>-3</SUP>
and ρ<SUB>c</SUB> = 0.494<SUB>-0.077</SUB><SUP>+0.066</SUP>
g cm<SUP>-3</SUP>. <P />Ground-based photometry
is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/628/A108">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/628/A108</A>
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M
dwarfs. Photospheric parameters of target stars from high-resolution
spectroscopy. II. Simultaneous multiwavelength range modeling of
activity insensitive lines
Authors: Passegger, V. M.; Schweitzer, A.; Shulyak, D.; Nagel, E.;
Hauschildt, P. H.; Reiners, A.; Amado, P. J.; Caballero, J. A.;
Cortés-Contreras, M.; Domínguez-Fernández, A. J.; Quirrenbach,
A.; Ribas, I.; Azzaro, M.; Anglada-Escudé, G.; Bauer, F. F.; Béjar,
V. J. S.; Dreizler, S.; Guenther, E. W.; Henning, T.; Jeffers, S. V.;
Kaminski, A.; Kürster, M.; Lafarga, M.; Martín, E. L.; Montes, D.;
Morales, J. C.; Schmitt, J. H. M. M.; Zechmeister, M.
2019A&A...627A.161P Altcode: 2019arXiv190700807P
We present precise photospheric parameters of 282 M dwarfs
determined from fitting the most recent version of PHOENIX models to
high-resolution CARMENES spectra in the visible (0.52-0.96 μm) and NIR
wavelength range (0.96-1.71 μm). With its aim to search for habitable
planets around M dwarfs, several planets of different masses have
been detected. The characterization of the target sample is important
for the ability to derive and constrain the physical properties of any
planetary systems that are detected. As a continuation of previous work
in this context, we derived the fundamental stellar parameters effective
temperature, surface gravity, and metallicity of the CARMENES M-dwarf
targets from PHOENIX model fits using a χ<SUP>2</SUP> method. We
calculated updated PHOENIX stellar atmosphere models that include a
new equation of state to especially account for spectral features
of low-temperature stellar atmospheres as well as new atomic and
molecular line lists. We show the importance of selecting magnetically
insensitive lines for fitting to avoid effects of stellar activity
in the line profiles. For the first time, we directly compare stellar
parameters derived from multiwavelength range spectra, simultaneously
observed for the same star. In comparison with literature values we
show that fundamental parameters derived from visible spectra and
visible and NIR spectra combined are in better agreement than those
derived from the same spectra in the NIR alone. <P />Full Tables
B.1 and B.2 are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/627/A161">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/627/A161</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: Radial velocities of GJ 357
(Luque+, 2019)
Authors: Luque, R.; Palle, E.; Kossakowski, D.; Dreizler, S.; Kemmer,
J.; Espinoza, N.; Burt, J.; Anglada-Escude, G.; Bejar, V. J. S.;
Caballero, J. A.; Collins, K. A.; Collins, K. I.; Cortes-Contreras,
M.; Diez-Alonso, E.; Feng, F.; Hatzes, A.; Hellier, C.; Henning,
T.; Jeffers, S. V.; Kaltenegger, L.; Kuerster, M.; Madden, J.;
Molaverdikhani, K.; Montes, D.; Narita, N.; Nowak, G.; Ofir, A.;
Oshagh, M.; Parviainen, H.; Quirrenbach, A.; Reffert, S.; Reiners,
A.; Rodriguez-Lopez, C.; Schlecker, M.; Stock, S.; Trifonov, T.;
Winn, J. N.; Zapatero Osorio, M. R.; Zechmeister, M.; Amado, P. J.;
Anderson, D. R.; Batalha, N. E.; Bauer, F. F.; Bluhm, P.; Burke, C. J.;
Butler, R. P.; Caldwell, D. A.; Chen, G.; Crane, J. D.; Dragomir,
D.; Dressing, C. D.; Dynes, S.; Jenkins, J. M.; Kaminski, A.; Klahr,
H.; Kotani, T.; Lafarga, M.; Latham, D. W.; Lewin, P.; McDermott, S.;
Montanes-Rodriguez, P.; Morales, J. C.; Murgas, F.; Nagel, E.; Pedraz,
S.; Ribas, I.; Ricker, G. R.; Rowden, P.; Seager, S.; Shectman, S. A.;
Tamura, M.; Teske, J.; Twicken, J. D.; Vanderspeck, R.; Wang, S. X.;
Wohler, B.
2019yCat..36280039L Altcode:
Radial velocities of GJ 357 from HIRES (Vogt et al., 1994, in
Proc. SPIE, Vol. 2198, 362), UVES (programs 072.C-0495, 078.C-0829,
and 173.C-0606), HARPS (Mayor et al., 2003Msngr.114...20M; programs
072.C-0488, 183.C-0437), CARMENES (Quirrenbach et al., 2016, in
Proc. SPIE, Vol. 9147,91471F; 2018, in Society of Photo-Optical
Instrumentation Engineers (SPIE) Conference Series, Vol. 10702,
107020W), and PFS (Crane et al., 2010aepr.confE..19C). <P />(1 data
file).
---------------------------------------------------------
Title: Proxima Centauri b is not a transiting exoplanet
Authors: Jenkins, James S.; Harrington, Joseph; Challener, Ryan C.;
Kurtovic, Nicolás T.; Ramirez, Ricardo; Peña, Jose; McIntyre,
Kathleen J.; Himes, Michael D.; Rodríguez, Eloy; Anglada-Escudé,
Guillem; Dreizler, Stefan; Ofir, Aviv; Peña Rojas, Pablo A.; Ribas,
Ignasi; Rojo, Patricio; Kipping, David; Butler, R. Paul; Amado, Pedro
J.; Rodríguez-López, Cristina; Kempton, Eliza M. -R.; Palle, Enric;
Murgas, Felipe
2019MNRAS.487..268J Altcode: 2019MNRAS.tmp.1236J; 2019arXiv190501336J
We report Spitzer Space Telescope observations during predicted transits
of the exoplanet Proxima Centauri b. As the nearest terrestrial
habitable-zone planet we will ever discover, any potential transit
of Proxima b would place strong constraints on its radius, bulk
density, and atmosphere. Subsequent transmission spectroscopy and
secondary-eclipse measurements could then probe the atmospheric
chemistry, physical processes, and orbit, including a search for
biosignatures. However, our photometric results rule out planetary
transits at the 200 ppm level at 4.5 μm, yielding a 3σ upper
radius limit of 0.4 R<SUB>⊕</SUB> (Earth radii). Previous claims of
possible transits from optical ground- and space-based photometry were
likely correlated noise in the data from Proxima Centauri's frequent
flaring. Our study indicates dramatically reduced stellar activity at
near-to-mid infrared wavelengths, compared to the optical. Proxima
b is an ideal target for space-based infrared telescopes, if their
instruments can be configured to handle Proxima's brightness.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Detection
of a mini-Neptune around LSPM J2116+0234 and refinement of orbital
parameters of a super-Earth around GJ 686 (BD+18 3421)
Authors: Lalitha, S.; Baroch, D.; Morales, J. C.; Passegger, V. M.;
Bauer, F. F.; Cardona Guillén, C.; Dreizler, S.; Oshagh, M.; Reiners,
A.; Ribas, I.; Caballero, J. A.; Quirrenbach, A.; Amado, P. J.; Béjar,
V. J. S.; Colomé, J.; Cortés-Contreras, M.; Galadí-Enríquez, D.;
González-Cuesta, L.; Guenther, E. W.; Hagen, H. -J.; Henning, T.;
Herrero, E.; Husser, T. -O.; Jeffers, S. V.; Kaminski, A.; Kürster,
M.; Lafarga, M.; Lodieu, N.; López-González, M. J.; Montes, D.;
Perger, M.; Rosich, A.; Rodríguez, E.; Rodríguez-López, C.; Schmitt,
J. H. M. M.; Tal-Or, L.; Zechmeister, M.
2019A&A...627A.116L Altcode: 2019arXiv190509075L
Although M dwarfs are known for high levels of stellar activity,
they are ideal targets for the search of low-mass exoplanets
with the radial velocity (RV) method. We report the discovery of a
planetary-mass companion around LSPM J2116+0234 (M3.0 V) and confirm
the existence of a planet orbiting GJ 686 (BD+18 3421; M1.0 V). The
discovery of the planet around LSPM J2116+0234 is based on CARMENES
RV observations in the visual and near-infrared channels. We confirm
the planet orbiting around GJ 686 by analyzing the RV data spanning
over two decades of observationsfrom CARMENES VIS, HARPS-N, HARPS,
and HIRES. We find planetary signals at 14.44 and 15.53 d in the
RV data for LSPM J2116+0234 and GJ 686, respectively. Additionally,
the RV, photometric time series, and various spectroscopic indicators
show hints of variations of 42 d for LSPM J2116+0234 and 37 d for GJ
686, which we attribute to the stellar rotation periods. The orbital
parameters of the planets are modeled with Keplerian fits together
with correlated noise from the stellar activity. A mini-Neptune with a
minimum mass of 11.8 M<SUB>⊕</SUB> orbits LSPM J2116+0234 producing a
RV semi-amplitude of 6.19 m s<SUP>-1</SUP>, while a super-Earth of mass
6.6 M<SUB>⊕</SUB> orbits GJ 686 and produces a RV semi-amplitude of
3.0 m s<SUP>-1</SUP>. Both LSPM J2116+0234 and GJ 686 have planetary
companions populating the regime of exoplanets with masses lower
than 15 M<SUB>⊕</SUB> and orbital periods <20 d. <P />Table
A.1 and A.2 are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/627/A116">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/627/A116</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: Photometry of Kepler-82b and c
transits (Freudenthal+, 2019)
Authors: Freudenthal, J.; von Essen, C.; Ofir, A.; Dreizler, S.; Agol,
E.; Wedemeyer, S.; Morris, B. M.; Becker, A. C.; Deeg, H. J.; Hoyer,
S.; Mallonn, M.; Poppenhaeger, K.; Herrero, E.; Ribas, I.; Boumis,
P.; Liakos, A.
2019yCat..36280108F Altcode:
All our observations were carried out using R-band filter. We provide
the differential photometry with varying reference stars for each
observation together with the used detrending components. We measured
one Kepler-82b and two Kepler-82c transits in three observations
between 2014 and 2018. <P />(4 data files).
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Two
temperate Earth-mass planet candidates around Teegarden's Star
Authors: Zechmeister, M.; Dreizler, S.; Ribas, I.; Reiners, A.;
Caballero, J. A.; Bauer, F. F.; Béjar, V. J. S.; González-Cuesta,
L.; Herrero, E.; Lalitha, S.; López-González, M. J.; Luque, R.;
Morales, J. C.; Pallé, E.; Rodríguez, E.; Rodríguez López, C.;
Tal-Or, L.; Anglada-Escudé, G.; Quirrenbach, A.; Amado, P. J.; Abril,
M.; Aceituno, F. J.; Aceituno, J.; Alonso-Floriano, F. J.; Ammler-von
Eiff, M.; Antona Jiménez, R.; Anwand-Heerwart, H.; Arroyo-Torres,
B.; Azzaro, M.; Baroch, D.; Barrado, D.; Becerril, S.; Benítez,
D.; Berdiñas, Z. M.; Bergond, G.; Bluhm, P.; Brinkmöller, M.;
del Burgo, C.; Calvo Ortega, R.; Cano, J.; Cardona Guillén, C.;
Carro, J.; Cárdenas Vázquez, M. C.; Casal, E.; Casasayas-Barris,
N.; Casanova, V.; Chaturvedi, P.; Cifuentes, C.; Claret, A.; Colomé,
J.; Cortés-Contreras, M.; Czesla, S.; Díez-Alonso, E.; Dorda, R.;
Fernández, M.; Fernández-Martín, A.; Fuhrmeister, B.; Fukui, A.;
Galadí-Enríquez, D.; Gallardo Cava, I.; Garcia de la Fuente, J.;
Garcia-Piquer, A.; García Vargas, M. L.; Gesa, L.; Góngora Rueda, J.;
González-Álvarez, E.; González Hernández, J. I.; González-Peinado,
R.; Grözinger, U.; Guàrdia, J.; Guijarro, A.; de Guindos, E.;
Hatzes, A. P.; Hauschildt, P. H.; Hedrosa, R. P.; Helmling, J.;
Henning, T.; Hermelo, I.; Hernández Arabi, R.; Hernández Castaño,
L.; Hernández Otero, F.; Hintz, D.; Huke, P.; Huber, A.; Jeffers,
S. V.; Johnson, E. N.; de Juan, E.; Kaminski, A.; Kemmer, J.; Kim,
M.; Klahr, H.; Klein, R.; Klüter, J.; Klutsch, A.; Kossakowski, D.;
Kürster, M.; Labarga, F.; Lafarga, M.; Llamas, M.; Lampón, M.; Lara,
L. M.; Launhardt, R.; Lázaro, F. J.; Lodieu, N.; López del Fresno,
M.; López-Puertas, M.; López Salas, J. F.; López-Santiago, J.;
Magán Madinabeitia, H.; Mall, U.; Mancini, L.; Mandel, H.; Marfil,
E.; Marín Molina, J. A.; Maroto Fernández, D.; Martín, E. L.;
Martín-Fernández, P.; Martín-Ruiz, S.; Marvin, C. J.; Mirabet,
E.; Montañés-Rodríguez, P.; Montes, D.; Moreno-Raya, M. E.;
Nagel, E.; Naranjo, V.; Narita, N.; Nortmann, L.; Nowak, G.; Ofir,
A.; Oshagh, M.; Panduro, J.; Parviainen, H.; Pascual, J.; Passegger,
V. M.; Pavlov, A.; Pedraz, S.; Pérez-Calpena, A.; Pérez Medialdea,
D.; Perger, M.; Perryman, M. A. C.; Rabaza, O.; Ramón Ballesta, A.;
Rebolo, R.; Redondo, P.; Reffert, S.; Reinhardt, S.; Rhode, P.; Rix,
H. -W.; Rodler, F.; Rodríguez Trinidad, A.; Rosich, A.; Sadegi, S.;
Sánchez-Blanco, E.; Sánchez Carrasco, M. A.; Sánchez-López, A.;
Sanz-Forcada, J.; Sarkis, P.; Sarmiento, L. F.; Schäfer, S.; Schmitt,
J. H. M. M.; Schöfer, P.; Schweitzer, A.; Seifert, W.; Shulyak, D.;
Solano, E.; Sota, A.; Stahl, O.; Stock, S.; Strachan, J. B. P.; Stuber,
T.; Stürmer, J.; Suárez, J. C.; Tabernero, H. M.; Tala Pinto, M.;
Trifonov, T.; Veredas, G.; Vico Linares, J. I.; Vilardell, F.; Wagner,
K.; Wolthoff, V.; Xu, W.; Yan, F.; Zapatero Osorio, M. R.
2019A&A...627A..49Z Altcode: 2019arXiv190607196Z
Context. Teegarden's Star is the brightest and one of the nearest
ultra-cool dwarfs in the solar neighbourhood. For its late spectral
type (M7.0 V), the star shows relatively little activity and is
a prime target for near-infrared radial velocity surveys such as
CARMENES. <BR /> Aims: As part of the CARMENES search for exoplanets
around M dwarfs, we obtained more than 200 radial-velocity measurements
of Teegarden's Star and analysed them for planetary signals. <BR />
Methods: We find periodic variability in the radial velocities of
Teegarden's Star. We also studied photometric measurements to rule
out stellar brightness variations mimicking planetary signals. <BR />
Results: We find evidence for two planet candidates, each with 1.1
M<SUB>⊕</SUB> minimum mass, orbiting at periods of 4.91 and 11.4 d,
respectively. No evidence for planetary transits could be found in
archival and follow-up photometry. Small photometric variability is
suggestive of slow rotation and old age. <BR /> Conclusions: The two
planets are among the lowest-mass planets discovered so far, and they
are the first Earth-mass planets around an ultra-cool dwarf for which
the masses have been determined using radial velocities. <P />Tables
D.1 and D.2 are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/627/A49">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/627/A49</A>
---------------------------------------------------------
Title: Magnetic fields in M dwarfs from the CARMENES survey
Authors: Shulyak, D.; Reiners, A.; Nagel, E.; Tal-Or, L.; Caballero,
J. A.; Zechmeister, M.; Béjar, V. J. S.; Cortés-Contreras, M.;
Martin, E. L.; Kaminski, A.; Ribas, I.; Quirrenbach, A.; Amado, P. J.;
Anglada-Escudé, G.; Bauer, F. F.; Dreizler, S.; Guenther, E. W.;
Henning, T.; Jeffers, S. V.; Kürster, M.; Lafarga, M.; Montes, D.;
Morales, J. C.; Pedraz, S.
2019A&A...626A..86S Altcode: 2019arXiv190412762S
Context. M dwarfs are known to generate the strongest magnetic fields
among main-sequence stars with convective envelopes, but we are still
lacking a consistent picture of the link between the magnetic fields
and underlying dynamo mechanisms, rotation, and activity. <BR /> Aims:
In this work we aim to measure magnetic fields from the high-resolution
near-infrared spectra taken with the CARMENES radial-velocity planet
survey in a sample of 29 active M dwarfs and compare our results
against stellar parameters. <BR /> Methods: We used the state-of-the-art
radiative transfer code to measure total magnetic flux densities from
the Zeeman broadening of spectral lines and filling factors. <BR />
Results: We detect strong kG magnetic fields in all our targets. In
16 stars the magnetic fields were measured for the first time. Our
measurements are consistent with the magnetic field saturation in stars
with rotation periods P < 4 d. The analysis of the magnetic filling
factors reveal two different patterns of either very smooth distribution
or a more patchy one, which can be connected to the dynamo state of
the stars and/or stellar mass. <BR /> Conclusions: Our measurements
extend the list of M dwarfs with strong surface magnetic fields. They
also allow us to better constrain the interplay between the magnetic
energy, stellar rotation, and underlying dynamo action. The high
spectral resolution and observations at near-infrared wavelengths are
the beneficial capabilities of the CARMENES instrument that allow us
to address important questions about the stellar magnetism.
---------------------------------------------------------
Title: VizieR Online Data Catalog: CARMENES stars multi wavelength
measurements (Passegger+, 2019)
Authors: Passegger, V. M.; Schweitzer, A.; Shulyak, D.; Nagel, E.;
Hauschildt, P. H.; Reiners, A.; Amado, P. J.; Caballero, J. A.;
Cortes-Contreras, M.; Dominguez-Fernandez, A. J.; Quirrenbach,
A.; Ribas, I.; Azarro, M.; Anglada-Escude, G.; Bauer, F. F.; Bejar,
V. J. S.; Dreizler, S.; Guenther, E. W.; Henning, T.; Jeffers, S. V.;
Kaminski, A.; Kuerster, M.; Lafarga, M.; Martin, E. L.; Montes, D.;
Morales, J. C.; Schmidt, J. H. M. M.; Zechmeister, M.
2019yCat..36270161P Altcode:
We present basic photospheric parameters of 282 M dwarfs within
the CARMENES survey in the visible and near-infrared wavelength
ranges. In table_b1 we provide Carmencita identifier (Karmn), Simbad
name, equatorial coordinates, spectral type, rotational velocity,
assumed age, and an activity flag for each star in our sample. In
table_b2 we give effective temperature, surface gravity and [Fe/H]
for each star in different wavelength ranges (VIS+NIR, NIR, and VIS),
together with their errors. <P />(2 data files).
---------------------------------------------------------
Title: BlueMUSE: Project Overview and Science Cases
Authors: Richard, Johan; Bacon, Roland; Blaizot, Jérémy; Boissier,
Samuel; Boselli, Alessandro; NicolasBouché; Brinchmann, Jarle; Castro,
Norberto; Ciesla, Laure; Crowther, Paul; Daddi, Emanuele; Dreizler,
Stefan; Duc, Pierre-Alain; Elbaz, David; Epinat, Benoit; Evans, Chris;
Fossati, Matteo; Fumagalli, Michele; Garcia, Miriam; Garel, Thibault;
Hayes, Matthew; Adamo, Angela; Herrero, Artemio; Hugot, Emmanuel;
Humphrey, Andrew; Jablonka, Pascale; Kamann, Sebastian; Kaper, Lex;
Kelz, Andreas; Kneib, Jean-Paul; de Koter, Alex; Krajnović, Davor;
Kudritzki, Rolf-Peter; Langer, Norbert; Lardo, Carmela; Leclercq,
Floriane; Lennon, Danny; Mahler, Guillaume; Martins, Fabrice; Massey,
Richard; Mitchell, Peter; Monreal-Ibero, Ana; Najarro, Paco; Opitom,
Cyrielle; Papaderos, Polychronis; Péroux, Céline; Revaz, Yves; Roth,
Martin M.; Rousselot, Philippe; Sander, Andreas; Simmonds Wagemann,
Charlotte; Smail, Ian; Swinbank, Anthony Mark; Tramper, Frank; Urrutia,
Tanya; Verhamme, Anne; Vink, Jorick; Walsh, Jeremy; Weilbacher, Peter;
Wendt, Martin; Wisotzki, Lutz; Yang, Bin
2019arXiv190601657R Altcode:
We present the concept of BlueMUSE, a blue-optimised, medium spectral
resolution, panoramic integral field spectrograph based on the MUSE
concept and proposed for the Very Large Telescope. With an optimised
transmission down to 350 nm, a larger FoV (1.4 x 1.4 arcmin$^2$) and a
higher spectral resolution compared to MUSE, BlueMUSE will open up a
new range of galactic and extragalactic science cases allowed by its
specific capabilities, beyond those possible with MUSE. For example
a survey of massive stars in our galaxy and the Local Group will
increase the known population of massive stars by a factor $>$100,
to answer key questions about their evolution. Deep field observations
with BlueMUSE will also significantly increase samples of Lyman-alpha
emitters, spanning the era of Cosmic Noon. This will revolutionise
the study of the distant Universe: allowing the intergalactic medium
to be detected unambiguously in emission, enabling the study of the
exchange of baryons between galaxies and their surroundings. By 2030,
at a time when the focus of most of the new large facilities (ELT,
JWST) will be on the infra-red, BlueMUSE will be a unique facility,
outperforming any ELT instrument in the Blue/UV. It will have a strong
synergy with ELT, JWST as well as ALMA, SKA, Euclid and Athena.
---------------------------------------------------------
Title: VizieR Online Data Catalog: LSPM J2116+0234 and GJ 686 radial
velocities (Lalitha+, 2019)
Authors: Lalitha, S.; Baroch, D.; Morales, J. C.; Passegger, V. M.;
Bauer, F. F.; Cardona Guillen, C.; Dreizler, S.; Oshagh, M.; Reiners,
A.; Ribas, I.; Caballero, J. A.; Quirrenbach, A.; Amado, P. J.;
Bejar, V. J. S.; Colome, J.; Cortes-Contreras, M.; Galadi-Enriquez,
D.; Gonzalez-Cuesta, L.; Guenther, E. W.; Hagen, H. -J.; Henning, T.;
Herrero, E.; Husser, T. -O.; Jeffers, S. V.; Kaminski, A.; Kuerster,
M.; Lafarga, M.; Lodieu, N.; Lopez-Gonzalez, M. J.; Montes, D.;
Perger, M.; Rosich, A.; Rodriguez, E.; Rodriguez-Lopez, C.; Schmitt,
J. H. M. M.; Tal-Or, L.; Zechmeister, M.
2019yCat..36270116L Altcode:
We analysed radial velocity data from the CARMENES NIR and VIS channels
for LSPM J2116+0234, and from CARMENES VIS channel, HARPS and HIRES for
GJ 686. All the RVs are corrected for barycentric motion and secular
acceleration. The CARMENES measurements were taken in the context
of the CARMENES search for exoplanets around M dwarfs. The CARMENES
instrument consists of two channels: the VIS channel obtains spectra
at a resolution of R=94600 in the wavelength range 520-960nm, while
the NIR channel yields spectra of R=80400 covering 960-1710nm. Both
channels are calibrated in wavelength with hollow-cathode lamps
and use temperature- and pressure-stabilized Fabry-Perot etalons
to interpolate the wavelength solution and simultaneously monitor
the spectrograph drift during nightly operations (Bauer et al.,
2015A&A...581A.117B). <P />(2 data files).
---------------------------------------------------------
Title: Discovery of an old nova remnant in the Galactic globular
cluster M 22
Authors: Göttgens, Fabian; Weilbacher, Peter M.; Roth, Martin M.;
Dreizler, Stefan; Giesers, Benjamin; Husser, Tim-Oliver; Kamann,
Sebastian; Brinchmann, Jarle; Kollatschny, Wolfram; Monreal-Ibero,
Ana; Schmidt, Kasper B.; Wendt, Martin; Wisotzki, Lutz; Bacon, Roland
2019A&A...626A..69G Altcode: 2019arXiv190411515G
A nova is a cataclysmic event on the surface of a white dwarf in a
binary system that increases the overall brightness by several orders
of magnitude. Although binary systems with a white dwarf are expected
to be overabundant in globular clusters compared with in the Galaxy,
only two novae from Galactic globular clusters have been observed. We
present the discovery of an emission nebula in the Galactic globular
cluster M 22 (NGC 6656) in observations made with the integral-field
spectrograph MUSE. We extracted the spectrum of the nebula and used
the radial velocity determined from the emission lines to confirm
that the nebula is part of NGC 6656. Emission-line ratios were used
to determine the electron temperature and density. It is estimated
to have a mass of 1-17 × 10<SUP>-5</SUP>M<SUB>⊙</SUB>. This mass
and the emission-line ratios indicate that the nebula is a nova
remnant. Its position coincides with the reported location of a
"guest star", an ancient Chinese term for transients, observed
in May 48 BCE. With this discovery, this nova may be one of the
oldest confirmed extra-solar events recorded in human history. <P
/>Datacubes are also available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/626/A69">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/626/A69</A>
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Different
roads to radii and masses of the target stars
Authors: Schweitzer, A.; Passegger, V. M.; Cifuentes, C.; Béjar,
V. J. S.; Cortés-Contreras, M.; Caballero, J. A.; del Burgo,
C.; Czesla, S.; Kürster, M.; Montes, D.; Zapatero Osorio, M. R.;
Ribas, I.; Reiners, A.; Quirrenbach, A.; Amado, P. J.; Aceituno, J.;
Anglada-Escudé, G.; Bauer, F. F.; Dreizler, S.; Jeffers, S. V.;
Guenther, E. W.; Henning, T.; Kaminski, A.; Lafarga, M.; Marfil,
E.; Morales, J. C.; Schmitt, J. H. M. M.; Seifert, W.; Solano, E.;
Tabernero, H. M.; Zechmeister, M.
2019A&A...625A..68S Altcode: 2019arXiv190403231S
<BR /> Aims: We determine the radii and masses of 293 nearby, bright M
dwarfs of the CARMENES survey. This is the first time that such a large
and homogeneous high-resolution (R > 80 000) spectroscopic survey
has been used to derive these fundamental stellar parameters. <BR
/> Methods: We derived the radii using Stefan-Boltzmann's law. We
obtained the required effective temperatures T<SUB>eff</SUB> from
a spectral analysis and we obtained the required luminosities L
from integrated broadband photometry together with the Gaia DR2
parallaxes. The mass was then determined using a mass-radius relation
that we derived from eclipsing binaries known in the literature. We
compared this method with three other methods: (1) We calculated
the mass from the radius and the surface gravity log g, which was
obtained from the same spectral analysis as T<SUB>eff</SUB>. (2) We
used a widely used infrared mass-magnitude relation. (3) We used a
Bayesian approach to infer stellar parameters from the comparison of
the absolute magnitudes and colors of our targets with evolutionary
models. <BR /> Results: Between spectral types M0 V and M7 V our radii
cover the range 0.1 R<SUB>⊙</SUB> < R < 0.6 R<SUB>⊙</SUB>
with an error of 2-3% and our masses cover 0.09 ℳ<SUB>⊙</SUB>
< ℳ< 0.6ℳ<SUB>⊙</SUB> with an error of 3-5%. We find
good agreement between the masses determined with these different
methods for most of our targets. Only the masses of very young
objects show discrepancies. This can be well explained with the
assumptions that we used for our methods. <P />Table B.1 (stellar
parameters) is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/625/A68">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/625/A68</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: Radii and masses of the CARMENES
targets (Schweitzer+, 2019)
Authors: Schweitzer, A.; Passegger, V. M.; Cifuentes, C.; Bejar,
V. J. S.; Cortes-Contreras, M.; Caballero, J. A.; Del Burgo, C.;
Czesla, S.; Kuerster, M.; Montes, D.; Zapatero Osorio, M. R.;
Ribas, I.; Reiners, A.; Quirrenbach, A.; Amado, P. J.; Aceituno,
J.; Anglada-Escude, G.; Bauer, F. F.; Dreizler, S.; Jeffers, S. V.;
Guenther, E. W.; Henning, T.; Kaminski, A.; Lafarga, M.; Marfil,
E.; Morales, J. C.; Schmitt, J. H. M. M.; Seifert, W.; Solano, E.;
Tabernero, H. M.; Zechmeister, M.
2019yCat..36250068S Altcode:
Table B1 contains the stellar parameters of our sample. The
sample consists of 293 nearby, bright M dwarfs with no known close
companions. Their metallicities spread around solar metallicity. Most
stars are inactive or mildly active and older than a few hundred million
years. However, known active or young stars are also included although
most of the analyses assume inactive main sequence stars. All parameters
are determined by us except where noted otherwise. <P />(1 data file).
---------------------------------------------------------
Title: VizieR Online Data Catalog: An old nova remnant in M22
(Goettgens+, 2019)
Authors: Goettgens, F.; Weilbacher, P. M.; Roth, M. M.; Dreizler, S.;
Giesers, B.; Husser, T. -O.; Kamann, S.; Brinchmann, J.; Kollatschny,
W.; Monreal-Ibero, A.; Schmidt, K. B.; Wendt, M.; Wisotzki, L.;
Bacon, R.
2019yCat..36260069G Altcode:
We release the 3D datacube of the nova remnant in M22. It was combined
from data of seven MUSE observations without adaptive optics (see
Table 1 in the paper for details). <P />We also release the spectrum
extracted from this datacube as displayed in Fig. 2 in the paper
(labelled 'observed' in this figure). <P />(2 data files).
---------------------------------------------------------
Title: Gliese 49: activity evolution and detection of a super-Earth. A
HADES and CARMENES collaboration
Authors: Perger, M.; Scandariato, G.; Ribas, I.; Morales, J. C.;
Affer, L.; Azzaro, M.; Amado, P. J.; Anglada-Escudé, G.; Baroch,
D.; Barrado, D.; Bauer, F. F.; Béjar, V. J. S.; Caballero, J. A.;
Cortés-Contreras, M.; Damasso, M.; Dreizler, S.; González-Cuesta,
L.; González Hernández, J. I.; Guenther, E. W.; Henning, T.;
Herrero, E.; Jeffers, S. V.; Kaminski, A.; Kürster, M.; Lafarga,
M.; Leto, G.; López-González, M. J.; Maldonado, J.; Micela, G.;
Montes, D.; Pinamonti, M.; Quirrenbach, A.; Rebolo, R.; Reiners, A.;
Rodríguez, E.; Rodríguez-López, C.; Schmitt, J. H. M. M.; Sozzetti,
A.; Suárez Mascareño, A.; Toledo-Padrón, B.; Zanmar Sánchez, R.;
Zapatero Osorio, M. R.; Zechmeister, M.
2019A&A...624A.123P Altcode: 2019arXiv190304808P
Context. Small planets around low-mass stars often show orbital periods
in a range that corresponds to the temperate zones of their host stars
which are therefore of prime interest for planet searches. Surface
phenomena such as spots and faculae create periodic signals in radial
velocities and in observational activity tracers in the same range,
so they can mimic or hide true planetary signals. <BR /> Aims: We
aim to detect Doppler signals corresponding to planetary companions,
determine their most probable orbital configurations, and understand
the stellar activity and its impact on different datasets. <BR />
Methods: We analyzed 22 yr of data of the M1.5 V-type star Gl 49
(BD+61 195) including HARPS-N and CARMENES spectrographs, complemented
by APT2 and SNO photometry. Activity indices are calculated from the
observed spectra, and all datasets are analyzed with periodograms and
noise models. We investigated how the variation of stellar activity
imprints on our datasets. We further tested the origin of the signals
and investigate phase shifts between the different sets. To search
for the best-fit model we maximize the likelihood function in a Markov
chain Monte Carlo approach. <BR /> Results: As a result of this study,
we are able to detect the super-Earth Gl 49b with a minimum mass of 5.6
M<SUB>⊕</SUB>. It orbits its host star with a period of 13.85 d at a
semi-major axis of 0.090 au and we calculate an equilibrium temperature
of 350 K and a transit probability of 2.0%. The contribution from the
spot-dominated host star to the different datasets is complex, and
includes signals from the stellar rotation at 18.86 d, evolutionary
timescales of activity phenomena at 40-80 d, and a long-term variation
of at least four years. <P />Based on observations made with the Italian
TNG, operated on the island of La Palma, Spain; the CARMENES instrument
installed at the 3.5 m telescope of the Calar Alto Observatory,
Spain; the robotic APT2 located at Serra La Nave on Mt. Etna, Italy;
and the T90 telescope at Sierra Nevada Observatory, Spain.Full
Table A.1 is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/624/A123">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/624/A123</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: Gl 49 radial velocities and
activity indicators (Perger+, 2019)
Authors: Perger, M.; Scandariato, G.; Ribas, I.; Morales, J. C.;
Affer, L.; Azzaro, M.; Amado, P. J.; Anglada-Escude, G.; Baroch,
D.; Barrado, D.; Bauer, F. F.; Bejar, V. J. S.; Caballero, J. A.;
Cortes-Contreras, M.; Damasso, M.; Dreizler, S.; Gonzalez-Cuesta,
L.; Gonzalez Hernandez, J. I.; Guenther, E. W.; Henning, T.;
Herrero, E.; Jeffers, S. V.; Kaminski, A.; Kuerster, M.; Lafarga,
M.; Leto, G.; Lopez-Gonzalez, M. J.; Maldonado, J.; Micela, G.;
Montes, D.; Pinamonti, M.; Quirrenbach, A.; Rebolo, R.; Reiners, A.;
Rodriguez, E.; Rodriguez-Lopez, C.; Schmitt, J. H. M. M.; Sozzetti,
A.; Suarezmascareno, A.; Toledo-Padron, B.; Zanmar Sanchez, R.;
Zapatero Osorio, M. R.; Zechmeister, M.
2019yCat..36240123P Altcode:
Radial velocity and activity indicator time-series data of Gl 49
from HIRES, HARPS-N, and CARMENES instruments. <P />We obtained 137
RVs from optical spectra of the HADES program. They were observed
over six seasons (S1 to S6) between 3 Sep 2012 and 11 Oct 2017 with
HARPS-N. <P />We obtained spectroscopic observations with the CARMENES
instrument, installed since 2015 at the 3.51m telescope of the Calar
Alto Observatory in Spain. <P />Gl 49 was also observed with the HIRES
instrument, installed since the late 1990s at the Keck I telescope
located in Hawaii, USA. <P />(1 data file).
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Period
search in Hα, Na I D, and Ca II IRT lines
Authors: Fuhrmeister, B.; Czesla, S.; Schmitt, J. H. M. M.; Johnson,
E. N.; Schöfer, P.; Jeffers, S. V.; Caballero, J. A.; Zechmeister,
M.; Reiners, A.; Ribas, I.; Amado, P. J.; Quirrenbach, A.; Bauer, F.;
Béjar, V. J. S.; Cortés-Contreras, M.; Díez Alonso, E.; Dreizler,
S.; Galadí-Enríquez, D.; Guenther, E. W.; Kaminski, A.; Kürster,
M.; Lafarga, M.; Montes, D.
2019A&A...623A..24F Altcode: 2019arXiv190105173F
We use spectra from CARMENES, the Calar Alto high-Resolution search
for M dwarfs with Exo-earths with Near-infrared and optical Echelle
Spectrographs, to search for periods in chromospheric indices in
16 M0-M2 dwarfs. We measure spectral indices in the Hα, the Ca
II infrared triplet (IRT), and the Na I D lines to study which of
these indices are best-suited to finding rotation periods in these
stars. Moreover, we test a number of different period-search algorithms,
namely the string length method, the phase dispersion minimisation,
the generalized Lomb-Scargle periodogram, and the Gaussian process
regression with quasi-periodic kernel. We find periods in four stars
using Hα and in five stars using the Ca II IRT, two of which have
not been found before. Our results show that both Hα and the Ca II
IRT lines are well suited for period searches, with the Ca II IRT
index performing slightly better than Hα. Unfortunately, the Na I D
lines are strongly affected by telluric airglow, and we could not find
any rotation period using this index. Further, different definitions
of the line indices have no major impact on the results. Comparing
the different search methods, the string length method and the phase
dispersion minimisation perform worst, while Gaussian process models
produce the smallest numbers of false positives and non-detections.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M
dwarfs. Chromospheric modeling of M 2-3 V stars with PHOENIX
Authors: Hintz, D.; Fuhrmeister, B.; Czesla, S.; Schmitt, J. H. M. M.;
Johnson, E. N.; Schweitzer, A.; Caballero, J. A.; Zechmeister, M.;
Jeffers, S. V.; Reiners, A.; Ribas, I.; Amado, P. J.; Quirrenbach, A.;
Anglada-Escudé, G.; Bauer, F. F.; Béjar, V. J. S.; Cortés-Contreras,
M.; Dreizler, S.; Galadí-Enríquez, D.; Guenther, E. W.; Hauschildt,
P. H.; Kaminski, A.; Kürster, M.; Lafarga, M.; López del Fresno,
M.; Montes, D.; Morales, J. C.; Passegger, V. M.; Seifert, W.
2019A&A...623A.136H Altcode: 2019arXiv190203992H
Chromospheric modeling of observed differences in stellar activity
lines is imperative to fully understand the upper atmospheres of
late-type stars. We present one-dimensional parametrized chromosphere
models computed with the atmosphere code PHOENIX using an underlying
photosphere of 3500 K. The aim of this work is to model chromospheric
lines of a sample of 50 M2-3 dwarfs observed in the framework of the
CARMENES, the Calar Alto high-Resolution search for M dwarfs with
Exo-earths with Near-infrared and optical Echelle Spectrographs,
exoplanet survey. The spectral comparison between observed data and
models is performed in the chromospheric lines of Na I D<SUB>2</SUB>,
Hα, and the bluest Ca II infrared triplet line to obtain best-fit
models for each star in the sample. We find that for inactive stars a
single model with a VAL C-like temperature structure is sufficient to
describe simultaneously all three lines adequately. Active stars are
rather modeled by a combination of an inactive and an active model, also
giving the filling factors of inactive and active regions. Moreover, the
fitting of linear combinations on variable stars yields relationships
between filling factors and activity states, indicating that more
active phases are coupled to a larger portion of active regions on
the surface of the star.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Activity
indicators at visible and near-infrared wavelengths
Authors: Schöfer, P.; Jeffers, S. V.; Reiners, A.; Shulyak,
D.; Fuhrmeister, B.; Johnson, E. N.; Zechmeister, M.; Ribas, I.;
Quirrenbach, A.; Amado, P. J.; Caballero, J. A.; Anglada-Escudé,
G.; Bauer, F. F.; Béjar, V. J. S.; Cortés-Contreras, M.; Dreizler,
S.; Guenther, E. W.; Kaminski, A.; Kürster, M.; Lafarga, M.; Montes,
D.; Morales, J. C.; Pedraz, S.; Tal-Or, L.
2019A&A...623A..44S Altcode: 2019arXiv190108861S
Context. The Calar Alto high-Resolution search for M dwarfs with
Exo-earths with Near-infrared and optical Echelle Spectrographs
(CARMENES) survey is searching for Earth-like planets orbiting M dwarfs
using the radial velocity method. Studying the stellar activity of
the target stars is important to avoid false planet detections and to
improve our understanding of the atmospheres of late-type stars. <BR
/> Aims: In this work we present measurements of activity indicators
at visible and near-infrared wavelengths for 331 M dwarfs observed
with CARMENES. Our aim is to identify the activity indicators that
are most sensitive and easiest to measure, and the correlations among
these indicators. We also wish to characterise their variability. <BR
/> Methods: Using a spectral subtraction technique, we measured
pseudo-equivalent widths of the He I D<SUB>3</SUB>, Hα, He I λ10833
Å, and Pa β lines, the Na I D doublet, and the Ca II infrared triplet,
which have a chromospheric component in active M dwarfs. In addition,
we measured an index of the strength of two TiO and two VO bands,
which are formed in the photosphere. We also searched for periodicities
in these activity indicators for all sample stars using generalised
Lomb-Scargle periodograms. <BR /> Results: We find that the most
slowly rotating stars of each spectral subtype have the strongest Hα
absorption. Hα is correlated most strongly with He I D<SUB>3</SUB>,
whereas Na I D and the Ca II infrared triplet are also correlated
with Hα. He I λ10833 Å and Paβ show no clear correlations with
the other indicators. The TiO bands show an activity effect that does
not appear in the VO bands. We find that the relative variations of
Hα and He I D<SUB>3</SUB> are smaller for stars with higher activity
levels, while this anti-correlation is weaker for Na I D and the Ca II
infrared triplet, and is absent for He I λ10833 Å and Paβ. Periodic
variation with the rotation period most commonly appears in the TiO
bands, Hα, and in the Ca II infrared triplet. <P />The full version
of Table A.1 is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/623/A44">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/623/A44</A>
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. The
enigmatic planetary system GJ 4276: one eccentric planet or two
planets in a 2:1 resonance?
Authors: Nagel, E.; Czesla, S.; Schmitt, J. H. M. M.; Dreizler,
S.; Anglada-Escudé, G.; Rodríguez, E.; Ribas, I.; Reiners, A.;
Quirrenbach, A.; Amado, P. J.; Caballero, J. A.; Aceituno, J.; Béjar,
V. J. S.; Cortés-Contreras, M.; González-Cuesta, L.; Guenther, E. W.;
Henning, T.; Jeffers, S. V.; Kaminski, A.; Kürster, M.; Lafarga,
M.; López-González, M. J.; Montes, D.; Morales, J. C.; Passegger,
V. M.; Rodríguez-López, C.; Schweitzer, A.; Zechmeister, M.
2019A&A...622A.153N Altcode: 2019arXiv190102367N
We report the detection of a Neptune-mass exoplanet around the M4.0
dwarf GJ 4276 (G 232-070) based on radial velocity (RV) observations
obtained with the CARMENES spectrograph. The RV variations of GJ
4276 are best explained by the presence of a planetary companion that
has a minimum mass of m<SUB>b</SUB> sin i ≈ 16 M<SUB>⊕</SUB> on a
P<SUB>b</SUB> = 13.35 day orbit. The analysis of the activity indicators
and spectral diagnostics exclude stellar induced RV perturbations
and prove the planetary interpretation of the RV signal. We show
that a circular single-planet solution can be excluded by means of
a likelihood ratio test. Instead, we find that the RV variations can
be explained either by an eccentric orbit or interpreted as a pair of
planets on circular orbits near a period ratio of 2:1. Although the
eccentric single-planet solution is slightly preferred, our statistical
analysis indicates that none of these two scenarios can be rejected
with high confidence using the RV time series obtained so far. Based
on the eccentric interpretation, we find that GJ 4276 b is the most
eccentric (e<SUB>b</SUB> = 0.37) exoplanet around an M dwarf with such
a short orbital period known today. <P />Photometric measurements
and Table C.1 are available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/622/A153">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/622/A153</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: Barnard's star radial velocity
curve (Ribas+, 2018)
Authors: Ribas, I.; Tuomi, M.; Reiners, A.; Butler, R. P.;
Morales, J. C.; Perger, M.; Dreizler, S.; Rodriguez-Lopez, C.;
Gonzalez Hernandez, J. I.; Rosich, A.; Feng, F.; Trifonov, T.; Vogt,
S. S.; Caballero, J. A.; Hatzes, A.; Herrero, E.; Jeffers, S. V.;
Lafarga, M.; Murgas, F.; Nelson, R. P.; Rodriguez, E.; Strachan,
J. B. P.; Tal-Or, L.; Teske, J.; Toledo-Padron, B.; Zechmeister, M.;
Quirrenbach, A.; Amado, P. J.; Azzaro, M.; Bejar, V. J. S.; Barnes,
J. R.; Berdinas, Z. M.; Burt, J.; Coleman, G.; Cortes-Contreras, M.;
Crane, J.; Engle, S. G.; Guinan, E. F.; Haswell, C. A.; Henning, T.;
Holden, B.; Jenkins, J.; Jones, H. R. A.; Kaminski, A.; Kiraga, M.;
Kurster, M.; Lee, M. H.; Lopez-Gonzalez, M. J.; Montes, D.; Morin, J.;
Ofir, A.; Palle, E.; Rebolo, R.; Reffert, S.; Schweitzer, A.; Seifert,
W.; Shectman, S. A.; Staab, D.; Street, R. A.; Suarez Mascareno, A.;
Tsapras, Y.; Wang, S. X.; Anglada-Escude, G.
2019yCatp038056301R Altcode:
An early analysis of archival radial-velocity datasets of Barnard's
star up to 2015 indicated the presence of at least one significant
signal, which had a period of about 230 days, but with rather poor
sampling. To elucidate its presence and nature we undertook an intensive
monitoring campaign with the CARMENES spectrometer, collecting precise
radial-velocity measurements on every possible night during 2016 and
2017. We also obtained overlapping observations with the European
Southern Observatory (ESO) HARPS and the HARPS-N instruments. The
combined Doppler monitoring of Barnard's star, including archival and
newly acquired observations, resulted in 771 radial-velocity epochs
(nightly averages), with typical individual precisions of 0.9-1.8m/s,
obtained over a timespan of more than 20 years from seven different
facilities, and yielded eight independent datasets. <P />(4 data files).
---------------------------------------------------------
Title: Outliers in globular clusters: the case of 47 Tucanae
Authors: Campos, Fabiola; Pelisoli, Ingrid; Kamann, Sebastian; Husser,
Tim-Oliver; Dreizler, Stefan; Bellini, Andrea; Robinson, Edward L.;
Nardiello, Domenico; Piotto, Giampaolo; Oliveira, Kepler; Istrate,
Alina; Winget, Don; Montgomery, Michael H.; Dotter, Aaron
2019AAS...23341408C Altcode:
We constructed multicolor photometric color-magnitude diagrams of the
globular cluster 47 Tucanae using photometry obtained with the Hubble
Space Telescope. We identify 24 previously-unremarked objects that
are outliers from the single-star model tracks in the color-magnitude
diagram.Based on their proper motions, all the objects are members
of the cluster with high probability. We show that the majority of
the sources are likely to be binary systems. Since only two of those
objects are possible counterparts to X-ray sources, we conclude that
most of the binaries consist of a white dwarf and a main-sequence
star. While three may be double-degenerate binaries. This is the
first time multicolor photometry is employed to search for binaries
in clusters. Extension of this work can help shed light in late stages
of binary stellar evolution in different environments.
---------------------------------------------------------
Title: Thorium in solar twins: implications for habitability in
rocky planets
Authors: Botelho, R. B.; Milone, A. de C.; Meléndez, J.; Bedell,
M.; Spina, L.; Asplund, M.; dos Santos, L.; Bean, J. L.; Ramírez,
I.; Yong, D.; Dreizler, S.; Alves-Brito, A.; Yana Galarza, J.
2019MNRAS.482.1690B Altcode: 2018MNRAS.tmp.2659B; 2018arXiv181010413B
We have investigated the thorium (Th) abundance in a sample of 53 thin
disc solar twins covering a wide range of ages. These data provide
constrains on the mantle energy budget of terrestrial planets that
can be formed over the evolution of the Galaxy's thin disc. We have
estimated Th abundances with an average precision of 0.025 dex (in both
[Th/H] and [Th/Fe]) through comprehensive spectral synthesis of a Th II
line present at 4019.1290 Å, using very high resolution (R = 115 000)
high quality HARPS spectra obtained at the ESO La Silla Observatory. We
have confirmed that there is a large energy budget from Th decay for
maintaining mantle convection inside potential rocky planets around
solar twins, from the Galactic thin disc formation until now, because
the pristine [Th/H]<SUB>ZAMS</SUB> is super-solar on average under
a uniform dispersion of 0.056 dex (varying from +0.037 up to +0.138
dex based on linear fits against isochrone stellar age). Comparing to
neodymium (Nd) and europium (Eu), two others neutron-capture elements,
the stellar pristine abundance of Th follows Eu along the Galactic thin
disc evolution, but it does not follow Nd, probably because neodymium
has a significant contribution from the s-process (about 60 per cent).
---------------------------------------------------------
Title: VizieR Online Data Catalog: Photometry & RV follow-up
observations of K2-18 (Sarkis+, 2018)
Authors: Sarkis, P.; Henning, T.; Kurster, M.; Trifonov, T.;
Zechmeister, M.; Tal-Or, L.; Anglada-Escude, G.; Hatzes, A. P.;
Lafarga, M.; Dreizler, S.; Ribas, I.; Caballero, J. A.; Reiners,
A.; Mallonn, M.; Morales, J. C.; Kaminski, A.; Aceituno, J.; Amado,
P. J.; Bejar, V. J. S.; Hagen, H. -J.; Jeffers, S.; Quirrenbach, A.;
Launhardt, R.; Marvin, C.; Montes, D.
2019yCat..51550257S Altcode:
We monitored the host star K2-18 for photometric variability with
the robotic 1.2 m twin-telescope STELLA on Tenerife (Strassmeier et
al. 2004AN....325..527S) and its wide-field imager WiFSIP. From 2017
February until 2017 June, we obtained blocks of four exposures in
Johnson B and four exposures in Cousins R over 33 nights. The exposure
time was 120 s in B and 60 s in R. We monitored K2-18 between 2016
December and 2017 June with CARMENES. CARMENES (Calar Alto search
for M dwarfs with Exo-earths with Near-infrared and optical Echelle
Spectrographs) is a pair of high-resolution echelle spectrographs
(Quirrenbach et al. 2014SPIE.9147E..1FQ) mounted on the 3.5 m telescope
of the Calar Alto Observatory (CAHA) in Spain. The VIS channel covers
the wavelength range from 0.52 to 0.96 μm and has a spectral resolution
R=94600 (Quirrenbach et al. 2016SPIE.9908E..12Q), with a demonstrated
precision similar to HARPS and better than Keck/HIRES (Trifonov et
al. 2018, J/A+A/609/A117). <P />(3 data files).
---------------------------------------------------------
Title: CARMENES input catalogue of M dwarfs. IV. New rotation periods
from photometric time series
Authors: Díez Alonso, E.; Caballero, J. A.; Montes, D.; de Cos Juez,
F. J.; Dreizler, S.; Dubois, F.; Jeffers, S. V.; Lalitha, S.; Naves,
R.; Reiners, A.; Ribas, I.; Vanaverbeke, S.; Amado, P. J.; Béjar,
V. J. S.; Cortés-Contreras, M.; Herrero, E.; Hidalgo, D.; Kürster,
M.; Logie, L.; Quirrenbach, A.; Rau, S.; Seifert, W.; Schöfer, P.;
Tal-Or, L.
2019A&A...621A.126D Altcode: 2018arXiv181003338D
<BR /> Aims: The main goal of this work is to measure rotation periods
of the M-type dwarf stars being observed by the CARMENES exoplanet
survey to help distinguish radial-velocity signals produced by magnetic
activity from those produced by exoplanets. Rotation periods are also
fundamental for a detailed study of the relation between activity and
rotation in late-type stars. <BR /> Methods: We look for significant
periodic signals in 622 photometric time series of 337 bright, nearby M
dwarfs obtained by long-time baseline, automated surveys (MEarth, ASAS,
SuperWASP, NSVS, Catalina, ASAS-SN, K2, and HATNet) and for 20 stars
which we obtained with four 0.2-0.8 m telescopes at high geographical
latitudes. <BR /> Results: We present 142 rotation periods (73 new) from
0.12 d to 133 d and ten long-term activity cycles (six new) from 3.0
a to 11.5 a. We compare our determinations with those in the existing
literature; we investigate the distribution of P<SUB>rot</SUB> in the
CARMENES input catalogue, the amplitude of photometric variability,
and their relation to v sini and pEW(Hα); and we identify three
very active stars with new rotation periods between 0.34 d and
23.6 d. <P />Tables A.1 and A.2, and tables of the photometric
measurements are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/621/A126">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/621/A126</A>
---------------------------------------------------------
Title: Outliers: multicolour photometry guiding the search for
evolved binary systems in the globular cluster 47 Tucanae
Authors: Campos, Fabíola; Pelisoli, I.; Kamann, S.; Husser, T. -O.;
Dreizler, S.; Bellini, A.; Robinson, E. L.; Nardiello, D.; Piotto,
G.; Kepler, S. O.; Istrate, A. G.; Winget, D. E.; Montgomery, M. H.;
Dotter, A.
2018MNRAS.481.4397C Altcode: 2018MNRAS.tmp.2465C; 2018arXiv180907746C
We use Hubble Space Telescope multicolour photometry of the globular
cluster 47 Tucanae to uncover a population of 24 objects with no
previous classification that are outliers from the single-star model
tracks in the colour-magnitude diagram and yet are likely cluster
members. By comparing those sources with evolutionary models and
X-ray source catalogues, we were able to show that the majority of
those sources are likely binary systems that do not have any X-ray
source detected nearby, most possibly formed by a white dwarf and a
main-sequence star and a small number of possible double-degenerate
systems.
---------------------------------------------------------
Title: Ground-based detection of an extended helium atmosphere in
the Saturn-mass exoplanet WASP-69b
Authors: Nortmann, Lisa; Pallé, Enric; Salz, Michael; Sanz-Forcada,
Jorge; Nagel, Evangelos; Alonso-Floriano, F. Javier; Czesla, Stefan;
Yan, Fei; Chen, Guo; Snellen, Ignas A. G.; Zechmeister, Mathias;
Schmitt, Jürgen H. M. M.; López-Puertas, Manuel; Casasayas-Barris,
Núria; Bauer, Florian F.; Amado, Pedro J.; Caballero, José A.;
Dreizler, Stefan; Henning, Thomas; Lampón, Manuel; Montes, David;
Molaverdikhani, Karan; Quirrenbach, Andreas; Reiners, Ansgar; Ribas,
Ignasi; Sánchez-López, Alejandro; Schneider, P. Christian; Zapatero
Osorio, María R.
2018Sci...362.1388N Altcode: 2018arXiv181203119N
Hot gas giant exoplanets can lose part of their atmosphere due
to strong stellar irradiation, and these losses can affect their
physical and chemical evolution. Studies of atmospheric escape
from exoplanets have mostly relied on space-based observations of
the hydrogen Lyman-α line in the far ultraviolet region, which is
strongly affected by interstellar absorption. Using ground-based
high-resolution spectroscopy, we detected excess absorption in the
helium triplet at 1083 nanometers during the transit of the Saturn-mass
exoplanet WASP-69b, at a signal-to-noise ratio of 18. We measured line
blueshifts of several kilometers per second and posttransit absorption,
which we interpret as the escape of part of the atmosphere trailing
behind the planet in comet-like form.
---------------------------------------------------------
Title: Detection of He I λ10830 Å absorption on HD 189733 b with
CARMENES high-resolution transmission spectroscopy
Authors: Salz, M.; Czesla, S.; Schneider, P. C.; Nagel, E.; Schmitt,
J. H. M. M.; Nortmann, L.; Alonso-Floriano, F. J.; López-Puertas, M.;
Lampón, M.; Bauer, F. F.; Snellen, I. A. G.; Pallé, E.; Caballero,
J. A.; Yan, F.; Chen, G.; Sanz-Forcada, J.; Amado, P. J.; Quirrenbach,
A.; Ribas, I.; Reiners, A.; Béjar, V. J. S.; Casasayas-Barris, N.;
Cortés-Contreras, M.; Dreizler, S.; Guenther, E. W.; Henning, T.;
Jeffers, S. V.; Kaminski, A.; Kürster, M.; Lafarga, M.; Lara, L. M.;
Molaverdikhani, K.; Montes, D.; Morales, J. C.; Sánchez-López, A.;
Seifert, W.; Zapatero Osorio, M. R.; Zechmeister, M.
2018A&A...620A..97S Altcode: 2018arXiv181202453S
We present three transit observations of HD 189733 b obtained with
the high-resolution spectrograph CARMENES at Calar Alto. A strong
absorption signal is detected in the near-infrared He I triplet at
10830 Å in all three transits. During mid-transit, the mean absorption
level is 0.88 ± 0.04% measured in a ±10 km s<SUP>-1</SUP> range at
a net blueshift of - 3.5 ± 0.4 km s<SUP>-1</SUP> (10829.84-10830.57
Å). The absorption signal exhibits radial velocities of + 6.5 ±
3.1 km s<SUP>-1</SUP> and - 12.6 ± 1.0 km s<SUP>-1</SUP> during
ingress and egress, respectively; all radial velocities are measured
in the planetary rest frame. We show that stellar activity related
pseudo-signals interfere with the planetary atmospheric absorption
signal. They could contribute as much as 80% of the observed signal
and might also affect the observed radial velocity signature, but
pseudo-signals are very unlikely to explain the entire signal. The
observed line ratio between the two unresolved and the third line
of the He I triplet is 2.8 ± 0.2, which strongly deviates from the
value expected for an optically thin atmospheres. When interpreted
in terms of absorption in the planetary atmosphere, this favors a
compact helium atmosphere with an extent of only 0.2 planetary radii
and a substantial column density on the order of 4 × 10<SUP>12</SUP>
cm<SUP>-2</SUP>. The observed radial velocities can be understood either
in terms of atmospheric circulation with equatorial superrotation
or as a sign of an asymmetric atmospheric component of evaporating
material. We detect no clear signature of ongoing evaporation, like pre-
or post-transit absorption, which could indicate material beyond the
planetary Roche lobe, or radial velocities in excess of the escape
velocity. These findings do not contradict planetary evaporation,
but only show that the detected helium absorption in HD 189733 b does
not trace the atmospheric layers that show pronounced escape signatures.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. The warm
super-Earths in twin orbits around the mid-type M dwarfs Ross 1020
(GJ 3779) and LP 819-052 (GJ 1265)
Authors: Luque, R.; Nowak, G.; Pallé, E.; Kossakowski, D.; Trifonov,
T.; Zechmeister, M.; Béjar, V. J. S.; Cardona Guillén, C.;
Tal-Or, L.; Hidalgo, D.; Ribas, I.; Reiners, A.; Caballero, J. A.;
Amado, P. J.; Quirrenbach, A.; Aceituno, J.; Cortés-Contreras, M.;
Díez-Alonso, E.; Dreizler, S.; Guenther, E. W.; Henning, T.; Jeffers,
S. V.; Kaminski, A.; Kürster, M.; Lafarga, M.; Montes, D.; Morales,
J. C.; Passegger, V. M.; Schmitt, J. H. M. M.; Schweitzer, A.
2018A&A...620A.171L Altcode: 2018arXiv181007572L
We announce the discovery of two planetary companions orbiting
around the low-mass stars Ross 1020 (GJ 3779, M4.0V) and LP 819-052
(GJ 1265, M4.5V). The discovery is based on the analysis of CARMENES
radial velocity (RV) observations in the visual channel as part of
its survey for exoplanets around M dwarfs. In the case of GJ 1265,
CARMENES observations were complemented with publicly available Doppler
measurements from HARPS. The datasets reveal two planetary companions,
one for each star, that share very similar properties: minimum
masses of 8.0 ± 0.5 M<SUB>⊕</SUB> and 7.4 ± 0.5 M<SUB>⊕</SUB>
in low-eccentricity orbits with periods of 3.023 ± 0.001 d and 3.651
± 0.001 d for GJ 3779 b and GJ 1265 b, respectively. The periodic
signals around 3 d found in the RV data have no counterpart in any
spectral activity indicator. Furthermore, we collected available
photometric data for the two host stars, which confirm that the
additional Doppler variations found at periods of approximately 95 d
can be attributed to the rotation of the stars. The addition of these
planets to a mass-period diagram of known planets around M dwarfs
suggests a bimodal distribution with a lack of short-period low-mass
planets in the range of 2-5 M<SUB>⊕</SUB>. It also indicates that
super-Earths (>5 M<SUB>⊕</SUB>) currently detected by RV and
transit techniques around M stars are usually found in systems dominated
by a single planet. <P />The RV and formal uncertainties of GJ 3779
and GJ 1265 are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/620/A171">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/620/A171</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: GJ 4276 radial velocity curve
(Nagel+, 2019)
Authors: Nagel, E.; Czesla, S.; Schmitt, J. H. M. M.; Dreizler,
S.; Anglada-Escude, G.; Rodriguez, E.; Ribas, I.; Reiners, A.;
Quirrenbach, A.; Amado, P. J.; Caballero, J. A.; Aceituno, J.; Bejar,
V. J. S.; Cortes-Contreras, M.; Gonzalez-Cuesta, L.; Guenther, E. W.;
Henning, T.; Jeffers, S. V.; Kaminski, A.; Kuerster, M.; Lafarga, M.;
Lopez-Gonzalez, M. J.; Montes, D.; Morales, J. C. Passegger V. M.;
Rodriguez-Lopez, C.; Schweitzer, A.; Zechmeister, M.
2018yCat..36220153N Altcode:
We analyzed radial velocity data from the CARMENES VIS channel. The
RVs are corrected for barycentric motion and secular acceleration. The
CARMENES measurements were taken in the context of the CARMENES search
for exoplanets around M dwarfs. The CARMENES instrument consists
of two channels: the VIS channel obtains spectra at a resolution of
R=94600 in the wavelength range 520-960nm, while the NIR channel yields
spectra of R=80400 covering 960-1710nm. Both channels are calibrated
in wavelength with hollow-cathode lamps and use temperature- and
pressure-stabilized Fabry-Perot etalons to interpolate the wavelength
solution and simultaneously monitor the spectrograph drift during
nightly operations (Bauer et al., 2015A&A...581A.117B). <P />To
determine the stellar rotation period, we obtained V band photometry
with the T150 telescope located at the Sierra Nevada Observatory (SNO)
in Spain. <P />(2 data files).
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. Nine new
double-line spectroscopic binary stars
Authors: Baroch, D.; Morales, J. C.; Ribas, I.; Tal-Or, L.;
Zechmeister, M.; Reiners, A.; Caballero, J. A.; Quirrenbach, A.;
Amado, P. J.; Dreizler, S.; Lalitha, S.; Jeffers, S. V.; Lafarga, M.;
Béjar, V. J. S.; Colomé, J.; Cortés-Contreras, M.; Díez-Alonso,
E.; Galadí-Enríquez, D.; Guenther, E. W.; Hagen, H. -J.; Henning,
T.; Herrero, E.; Kürster, M.; Montes, D.; Nagel, E.; Passegger,
V. M.; Perger, M.; Rosich, A.; Schweitzer, A.; Seifert, W.
2018A&A...619A..32B Altcode: 2018arXiv180806895B
Context. The CARMENES spectrograph is surveying ∼300 M dwarf stars
in search for exoplanets. Among the target stars, spectroscopic binary
systems have been discovered, which can be used to measure fundamental
properties of stars. <BR /> Aims: Using spectroscopic observations, we
determine the orbital and physical properties of nine new double-line
spectroscopic binary systems by analysing their radial velocity
curves. <BR /> Methods: We use two-dimensional cross-correlation
techniques to derive the radial velocities of the targets, which are
then employed to determine the orbital properties. Photometric data from
the literature are also analysed to search for possible eclipses and
to measure stellar variability, which can yield rotation periods. <BR
/> Results: Out of the 342 stars selected for the CARMENES survey, 9
have been found to be double-line spectroscopic binaries, with periods
ranging from 1.13 to ∼8000 days and orbits with eccentricities up
to 0.54. We provide empirical orbital properties and minimum masses
for the sample of spectroscopic binaries. Absolute masses are also
estimated from mass-luminosity calibrations, ranging between ∼0.1 and
∼0.6 M<SUB>⊙</SUB>. <BR /> Conclusions: These new binary systems
increase the number of double-line M dwarf binary systems with known
orbital parameters by 15%, and they have lower mass ratios on average.
---------------------------------------------------------
Title: A candidate super-Earth planet orbiting near the snow line
of Barnard's star
Authors: Ribas, I.; Tuomi, M.; Reiners, A.; Butler, R. P.; Morales,
J. C.; Perger, M.; Dreizler, S.; Rodríguez-López, C.; González
Hernández, J. I.; Rosich, A.; Feng, F.; Trifonov, T.; Vogt, S. S.;
Caballero, J. A.; Hatzes, A.; Herrero, E.; Jeffers, S. V.; Lafarga, M.;
Murgas, F.; Nelson, R. P.; Rodríguez, E.; Strachan, J. B. P.; Tal-Or,
L.; Teske, J.; Toledo-Padrón, B.; Zechmeister, M.; Quirrenbach, A.;
Amado, P. J.; Azzaro, M.; Béjar, V. J. S.; Barnes, J. R.; Berdiñas,
Z. M.; Burt, J.; Coleman, G.; Cortés-Contreras, M.; Crane, J.;
Engle, S. G.; Guinan, E. F.; Haswell, C. A.; Henning, Th.; Holden,
B.; Jenkins, J.; Jones, H. R. A.; Kaminski, A.; Kiraga, M.; Kürster,
M.; Lee, M. H.; López-González, M. J.; Montes, D.; Morin, J.; Ofir,
A.; Pallé, E.; Rebolo, R.; Reffert, S.; Schweitzer, A.; Seifert,
W.; Shectman, S. A.; Staab, D.; Street, R. A.; Suárez Mascareño,
A.; Tsapras, Y.; Wang, S. X.; Anglada-Escudé, G.
2018Natur.563..365R Altcode: 2018arXiv181105955R
Barnard's star is a red dwarf, and has the largest proper motion
(apparent motion across the sky) of all known stars. At a distance of
1.8 parsecs<SUP>1</SUP>, it is the closest single star to the Sun; only
the three stars in the α Centauri system are closer. Barnard's star is
also among the least magnetically active red dwarfs known<SUP>2,3</SUP>
and has an estimated age older than the Solar System. Its properties
make it a prime target for planetary searches; various techniques with
different sensitivity limits have been used previously, including
radial-velocity imaging<SUP>4-6</SUP>, astrometry<SUP>7,8</SUP> and
direct imaging<SUP>9</SUP>, but all ultimately led to negative or null
results. Here we combine numerous measurements from high-precision
radial-velocity instruments, revealing the presence of a low-amplitude
periodic signal with a period of 233 days. Independent photometric
and spectroscopic monitoring, as well as an analysis of instrumental
systematic effects, suggest that this signal is best explained
as arising from a planetary companion. The candidate planet around
Barnard's star is a cold super-Earth, with a minimum mass of 3.2 times
that of Earth, orbiting near its snow line (the minimum distance from
the star at which volatile compounds could condense). The combination
of all radial-velocity datasets spanning 20 years of measurements
additionally reveals a long-term modulation that could arise from
a stellar magnetic-activity cycle or from a more distant planetary
object. Because of its proximity to the Sun, the candidate planet has
a maximum angular separation of 220 milliarcseconds from Barnard's
star, making it an excellent target for direct imaging and astrometric
observations in the future.
---------------------------------------------------------
Title: VizieR Online Data Catalog: RV variability of the K-giant γ
Draconis (Hatzes+, 2018)
Authors: Hatzes, A. P.; Endl, M.; Cochran, W. D.; MacQueen, P. J.;
Han, I.; Lee, B. -C.; Kim, K. -M.; Mkrtichian, D.; Dollinger, M.;
Hartmann, M.; Karjalainen, M.; Dreizler, S.
2018yCat..51550120H Altcode:
A total of four RV data sets were used in the analysis. The earliest
observations were made with the coude spectrograph of the 2.1 m Otto
Struve Telescope at McDonald Observatory. A 1200 grooves/mm grating
was used in second order in combination with a Tektronix 512x512
CCD. Blocking filters were used to isolate the desired order. This
instrumental setup resulted in a spectral dispersion of 0.046 Å/pixel
at the central wavelength of 5520 Å. An 85 μm slit provided a spectral
resolution of 0.11 Å (resolving power R=λ/Δλ=50000). The "McD-2.7"
data set used the Tull Spectrograph (Tull et al. 1995PASP..107..251T)
at the Harlan J. Smith 2.7 m telescope. This instrument provided a
nominal wavelength coverage of 3600-10000 Å at a resolving power of
R=60000. RV measurements were also made with the Bohyunsan Observatory
Echelle Spectrograph or BOES (Kim et al. 2006A&A...454..839K)
of the 1.8 m telescope at the BOAO in South Korea. An 80 μm fiber
resulted in a resolving power of R=90000 with a wavelength coverage
of 3600-10500 Å. The TLS observations of γ Dra were made as part
of the Tautenburg Observatory Planet Search (TOPS) program using the
high-resolution coude echelle spectrometer of the Alfred Jensch 2 m
telescope and an iodine absorption cell placed in the optical path. The
spectrometer is grism cross-dispersed and it has a resolving power
R=67000 and wavelength coverage 4630-7370 Å. <P />(1 data file).
---------------------------------------------------------
Title: VizieR Online Data Catalog: Solar Twins age-chromospheric
activity (Lorenzo-Oliveira+, 2018))
Authors: Lorenzo-Oliveira, D.; Freitas, F.; Melendez, J.; Bedell,
M.; Ramirez, I.; Bean, J.; Asplund, M.; Spina, L.; Dreizler, S.;
Alves-Brito, A.; Casagrande, L.
2018yCat..36190073L Altcode:
Our sample was selected from the 88 solar twins presented in Ramirez et
al. (2014A&A...572A..48R). From this sample, we obtained data for
70 stars with the HARPS instrument (Mayor et al., 2003Msngr.114...20M)
at the 3.6 m telescope at the La Silla observatory, to search for
planets around solar twins (program 188.C-0265, Bedell et al.,
2015A&A...581A..34B; Melendez et al., 2015Msngr.161...28M,
2017A&A...597A..34M). Additional data for 12 stars were found in
the ESO archive. <P />(2 data files).
---------------------------------------------------------
Title: Activity induced variation in spin-orbit angles as derived
from Rossiter-McLaughlin measurements
Authors: Oshagh, M.; Triaud, A. H. M. J.; Burdanov, A.; Figueira,
P.; Reiners, A.; Santos, N. C.; Faria, J.; Boue, G.; Díaz, R. F.;
Dreizler, S.; Boldt, S.; Delrez, L.; Ducrot, E.; Gillon, M.; Guzman
Mesa, A.; Jehin, E.; Khalafinejad, S.; Kohl, S.; Serrano, L.; Udry, S.
2018A&A...619A.150O Altcode: 2018arXiv180901027O
One of the most powerful methods used to estimate sky-projected
spin-orbit angles of exoplanetary systems is through a spectroscopic
transit observation known as the RossiterMcLaughlin (RM) effect. So far
mostly single RM observations have been used to estimate the spin-orbit
angle, and thus there have been no studies regarding the variation of
estimated spin-orbit angle from transit to transit. Stellar activity
can alter the shape of photometric transit light curves and in a
similar way they can deform the RM signal. In this paper we present
several RM observations, obtained using the HARPS spectrograph, of
known transiting planets that all transit extremely active stars,
and by analyzing them individually we assess the variation in the
estimated spin-orbit angle. Our results reveal that the estimated
spin-orbit angle can vary significantly (up to 42°) from transit
to transit, due to variation in the configuration of stellar active
regions over different nights. This finding is almost two times larger
than the expected variation predicted from simulations. We could not
identify any meaningful correlation between the variation of estimated
spin-orbit angles and the stellar magnetic activity indicators. We
also investigated two possible approaches to mitigate the stellar
activity influence on RM observations. The first strategy was based
on obtaining several RM observations and folding them to reduce the
stellar activity noise. Our results demonstrated that this is a feasible
and robust way to overcome this issue. The second approach is based on
acquiring simultaneous high-precision short-cadence photometric transit
light curves using TRAPPIST/SPECULOOS telescopes, which provide more
information about the stellar active region's properties and allow a
better RM modeling.
---------------------------------------------------------
Title: The Solar Twin Planet Search. The age-chromospheric activity
relation
Authors: Lorenzo-Oliveira, Diego; Freitas, Fabrício C.; Meléndez,
Jorge; Bedell, Megan; Ramírez, Iván; Bean, Jacob L.; Asplund, Martin;
Spina, Lorenzo; Dreizler, Stefan; Alves-Brito, Alan; Casagrande, Luca
2018A&A...619A..73L Altcode: 2018arXiv180608014L
Context. It is well known that the magnetic activity of solar-type stars
decreases with age, but it is widely debated in the literature whether
there is a smooth decline or if there is an early sharp drop until
1-2 Gyr that is followed by a relatively inactive constant phase. <BR
/> Aims: We revisited the activity-age relation using time-series
observations of a large sample of solar twins whose precise isochronal
ages and other important physical parameters have been determined. <BR
/> Methods: We measured the Ca II H and K activity indices using ≈9000
HARPS spectra of 82 solar twins. In addition, the average solar activity
was calculated through asteroids and Moon reflection spectra using
the same instrumentation. Thus, we transformed our activity indices
into the S Mount Wilson scale (S<SUB>MW</SUB>), recalibrated the
Mount Wilson absolute flux and photospheric correction equations as a
function of T<SUB>eff</SUB>, and then computed an improved bolometric
flux normalized activity index log R'<SUB>HK</SUB> (T<SUB>eff</SUB>)
for the entire sample. <BR /> Results: New relations between activity
and the age of solar twins were derived by assessing the chromospheric
age-dating limits using log R'<SUB>HK</SUB> (T<SUB>eff</SUB>). We
measured an average solar activity of S<SUB>MW</SUB> = 0.1712 ± 0.0017
during solar magnetic cycles 23-24 covered by HARPS observations,
and we also inferred an average of S<SUB>MW</SUB> = 0.1694 ± 0.0025
for cycles 10-24, anchored on a sunspot number correlation of S index
versus. We also found a simple relation between the average and the
dispersion of the activity levels of solar twins. This enabled us to
predict the stellar variability effects on the age-activity diagram,
and consequently, to estimate the chromospheric age uncertainties that
are due to the same phenomena. The age-activity relation is still
statistically significant up to ages around 6-7 Gyr, in agreement
with previous works using open clusters and field stars with precise
ages. <BR /> Conclusions: Our research confirms that Ca II H &
K lines remain a useful chromospheric evolution tracer until stars
reach ages of at least 6-7 Gyr. We found evidence that for the most
homogenous set of old stars, the chromospheric activity indices seem
to continue to decrease after the solar age toward the end of the main
sequence. Our results indicate that a significant part of the scatter
observed in the age-activity relation of solar twins can be attributed
to stellar cycle modulations effects. The Sun seems to have a normal
activity level and variability for its age. <P />Based on observations
collected at the European Organisation for Astronomical Research in
the Southern Hemisphere under ESO programs 188.C-0265, 183.D-0729,
292.C-5004, 097.C-0571, 092.C-0721, 093.C-0409, 072.C-0488, 183.C-0972,
091.C-0936, 192.C-0852, 196.C-1006, 076.C-0155, 096.C-0499, 185.D-0056,
192.C-0224, 075.C-0332, 090.C-0421, 091.C-0034, 077.C-0364, 089.C-0415,
60.A-9036, 092.C-0832, 295.C-5035, 295.C-5031, 60.A-9700, 289.D-5015,
096.C-0210, 086.C-0284, 088.C-0323, 0100.D-0444, and 099.C-0491.Tables
1 and 2 are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/619/A73">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/619/A73</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: Radial velocities of GJ 3779 and
GJ 1265 (Luque+, 2018)
Authors: Luque, R.; Nowak, G.; Palle, E.; Kossakowski, D.; Trifonov,
T.; Zechmeister, M.; Bejar, V. J. S.; Cardona Guillen, C.; Tal-Or, L.;
Hidalgo, D.; Ribas, I.; Reiners, A.; Caballero, J. A.; Amado, P. J.;
Quirrenbach, A.; Aceituno, J.; Cortes-Contreras, M.; Diez-Alonso, E.;
Dreizler, S.; Guenther, E. W.; Henning, T.; Jeffers, S. V.; Kaminski,
A.; Kuerster, M.; Lafarga, M.; Montes, D.; Morales, J. C.; Passegger,
V. M.; Schmitt, J. H. M. M.; Schweitzer, A.
2018yCat..36200171L Altcode:
We analyzed radial velocity data from the CARMENES VIS channel for GJ
3779, and from the CARMENES VIS channel and HARPS for GJ 1265. All the
RVs are corrected for barycentric motion and secular acceleration. The
CARMENES measurements were taken in the context of the CARMENES search
for exoplanets around M dwarfs. The CARMENES instrument consists of two
channels: the VIS channel obtains spectra at a resolution of R=94600 in
the wavelength range 520-960nm, while the NIR channel yields spectra of
R=80400 covering 960-1710nm. Both channels are calibrated in wavelength
with hollow-cathode lamps and use temperature- and pressure-stabilized
Fabry-Perot etalons to interpolate the wavelength solution and
simultaneously monitor the spectrograph drift during nightly operations
(Bauer et al., 2015A&A...581A.117B). <P />(2 data files).
---------------------------------------------------------
Title: Spitzer's Search for Proxima Centauri b Transits
Authors: Harrington, Joseph; Jenkins, James; Challener, Ryan C.;
Kurtovic, Nicolás T.; Ramirez, Ricardo; Peña Zamudio, José;
McIntyre, Kathleen J.; Himes, Michael D.; Rodríguez, Eloy;
Anglada-Escudé, Guillem; Dreizler, Stefan; Ofir, Aviv; Ribas,
Ignasi; Rojo, Patricio; Kipping, David; Butler, R. Paul; Amado,
Pedro J.; Rodríguez-López, Cristina; Kempton, Eliza M.; Palle,
Enric; Murgas, Felipe
2018DPS....5040509H Altcode:
Proxima Centauri, the nearest star to the sun, hosts a habitable-zone
planet (Anglada-Escude' et al. 2016 Nature 536, 437). Several teams
have sought Proxima b's transits using ground-based photometry,
and have reported tentative transit detections (Liu et al. 2018
AJ 155, 12; Blank et al. 2018 AJ 155, 228; others). Proxima, a
modest-sized M-dwarf star, flares at the 0.5% level (the predicted
Proxima b transit depth) 63 times per day, according to our team's
prior analysis of optical photometry from the Microvariability and
Oscillations of STars spacecraft (Davenport et al. 2016 ApJL 829,
L31). This dramatically limits optical precision. However, the effect
of flares is much reduced in the infrared. We observed the system
with the Spitzer Space Telescope's Infrared Array Camera in November
2016. Our first observation was a 48-hour stare at 4.5 um. It was
centered on the predicted transit and covered the 99% credible region
for the transit time, based on the discovery radial-velocity (RV)
data. Despite a transit-depth precision of 0.01% for a 1 hour transit,
we did not detect the predicted 0.5% transit. There was structure in
the light curve, including some asymmetric transit-like features,
that led us to conduct follow-up observations in May, June, July,
and November 2017. None of these observations contained detections,
once we accounted for a new manifestation of systematics due to
spacecraft vibration. Our improved methods for identifying and partly
removing this effect is the topic of the next presentation. This work
is based on observations made with the Spitzer Space Telescope, which
is operated by the Jet Propulsion Laboratory, California Institute of
Technology under a contract with NASA. We acknowledge support from:
NASA Planetary Atmospheres Program grant NNX12AI69G, NASA Astrophysics
Data Analysis Program grant NNX13AF38G. CATA-Basal/Chile PB06 Conicyt
and Fondecyt/Chile project #1161218 (JSJ). Spanish MINECO programs
AYA2016-79245-C03-03-P (PJA, CRL, and ER) and ESP2017-87676-C05-02-R
(ER).
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. A
Neptune-mass planet traversing the habitable zone around HD 180617
Authors: Kaminski, A.; Trifonov, T.; Caballero, J. A.; Quirrenbach,
A.; Ribas, I.; Reiners, A.; Amado, P. J.; Zechmeister, M.; Dreizler,
S.; Perger, M.; Tal-Or, L.; Bonfils, X.; Mayor, M.; Astudillo-Defru,
N.; Bauer, F. F.; Béjar, V. J. S.; Cifuentes, C.; Colomé, J.;
Cortés-Contreras, M.; Delfosse, X.; Díez-Alonso, E.; Forveille, T.;
Guenther, E. W.; Hatzes, A. P.; Henning, Th.; Jeffers, S. V.; Kürster,
M.; Lafarga, M.; Luque, R.; Mandel, H.; Montes, D.; Morales, J. C.;
Passegger, V. M.; Pedraz, S.; Reffert, S.; Sadegi, S.; Schweitzer,
A.; Seifert, W.; Stahl, O.; Udry, S.
2018A&A...618A.115K Altcode: 2018arXiv180801183K
Despite their activity, low-mass stars are of particular importance
for the search of exoplanets by the means of Doppler spectroscopy,
as planets with lower masses become detectable. We report on the
discovery of a planetary companion around HD 180617, a bright (J =
5.58 mag), low-mass (M = 0.45M<SUB>⊙</SUB>) star of spectral type
M2.5 V. The star, located at a distance of 5.9 pc, is the primary of
the high proper motion binary system containing vB 10, a star with
one of the lowest masses known in most of the twentieth century. Our
analysis is based on new radial velocity (RV) measurements made at
red-optical wavelengths provided by the high-precision spectrograph
CARMENES, which was designed to carry out a survey for Earth-like
planets around M dwarfs. The available CARMENES data are augmented
by archival Doppler measurements from HIRES and HARPS. Altogether,
the RVs span more than 16 yr. The modeling of the RV variations,
with a semi-amplitude of K = 2.85<SUB>-0.25</SUB><SUP>+0.16</SUP>
m s<SUP>-1</SUP>, yields a Neptune-like planet with a minimum
mass of 12.2<SUB>-1.4</SUB><SUP>+1.0</SUP> M<SUB>⊕</SUB> on a
105.90<SUB>-0.10</SUB><SUP>+0.09</SUP> d circumprimary orbit, which
is partly located in the host star's habitable zone. The analysis of
time series of common activity indicators does not show any dependence
on the detected RV signal. The discovery of HD 180617 b not only adds
information to a currently hardly filled region of the mass-period
diagram of exoplanets around M dwarfs, but the investigated system
becomes the third known binary consisting of M dwarfs and hosting
an exoplanet in an S-type configuration. Its proximity makes
it an attractive candidate for future studies. <P />The RV data
(Table C.1) are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (<A
href="http://cdsarc.u-strasbg.fr">http://130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/618/A115">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/618/A115</A>
---------------------------------------------------------
Title: Cluster kinematics and stellar rotation in NGC 419 with MUSE
and adaptive optics
Authors: Kamann, S.; Bastian, N.; Husser, T. -O.; Martocchia, S.;
Usher, C.; den Brok, M.; Dreizler, S.; Kelz, A.; Krajnović, D.;
Richard, J.; Steinmetz, M.; Weilbacher, P. M.
2018MNRAS.480.1689K Altcode: 2018MNRAS.tmp.1865K; 2018arXiv180710612K
We present adaptive optics (AO)-assisted integral-field spectroscopy
of the intermediate-age star cluster NGC 419 in the Small Magellanic
Cloud. By investigating the cluster dynamics and the rotation properties
of main-sequence turn-off (MSTO) stars, we demonstrate the power of
AO-fed MUSE observations for this class of objects. Based on 1 049
radial velocity measurements, we determine a dynamical cluster mass
of 1.4± 0.2× 10^5 M_⊙ and a dynamical mass-to-light ratio of 0.67
± 0.08, marginally higher than simple stellar population predictions
for a Kroupa initial mass function. A stacking analysis of spectra
at both sides of the extended MSTO reveals significant rotational
broadening. Our analysis further provides tentative evidence that
red MSTO stars rotate faster than their blue counterparts. We find
average Vsin i values of 87± 16 and 130± 22 {km s^{-1}} for blue
and red MSTO stars, respectively. Potential systematic effects due to
the low-spectral resolution of MUSE can reach 30 {km s^{-1}} but the
difference in Vsin i between the populations is unlikely to be affected.
---------------------------------------------------------
Title: Kepler Object of Interest Network. II. Photodynamical modelling
of Kepler-9 over 8 years of transit observations
Authors: Freudenthal, J.; von Essen, C.; Dreizler, S.; Wedemeyer, S.;
Agol, E.; Morris, B. M.; Becker, A. C.; Mallonn, M.; Hoyer, S.; Ofir,
A.; Tal-Or, L.; Deeg, H. J.; Herrero, E.; Ribas, I.; Khalafinejad,
S.; Hernández, J.; Rodríguez S., M. M.
2018A&A...618A..41F Altcode: 2018arXiv180700007F
Context. The Kepler Object of Interest Network (KOINet) is a multi-site
network of telescopes around the globe organised to follow up transiting
planet-candidate Kepler objects of interest (KOIs) with large transit
timing variations (TTVs). Its main goal is to complete their TTV
curves, as the Kepler telescope no longer observes the original
Kepler field. <BR /> Aims: Combining Kepler and new ground-based
transit data we improve the modelling of these systems. To this end,
we have developed a photodynamical model, and we demonstrate its
performance using the Kepler-9 system as an example. <BR /> Methods:
Our comprehensive analysis combines the numerical integration of the
system's dynamics over the time span of the observations along with
the transit light curve model. This provides a coherent description of
all observations simultaneously. This model is coupled with a Markov
chain Monte Carlo algorithm, allowing for the exploration of the
model parameter space. <BR /> Results: Applied to the Kepler-9 long
cadence data, short cadence data, and 13 new transit observations
collected by KOINet between the years 2014 and 2017, our modelling
provides well constrained predictions for the next transits and the
system's parameters. We have determined the densities of the planets
Kepler-9b and 9c to the very precise values of ρ<SUB>b</SUB> =
0.439 ± 0.023 g cm<SUP>-3</SUP> and ρ<SUB>c</SUB> = 0.322 ±
0.017 g cm<SUP>-3</SUP>. Our analysis reveals that Kepler-9c will
stop transiting in about 30 yr due to strong dynamical interactions
between Kepler-9b and 9c, near 2:1 resonance, leading to a periodic
change in inclination. <BR /> Conclusions: Over the next 30 years, the
inclination of Kepler-9c (-9b) will decrease (increase) slowly. This
should be measurable by a substantial decrease (increase) in the transit
duration, in as soon as a few years' time. Observations that contradict
this prediction might indicate the presence of additional objects
in this system. If this prediction turns out to be accurate, this
behaviour opens up a unique chance to scan the different latitudes of a
star: high latitudes with planet c and low latitudes with planet b. <P
/>Ground-based photometry is only available at the CDS via anonymous ftp
to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(<A href="http://cdsarc.u-strasbg.fr">http://130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/618/A41">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/618/A41</A>
---------------------------------------------------------
Title: MUSE crowded field 3D spectroscopy in NGC 300. I. First
results from central fields
Authors: Roth, Martin M.; Sandin, Christer; Kamann, Sebastian; Husser,
Tim-Oliver; Weilbacher, Peter M.; Monreal-Ibero, Ana; Bacon, Roland;
den Brok, Mark; Dreizler, Stefan; Kelz, Andreas; Marino, Raffaella
Anna; Steinmetz, Matthias
2018A&A...618A...3R Altcode: 2018arXiv180604280R
<BR /> Aims: As a new approach to the study of resolved stellar
populations in nearby galaxies, our goal is to demonstrate with a pilot
study in NGC 300 that integral field spectroscopy with high spatial
resolution and excellent seeing conditions reaches an unprecedented
depth in severely crowded fields. <BR /> Methods: Observations by MUSE
with seven pointings in NGC 300 have resulted in data cubes that are
analyzed in four ways: (1) Point spread function-fitting 3D spectroscopy
with PampelMUSE, as already successfully pioneered in globular clusters,
yields de-blended spectra of individually distinguishable stars,
thus providing a complete inventory of blue and red supergiants, and
asymptotic giant branch (AGB) stars of type M and C. The technique is
also applicable to emission line point sources and provides samples of
planetary nebulae (PNe) that are complete down to m<SUB>5007</SUB> =
28. (2) Pseudo-monochromatic images, created at the wavelengths of the
most important emission lines and corrected for continuum light with
the P3D visualization tool, provide maps of H II regions, supernova
remnants (SNR), and the diffuse interstellar medium (ISM) at a high
level of sensitivity, where also faint point sources stand out and
allow for the discovery of PNe, Wolf-Rayet (WR) stars, etc. (3) The
use of the P3D line-fitting tool yields emission line fluxes, surface
brightness, and kinematic information for gaseous objects, corrected
for absorption line profiles of the underlying stellar population in
the case of Hα. (4) Visual inspection of the data cubes by browsing
through the row-stacked spectra image in P3D is demonstrated to be
efficient for data mining and the discovery of background galaxies
and unusual objects. <BR /> Results: We present a catalog of luminous
stars, rare stars such as WR, and other emission line stars, carbon
stars, symbiotic star candidates, PNe, H II regions, SNR, giant
shells, peculiar diffuse and filamentary emission line objects, and
background galaxies, along with their spectra. <BR /> Conclusions:
The technique of crowded-field 3D spectroscopy, using the PampelMUSE
code, is capable of deblending individual bright stars, the unresolved
background of faint stars, gaseous nebulae, and the diffuse component
of the ISM, resulting in unprecedented legacy value for observations
of nearby galaxies with MUSE. <P />Based on observations obtained at
the Very Large Telescope (VLT) of the European Southern Observatory,
Paranal, Chile (ESO Programme ID 094.D-0116(A), 094.D-0116(B),
095.D-0173(A)).The full version of Tables 6, 9 and the reduced dat-acube
(FITS file) are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/618/A3">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/618/A3</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: NGC 300 MUSE spectroscopy for
central fields (Roth+, 2018)
Authors: Roth, M. M.; Sandin, C.; Kamann, S.; Husser, T. -O.,
Weilbacher, P. M.; Monreal-Ibero, A.; Bacon, R.; den Brok, M.;
Dreizler, S.; Kelz, A.; Marino, R. A.; Steinmetz, M.
2018yCat..36180003R Altcode:
Observations were made with the multi unit spectroscopic explorer
instrument (MUSE), which is placed at the Nasmyth focus of the UT4 8.2m
telescope at the Very Large Telescope observatory (VLT) of the European
Southern Observatory (ESO) in Chile. NGC 300 was observed as part of
guaranteed time observations of the MUSE instrument-building consortium
during the three periods P93, P94, and P95. <P />We present a catalog
of luminous stars, rare stars such as WR, and other emission line
stars, carbon stars, symbiotic star candidates, PNe, HII regions, SNR,
giant shells, peculiar diffuse and filamentary emission line objects,
and background galaxies, along with their spectra. <P />(4 data files).
---------------------------------------------------------
Title: The atmosphere of WASP-17b: Optical high-resolution
transmission spectroscopy
Authors: Khalafinejad, Sara; Salz, Michael; Cubillos, Patricio E.;
Zhou, George; von Essen, Carolina; Husser, Tim-Oliver; Bayliss,
Daniel D. R.; López-Morales, Mercedes; Dreizler, Stefan; Schmitt,
Jürgen H. M. M.; Lüftinger, Theresa
2018A&A...618A..98K Altcode: 2018arXiv180710621K
High-resolution transmission spectroscopy is a method for understanding
the chemical and physical properties of upper exoplanetary
atmospheres. Due to large absorption cross-sections, resonance lines
of atomic sodium D-lines (at 5889.95 and 5895.92 Å) produce large
transmission signals. Our aim is to unveil the physical properties
of WASP-17b through an accurate measurement of the sodium absorption
in the transmission spectrum. We analyze 37 high-resolution spectra
observed during a single transit of WASP-17b with the MIKE instrument
on the 6.5 m Magellan Telescopes. We exclude stellar flaring activity
during the observations by analyzing the temporal variations of
H<SUB>α</SUB> and Ca II infrared triplet (IRT) lines. We then obtain
the excess absorption light curves in wavelength bands of 0.75, 1,
1.5, and 3 Å around the center of each sodium line (i.e., the light
curve approach). We model the effects of differential limb-darkening,
and the changing planetary radial velocity on the light curves. We also
analyze the sodium absorption directly in the transmission spectrum,
which is obtained by dividing in-transit by out-of-transit spectra
(i.e., the division approach). We then compare our measurements with
a radiative transfer atmospheric model. Our analysis results in a
tentative detection of exoplanetary sodium: we measure the width and
amplitude of the exoplanetary sodium feature to be σ<SUB>Na</SUB> =
(0.128 ± 0.078) Å and A<SUB>Na</SUB> = (1.7 ± 0.9)% in the excess
light curve approach and σ<SUB>Na</SUB> = (0.850 ± 0.034) Å and
A<SUB>Na</SUB> = (1.3 ± 0.6)% in the division approach. By comparing
our measurements with a simple atmospheric model, we retrieve an
atmospheric temperature of 15501550 <SUB>-200</SUB><SUP>+700</SUP>
K and radius (at 0.1 bar) of 1.81 ± 0.02 R<SUB>Jup</SUB> for WASP-17b.
---------------------------------------------------------
Title: Improved Methods for Spitzer Systematic Identification
and Removal
Authors: Challener, Ryan C.; Harrington, Joseph; Jenkins, James;
Kurtovic, Nicolás T.; Ramirez, Ricardo; Peña Zamudio, José;
McIntyre, Kathleen J.; Himes, Michael D.; Rodríguez, Eloy;
Anglada-Escudé, Guillem; Dreizler, Stefan; Ofir, Aviv; Ribas,
Ignasi; Rojo, Patricio; Kipping, David; Butler, R. Paul; Amado,
Pedro J.; Rodríguez-López, Cristina; Kempton, Eliza M.; Palle,
Enric; Murgas, Felipe
2018DPS....5040510C Altcode:
After the discovery of Proxima Centauri b in 2016, we observed the
system with the Spitzer Space Telescope to look for transits. We
confirmed that the planet does not transit. However, we observed
three asymmetric, periodic, comet-like events. Unfortunately, we now
understand these events to be systematic effects due to telescope
vibration, which is occasionally temporally resolved with our 0.02
second frame time. This systematic has been previously identified as a
spike in the number of pixels significantly contributing to photometry,
but that metric can be misleading. We show that coherent, high-frequency
activity in the point-spread function area, measured several ways,
is more indicative of this systematic, and that the effect can be
partially removed by a quadratic model dependent on point-spread
function width. This systematic occurs at an exoplanet-signal level
three times in our 80 hours, and more frequently at a lower level, which
has implications for transits and eclipses of small and cool planets,
respectively. Spitzer is operated by the Jet Propulsion Laboratory,
California Institute of Technology, under a contract with NASA. This
work was supported by NASA Planetary Atmospheres grant NNX12AI69G and
NASA Astrophysics Data Analysis Program grant NNX13AF38G.
---------------------------------------------------------
Title: VizieR Online Data Catalog: KOINet. Study of exoplanet systems
via TTVs (von Essen+, 2018)
Authors: von Essen, C.; Ofir, A.; Dreizler, S.; Agol, E.; Freudenthal,
J.; Hernandez, J.; Wedemeyer, S.; Parkash, V.; Deeg, H. J.; Hoyer,
S.; Morris, B. M.; Becker, A. C.; Sun, L.; Gu, S. H.; Herrero, E.;
Tal-Or, L.; Poppenhaeger, K.; Mallonn, M.; Albrecht, S.; Khalafinejad,
S.; Boumis, P.; Delgado-Correal, C.; Fabrycky, D. C.; Janulis, R.;
Lalitha, S.; Liakos, A.; Mikolaitis, S.; Moyano D'Angelo, M. L.; Sokov,
E.; Pakstiene, E.; Popov, A.; Krushinsky, V.; Ribas, I.; Rodriguez,
M. M. S.; Rusov, S.; Sokova, I.; Tautvaisiene, G.; Wang, X.
2018yCat..36150079V Altcode:
All our observations were carried out using R-band filter. We
provide the differential photometry with varying reference stars for
each observation together with the used detrending components. We
provide four transits of KOI-0410.01, and one transit of KOI-0902.01,
KOI-0525.01, and KOI-0760.01, respectively. The telescope nomenclature,
in agreement with the names of the files, is the following: <P
/>IAC0.8: IAC80 telescope (0.8m), Instituto de Astrofisica de Canarias,
Spain. ARC3.5: Apache Point Observatory (3.5 m), USA. NOT2.5: Nordic
Optical Telescope (2.5 m), Spain. YO2.4: Yunnan Observatories (2.4 m),
PR China. <P />(8 data files).
---------------------------------------------------------
Title: The Chemical Homogeneity of Sun-like Stars in the Solar
Neighborhood
Authors: Bedell, Megan; Bean, Jacob L.; Meléndez, Jorge; Spina,
Lorenzo; Ramírez, Ivan; Asplund, Martin; Alves-Brito, Alan; dos
Santos, Leonardo; Dreizler, Stefan; Yong, David; Monroe, TalaWanda;
Casagrande, Luca
2018ApJ...865...68B Altcode: 2018arXiv180202576B
The compositions of stars are a critical diagnostic tool for many
topics in astronomy such as the evolution of our Galaxy, the formation
of planets, and the uniqueness of the Sun. Previous spectroscopic
measurements indicate a large intrinsic variation in the elemental
abundance patterns of stars with similar overall metal content. However,
systematic errors arising from inaccuracies in stellar models are known
to be a limiting factor in such studies, and thus it is uncertain to
what extent the observed diversity of stellar abundance patterns is
real. Here we report the abundances of 30 elements with precisions of 2%
for 79 Sun-like stars within 100 pc. Systematic errors are minimized in
this study by focusing on solar twin stars and performing a line-by-line
differential analysis using high-resolution, high-signal-to-noise
spectra. We resolve [X/Fe] abundance trends in galactic chemical
evolution at precisions of 10<SUP>-3</SUP> dex Gyr<SUP>-1</SUP>
and reveal that stars with similar ages and metallicities have
nearly identical abundance patterns. Contrary to previous results,
we find that the ratios of carbon-to-oxygen and magnesium-to-silicon
in solar-metallicity stars are homogeneous to within 10% throughout
the solar neighborhood, implying that exoplanets may exhibit much less
compositional diversity than previously thought. Finally, we demonstrate
that the Sun has a subtle deficiency in refractory material relative
to >80% of solar twins (at 2σ confidence), suggesting a possible
signpost for planetary systems like our own.
---------------------------------------------------------
Title: VizieR Online Data Catalog: CARMENES input catalogue of M
dwarfs. IV. (Diez Alonso+ 2019)
Authors: Diez Alonso, E.; Caballero, J. A.; Montes, D.; de Cos Juez,
F. J.; Dreizler, S.; Dubois, F.; Jeffers, S. V.; Lalitha, S.; Naves,
R.; Reiners, A.; Ribas, I.; Vanaverbeke, S.; Amado, P. J.; Bejar,
V. J. S.; Cortes-Contreras, M.; Herrero, E.; Hidalgo, D.; Kuerster,
M.; Logie, L.; Quirrenbach, A.; Rau, S.; Seifert, W.; Schoefer, P.;
Tal-Or, L.
2018yCat..36210126D Altcode:
During guaranteed time observations (GTOs), the double-channel
CARMENES spectrograph has so far observed a sample of 336 bright,
nearby M dwarfs with the goal of detecting low-mass planets in their
habitable zone with the radial-velocity method (Quirrenbach et al.,
2015, in 18th Cambridge Workshop on Cool Stars, Stellar Systems, and
the Sun, Proceedings of the conference held at Lowell Observatory,
8-14 June 2014. Edited by G. van Belle and H.C. Harris., pp. 897-906;
Reiners et al., 2018, Cat. J/A+A/612/A49). Of these, 324 were presented
by Reiners et al. (2018, Cat. J/A+A/612/A49), three did not have enough
CARMENES observations at the time of preparing the spectral templates
for the study, and nine are new spectroscopic binaries (Baroch et
al., 2018, A&A, in prep, arXiv:1808.06895). Here, we investigate
the photometric variability of these 336 M dwarfs and of G 34-23 AB
(J01221+221AB), which Cortes-Contreras et al. (2017, Cat. J/A+A/597/A47)
found to be a close physical binary just before GTO start. This results
in a final sample size of 337 stars. <P />(2 data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: A Neptune-mass planet traversing
the habitable zone around HD 180617 (Kaminski+, 2018)
Authors: Kaminski, A.; Trifonov, T.; Caballero, J. A.; Quirrenbach,
A.; Ribas, I.; Reiners, A.; Amado, P. J.; Zechmeister, M.; Dreizler,
S.; Perger, M.; Tal-Or, L.; Bonfils, X.; Mayor, M.; Astudillo-Defru,
N.; Bauer, F. F.; Bejar, V. J. S.; Cifuentes, C.; Colome, J.;
Cortes-Contreras, M.; Delfosse, X.; Diez-Alonso, E.; Forveille, T.;
Guenther, E. W.; Hatzes, A. P.; Henning, Th.; Jeffers, S. V.; Kuerster,
M.; Lafarga, M.; Luque, R.; Mandel, H.; Montes, D.; Morales, J. C.;
Passegger, V. M.; Pedraz, S.; Reffert, S.; Sadegi, S.; Schweitzer,
A.; Seifert, W.; Stahl, O.; Udry, S.
2018yCat..36180115K Altcode:
We analyzed radial velocity data from the CARMENES VIS channel,
HIRES/Keck, and HARPS. All the RVs are corrected for barycentric
motion and secular acceleration. The CARMENES measurements were
taken in the context of the CARMENES search for exoplanets around
M dwarfs. The CARMENES instrument consists of two channels: the VIS
channel obtains spectra at a resolution of R=94600 in the wavelength
range 520-960nm, while the NIR channel yields spectra of R=80400
covering 960-1710nm. Both channels are calibrated in wavelength with
hollow-cathode lamps and use temperature- and pressure-stabilized
Fabry-Perot etalons to interpolate the wavelength solution and
simultaneously monitor the spectrograph drift during nightly operations
(Bauer et al., 2015A&A...581A.117B). <P />(1 data file).
---------------------------------------------------------
Title: VizieR Online Data Catalog: Photometry of Kepler-9b and c
transits (Freudenthal+, 2018)
Authors: Freudenthal, J.; von Essen, C.; Dreizler, S.; Wedemeyer, S.;
Agol, E.; Morris, B. M.; Becker, A. C.; Mallonn, M.; Hoyer, S.; Ofir,
A.; Tal-Or, L.; Deeg, H. J.; Herrero, E.; Ribas, I.; Khalafinejad,
S.; Hernandez, J.; Rodriguez, S. M. M.
2018yCat..36180041F Altcode:
All our observations were carried out using R-band filter. We provide
the differential photometry with varying reference stars for each
observation together with the used detrending components. We measured
five Kepler-9b and four Kepler-9c transits in thirteen observations
between 2014 and 2017. <P />(14 data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: CARMENES SB2 orbital parameters
(Baroch+, 2018)
Authors: Baroch, D.; Morales, J. C.; Ribas, I.; Tal-Or, L.;
Zechmeister, M.; Reiners, A.; Caballero, J. A.; Quirrenbach, A.;
Amado, P. J.; Dreizler, S.; Lalitha, S.; Jeers, S. V.; Lafarga, M.;
Bejar, V. J. S.; Colome, J.; Cortes-Contreras, M.; Diez-Alonso, E.;
Galadi-Enriquez, D.; Guenther, E. W.; Hagen, H. -J.; Henning, T.;
Herrero, E.; Kuerster, M.; Montes, D.; Nagel, E.; Passegger, V. M.;
Perger, M.; Rosich, A.; Schweitzer, A.; Seifert, W.
2018yCat..36190032B Altcode:
These tables list the radial velocities of the SB2 binary systems
detected with CARMENES which are used to compute their orbital and
physical properties. Besides, Table D1 is an effort to compile all known
M-dwarf SB2s with published orbital parameters. A total of 67 systems,
29 of which are eclipsing, have been found. Most of the systems are
taken from the SB9 catalogue of spectroscopic binaries (Pourbaix et
al., 2004, Cat. B/sb9), while additional systems have been found in
a bibliographic search. CARMENES spectroscopic binaries are included
in this table. <P />(2 data files).
---------------------------------------------------------
Title: The MICADO first light imager for the ELT: overview, operation,
simulation
Authors: Davies, R.; Alves, J.; Clénet, Y.; Lang-Bardl, F.;
Nicklas, H.; Pott, J. -U.; Ragazzoni, R.; Tolstoy, E.; Amico, P.;
Anwand-Heerwart, H.; Barboza, S.; Barl, L.; Baudoz, P.; Bender, R.;
Bezawada, N.; Bizenberger, P.; Boland, W.; Bonifacio, P.; Borgo, B.;
Buey, T.; Chapron, F.; Chemla, F.; Cohen, M.; Czoske, O.; Déo, V.;
Disseau, K.; Dreizler, S.; Dupuis, O.; Fabricius, M.; Falomo, R.;
Fedou, P.; Förster Schreiber, N.; Garrel, V.; Geis, N.; Gemperlein,
H.; Gendron, E.; Genzel, R.; Gillessen, S.; Glück, M.; Grupp,
F.; Hartl, M.; Häuser, M.; Hess, H. -J.; Hofferbert, R.; Hopp, U.;
Hörmann, V.; Hubert, Z.; Huby, E.; Huet, J. -M.; Hutterer, V.; Ives,
D.; Janssen, A.; Jellema, W.; Kausch, W.; Kerber, F.; Kravcar, H.; Le
Ruyet, B.; Leschinski, K.; Mandla, C.; Manhart, M.; Massari, D.; Mei,
S.; Merlin, F.; Mohr, L.; Monna, A.; Muench, N.; Müller, F.; Musters,
G.; Navarro, R.; Neumann, U.; Neumayer, N.; Niebsch, J.; Plattner, M.;
Przybilla, N.; Rabien, S.; Ramlau, R.; Ramos, J.; Ramsay, S.; Rhode,
P.; Richter, A.; Richter, J.; Rix, H. -W.; Rodeghiero, G.; Rohloff,
R. -R.; Rosensteiner, M.; Rousset, G.; Schlichter, J.; Schubert, J.;
Sevin, A.; Stuik, R.; Sturm, E.; Thomas, J.; Tromp, N.; Verdoes-Kleijn,
G.; Vidal, F.; Wagner, R.; Wegner, M.; Zeilinger, W.; Ziegleder, J.;
Ziegler, B.; Zins, G.
2018SPIE10702E..1SD Altcode: 2018arXiv180710003D
MICADO will enable the ELT to perform diffraction limited near-infrared
observations at first light. The instrument's capabilities focus on
imaging (including astrometric and high contrast) as well as single
object spectroscopy. This contribution looks at how requirements
from the observing modes have driven the instrument design and
functionality. Using examples from specific science cases, and making
use of the data simulation tool, an outline is presented of what we
can expect the instrument to achieve.
---------------------------------------------------------
Title: CARMENES: high-resolution spectra and precise radial velocities
in the red and infrared
Authors: Quirrenbach, A.; Amado, P. J.; Ribas, I.; Reiners, A.;
Caballero, J. A.; Seifert, W.; Aceituno, J.; Azzaro, M.; Baroch, D.;
Barrado, D.; Bauer, F.; Becerril, S.; Bèjar, V. J. S.; Benítez,
D.; Brinkmöller, M.; Cardona Guillén, C.; Cifuentes, C.; Colomé,
J.; Cortés-Contreras, M.; Czesla, S.; Dreizler, S.; Frölich, K.;
Fuhrmeister, B.; Galadí-Enríquez, D.; González Hernández, J. I.;
González Peinado, R.; Guenther, E. W.; de Guindos, E.; Hagen, H. -J.;
Hatzes, A. P.; Hauschildt, P. H.; Helmling, J.; Henning, Th.; Herbort,
O.; Hernández Castaño, L.; Herrero, E.; Hintz, D.; Jeffers, S. V.;
Johnson, E. N.; de Juan, E.; Kaminski, A.; Klahr, H.; Kürster,
M.; Lafarga, M.; Sairam, L.; Lampón, M.; Lara, L. M.; Launhardt,
R.; López del Fresno, M.; López-Puertas, M.; Luque, R.; Mandel,
H.; Marfil, E. G.; Martín, E. L.; Martín-Ruiz, S.; Mathar, R. J.;
Montes, D.; Morales, J. C.; Nagel, E.; Nortmann, L.; Nowak, G.; Pallé,
E.; Passegger, V. -M.; Pavlov, A.; Pedraz, S.; Pérez-Medialdea, D.;
Perger, M.; Rebolo, R.; Reffert, S.; Rodríguez, E.; Rodríguez López,
C.; Rosich, A.; Sabotta, S.; Sadegi, S.; Salz, M.; Sánchez-López,
A.; Sanz-Forcada, J.; Sarkis, P.; Schäfer, S.; Schiller, J.; Schmitt,
J. H. M. M.; Schöfer, P.; Schweitzer, A.; Shulyak, D.; Solano, E.;
Stahl, O.; Tala Pinto, M.; Trifonov, T.; Zapatero Osorio, M. R.; Yan,
F.; Zechmeister, M.; Abellán, F. J.; Abril, M.; Alonso-Floriano,
F. J.; Ammler-von Eiff, M.; Anglada-Escudé, G.; Anwand-Heerwart, H.;
Arroyo-Torres, B.; Berdiñas, Z. M.; Bergondy, G.; Blümcke, M.; del
Burgo, C.; Cano, J.; Carro, J.; Cárdenas, M. C.; Casal, E.; Claret,
A.; Díez-Alonso, E.; Doellinger, M.; Dorda, R.; Feiz, C.; Fernández,
M.; Ferro, I. M.; Gaisné, G.; Gallardo, I.; Gálvez-Ortiz, M. C.;
García-Piquer, A.; García-Vargas, M. L.; Garrido, R.; Gesa, L.;
Gómez Galera, V.; González-Álvarez, E.; González-Cuesta, L.;
Grohnert, S.; Grözinger, U.; Guàrdia, J.; Guijarro, A.; Hedrosa,
R. P.; Hermann, D.; Hermelo, I.; Hernández Arabí, R.; Hernández
Hernando, F.; Hidalgo, D.; Holgado, G.; Huber, A.; Huber, K.; Huke,
P.; Kehr, M.; Kim, M.; Klein, R.; Klüter, J.; Klutsch, A.; Labarga,
F.; Labiche, N.; Lamert, A.; Laun, W.; Lázaro, F. J.; Lemke, U.;
Lenzen, R.; Llamas, M.; Lizon, J. -L.; Lodieu, N.; López González,
M. J.; López-Morales, M.; López Salas, J. F.; López-Santiago,
J.; Magán Madinabeitia, H.; Mall, U.; Mancini, L.; Marín Molina,
J. A.; Martínez-Rodríguez, H.; Maroto Fernández, D.; Marvin, C. J.;
Mirabet, E.; Moreno-Raya, M. E.; Moya, A.; Mundt, R.; Naranjo, V.;
Panduro, J.; Pascual, J.; Pérez-Calpena, A.; Perryman, M. A. C.;
Pluto, M.; Ramón, A.; Redondo, P.; Reinhart, S.; Rhode, P.; Rix,
H. -W.; Rodler, F.; Rohloff, R. -R.; Sánchez-Blanco, E.; Sánchez
Carrasco, M. A.; Sarmiento, L. F.; Schmidt, C.; Storz, C.; Strachan,
J. B. P.; Stürmer, J.; Suárez, J. C.; Tabernero, H. M.; Tal-Or, L.;
Tulloch, S. M.; Ulbrich, R. -G.; Veredas, G.; Vico Linares, J. L.;
Vidal-Dasilva, M.; Vilardell, F.; Wagner, K.; Winkler, J.; Wolthoff,
V.; Xu, W.; Zhao, Z.
2018SPIE10702E..0WQ Altcode:
The design and construction of CARMENES has been presented at previous
SPIE conferences. It is a next-generation radial-velocity instrument at
the 3.5m telescope of the Calar Alto Observatory, which was built by a
consortium of eleven Spanish and German institutions. CARMENES consists
of two separate échelle spectrographs covering the wavelength range
from 0.52 to 1.71μm at a spec-tral resolution of R < 80,000, fed by
fibers from the Cassegrain focus of the telescope. CARMENES saw "First
Light" on Nov 9, 2015. During the commissioning and initial operation
phases, we established basic performance data such as throughput and
spectral resolution. We found that our hollow-cathode lamps are suitable
for precise wavelength calibration, but their spectra contain a number
of lines of neon or argon that are so bright that the lamps cannot be
used in simultaneous exposures with stars. We have therefore adopted
a calibration procedure that uses simultaneous star / Fabry Pérot
etalon exposures in combination with a cross-calibration between the
etalons and hollow-cathode lamps during daytime. With this strategy
it has been possible to achieve 1-2 m/s precision in the visible and
5-10 m/s precision in the near-IR; further improvements are expected
from ongoing work on temperature control, calibration procedures
and data reduction. Comparing the RV precision achieved in different
wavelength bands, we find a "sweet spot" between 0.7 and 0.8μm, where
deep TiO bands provide rich RV information in mid-M dwarfs. This is
in contrast to our pre-survey models, which predicted comparatively
better performance in the near-IR around 1μm, and explains in
part why our near-IR RVs do not reach the same precision level as
those taken with the visible spectrograph. We are now conducting a
large survey of 340 nearby M dwarfs (with an average distance of only
12pc), with the goal of finding terrestrial planets in their habitable
zones. We have detected the signatures of several previously known or
suspected planets and also discovered several new planets. We find
that the radial velocity periodograms of many M dwarfs show several
significant peaks. The development of robust methods to distinguish
planet signatures from activity-induced radial velocity jitter is
therefore among our priorities. Due to its large wavelength coverage,
the CARMENES survey is generating a unique data set for studies of M
star atmospheres, rotation, and activity. The spectra cover important
diagnostic lines for activity (H alpha, Na I D1 and D2, and the Ca II
infrared triplet), as well as FeH lines, from which the magnetic field
can be inferred. Correlating the time series of these features with
each other, and with wavelength-dependent radial velocities, provides
excellent handles for the discrimination between planetary companions
and stellar radial velocity jitter. These data are also generating
new insight into the physical properties of M dwarf atmospheres, and
the impact of activity and flares on the habitability of M star planets.
---------------------------------------------------------
Title: Kepler Object of Interest Network. I. First results combining
ground- and space-based observations of Kepler systems with transit
timing variations
Authors: von Essen, C.; Ofir, A.; Dreizler, S.; Agol, E.; Freudenthal,
J.; Hernández, J.; Wedemeyer, S.; Parkash, V.; Deeg, H. J.; Hoyer, S.;
Morris, B. M.; Becker, A. C.; Sun, L.; Gu, S. H.; Herrero, E.; Tal-Or,
L.; Poppenhaeger, K.; Mallonn, M.; Albrecht, S.; Khalafinejad, S.;
Boumis, P.; Delgado-Correal, C.; Fabrycky, D. C.; Janulis, R.; Lalitha,
S.; Liakos, A.; Mikolaitis, Š.; Moyano D'Angelo, M. L.; Sokov, E.;
Pakštienė, E.; Popov, A.; Krushinsky, V.; Ribas, I.; Rodríguez S.,
M. M.; Rusov, S.; Sokova, I.; Tautvaišienė, G.; Wang, X.
2018A&A...615A..79V Altcode: 2018arXiv180106191V
During its four years of photometric observations, the Kepler
space telescope detected thousands of exoplanets and exoplanet
candidates. One of Kepler's greatest heritages has been the confirmation
and characterization of hundreds of multi-planet systems via transit
timing variations (TTVs). However, there are many interesting candidate
systems displaying TTVs on such long timescales that the existing Kepler
observations are of insufficient length to confirm and characterize
them by means of this technique. To continue with Kepler's unique work,
we have organized the "Kepler Object of Interest Network" (KOINet),
a multi-site network formed of several telescopes located throughout
America, Europe, and Asia. The goals of KOINet are to complete the TTV
curves of systems where Kepler did not cover the interaction timescales
well, to dynamically prove that some candidates are true planets (or
not), to dynamically measure the masses and bulk densities of some
planets, to find evidence for non-transiting planets in some of the
systems, to extend Kepler's baseline adding new data with the main
purpose of improving current models of TTVs, and to build a platform
that can observe almost anywhere on the northern hemisphere, at almost
any time. KOINet has been operational since March 2014. Here we show
some promising first results obtained from analyzing seven primary
transits of KOI-0410.01, KOI-0525.01, KOI-0760.01, and KOI-0902.01,
in addition to the Kepler data acquired during the first and second
observing seasons of KOINet. While carefully choosing the targets
we set demanding constraints on timing precision (at least 1 min)
and photometric precision (as good as one part per thousand) that
were achieved by means of our observing strategies and data analysis
techniques. For KOI-0410.01, new transit data revealed a turnover
of its TTVs. We carried out an in-depth study of the system, which is
identified in the NASA Data Validation Report as a false positive. Among
others, we investigated a gravitationally bound hierarchical triple
star system and a planet-star system. While the simultaneous transit
fitting of ground- andspace-based data allowed for a planet solution,
we could not fully reject the three-star scenario. New data,
already scheduled in the upcoming 2018 observing season, will set
tighter constraints on the nature of the system. <P />Ground-based
photometry is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/615/A79">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/615/A79</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: 324 CARMENES M dwarfs velocities
(Reiners+, 2018)
Authors: Reiners, A.; Zechmeister, M.; Caballero, J. A.; Ribas, I.;
Morales, J. C.; Jeffers, S. V.; Schofer, P.; Tal-Or, L.; Quirrenbach,
A.; Amado, P. J.; Kaminski, A.; Seifert, W.; Abril, M.; Aceituno,
J.; Alonso-Floriano, F. J.; Ammler-von Eiff, M.; Antona, R.;
Anglada-Escude, G.; Anwand-Heerwart, H.; Arroyo-Torres, B.; Azzaro,
M.; Baroch, D.; Barrado, D.; Bauer, F. F.; Becerril, S.; Bejar,
V. J. S.; Benitez, D.; Berdinas, Z. M.; Bergond, G.; Blumcke, M.;
Brinkmoller, M.; Del Burgo, C.; Cano, J.; Cardenas Vazquez, M. C.;
Casal, E.; Cifuentes, C.; Claret, A.; Colome, J.; Cortes-Contreras,
M.; Czesla, S.; Diez-Alonso, E.; Dreizler, S.; Feiz, C.; Fernandez, M.;
Ferro, I. M.; Fuhrmeister, B.; Galadi-Enriquez, D.; Garcia-Piquer, A.;
Garcia Vargas, M. L.; Gesa, L.; Gomez Galera, V.; Gonzalez Hernandez,
J. I.; Gonzalez-Peinado, R.; Grozinger, U.; Grohnert, S.; Guardia,
J.; Guenther, E. W.; Guijarro, A.; de Guindos, E.; Gutierrez-Soto,
J.; Hagen, H. -J.; Hatzes, A. P.; Hauschildt, P. H.; Hedrosa,
R. P.; Helmling, J.; Henning, T.; Hermelo, I.; Hernandez Arabi, R.;
Hernandez Castano, L.; Hernandez Hernando, F.; Herrero, E.; Huber, A.;
Huke, P.; Johnson, E. N.; de Juan, E.; Kim, M.; Klein, R.; Kluter,
J.; Klutsch, A.; Kurster, M.; Lafarga, M.; Lamert, A.; Lampon, M.;
Lara, L. M.; Laun, W.; Lemke, U.; Lenzen, R.; Launhardt, R.; Lopez
Del Fresno, M.; Lopez-Gonzalez, J.; Lopez-Puertas, M.; Lopez Salas,
J. F.; Lopez-Santiago, J.; Luque, R.; Magan Madinabeitia, H.; Mall,
U.; Mancini, L.; Mandel, H.; Marfil, E.; Marin Molina, J. A.; Maroto
Fernandez, D.; Martin, E. L.; Martin-Ruiz, S.; Marvin, C. J.; Mathar,
R. J.; Mirabet, E.; Montes, D.; Moreno-Raya, M. E.; Moya, A.; Mundt,
R.; Nagel, E.; Naranjo, V.; Nortmann, L.; Nowak, G.; Ofir, A.; Oreiro,
R.; Palle, E.; Panduro, J.; Pascual, J.; Passegger, V. M.; Pavlov,
A.; Pedraz, S.; Perez-Calpena, A.; Perez Medialdea, D.; Perger,
M.; Perryman, M. A. C.; Pluto, M.; Rabaza, O.; Ramon, A.; Rebolo,
R.; Redondo, P.; Reffert, S.; Reinhart, S.; Rhode, P.; Rix, H. -W.;
Rodler, F.; Rodriguez, E.; Rodriguez-Lopez, C.; Rodriguez Trinidad,
A.; Rohloff, R. -R.; Rosich, A.; Sadegi, S.; Sanchez-Blanco, E.;
Sanchez Carrasco, M. A.; Sanchez-Lopez, A.; Sanz-Forcada, J.; Sarkis,
P.; Sarmiento, L. F.; Schafer, S.; Schmitt, J. H. M. M.; Schiller, J.;
Schweitzer, A.; Solano, E.; Stahl, O.; Strachan, J. B. P.; Sturmer,
J.; Suarez, J. C.; Tabernero, H. M.; Tala, M.; Trifonov, T.; Tulloch,
S. M.; Ulbrich, R. G.; Veredas, G.; Vico Linares, J. I.; Vilardell,
F.; Wagner, K.; Winkler, J.; Wolthoff, V.; Xu, W.; Yan, F.; Zapatero
Osorio, M. R.
2018yCat..36120049R Altcode:
As part of the GTO agreement, we provide early access to one CARMENES
spectrum for each of our sample targets (Table B.1). They can be
downloaded from the CARMENES GTO Data Archive (Caballero et al., 2016,
in Observatory Operations: Strategies, Processes, and Systems VI,
Proc. SPIE, 9910, 99100E) (http://carmenes.cab.inta-csic.es) <P />(1
data file).
---------------------------------------------------------
Title: The CARMENES Search for Exoplanets around M Dwarfs: A Low-mass
Planet in the Temperate Zone of the Nearby K2-18
Authors: Sarkis, Paula; Henning, Thomas; Kürster, Martin; Trifonov,
Trifon; Zechmeister, Mathias; Tal-Or, Lev; Anglada-Escudé, Guillem;
Hatzes, Artie P.; Lafarga, Marina; Dreizler, Stefan; Ribas, Ignasi;
Caballero, José A.; Reiners, Ansgar; Mallonn, Matthias; Morales,
Juan C.; Kaminski, Adrian; Aceituno, Jesús; Amado, Pedro J.; Béjar,
Victor J. S.; Hagen, Hans-Jürgen; Jeffers, Sandra; Quirrenbach,
Andreas; Launhardt, Ralf; Marvin, Christopher; Montes, David
2018AJ....155..257S Altcode: 2018arXiv180500830S; 2018arXiv180500830P
K2-18 is a nearby M2.5 dwarf, located at 34 pc and hosting a transiting
planet that was first discovered by the K2 mission and later confirmed
with Spitzer Space Telescope observations. With a radius of ∼2 R
<SUB>⊕</SUB> and an orbital period of ∼33 days, the planet lies in
the temperate zone of its host star and receives stellar irradiation
similar to that of Earth. Here we perform radial velocity follow-up
observations with the visual channel of CARMENES with the goal of
determining the mass and density of the planet. We measure a planetary
semi-amplitude of K <SUB> b </SUB> ∼ 3.5 {{m}} {{{s}}}<SUP>-1</SUP>
and a mass of M <SUB> b </SUB> ∼ 9 M <SUB>⊕</SUB>, yielding a bulk
density around {ρ }<SUB>b</SUB>∼ 4 {{g}} {cm}}<SUP>-3</SUP>. This
indicates a low-mass planet with a composition consistent with a solid
core and a volatile-rich envelope. A signal at 9 days was recently
reported using radial velocity measurements taken with the HARPS
spectrograph. This was interpreted as being due to a second planet. We
see a weaker, time- and wavelength-dependent signal in the CARMENES
data set and thus favor stellar activity for its origin. K2-18 b joins
the growing group of low-mass planets detected in the temperate zone
of M dwarfs. The brightness of the host star in the near-infrared
makes the system a good target for detailed atmospheric studies with
the James Webb Space Telescope.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M
dwarfs. Radial-velocity variations of active stars in visual-channel
spectra
Authors: Tal-Or, L.; Zechmeister, M.; Reiners, A.; Jeffers, S. V.;
Schöfer, P.; Quirrenbach, A.; Amado, P. J.; Ribas, I.; Caballero,
J. A.; Aceituno, J.; Bauer, F. F.; Béjar, V. J. S.; Czesla,
S.; Dreizler, S.; Fuhrmeister, B.; Hatzes, A. P.; Johnson, E. N.;
Kürster, M.; Lafarga, M.; Montes, D.; Morales, J. C.; Reffert, S.;
Sadegi, S.; Seifert, W.; Shulyak, D.
2018A&A...614A.122T Altcode: 2018arXiv180302338T
Context. Previous simulations predicted the activity-induced
radial-velocity (RV) variations of M dwarfs to range from 1 cm
s<SUP>-1</SUP> to 1 km s<SUP>-1</SUP>, depending on various stellar
and activity parameters. <BR /> Aims: We investigate the observed
relations between RVs, stellar activity, and stellar parameters of M
dwarfs by analyzing CARMENES high-resolution visual-channel spectra
(0.5-1μm), which were taken within the CARMENES RV planet survey
during its first 20 months of operation. <BR /> Methods: During this
time, 287 of the CARMENES-sample stars were observed at least five
times. From each spectrum we derived a relative RV and a measure of
chromospheric Hα emission. In addition, we estimated the chromatic
index (CRX) of each spectrum, which is a measure of the RV wavelength
dependence. <BR /> Results: Despite having a median number of only
11 measurements per star, we show that the RV variations of the
stars with RV scatter of >10 m s<SUP>-1</SUP> and a projected
rotation velocity v sin i > 2 km s<SUP>-1</SUP> are caused mainly
by activity. We name these stars "active RV-loud stars" and find their
occurrence to increase with spectral type: from 3% for early-type M
dwarfs (M0.0-2.5 V) through 30% for mid-type M dwarfs (M3.0-5.5 V)
to >50% for late-type M dwarfs (M6.0-9.0 V). Their RV-scatter
amplitude is found to be correlated mainly with v sin i. For about
half of the stars, we also find a linear RV-CRX anticorrelation, which
indicates that their activity-induced RV scatter is lower at longer
wavelengths. For most of them we can exclude a linear correlation
between RV and Hα emission. <BR /> Conclusions: Our results are
in agreement with simulated activity-induced RV variations in M
dwarfs. The RV variations of most active RV-loud M dwarfs are likely
to be caused by dark spots on their surfaces, which move in and out of
view as the stars rotate. <P />The data presented in Figs. 5 and A.1
are only available in electronic form at the CDS via anonymous ftp to
<A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/614/A122">http://cdsarc.u-strasbg.fr/viz-
bin/qcat?J/A+A/614/A122</A>
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M
dwarfs. High-resolution optical and near-infrared spectroscopy of
324 survey stars
Authors: Reiners, A.; Zechmeister, M.; Caballero, J. A.; Ribas,
I.; Morales, J. C.; Jeffers, S. V.; Schöfer, P.; Tal-Or, L.;
Quirrenbach, A.; Amado, P. J.; Kaminski, A.; Seifert, W.; Abril, M.;
Aceituno, J.; Alonso-Floriano, F. J.; Ammler-von Eiff, M.; Antona,
R.; Anglada-Escudé, G.; Anwand-Heerwart, H.; Arroyo-Torres, B.;
Azzaro, M.; Baroch, D.; Barrado, D.; Bauer, F. F.; Becerril,
S.; Béjar, V. J. S.; Benítez, D.; Berdinas, Z. M.; Bergond,
G.; Blümcke, M.; Brinkmöller, M.; del Burgo, C.; Cano, J.;
Cárdenas Vázquez, M. C.; Casal, E.; Cifuentes, C.; Claret, A.;
Colomé, J.; Cortés-Contreras, M.; Czesla, S.; Díez-Alonso, E.;
Dreizler, S.; Feiz, C.; Fernández, M.; Ferro, I. M.; Fuhrmeister, B.;
Galadí-Enríquez, D.; Garcia-Piquer, A.; García Vargas, M. L.; Gesa,
L.; Gómez Galera, V.; González Hernández, J. I.; González-Peinado,
R.; Grözinger, U.; Grohnert, S.; Guàrdia, J.; Guenther, E. W.;
Guijarro, A.; de Guindos, E.; Gutiérrez-Soto, J.; Hagen, H. -J.;
Hatzes, A. P.; Hauschildt, P. H.; Hedrosa, R. P.; Helmling, J.;
Henning, Th.; Hermelo, I.; Hernández Arabí, R.; Hernández Castaño,
L.; Hernández Hernando, F.; Herrero, E.; Huber, A.; Huke, P.; Johnson,
E. N.; de Juan, E.; Kim, M.; Klein, R.; Klüter, J.; Klutsch, A.;
Kürster, M.; Lafarga, M.; Lamert, A.; Lampón, M.; Lara, L. M.;
Laun, W.; Lemke, U.; Lenzen, R.; Launhardt, R.; López del Fresno,
M.; López-González, J.; López-Puertas, M.; López Salas, J. F.;
López-Santiago, J.; Luque, R.; Magán Madinabeitia, H.; Mall, U.;
Mancini, L.; Mandel, H.; Marfil, E.; Marín Molina, J. A.; Maroto
Fernández, D.; Martín, E. L.; Martín-Ruiz, S.; Marvin, C. J.;
Mathar, R. J.; Mirabet, E.; Montes, D.; Moreno-Raya, M. E.; Moya, A.;
Mundt, R.; Nagel, E.; Naranjo, V.; Nortmann, L.; Nowak, G.; Ofir,
A.; Oreiro, R.; Pallé, E.; Panduro, J.; Pascual, J.; Passegger,
V. M.; Pavlov, A.; Pedraz, S.; Pérez-Calpena, A.; Pérez Medialdea,
D.; Perger, M.; Perryman, M. A. C.; Pluto, M.; Rabaza, O.; Ramón,
A.; Rebolo, R.; Redondo, P.; Reffert, S.; Reinhart, S.; Rhode, P.;
Rix, H. -W.; Rodler, F.; Rodríguez, E.; Rodríguez-López, C.;
Rodríguez Trinidad, A.; Rohloff, R. -R.; Rosich, A.; Sadegi, S.;
Sánchez-Blanco, E.; Sánchez Carrasco, M. A.; Sánchez-López, A.;
Sanz-Forcada, J.; Sarkis, P.; Sarmiento, L. F.; Schäfer, S.; Schmitt,
J. H. M. M.; Schiller, J.; Schweitzer, A.; Solano, E.; Stahl, O.;
Strachan, J. B. P.; Stürmer, J.; Suárez, J. C.; Tabernero, H. M.;
Tala, M.; Trifonov, T.; Tulloch, S. M.; Ulbrich, R. G.; Veredas, G.;
Vico Linares, J. I.; Vilardell, F.; Wagner, K.; Winkler, J.; Wolthoff,
V.; Xu, W.; Yan, F.; Zapatero Osorio, M. R.
2018A&A...612A..49R Altcode: 2017arXiv171106576R
The CARMENES radial velocity (RV) survey is observing 324 M dwarfs to
search for any orbiting planets. In this paper, we present the survey
sample by publishing one CARMENES spectrum for each M dwarf. These
spectra cover the wavelength range 520-1710 nm at a resolution of
at least R >80 000, and we measure its RV, Hα emission, and
projected rotation velocity. We present an atlas of high-resolution
M-dwarf spectra and compare the spectra to atmospheric models. To
quantify the RV precision that can be achieved in low-mass stars over
the CARMENES wavelength range, we analyze our empirical information
on the RV precision from more than 6500 observations. We compare our
high-resolution M-dwarf spectra to atmospheric models where we determine
the spectroscopic RV information content, Q, and signal-to-noise
ratio. We find that for all M-type dwarfs, the highest RV precision can
be reached in the wavelength range 700-900 nm. Observations at longer
wavelengths are equally precise only at the very latest spectral types
(M8 and M9). We demonstrate that in this spectroscopic range, the large
amount of absorption features compensates for the intrinsic faintness
of an M7 star. To reach an RV precision of 1 m s<SUP>-1</SUP> in very
low mass M dwarfs at longer wavelengths likely requires the use of a 10
m class telescope. For spectral types M6 and earlier, the combination
of a red visual and a near-infrared spectrograph is ideal to search
for low-mass planets and to distinguish between planets and stellar
variability. At a 4 m class telescope, an instrument like CARMENES has
the potential to push the RV precision well below the typical jitter
level of 3-4 m s<SUP>-1</SUP>.
---------------------------------------------------------
Title: Lyman-continuum leakage as dominant source of diffuse ionized
gas in the Antennae galaxy
Authors: Weilbacher, Peter M.; Monreal-Ibero, Ana; Verhamme,
Anne; Sandin, Christer; Steinmetz, Matthias; Kollatschny, Wolfram;
Krajnović, Davor; Kamann, Sebastian; Roth, Martin M.; Erroz-Ferrer,
Santiago; Marino, Raffaella Anna; Maseda, Michael V.; Wendt, Martin;
Bacon, Roland; Dreizler, Stefan; Richard, Johan; Wisotzki, Lutz
2018A&A...611A..95W Altcode: 2017arXiv171204450W
The Antennae galaxy (NGC 4038/39) is the closest major interacting
galaxy system and is therefore often studied as a merger prototype. We
present the first comprehensive integral field spectroscopic dataset of
this system, observed with the MUSE instrument at the ESO VLT. We cover
the two regions in this system which exhibit recent star formation:
the central galaxy interaction and a region near the tip of the
southern tidal tail. In these fields, we detect HII regions and diffuse
ionized gas to unprecedented depth. About 15% of the ionized gas was
undetected by previous observing campaigns. This newly detected faint
ionized gas is visible everywhere around the central merger, and shows
filamentary structure. We estimate diffuse gas fractions of about
60% in the central field and 10% in the southern region. We are able
to show that the southern region contains a significantly different
population of HII regions, showing fainter luminosities. By comparing
HII region luminosities with the HST catalog of young star clusters
in the central field, we estimate that there is enough Lyman-continuum
leakage in the merger to explain the amount of diffuse ionized gas that
we detect. We compare the Lyman-continuum escape fraction of each HII
region against emission line ratios that are sensitive to the ionization
parameter. While we find no systematic trend between these properties,
the most extreme line ratios seem to be strong indicators of density
bounded ionization. Extrapolating the Lyman-continuum escape fractions
to the southern region, we conclude that simply from the comparison
of the young stellar populations to the ionized gas there is no need
to invoke other ionization mechanisms than Lyman-continuum leaking HII
regions for the diffuse ionized gas in the Antennae. <P />FITS images
and Table of HII regions are available at the CDS via anonymous ftp
to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(<A href="http://cdsarc.u-strasbg.fr">http://130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/611/A95">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/611/A95</A>
and at <A
href="https://muse-vlt.eu/science/antennae/">http://muse-vlt.eu/science/antennae/</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: Radial-velocity of CARMENES M
dwarfs (Tal-Or+, 2018)
Authors: Tal-Or, L.; Zechmeister, M.; Reiners, A.; Jeffers, S. V.;
Schoefer, P.; Quirrenbach, A.; Amado, P. J.; Ribas, I.; Caballero,
J. A.; Aceituno, J.; Bauer, F. F.; Bejar, V. J. S.; Czesla, S.;
Dreizler, S.; Fuhrmeister, B.; Hatzes, A. P.; Johnson, E. N.; Kurster,
M.; Lafarga, M.; Montes, D.; Morales, J. C.; Reffert, S.; Sadegi,
S.; Seifert, W.; Shulyak, D.
2018yCat..36140122T Altcode:
The catalogue contains the data presented in Figures 5 and A.1 of the
source paper. <P />(2 data files).
---------------------------------------------------------
Title: The Radial Velocity Variability of the K-giant γ Draconis:
Stellar Variability Masquerading as a Planet
Authors: Hatzes, A. P.; Endl, M.; Cochran, W. D.; MacQueen, P. J.;
Han, I.; Lee, B. -C.; Kim, K. -M.; Mkrtichian, D.; Döllinger, M.;
Hartmann, M.; Karjalainen, M.; Dreizler, S.
2018AJ....155..120H Altcode: 2018arXiv180105239H
We present precise stellar radial velocity (RV) measurements of γ Dra
taken from 2003 to 2017. The data from 2003 to 2011 show coherent,
long-lived variations with a period of 702 days. These variations
are consistent with the presence of a planetary companion having m
sin i = 10.7 M <SUB>Jup</SUB> whose orbital properties are typical
for giant planets found around evolved stars. An analysis of the
Hipparcos photometry, Ca II S-index measurements, and measurements
of the spectral line shapes during this time show no variations with
the RV of the planet, which seems to “confirm” the presence of
the planet. However, RV measurements taken from 2011-2017 seem to
refute this. From 2011-2013, the RV variations virtually disappear,
only to return in 2014 but with a noticeable phase shift. The total RV
variations are consistent either with amplitude variations on timescales
of ≈10.6 year, or the beating effect between two periods of 666
and 801 days. It seems unlikely that both these signals stem from a
two-planet system. A simple dynamical analysis indicates that there
is only a 1%-2% chance that the two-planet system is stable. Rather,
we suggest that this multi-periodic behavior may represent a new form
of stellar variability, possibly related to oscillatory convective
modes. If such intrinsic stellar variability is common around K
giant stars and is attributed to planetary companions, then the
planet occurrence rate among these stars may be significantly lower
than thought.
---------------------------------------------------------
Title: A detached stellar-mass black hole candidate in the globular
cluster NGC 3201
Authors: Giesers, Benjamin; Dreizler, Stefan; Husser, Tim-Oliver;
Kamann, Sebastian; Anglada Escudé, Guillem; Brinchmann, Jarle;
Carollo, C. Marcella; Roth, Martin M.; Weilbacher, Peter M.; Wisotzki,
Lutz
2018MNRAS.475L..15G Altcode: 2018arXiv180105642G
As part of our massive spectroscopic survey of 25 Galactic globular
clusters with MUSE, we performed multiple epoch observations of NGC
3201 with the aim of constraining the binary fraction. In this cluster,
we found one curious star at the main-sequence turn-off with radial
velocity variations of the order of 100 km s<SUP>- 1</SUP>, indicating
the membership to a binary system with an unseen component since no
other variations appear in the spectra. Using an adapted variant of the
generalized Lomb-Scargle periodogram, we could calculate the orbital
parameters and found the companion to be a detached stellar-mass
black hole with a minimum mass of 4.36 ± 0.41 M<SUB>⊙</SUB>. The
result is an important constraint for binary and black hole evolution
models in globular clusters as well as in the context of gravitational
wave sources.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Temporal evolution of
neutron-capture elements (Spina+, 2018)
Authors: Spina, L.; Melendez, J.; Karakas, A. I.; Dos Santos, L.;
Bedell, M.; Asplund, M.; Ramirez, I.; Yong, D.; Alves-Brito, A.;
Bean, J. L.; Dreizler, S.
2018yCat..74742580S Altcode:
Spectroscopic parameters and abundances for the 79 solar twin stars
analysed in this paper. <P />(4 data files).
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs . First
visual-channel radial-velocity measurements and orbital parameter
updates of seven M-dwarf planetary systems
Authors: Trifonov, T.; Kürster, M.; Zechmeister, M.; Tal-Or,
L.; Caballero, J. A.; Quirrenbach, A.; Amado, P. J.; Ribas, I.;
Reiners, A.; Reffert, S.; Dreizler, S.; Hatzes, A. P.; Kaminski, A.;
Launhardt, R.; Henning, Th.; Montes, D.; Béjar, V. J. S.; Mundt,
R.; Pavlov, A.; Schmitt, J. H. M. M.; Seifert, W.; Morales, J. C.;
Nowak, G.; Jeffers, S. V.; Rodríguez-López, C.; del Burgo, C.;
Anglada-Escudé, G.; López-Santiago, J.; Mathar, R. J.; Ammler-von
Eiff, M.; Guenther, E. W.; Barrado, D.; González Hernández, J. I.;
Mancini, L.; Stürmer, J.; Abril, M.; Aceituno, J.; Alonso-Floriano,
F. J.; Antona, R.; Anwand-Heerwart, H.; Arroyo-Torres, B.; Azzaro,
M.; Baroch, D.; Bauer, F. F.; Becerril, S.; Benítez, D.; Berdiñas,
Z. M.; Bergond, G.; Blümcke, M.; Brinkmöller, M.; Cano, J.; Cárdenas
Vázquez, M. C.; Casal, E.; Cifuentes, C.; Claret, A.; Colomé,
J.; Cortés-Contreras, M.; Czesla, S.; Díez-Alonso, E.; Feiz, C.;
Fernández, M.; Ferro, I. M.; Fuhrmeister, B.; Galadí-Enríquez, D.;
Garcia-Piquer, A.; García Vargas, M. L.; Gesa, L.; Gómez Galera,
V.; González-Peinado, R.; Grözinger, U.; Grohnert, S.; Guàrdia,
J.; Guijarro, A.; de Guindos, E.; Gutiérrez-Soto, J.; Hagen,
H. -J.; Hauschildt, P. H.; Hedrosa, R. P.; Helmling, J.; Hermelo, I.;
Hernández Arabí, R.; Hernández Castaño, L.; Hernández Hernando,
F.; Herrero, E.; Huber, A.; Huke, P.; Johnson, E.; de Juan, E.; Kim,
M.; Klein, R.; Klüter, J.; Klutsch, A.; Lafarga, M.; Lampón, M.;
Lara, L. M.; Laun, W.; Lemke, U.; Lenzen, R.; López del Fresno, M.;
López-González, M. J.; López-Puertas, M.; López Salas, J. F.;
Luque, R.; Magán Madinabeitia, H.; Mall, U.; Mandel, H.; Marfil,
E.; Marín Molina, J. A.; Maroto Fernández, D.; Martín, E. L.;
Martín-Ruiz, S.; Marvin, C. J.; Mirabet, E.; Moya, A.; Moreno-Raya,
M. E.; Nagel, E.; Naranjo, V.; Nortmann, L.; Ofir, A.; Oreiro, R.;
Pallé, E.; Panduro, J.; Pascual, J.; Passegger, V. M.; Pedraz,
S.; Pérez-Calpena, A.; Pérez Medialdea, D.; Perger, M.; Perryman,
M. A. C.; Pluto, M.; Rabaza, O.; Ramón, A.; Rebolo, R.; Redondo,
P.; Reinhardt, S.; Rhode, P.; Rix, H. -W.; Rodler, F.; Rodríguez,
E.; Rodríguez Trinidad, A.; Rohloff, R. -R.; Rosich, A.; Sadegi, S.;
Sánchez-Blanco, E.; Sánchez Carrasco, M. A.; Sánchez-López, A.;
Sanz-Forcada, J.; Sarkis, P.; Sarmiento, L. F.; Schäfer, S.; Schiller,
J.; Schöfer, P.; Schweitzer, A.; Solano, E.; Stahl, O.; Strachan,
J. B. P.; Suárez, J. C.; Tabernero, H. M.; Tala, M.; Tulloch, S. M.;
Veredas, G.; Vico Linares, J. I.; Vilardell, F.; Wagner, K.; Winkler,
J.; Wolthoff, V.; Xu, W.; Yan, F.; Zapatero Osorio, M. R.
2018A&A...609A.117T Altcode: 2017arXiv171001595T
Context. The main goal of the CARMENES survey is to find Earth-mass
planets around nearby M-dwarf stars. Seven M dwarfs included in the
CARMENES sample had been observed before with HIRES and HARPS and
either were reported to have one short period planetary companion (GJ
15 A, GJ 176, GJ 436, GJ 536 and GJ 1148) or are multiple planetary
systems (GJ 581 and GJ 876). <BR /> Aims: We aim to report new precise
optical radial velocity measurements for these planet hosts and test
the overall capabilities of CARMENES. <BR /> Methods: We combined our
CARMENES precise Doppler measurements with those available from HIRES
and HARPS and derived new orbital parameters for the systems. Bona-fide
single planet systems were fitted with a Keplerian model. The multiple
planet systems were analyzed using a self-consistent dynamical model
and their best fit orbits were tested for long-term stability. <BR />
Results: We confirm or provide supportive arguments for planets around
all the investigated stars except for GJ 15 A, for which we find that
the post-discovery HIRES data and our CARMENES data do not show a
signal at 11.4 days. Although we cannot confirm the super-Earth planet
GJ 15 Ab, we show evidence for a possible long-period (P<SUB>c</SUB> =
7030<SUB>-630</SUB><SUP>+970</SUP> d) Saturn-mass (m<SUB>c</SUB>sini
= 51.8M<SUB>⊕</SUB>) planet around GJ 15 A. In addition, based
on our CARMENES and HIRES data we discover a second planet around
GJ 1148, for which we estimate a period P<SUB>c</SUB> = 532.6 days,
eccentricity e<SUB>c</SUB> = 0.342 and minimum mass m<SUB>c</SUB>sini =
68.1M<SUB>⊕</SUB>. <BR /> Conclusions: The CARMENES optical radial
velocities have similar precision and overall scatter when compared
to the Doppler measurements conducted with HARPS and HIRES. We
conclude that CARMENES is an instrument that is up to the challenge
of discovering rocky planets around low-mass stars. <P />Based on
observations collected at the European Organisation for Astronomical
Research in the Southern Hemisphere under ESO programmes 072.C-0488,
072.C-0513, 074.C-0012, 074.C-0364, 075.D-0614, 076.C-0878, 077.C-0364,
077.C-0530, 078.C-0044, 078.C-0833, 079.C-0681, 183.C-0437, 60.A-9036,
082.C-0718, 183.C-0972, 085.C-0019, 087.C-0831, 191.C-0873. The
appendix tables are only available at the CDS via anonymous ftp to
<A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/609/A117">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/609/A117</A>
---------------------------------------------------------
Title: A stellar census in globular clusters with MUSE: The
contribution of rotation to cluster dynamics studied with 200
000 stars
Authors: Kamann, S.; Husser, T. -O.; Dreizler, S.; Emsellem, E.;
Weilbacher, P. M.; Martens, S.; Bacon, R.; den Brok, M.; Giesers,
B.; Krajnović, D.; Roth, M. M.; Wendt, M.; Wisotzki, L.
2018MNRAS.473.5591K Altcode: 2017arXiv171007257K
This is the first of a series of papers presenting the results from our
survey of 25 Galactic globular clusters with the MUSE integral-field
spectrograph. In combination with our dedicated algorithm for source
deblending, MUSE provides unique multiplex capabilities in crowded
stellar fields and allows us to acquire samples of up to 20 000 stars
within the half-light radius of each cluster. The present paper focuses
on the analysis of the internal dynamics of 22 out of the 25 clusters,
using about 500 000 spectra of 200 000 individual stars. Thanks to the
large stellar samples per cluster, we are able to perform a detailed
analysis of the central rotation and dispersion fields using both
radial profiles and two-dimensional maps. The velocity dispersion
profiles we derive show a good general agreement with existing radial
velocity studies but typically reach closer to the cluster centres. By
comparison with proper motion data, we derive or update the dynamical
distance estimates to 14 clusters. Compared to previous dynamical
distance estimates for 47 Tuc, our value is in much better agreement
with other methods. We further find significant (>3σ) rotation in
the majority (13/22) of our clusters. Our analysis seems to confirm
earlier findings of a link between rotation and the ellipticities
of globular clusters. In addition, we find a correlation between the
strengths of internal rotation and the relaxation times of the clusters,
suggesting that the central rotation fields are relics of the cluster
formation that are gradually dissipated via two-body relaxation.
---------------------------------------------------------
Title: The temporal evolution of neutron-capture elements in the
Galactic discs
Authors: Spina, Lorenzo; Meléndez, Jorge; Karakas, Amanda I.; dos
Santos, Leonardo; Bedell, Megan; Asplund, Martin; Ramírez, Ivan;
Yong, David; Alves-Brito, Alan; Bean, Jacob L.; Dreizler, Stefan
2018MNRAS.474.2580S Altcode: 2017arXiv171103643S
Important insights into the formation and evolution of the Galactic
disc(s) are contained in the chemical compositions of stars. We
analysed high-resolution and high signal-to-noise HARPS spectra of 79
solar twin stars in order to obtain precise determinations of their
atmospheric parameters, ages (σ ∼0.4 Gyr) and chemical abundances
(σ <0.01 dex) of 12 neutron-capture elements (Sr, Y, Zr, Ba, La,
Ce, Pr, Nd, Sm, Eu, Gd and Dy). This valuable data set allows us to
study the [X/Fe]-age relations over a time interval of ∼10 Gyr and
among stars belonging to the thin and thick discs. These relations show
that (i) the s-process has been the main channel of nucleosynthesis
of n-capture elements during the evolution of the thin disc; (ii)
the thick disc is rich in r-process elements which suggests that its
formation has been rapid and intensive. In addition, the heavy (Ba,
La, Ce) and light (Sr, Y, Zr) s-process elements revealed details on
the dependence between the yields of AGB stars and the stellar mass
or metallicity. Finally, we confirmed that both [Y/Mg] and [Y/Al]
ratios can be employed as stellar clocks, allowing ages of solar twin
stars to be estimated with an average precision of ∼0.5 Gyr.
---------------------------------------------------------
Title: The CARMENES search for exoplanets around M dwarfs. HD147379 b:
A nearby Neptune in the temperate zone of an early-M dwarf
Authors: Reiners, A.; Ribas, I.; Zechmeister, M.; Caballero, J. A.;
Trifonov, T.; Dreizler, S.; Morales, J. C.; Tal-Or, L.; Lafarga,
M.; Quirrenbach, A.; Amado, P. J.; Kaminski, A.; Jeffers, S. V.;
Aceituno, J.; Béjar, V. J. S.; Guàrdia, J.; Guenther, E. W.; Hagen,
H. -J.; Montes, D.; Passegger, V. M.; Seifert, W.; Schweitzer, A.;
Cortés-Contreras, M.; Abril, M.; Alonso-Floriano, F. J.; Ammler-von
Eiff, M.; Antona, R.; Anglada-Escudé, G.; Anwand-Heerwart, H.;
Arroyo-Torres, B.; Azzaro, M.; Baroch, D.; Barrado, D.; Bauer,
F. F.; Becerril, S.; Benítez, D.; Berdiñas, Z. M.; Bergond, G.;
Blümcke, M.; Brinkmöller, M.; del Burgo, C.; Cano, J.; Cárdenas
Vázquez, M. C.; Casal, E.; Cifuentes, C.; Claret, A.; Colomé, J.;
Czesla, S.; Díez-Alonso, E.; Feiz, C.; Fernández, M.; Ferro, I. M.;
Fuhrmeister, B.; Galadí-Enríquez, D.; Garcia-Piquer, A.; García
Vargas, M. L.; Gesa, L.; Gómez Galera, V.; González Hernández,
J. I.; González-Peinado, R.; Grözinger, U.; Grohnert, S.; Guijarro,
A.; de Guindos, E.; Gutiérrez-Soto, J.; Hatzes, A. P.; Hauschildt,
P. H.; Hedrosa, R. P.; Helmling, J.; Henning, Th.; Hermelo, I.;
Hernández Arabí, R.; Hernández Castaño, L.; Hernández Hernando,
F.; Herrero, E.; Huber, A.; Huke, P.; Johnson, E. N.; de Juan, E.; Kim,
M.; Klein, R.; Klüter, J.; Klutsch, A.; Kürster, M.; Labarga, F.;
Lamert, A.; Lampón, M.; Lara, L. M.; Laun, W.; Lemke, U.; Lenzen,
R.; Launhardt, R.; López del Fresno, M.; López-González, M. J.;
López-Puertas, M.; López Salas, J. F.; López-Santiago, J.; Luque,
R.; Magán Madinabeitia, H.; Mall, U.; Mancini, L.; Mandel, H.;
Marfil, E.; Marín Molina, J. A.; Maroto Fernández, D.; Martín,
E. L.; Martín-Ruiz, S.; Marvin, C. J.; Mathar, R. J.; Mirabet, E.;
Moreno-Raya, M. E.; Moya, A.; Mundt, R.; Nagel, E.; Naranjo, V.;
Nortmann, L.; Nowak, G.; Ofir, A.; Oreiro, R.; Pallé, E.; Panduro,
J.; Pascual, J.; Pavlov, A.; Pedraz, S.; Pérez-Calpena, A.; Pérez
Medialdea, D.; Perger, M.; Perryman, M. A. C.; Pluto, M.; Rabaza,
O.; Ramón, A.; Rebolo, R.; Redondo, P.; Reffert, S.; Reinhart, S.;
Rhode, P.; Rix, H. -W.; Rodler, F.; Rodríguez, E.; Rodríguez-López,
C.; Rodríguez Trinidad, A.; Rohloff, R. -R.; Rosich, A.; Sadegi,
S.; Sánchez-Blanco, E.; Sánchez Carrasco, M. A.; Sánchez-López,
A.; Sanz-Forcada, J.; Sarkis, P.; Sarmiento, L. F.; Schäfer, S.;
Schmitt, J. H. M. M.; Schiller, J.; Schöfer, P.; Solano, E.; Stahl,
O.; Strachan, J. B. P.; Stürmer, J.; Suárez, J. C.; Tabernero, H. M.;
Tala, M.; Tulloch, S. M.; Ulbrich, R. -G.; Veredas, G.; Vico Linares,
J. I.; Vilardell, F.; Wagner, K.; Winkler, J.; Wolthoff, V.; Xu, W.;
Yan, F.; Zapatero Osorio, M. R.
2018A&A...609L...5R Altcode: 2017arXiv171205797R
We report on the first star discovered to host a planet detected by
radial velocity (RV) observations obtained within the CARMENES survey
for exoplanets around M dwarfs. HD 147379 (V = 8.9 mag, M = 0.58 ±
0.08 M<SUB>⊙</SUB>), a bright M0.0 V star at a distance of 10.7 pc,
is found to undergo periodic RV variations with a semi-amplitude of
K = 5.1 ± 0.4 m s<SUP>-1</SUP> and a period of P = 86.54 ± 0.06
d. The RV signal is found in our CARMENES data, which were taken
between 2016 and 2017, and is supported by HIRES/Keck observations
that were obtained since 2000. The RV variations are interpreted
as resulting from a planet of minimum mass m<SUB>P</SUB> sin i =
25 ± 2 M<SUB>⊕</SUB>, 1.5 times the mass of Neptune, with an
orbital semi-major axis a = 0.32 au and low eccentricity (e <
0.13). HD 147379 b is orbiting inside the temperate zone around the
star, where water could exist in liquid form. The RV time-series and
various spectroscopic indicators show additional hints of variations
at an approximate period of 21.1 d (and its first harmonic), which
we attribute to the rotation period of the star. <P />RV data
(Table A.1) are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/609/L5">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/609/L5</A>
---------------------------------------------------------
Title: Spectroscopic binaries in the Solar Twin Planet Search program:
from substellar-mass to M dwarf companions
Authors: dos Santos, Leonardo A.; Meléndez, Jorge; Bedell, Megan;
Bean, Jacob L.; Spina, Lorenzo; Alves-Brito, Alan; Dreizler, Stefan;
Ramírez, Iván; Asplund, Martin
2017MNRAS.472.3425D Altcode: 2017arXiv170807465D
Previous studies on the rotation of Sun-like stars revealed that
the rotational rates of young stars converge towards a well-defined
evolution that follows a power-law decay. It seems, however, that some
binary stars do not obey this relation, often by displaying enhanced
rotational rates and activity. In the Solar Twin Planet Search program,
we observed several solar twin binaries, and found a multiplicity
fraction of 42 per cent ± 6 per cent in the whole sample; moreover,
at least three of these binaries (HIP 19911, HIP 67620 and HIP 103983)
clearly exhibit the aforementioned anomalies. We investigated the
configuration of the binaries in the program, and discovered new
companions for HIP 6407, HIP 54582, HIP 62039 and HIP 30037, of which
the latter is orbited by a 0.06 M<SUB>⊙</SUB> brown dwarf in a 1
m long orbit. We report the orbital parameters of the systems with
well-sampled orbits and, in addition, the lower limits of parameters
for the companions that only display a curvature in their radial
velocities. For the linear trend binaries, we report an estimate
of the masses of their companions when their observed separation
is available, and a minimum mass otherwise. We conclude that solar
twin binaries with low-mass stellar companions at moderate orbital
periods do not display signs of a distinct rotational evolution when
compared to single stars. We confirm that the three peculiar stars are
double-lined binaries, and that their companions are polluting their
spectra, which explains the observed anomalies.
---------------------------------------------------------
Title: Mapping diffuse interstellar bands in the local ISM on small
scales via MUSE 3D spectroscopy. A pilot study based on globular
cluster NGC 6397
Authors: Wendt, Martin; Husser, Tim-Oliver; Kamann, Sebastian;
Monreal-Ibero, Ana; Richter, Philipp; Brinchmann, Jarle; Dreizler,
Stefan; Weilbacher, Peter M.; Wisotzki, Lutz
2017A&A...607A.133W Altcode: 2017arXiv170903982W
Context. We map the interstellar medium (ISM) including the diffuse
interstellar bands (DIBs) in absorption toward the globular cluster NGC
6397 using VLT/MUSE. Assuming the absorbers are located at the rim of
the Local Bubble we trace structures on the order of mpc (milliparsec,
a few thousand AU). <BR /> Aims: We aimed to demonstrate the feasibility
to map variations of DIBs on small scales with MUSE. The sightlines
defined by binned stellar spectra are separated by only a few arcseconds
and we probe the absorption within a physically connected region. <BR />
Methods: This analysis utilized the fitting residuals of individual
stellar spectra of NGC 6397 member stars and analyzed lines from
neutral species and several DIBs in Voronoi-binned composite spectra
with high signal-to-noise ratio (S/N). <BR /> Results: This pilot study
demonstrates the power of MUSE for mapping the local ISM on very small
scales which provides a new window for ISM observations. We detect small
scale variations in Na I and K I as well as in several DIBs within
few arcseconds, or mpc with regard to the Local Bubble. We verify
the suitability of the MUSE 3D spectrograph for such measurements and
gain new insights by probing a single physical absorber with multiple
sight lines.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Diffuse ionized gas in the Antennae
galaxy (Weilbacher+, 2018)
Authors: Weilbacher, P. M.; Monreal-Ibero, A.; Verhamme, A.; Sandin,
C.; Steinmetz, M.; Kollatschny, W.; Krajnovic, D.; Kamann, S.; Roth,
M. M.; Erroz-Ferrer, S.; Marino, R. A.; Maseda, M. V.; Wendt, M.;
Bacon, R.; Dreizler, S.; Richard, J.; Wisotzki, L.
2017yCat..36110095W Altcode:
We provide two-dimensional maps of two different ways to measure
the diffuse ionized gas as traced by the Halpha emission line in the
Antennae Galaxy, both for the central field and the field at the end
of the southern tidal tail. We provide a velocity map derived from
the Halpha emission line, binned to a S/N~30. Finally, we provide line
measurements and derived properties for all HII regions discussed in
the paper. <P />(4 data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: HD147379 b velocity curve
(Reiners+, 2018)
Authors: Reiners, A.; Ribas, I.; Zechmeister, M.; Caballero, J. A.;
Trifonov, T.; Dreizler, S.; Morales, J. C.; Tal-Or, L.; Lafarga,
M.; Quirrenbach, A.; Amado, P. J.; Kaminski, A.; Jeffers, S. V.;
Aceituno, J.; Bejar, V. J. S.; Guardia, J.; Guenther, E. W.; Hagen,
H. -J.; Montes, D.; Passegger, V. M.; Seifert, W.; Schweitzer, A.;
Cortes-Contreras, M.; Abril, M.; Alonso-Floriano, F. J.; Ammler-von
Eiff, M.; Antona, R.; Anglada-Escude, G.; Anwand-Heerwart, H.;
Arroyo-Torres, B.; Azzaro, M.; Baroch, D.; Barrado, D.; Bauer, F. F.;
Becerril, S.; Benitez, D.; Berdinas, Z. M.; Bergond, G.; Bluemcke,
M.; Brinkmoeller, M.; Del Burgo, C.; Cano, J.; Cardenas Vazquez,
M. C.; Casal, E.; Cifuentes, C.; Claret, A.; Colome, J.; Czesla, S.;
Diez-Alonso, E.; Feiz, C.; Fernandez, M.; Ferro, I. M.; Fuhrmeister,
B.; Galadi-Enriquez, D.; Garcia-Piquer, A.; Garcia Vargas, M. L.; Gesa,
L.; Gomez Galera, V.; Gonzalez Hernandez, J. I.; Gonzalez-Peinado,
R.; Groezinger, U.; Grohnert, S.; Guijarro, A.; de Guindos, E.;
Gutierrez-Soto, J.; Hatzes, A. P.; Hauschildt, P. H.; Hedrosa,
R. P.; Helml!, Ing J.; H Enning, Th.; Hermelo, I.; Hernandez Arabi,
R.; Hernandez Castano, L.; Hernandez Hernando, F.; Herrero, E.;
Huber, A.; Huke, P.; Johnson, E. N.; de Juan, E.; Kim, M.; Klein,
R.; Klueter, J.; Klutsch, A.; Kuerster, M.; Labarga, F.; Lamert, A.;
Lampon, M.; Lara, L. M.; Laun, W.; Lemke, U.; Lenzen, R.; Launhardt,
R.; Lopez Del Fresno, M.; Lopez-Gonzalez, M. J.; Lopez-Puertas, M.;
Lopez Salas, J. F.; Lopez-Santiago, J.; Luque, R.; Magan Madinabeitia,
H.; Mall, U.; Mancini, L.; Mandel, H.; Marfil, E.; Marin Molina,
J. A.; Maroto Fernandez, D.; Martin, E. L.; Martin-Ruiz, S.; Marvin,
C. J.; Mathar, R. J.; Mirabet, E.; Moreno-Raya, M. E.; Moya, A.;
Mundt, R.; Nagel, E.; Naranjo, V.; Nortmann, L.; Nowak, G.; Ofir, A.;
Oreiro, R.; Palle, E.; Panduro, J.; Pascual, J.; Pavlov, A.; Pedraz,
S.; Perez-Calpena, A.; Perez Medialdea, D.; Perger, M.; Perryman,
M. A. C.; Pluto, M.; Rabaza, O.; Ramon, A.; Rebolo, R.; Redondo,
P.; Reffert, S.; Reinhart, S.; Rhode, P.; Rix, H. -W.; Rodler, F.;
Rodriguez, E.; Rodriguez-Lopez, C.; Rodriguez Trinidad, A.; Rohloff,
R. -R.; Rosich, A.; ! Sadegi, S.; Sanchez-Blanco, E.; Sanchez Carrasco,
M. A.; Sanchez-Lopez, A.; Sanz-Forcada, J.; Sarkis, P.; Sarmiento,
L. F.; Schaefer, S.; Schmitt, J. H. M. M.; Schiller, J.; Schoefer,
P.; Solano, E.; Stahl, O.; Strachan, J. B. P.; Stuermer, J.; Suarez,
J. C.; Tabernero, H. M.; Tala, M.; Tulloch, S. M.; Ulbrich, R. -G.;
Veredas, G.; Vico Linares, J. I.; Vilardell, F.; Wagner, K.; Winkler,
J.; Wolthoff, V.; Xu, W.; Yan, F.; Zapatero Osorio, M. R.
2017yCat..36099005R Altcode:
We analyzed data from the CARMENES VIS channel and HIRES/Keck. The
CARMENES measurements were taken in the context of the CARMENES search
for exoplanets around M dwarfs. The CARMENES instrument consists of two
channels: the VIS channel obtains spectra at a resolution of R=94600 in
the wavelength range 520-960nm, while the NIR channel yields spectra of
R=80400 covering 960-1710nm. Both channels are calibrated in wavelength
with hollow-cathode lamps and use temperature- and pressure-stabilized
Fabry-Perot etalons to interpolate the wavelength solution and
simultaneously monitor the spectrograph drift during nightly operations
(Bauer et al., 2015A&A...581A.117B). <P />(1 data file).
---------------------------------------------------------
Title: VizieR Online Data Catalog: CARMENES radial velocity curves
of 7 M-dwarf (Trifonov+, 2018)
Authors: Trifonov, T.; Kuerster, M.; Zechmeister, M.; Tal-Or, L.;
Caballero, J. A.; Quirrenbach, A.; Amado, P. J.; Ribas, I.; Reiners,
A.; Reffert, S.; Dreizler, S.; Hatzes, A. P.; Kaminski, A.; Launhardt,
R.; Henning, T.; Montes, D.; Bejar, V. J. S.; Mundt, R.; Pavlov,
A.; Schmitt, J. H. M. M.; Seifert, W.; Morales, J. C.; Nowak, G.;
Jeffers, S. V.; Rodriguez-Lopez, C.; Del Burgo, C.; Anglada-Escude,
G.; Lopez-Santiago, J.; Mathar, R. J.; Ammler-von Eiff, M.; Guenther,
E. W.; Barrado, D.; Gonzalez Hernandez, J. I.; Mancini, L.; Stuermer,
J.; Abril, M.; Aceituno, J.; Alonso-Floriano, F. J.; Antona, R.;
Anwand-Heerwart, H.; Arroyo-Torres, B.; Azzaro, M.; Baroch, D.;
Bauer, F. F.; Becerril, S.; Benitez, D.; Berdinas, Z. M.; Bergond,
G.; Bluemcke, M.; Brinkmoeller, M.; Cano, J.; Cardenas Vazquez, M. C.;
Casal, E.; Cifuentes, C.; Claret, A.; Colome, J.; Cortes-Contreras, M.;
Czesla, S.; Diez-Alonso, E.; Feiz, C.; Fernandez, M.; Ferro, I. M.;
Fuhrmeister, B.; Galadi-Enriquez, D.; Garcia-Piquer, A.; Garcia
Vargas, M. L.; Gesa, L.; Gomez Galera, V.; Gonzalez-Peinado, R.;
Groezinger, U.; Grohnert, S.; Guardia, J.; Guijarro, A.; de Guindos,
E.; Gutierrez-Soto, J.; Hagen, H. -J.; Hauschildt, P. H.; Hedrosa,
R. P.; Helmling, J.; Hermelo, I.; Hernandez Arabi, R.; Hernandez
Castano, L.; Hernandez Hernando, F.; Herrero, E.; Huber, A.; Huke, P.;
Johnson, E.; de Juan, E.; Kim, M.; Klein, R.; Klueter, J.; Klutsch, A.;
Lafarga, M.; Lampon, M.; Lara, L. M.; Laun, W.; Lemke, U.; Lenzen,
R.; Lopez Del Fresno, M.; Lopez-Gonzalez, J.; Lopez-Puertas, M.;
Lopez Salas, J. F.; Luque, R.; Magan Madinabeitia, H.; Mall, U.;
Mandel, H.; Marfil, E.; Marin Molina, J. A.; Maroto Fernandez, D.;
Martin, E. L.; Martin-Ruiz, S.; Marvin, C. J.; Mirabet, E.; Moya,
A.; Moreno-Raya, M. E.; Nagel, E.; Naranjo, V.; Nortmann, L.; Ofir,
A.; Oreiro, R.; Palle, E.; Panduro, J.; Pascual, J.; Passegger,
V. M.; Pedraz, S.; Perez-Calpena, A.; Perez Medialdea, D.; Perger,
M.; Perryman, M. A. C.; Pluto, M.; Rabaza, O.; Ramon, A.; Rebolo,
R.; Redondo, P.; Reinhardt, S.; Rhode, P.; Rix, H. -W.; Rodler, F.;
Rodriguez, E.; Rodriguez Trinidad, A.; Rohlo, R. -R.; Rosich, A.;
Sadegi, S.; Sanchez-Blanco, E.; Sanchez Carrasco, M. A.; Sanchez-Lopez,
A.; Sanz-Forcada, J.; Sarkis, P.; Sarmiento, L. F.; Schaefer, S.;
Schiller, J.; Schoefer, P.; Schweitzer, A.; Solano, E.; Stahl, O.;
Strachan, J. B. P.; Suarez, J. C.; Tabernero, H. M.; Tala, M.; Tulloch,
S. M.; Veredas, G.; Vico Linares, J. I.; Vilardel, F.; Wagner, K.;
Winkler, J.; Woltho, V.; Xu, W.; Yan, F.; Zapatero Osorio, M. R.
2017yCat..36090117T Altcode:
The two CARMENES spectrographs are grism cross-dispersed, white pupil,
echelle spectrograph working in quasi-Littrow mode using a two-beam,
two-slice image slicer. The visible spectrograph covers the wavelength
range from 0.52um to 1.05um with 61 orders, a resolving power of
R=94600, and a mean sampling of 2.8 pixels per resolution element. <P
/>The data presented in this paper were taken during the early phase
of operation of the CARMENES visible-light spectrograph. <P />(8
data files).
---------------------------------------------------------
Title: Understanding stellar activity-induced radial velocity jitter
using simultaneous K2 photometry and HARPS RV measurements
Authors: Oshagh, M.; Santos, N. C.; Figueira, P.; Barros, S. C. C.;
Donati, J. -F.; Adibekyan, V.; Faria, J. P.; Watson, C. A.; Cegla,
H. M.; Dumusque, X.; Hébrard, E.; Demangeon, O.; Dreizler, S.;
Boisse, I.; Deleuil, M.; Bonfils, X.; Pepe, F.; Udry, S.
2017A&A...606A.107O Altcode: 2017arXiv170701827O
One of the best ways to improve our understanding of the stellar
activity-induced signal in radial velocity (RV) measurements is through
simultaneous high-precision photometric and RV observations. This is of
prime importance to mitigate the RV signal induced by stellar activity
and therefore unveil the presence of low-mass exoplanets. The K2
Campaign 7 and 8 fields of view were located in the southern hemisphere,
and provided a unique opportunity to gather unprecedented simultaneous
high-precision photometric observation with K2 and high-precision RV
measurements with the HARPS spectrograph to study the relationship
between photometric variability and RV jitter. We observed nine stars
with different levels of activity, from quiet to very active. We first
probed the presence of any meaningful relation between measured RV
jitter and the simultaneous photometric variation, and also other
activity indicators (such as BIS, FWHM, log R'<SUB>HK</SUB>, and
F8) by evaluating the strength and significance of the monotonic
correlation between RVs and each indicator. We found that for the
case of very active stars, strong and significant correlations
exist between almost all the observables and measured RVs; however,
when we move towards lower activity levels the correlations become
random, and we could not reach any conclusion regarding the tendency
of correlations depending on the stellar activity level. Except for
the F8 whose strong correlation with RV jitter persists over a wide
range of stellar activity level, and thus our result suggests that F8
might be a powerful proxy for activity-induced RV jitter over a wide
range of stellar activity. Moreover, we examine the capability of two
state-of-the-art modeling techniques, namely the FF' method and SOAP2.0,
to accurately predict the RV jitter amplitude using the simultaneous
photometric observation. We found that for the very active stars both
techniques can predict the amplitude of the RV jitter reasonably well;
however, at lower activity levels the FF' method underpredicts the RV
jitter amplitude. <P />RV measurements obtained from the HARPS pipeline
are only available in electronic form at the CDS via anonymous ftp to
<A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/606/A107">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/606/A107</A>
---------------------------------------------------------
Title: Hot horizontal branch stars in NGC 288 - effects of diffusion
and stratification on their atmospheric parameters (Corrigendum)
Authors: Moehler, S.; Dreizler, S.; LeBlanc, F.; Khalack, V.; Michaud,
G.; Richer, J.; Sweigart, A. V.; Grundahl, F.
2017A&A...605C...4M Altcode:
We found that the script to determine the masses of the stars contains
two errors. This script and a related one have been used to determine
masses of globular cluster stars and distances to field stars in 12
papers published between 1990 and 2014. While the numerical values
need to be revised none of the conclusions are affected. We provide the
updated numerical values and figures for all 12 publications here. In
addition we describe the effects on those refereed publications that
used the distances to the field stars.
---------------------------------------------------------
Title: VizieR Online Data Catalog: K2/HARPS measurements for 8 stars
(Oshagh+, 2017)
Authors: Oshagh, M.; Santos, N. C.; Figueira, P.; Barros, S. C. C.;
Donati, J. -F.; Adibekyan, V.; Faria, J. P.; Watson, C. A.; Cegla,
H. M.; Dumusque, X.; Hebrard, E.; Demangeon, O.; Dreizler, S.; Boisse,
I.; Deleuil, M.; Bonfils, X.; Pepe, F.; Udry, S.
2017yCat..36060107O Altcode:
Tables contain the radial velocity, BIS, FWHM, S-index, and logR'HK
obtained from the HARPS pipeline for 8 stars in our sample. <P />(2
data files).
---------------------------------------------------------
Title: Exploring plausible formation scenarios for the planet
candidate orbiting Proxima Centauri
Authors: Coleman, G. A. L.; Nelson, R. P.; Paardekooper, S. J.;
Dreizler, S.; Giesers, B.; Anglada-Escudé, G.
2017MNRAS.467..996C Altcode: 2016arXiv160806908C; 2017MNRAS.tmp..175C
We present a study of four different formation scenarios that
may be able to explain the origin of the recently announced planet
('Proxima b') orbiting Proxima Centauri. The aim is to examine how the
formation scenarios differ in their predictions for the multiplicity
of the Proxima system, the water/volatile content of Proxima b and
its orbital eccentricity, so that these can be tested by future
observations. A scenario of in situ formation via giant impacts from
a locally enhanced disc of planetary embryos/planetesimals predicts
that Proxima b will be in a multiplanet system with a measurably
finite eccentricity. Assuming that the local solid enhancement needed
to form a Proxima b analogue arises because of the inwards drift of
solids in the form of small planetesimals/boulders, this scenario also
results in Proxima b analogues being only moderately endowed with
water/volatiles. A scenario in which multiple embryos form, migrate
and mutually collide within a gas disc results in Proxima b being a
member of a multiple system, possibly displaying mean-motion resonances,
but where the constituent members are Ocean planets due to accretion
occurring mainly outside of the snowline. A scenario in which a single
accreting embryo forms outside the snowline, and migrates inwards while
accreting planetesimals/pebbles results in Proxima b being an isolated
Ocean planet on a circular orbit. A scenario in which Proxima b formed
via pebble accretion interior to the snowline produces a dry planet on
a circular orbit. Future observations that characterize the physical
and orbital properties of Proxima b, and any additional planets in the
system, will provide valuable insights into the formation history of
this neighbouring planetary system.
---------------------------------------------------------
Title: How eclipse time variations, eclipse duration variations,
and radial velocities can reveal S-type planets in close eclipsing
binaries
Authors: Oshagh, M.; Heller, R.; Dreizler, S.
2017MNRAS.466.4683O Altcode: 2016arXiv161004047O; 2016MNRAS.tmp.1555O
While about a dozen transiting planets have been found in wide orbits
around an inner, close stellar binary (so-called P-type planets),
no planet has yet been detected orbiting only one star (a so-called
S-type planet) in an eclipsing binary. This is despite a large number
of eclipsing binary systems discovered with the Kepler telescope. Here
we propose a new detection method for these S-type planets, which uses a
correlation between the stellar radial velocities (RVs), eclipse timing
variations (ETVs) and eclipse duration variations (EDVs). We test the
capability of this technique by simulating a realistic benchmark system
and demonstrate its detectability with existing high-accuracy RV and
photometry instruments. We illustrate that with a small number of RV
observations, the RV-ETV diagrams allows us to distinguish between
prograde and retrograde planetary orbits and also the planetary mass
can be estimated if the stellar cross-correlation functions can be
disentangled. We also identify a new (though minimal) contribution
of S-type planets to the Rossiter-McLaughlin effect in eclipsing
stellar binaries. We finally explore possible detection of exomoons
around transiting luminous giant planets and find that the precision
required to detect moons in the RV curves of their host planets is
of the order of cm s<SUP>-1</SUP> and therefore not accessible with
current instruments.
---------------------------------------------------------
Title: Faint-source-star planetary microlensing: the discovery of
the cold gas-giant planet OGLE-2014-BLG-0676Lb
Authors: Rattenbury, N. J.; Bennett, D. P.; Sumi, T.; Koshimoto,
N.; Bond, I. A.; Udalski, A.; Shvartzvald, Y.; Maoz, D.; Jørgensen,
U. G.; Dominik, M.; Street, R. A.; Tsapras, Y.; Abe, F.; Asakura, Y.;
Barry, R.; Bhattacharya, A.; Donachie, M.; Evans, P.; Freeman, M.;
Fukui, A.; Hirao, Y.; Itow, Y.; Li, M. C. A.; Ling, C. H.; Masuda,
K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Oyokawa,
H.; Saito, To.; Sharan, A.; Sullivan, D. J.; Suzuki, D.; Tristram,
P. J.; Yonehara, A.; Poleski, R.; Skowron, J.; Mróz, P.; Szymański,
M. K.; Soszyński, I.; Pietrukowicz, P.; Kozłowski, S.; Ulaczyk, K.;
Wyrzykowski, Ł.; Friedmann, M.; Kaspi, S.; Alsubai, K.; Browne, P.;
Andersen, J. M.; Bozza, V.; Calchi Novati, S.; Damerdji, Y.; Diehl,
C.; Dreizler, S.; Elyiv, A.; Giannini, E.; Hardis, S.; Harpsøe, K.;
Hinse, T. C.; Liebig, C.; Hundertmark, M.; Juncher, D.; Kains, N.;
Kerins, E.; Korhonen, H.; Mancini, L.; Martin, R.; Mathiasen, M.;
Rabus, M.; Rahvar, S.; Scarpetta, G.; Skottfelt, J.; Snodgrass, C.;
Surdej, J.; Taylor, J.; Tregloan-Reed, J.; Vilela, C.; Wambsganss,
J.; Williams, A.; D'Ago, G.; Bachelet, E.; Bramich, D. M.; Figuera
Jaimes, R.; Horne, K.; Menzies, J.; Schmidt, R.; Steele, I. A.
2017MNRAS.466.2710R Altcode: 2016arXiv161203511R
We report the discovery of a planet - OGLE-2014-BLG-0676Lb- via
gravitational microlensing. Observations for the lensing event were
made by the following groups: Microlensing Observations in Astrophysics;
Optical Gravitational Lensing Experiment; Wise Observatory; RoboNET/Las
Cumbres Observatory Global Telescope; Microlensing Network for
the Detection of Small Terrestrial Exoplanets; and μ-FUN. All
analyses of the light-curve data favour a lens system comprising a
planetary mass orbiting a host star. The most-favoured binary lens
model has a mass ratio between the two lens masses of (4.78 ±
0.13) × 10<SUP>-3</SUP>. Subject to some important assumptions,
a Bayesian probability density analysis suggests the lens system
comprises a 3.09_{-1.12}^{+1.02} M<SUB>J</SUB> planet orbiting a
0.62_{-0.22}^{+0.20} M<SUB>⊙</SUB> host star at a deprojected orbital
separation of 4.40_{-1.46}^{+2.16} au. The distance to the lens system
is 2.22_{-0.83}^{+0.96} kpc. Planet OGLE-2014-BLG-0676Lb provides
additional data to the growing number of cool planets discovered
using gravitational microlensing against which planetary formation
theories may be tested. Most of the light in the baseline of this
event is expected to come from the lens and thus high-resolution
imaging observations could confirm our planetary model interpretation.
---------------------------------------------------------
Title: Exoplanetary atmospheric sodium revealed by orbital
motion. Narrow-band transmission spectroscopy of HD 189733b with UVES
Authors: Khalafinejad, S.; von Essen, C.; Hoeijmakers, H. J.; Zhou,
G.; Klocová, T.; Schmitt, J. H. M. M.; Dreizler, S.; Lopez-Morales,
M.; Husser, T. -O.; Schmidt, T. O. B.; Collet, R.
2017A&A...598A.131K Altcode: 2016arXiv161001610K
Context. During primary transits, the spectral signatures of exoplanet
atmospheres can be measured using transmission spectroscopy. We
can obtain information on the upper atmosphere of these planets by
investigating the exoplanets' excess sodium absorption in the optical
region. However, a number of factors can affect the observed sodium
absorption signature. We present a detailed model correcting for
systematic biases to yield an accurate depth for the sodium absorption
in HD 189733b. <BR /> Aims: The goal of this work is to accurately
measure the atomspheric sodium absorption light curve in HD 189733b,
correcting for the effects of stellar differential limb-darkening,
stellar activity, and a "bump" caused by the changing radial velocity
of the exoplanet. In fact, owing to the high cadence and quality of
our data, it is the first time that the last feature can be detected
even by visual inspection. <BR /> Methods: We use 244 high-resolution
optical spectra taken by the UVES instrument mounted at the VLT. Our
observations cover a full transit of HD 189733b, with a cadence of
45 s. To probe the transmission spectrum of sodium we produce excess
light curves integrating the stellar flux in passbands of 1 Å, 1.5 Å,
and 3 Å inside the core of each sodium D-line. We model the effects
of external sources on the excess light curves, which correspond
to an observed stellar flare beginning close to mid-transit time
and the wavelength dependent limb-darkening effects. In addition, by
characterizing the effect of the changing radial velocity and Doppler
shifts of the planetary sodium lines inside the stellar sodium lines,
we estimate the depth and width of the exoplanetary sodium feature. <BR
/> Results: We estimate the shape of the planetary sodium line by
a Gaussian profile with an equivalent width of 0.0023 ± 0.0010Å,
thereby confirming the presence of sodium in the atmosphere of HD
189733b with excess absorption levels of 0.72 ± 0.25%, 0.34 ± 0.11%,
and 0.20 ± 0.06% for the integration bands of 1 Å, 1.5 Å, and 3 Å,
respectively. Using the equivalent width of the planetary sodium line,
we produce a first order estimate of the number density of sodium in
the exoplanet atmosphere.
---------------------------------------------------------
Title: The Solar Twin Planet Search. V. Close-in, low-mass planet
candidates and evidence of planet accretion in the solar twin
HIP 68468
Authors: Meléndez, Jorge; Bedell, Megan; Bean, Jacob L.; Ramírez,
Iván; Asplund, Martin; Dreizler, Stefan; Yan, Hong-Liang; Shi,
Jian-Rong; Lind, Karin; Ferraz-Mello, Sylvio; Galarza, Jhon Yana; dos
Santos, Leonardo; Spina, Lorenzo; Maia, Marcelo Tucci; Alves-Brito,
Alan; Monroe, TalaWanda; Casagrande, Luca
2017A&A...597A..34M Altcode: 2016arXiv161009067M; 2016A&A...597A..34M
Context. More than two thousand exoplanets have been discovered to
date. Of these, only a small fraction have been detected around solar
twins, which are key stars because we can obtain accurate elemental
abundances especially for them, which is crucial for studying the
planet-star chemical connection with the highest precision. <BR />
Aims: We aim to use solar twins to characterise the relationship between
planet architecture and stellar chemical composition. <BR /> Methods:
We obtained high-precision (1 m s<SUP>-1</SUP>) radial velocities
with the HARPS spectrograph on the ESO 3.6 m telescope at La Silla
Observatory and determined precise stellar elemental abundances ( 0.01
dex) using spectra obtained with the MIKE spectrograph on the Magellan
6.5 m telescope. <BR /> Results: Our data indicate the presence of a
planet with a minimum mass of 26 ± 4 Earth masses around the solar
twin HIP 68468. The planet is more massive than Neptune (17 Earth
masses), but unlike the distant Neptune in our solar system (30 AU),
HIP 68468c is close-in, with a semi-major axis of 0.66 AU, similar to
that of Venus. The data also suggest the presence of a super-Earth with
a minimum mass of 2.9 ± 0.8 Earth masses at 0.03 AU; if the planet is
confirmed, it will be the fifth least massive radial velocity planet
candidate discovery to date and the first super-Earth around a solar
twin. Both isochrones (5.9 ± 0.4 Gyr) and the abundance ratio [Y/Mg]
(6.4 ± 0.8 Gyr) indicate an age of about 6 billion years. The star
is enhanced in refractory elements when compared to the Sun, and the
refractory enrichment is even stronger after corrections for Galactic
chemical evolution. We determined a nonlocal thermodynamic equilibrium
Li abundance of 1.52 ± 0.03 dex, which is four times higher than
what would be expected for the age of HIP 68468. The older age is
also supported by the low log () (-5.05) and low jitter (<1 m
s<SUP>-1</SUP>). Engulfment of a rocky planet of 6 Earth masses can
explain the enhancement in both lithium and the refractory elements. <BR
/> Conclusions: The super-Neptune planet candidate is too massive for in
situ formation, and therefore its current location is most likely the
result of planet migration that could also have driven other planets
towards its host star, enhancing thus the abundance of lithium and
refractory elements in HIP 68468. The intriguing evidence of planet
accretion warrants further observations to verify the existence of
the planets that are indicated by our data and to better constrain
the nature of the planetary system around this unique star.
---------------------------------------------------------
Title: No Evidence for Activity Correlations in the Radial Velocities
of Kapteyn’s Star
Authors: Anglada-Escudé, G.; Tuomi, M.; Arriagada, P.; Zechmeister,
M.; Jenkins, J. S.; Ofir, A.; Dreizler, S.; Gerlach, E.; Marvin, C. J.;
Reiners, A.; Jeffers, S. V.; Butler, R. Paul; Vogt, S. S.; Amado,
P. J.; Rodríguez-López, C.; Berdiñas, Z. M.; Morin, J.; Crane,
J. D.; Shectman, S. A.; Díaz, M. R.; Sarmiento, L. F.; Jones, H. R. A.
2016ApJ...830...74A Altcode: 2015arXiv150609072A
Stellar activity may induce Doppler variability at the level of a few
m s<SUP>-1</SUP> which can then be confused by the Doppler signal of
an exoplanet orbiting the star. To first order, linear correlations
between radial velocity measurements and activity indices have been
proposed to account for any such correlation. The likely presence of two
super-Earths orbiting Kapteyn’s star was reported in Anglada-Escudé
et al., but this claim was recently challenged by Robertson et al.,
who argued for evidence of a rotation period (143 days) at three times
the orbital period of one of the proposed planets (Kapteyn’s b, P =
48.6 days) and the existence of strong linear correlations between
its Doppler signal and activity data. By re-analyzing the data using
global statistics and model comparison, we show that such a claim is
incorrect given that (1) the choice of a rotation period at 143 days
is unjustified, and (2) the presence of linear correlations is not
supported by the data. We conclude that the radial velocity signals of
Kapteyn’s star remain more simply explained by the presence of two
super-Earth candidates orbiting it. We note that analysis of time series
of activity indices must be executed with the same care as Doppler time
series. We also advocate for the use of global optimization procedures
and objective arguments, instead of claims based on residual analyses
which are prone to biases and incorrect interpretations.
---------------------------------------------------------
Title: The GTC exoplanet transit spectroscopy survey. IV. Confirmation
of the flat transmission spectrum of HAT-P-32b
Authors: Nortmann, L.; Pallé, E.; Murgas, F.; Dreizler, S.; Iro,
N.; Cabrera-Lavers, A.
2016A&A...594A..65N Altcode: 2016arXiv160406041N
We observed the hot Jupiter <ASTROBJ>HAT-P-32b</ASTROBJ> (also known
as HAT-P-32Ab) to determine its optical transmission spectrum by
measuring the wavelength-dependent, planet-to-star radius ratios
in the region between 518-918 nm. We used the OSIRIS instrument at
the Gran Telescopio CANARIAS (GTC) in long-slit spectroscopy mode,
placing <ASTROBJ>HAT-P-32</ASTROBJ> and a reference star in the same
slit and obtaining a time series of spectra covering two transit
events. Using the best quality data set, we were able to yield 20
narrowband transit light curves, with each passband spanning a 20
nm wide interval. After removal of all systematic noise signals and
light curve modeling, the uncertainties for the resulting radius
ratios lie between 337 and 972 ppm. The radius ratios show little
variation with wavelength, suggesting a high altitude cloud layer
masking any atmospheric features. Alternatively, a strong depletion in
alkali metals or a much smaller than expected planetary atmospheric
scale height could be responsible for the lack of atmospheric
features. Our result of a flat transmission spectrum is consistent
with a previous ground-based study of the optical spectrum of this
planet. This agreement between independent results demonstrates
that ground-based measurements of exoplanet atmospheres can give
reliable and reproducible results despite the fact that the data
often is heavily affected by systematic noise as long as the noise
source is well understood and properly corrected. We also extract
an optical spectrum of the M-dwarf companion HAT-P-32B. Using
PHOENIX stellar atmosphere models we determine an effective
temperature of T<SUB>eff</SUB> = 3187<SUP>+60</SUP><SUB>-71</SUB>
K, which is slightly colder than previous studies relying only on
broadband infrared data. <P />The 20 narrowband and white light
curves are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/594/A65">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/594/A65</A>
---------------------------------------------------------
Title: Search for Transits by the Earth Analogue around Proxima
Centauri
Authors: Jenkins, James; Harrington, Joseph; Challener, Ryan; Rojo,
Patricio; Kempton, Eliza; Ramirez, Ricardo; Ofir, Aviv; Ribas,
Ignasi; Kipping, David; Rodriguez-Lopez, Cristina; Dreizler, Stefan;
Freudenthal, Jantje; Rodriguez-Martinez, Eloy; Anglada-Escude, Guillem
2016sptz.prop13155J Altcode:
We will search for transits of the recently discovered Proxima Centauri
b. Radial-velocity (RV) data indicate a planet with >1.5 Me (Earth
masses) and an equilibrium temperature of 230 K (assuming 0.3 albedo and
complete heat redistribution). Comparing to Earth's 255 K equilibrium
temperature, the planet may be an excellent candidate to host life,
and its proximity, at just 1.3 pc, makes it particularly favorable
for observation, compared to more distant planets. It is thus the
exoplanet with the highest priority for characterization. Due to the
red-dwarf star's high activity level, the small size of the planet,
and the orbital period, optical ground-based transit surveys have not
achieved the sensitivity needed to detect the transit, but Spitzer
easily can. The Pale Red Dot project, the planet's discoverers,
thus request observations that should find any transit with 99%
confidence, and that will characterize the atmosphere with transits
at both Spitzer wavelengths.
---------------------------------------------------------
Title: A terrestrial planet candidate in a temperate orbit around
Proxima Centauri
Authors: Anglada-Escudé, Guillem; Amado, Pedro J.; Barnes, John;
Berdiñas, Zaira M.; Butler, R. Paul; Coleman, Gavin A. L.; de La
Cueva, Ignacio; Dreizler, Stefan; Endl, Michael; Giesers, Benjamin;
Jeffers, Sandra V.; Jenkins, James S.; Jones, Hugh R. A.; Kiraga,
Marcin; Kürster, Martin; López-González, María J.; Marvin,
Christopher J.; Morales, Nicolás; Morin, Julien; Nelson, Richard P.;
Ortiz, José L.; Ofir, Aviv; Paardekooper, Sijme-Jan; Reiners, Ansgar;
Rodríguez, Eloy; Rodríguez-López, Cristina; Sarmiento, Luis F.;
Strachan, John P.; Tsapras, Yiannis; Tuomi, Mikko; Zechmeister, Mathias
2016Natur.536..437A Altcode: 2016arXiv160903449A
At a distance of 1.295 parsecs, the red dwarf Proxima Centauri (α
Centauri C, GL 551, HIP 70890 or simply Proxima) is the Sun’s closest
stellar neighbour and one of the best-studied low-mass stars. It has
an effective temperature of only around 3,050 kelvin, a luminosity of
0.15 per cent of that of the Sun, a measured radius of 14 per cent of
the radius of the Sun and a mass of about 12 per cent of the mass of
the Sun. Although Proxima is considered a moderately active star, its
rotation period is about 83 days (ref. 3) and its quiescent activity
levels and X-ray luminosity are comparable to those of the Sun. Here
we report observations that reveal the presence of a small planet
with a minimum mass of about 1.3 Earth masses orbiting Proxima with
a period of approximately 11.2 days at a semi-major-axis distance of
around 0.05 astronomical units. Its equilibrium temperature is within
the range where water could be liquid on its surface.
---------------------------------------------------------
Title: CARMENES: an overview six months after first light
Authors: Quirrenbach, A.; Amado, P. J.; Caballero, J. A.; Mundt,
R.; Reiners, A.; Ribas, I.; Seifert, W.; Abril, M.; Aceituno, J.;
Alonso-Floriano, F. J.; Anwand-Heerwart, H.; Azzaro, M.; Bauer, F.;
Barrado, D.; Becerril, S.; Bejar, V. J. S.; Benitez, D.; Berdinas,
Z. M.; Brinkmöller, M.; Cardenas, M. C.; Casal, E.; Claret, A.;
Colomé, J.; Cortes-Contreras, M.; Czesla, S.; Doellinger, M.;
Dreizler, S.; Feiz, C.; Fernandez, M.; Ferro, I. M.; Fuhrmeister,
B.; Galadi, D.; Gallardo, I.; Gálvez-Ortiz, M. C.; Garcia-Piquer,
A.; Garrido, R.; Gesa, L.; Gómez Galera, V.; González Hernández,
J. I.; Gonzalez Peinado, R.; Grözinger, U.; Guàrdia, J.; Guenther,
E. W.; de Guindos, E.; Hagen, H. -J.; Hatzes, A. P.; Hauschildt,
P. H.; Helmling, J.; Henning, T.; Hermann, D.; Hernández Arabi, R.;
Hernández Castaño, L.; Hernández Hernando, F.; Herrero, E.; Huber,
A.; Huber, K. F.; Huke, P.; Jeffers, S. V.; de Juan, E.; Kaminski,
A.; Kehr, M.; Kim, M.; Klein, R.; Klüter, J.; Kürster, M.; Lafarga,
M.; Lara, L. M.; Lamert, A.; Laun, W.; Launhardt, R.; Lemke, U.;
Lenzen, R.; Llamas, M.; Lopez del Fresno, M.; López-Puertas, M.;
López-Santiago, J.; Lopez Salas, J. F.; Magan Madinabeitia, H.; Mall,
U.; Mandel, H.; Mancini, L.; Marin Molina, J. A.; Maroto Fernández,
D.; Martín, E. L.; Martín-Ruiz, S.; Marvin, C.; Mathar, R. J.;
Mirabet, E.; Montes, D.; Morales, J. C.; Morales Muñoz, R.; Nagel,
E.; Naranjo, V.; Nowak, G.; Palle, E.; Panduro, J.; Passegger, V. M.;
Pavlov, A.; Pedraz, S.; Perez, E.; Pérez-Medialdea, D.; Perger,
M.; Pluto, M.; Ramón, A.; Rebolo, R.; Redondo, P.; Reffert, S.;
Reinhart, S.; Rhode, P.; Rix, H. -W.; Rodler, F.; Rodríguez, E.;
Rodríguez López, C.; Rohloff, R. R.; Rosich, A.; Sanchez Carrasco,
M. A.; Sanz-Forcada, J.; Sarkis, P.; Sarmiento, L. F.; Schäfer,
S.; Schiller, J.; Schmidt, C.; Schmitt, J. H. M. M.; Schöfer,
P.; Schweitzer, A.; Shulyak, D.; Solano, E.; Stahl, O.; Storz, C.;
Tabernero, H. M.; Tala, M.; Tal-Or, L.; Ulbrich, R. -G.; Veredas, G.;
Vico Linares, J. I.; Vilardell, F.; Wagner, K.; Winkler, J.; Zapatero
Osorio, M. -R.; Zechmeister, M.; Ammler-von Eiff, M.; Anglada-Escudé,
G.; del Burgo, C.; Garcia-Vargas, M. L.; Klutsch, A.; Lizon, J. -L.;
Lopez-Morales, M.; Ofir, A.; Pérez-Calpena, A.; Perryman, M. A. C.;
Sánchez-Blanco, E.; Strachan, J. B. P.; Stürmer, J.; Suárez, J. C.;
Trifonov, T.; Tulloch, S. M.; Xu, W.
2016SPIE.9908E..12Q Altcode:
The CARMENES instrument is a pair of high-resolution (R> 80,000)
spectrographs covering the wavelength range from 0.52 to 1.71 μm,
optimized for precise radial velocity measurements. It was installed
and commissioned at the 3.5m telescope of the Calar Alto observatory
in Southern Spain in 2015. The first large science program of CARMENES
is a survey of 300 M dwarfs, which started on Jan 1, 2016. We present
an overview of all subsystems of CARMENES (front end, fiber system,
visible-light spectrograph, near-infrared spectrograph, calibration
units, etalons, facility control, interlock system, instrument control
system, data reduction pipeline, data flow, and archive), and give an
overview of the assembly, integration, verification, and commissioning
phases of the project. We show initial results and discuss further
plans for the scientific use of CARMENES.
---------------------------------------------------------
Title: MICADO: first light imager for the E-ELT
Authors: Davies, R.; Schubert, J.; Hartl, M.; Alves, J.; Clénet, Y.;
Lang-Bardl, F.; Nicklas, H.; Pott, J. -U.; Ragazzoni, R.; Tolstoy, E.;
Agocs, T.; Anwand-Heerwart, H.; Barboza, S.; Baudoz, P.; Bender, R.;
Bizenberger, P.; Boccaletti, A.; Boland, W.; Bonifacio, P.; Briegel,
F.; Buey, T.; Chapron, F.; Cohen, M.; Czoske, O.; Dreizler, S.; Falomo,
R.; Feautrier, P.; Förster Schreiber, N.; Gendron, E.; Genzel, R.;
Glück, M.; Gratadour, D.; Greimel, R.; Grupp, F.; Häuser, M.; Haug,
M.; Hennawi, J.; Hess, H. J.; Hörmann, V.; Hofferbert, R.; Hopp, U.;
Hubert, Z.; Ives, D.; Kausch, W.; Kerber, F.; Kravcar, H.; Kuijken, K.;
Lang-Bardl, F.; Leitzinger, M.; Leschinski, K.; Massari, D.; Mei, S.;
Merlin, F.; Mohr, L.; Monna, A.; Müller, F.; Navarro, R.; Plattner,
M.; Przybilla, N.; Ramlau, R.; Ramsay, S.; Ratzka, T.; Rhode, P.;
Richter, J.; Rix, H. -W.; Rodeghiero, G.; Rohloff, R. -R.; Rousset,
G.; Ruddenklau, R.; Schaffenroth, V.; Schlichter, J.; Sevin, A.; Stuik,
R.; Sturm, E.; Thomas, J.; Tromp, N.; Turatto, M.; Verdoes-Kleijn, G.;
Vidal, F.; Wagner, R.; Wegner, M.; Zeilinger, W.; Ziegler, B.; Zins, G.
2016SPIE.9908E..1ZD Altcode: 2016arXiv160701954D
MICADO will equip the E-ELT with a first light capability for
diffraction limited imaging at near-infrared wavelengths. The
instrument's observing modes focus on various flavours of imaging,
including astrometric, high contrast, and time resolved. There is also
a single object spectroscopic mode optimised for wavelength coverage
at moderately high resolution. This contribution provides an overview
of the key functionality of the instrument, outlining the scientific
rationale for its observing modes. The interface between MICADO and
the adaptive optics system MAORY that feeds it is summarised. The
design of the instrument is discussed, focusing on the optics and
mechanisms inside the cryostat, together with a brief overview of the
other key sub-systems.
---------------------------------------------------------
Title: Can stellar activity make a planet seem misaligned?
Authors: Oshagh, M.; Dreizler, S.; Santos, N. C.; Figueira, P.;
Reiners, A.
2016A&A...593A..25O Altcode: 2016arXiv160703134O
Several studies have shown that the occultation of stellar active
regions by the transiting planet can generate anomalies in the
high-precision transit light curves, and these anomalies may lead to
an inaccurate estimate of the planetary parameters (e.g., the planet
radius). Since the physics and geometry behind the transit light curve
and the Rossiter-McLaughlin effect (spectroscopic transit) are the
same, the Rossiter-McLaughlin observations are expected to be affected
by the occultation of stellar active regions in a similar way. In
this paper we perform a fundamental test on the spin-orbit angles
as derived by Rossiter-McLaughlin measurements, and we examine the
impact of the occultation of stellar active regions by the transiting
planet on the spin-orbit angle estimations. Our results show that the
inaccurate estimation on the spin-orbit angle due to stellar activity
can be quite significant (up to ~30 deg), particularly for the edge-on,
aligned, and small transiting planets. Therefore, our results suggest
that the aligned transiting planets are the ones that can be easily
misinterpreted as misaligned owing to the stellar activity. In other
words, the biases introduced by ignoring stellar activity are unlikely
to be the culprit for the highly misaligned systems.
---------------------------------------------------------
Title: The Solar Twin Planet Search. IV. The Sun as a typical rotator
and evidence for a new rotational braking law for Sun-like stars
Authors: dos Santos, Leonardo A.; Meléndez, Jorge; do Nascimento,
José-Dias; Bedell, Megan; Ramírez, Iván; Bean, Jacob L.; Asplund,
Martin; Spina, Lorenzo; Dreizler, Stefan; Alves-Brito, Alan;
Casagrande, Luca
2016A&A...592A.156D Altcode: 2016arXiv160606214D
Context. It is still unclear how common the Sun is when compared to
other similar stars in regards to some of its physical properties,
such as rotation. Considering that gyrochronology relations are
widely used today to estimate ages of stars in the main sequence,
and that the Sun is used to calibrate it, it is crucial to assess
whether these procedures are acceptable. <BR /> Aims: We analyze the
rotational velocities, limited by the unknown rotation axis inclination
angle, of an unprecedented large sample of solar twins to study the
rotational evolution of Sun-like stars, and assess whether the Sun is a
typical rotator. <BR /> Methods: We used high-resolution (R = 115 000)
spectra obtained with the HARPS spectrograph and the 3.6 m telescope
at La Silla Observatory. The projected rotational velocities for 81
solar twins were estimated by line profile fitting with synthetic
spectra. Macroturbulence velocities were inferred from a prescription
that accurately reflects their dependence with effective temperature
and luminosity of the stars. <BR /> Results: Our sample of solar twins
include some spectroscopic binaries with enhanced rotational velocities,
and we do not find any nonspectroscopic binaries with unusually high
rotation velocities. We verified that the Sun does not have a peculiar
rotation, but the solar twins exhibit rotational velocities that depart
from the Skumanich relation. <BR /> Conclusions: The Sun is a regular
rotator when compared to solar twins with a similar age. Additionally,
we obtain a rotational braking law that better describes the stars in
our sample (v ∝ t<SUP>-0.6</SUP>) in contrast to previous, often-used
scalings. <P />Based on observations collected at the European
Organisation for Astronomical Research in the Southern Hemisphere under
ESO programs 188.C-0265, 183.D-0729, 292.C-5004, 077.C-0364, 072.C-0488,
092.C-0721, 093.C-0409, 183.C-0972, 192.C-0852, 091.C-0936, 089.C-0732,
091.C-0034, 076.C-0155, 185.D-0056, 074.C-0364, 075.C-0332, 089.C-0415,
60.A-9036, 075.C-0202, 192.C-0224, 090.C-0421 and 088.C-0323.Full
Table 3 is only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/592/A156">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/592/A156</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: The Solar Twin Planet
Search. IV. (dos Santos+, 2016)
Authors: Dos Santos, L. A.; Melendez, J.; Do Nascimento, J. -D. Jr;
Bedell, M.; Ramirez, I.; Bean, J. L.; Asplund, M.; Spina, L.; Dreizler,
S.; Alves-Brito, A.; Casagrande, L.
2016yCat..35920156D Altcode:
Ages, the measured projected rotational velocities (vsini) and stellar
parameters of the 81 solar twins and the Sun. The ages of all solar
twins and stellar parameters for HIP68468 were obtained by Tucci Maia et
al. (2016A&A...590A..32T). Stellar parameters for the other solar
twins were obtained by Ramirez et al. (2014A&A...572A..48R). The
vsini were measured by line profile fitting using red spectra from
HARPS (R=115000). Macroturbulence velocities were inferred from the
scaling Eq. 2 in our study. <P />(1 data file).
---------------------------------------------------------
Title: A Stellar Census in NGC 6397 with MUSE
Authors: Kamann, S.; Husser, T. -O.; Wendt, M.; Bacon, R.; Brinchmann,
J.; Dreizler, S.; Emsellem, E.; Krajnović, D.; Monreal-Ibero, A.;
Roth, M. M.; Weilbacher, P. M.; Wisotzki, L.
2016Msngr.164...18K Altcode:
The new and powerful integral-field spectrograph on the VLT, the Multi-
Unit Spectroscopic Explorer (MUSE), was designed to search for distant
galaxies to an unprecedented depth, but it is also capable of opening
new science windows on the Galaxy. To demonstrate this capability,
the globular cluster NGC 6397 was observed during the commissioning
of MUSE in August 2014. We outline how the analysis of this unique
dataset allowed us to assemble the largest spectroscopic sample of
stars in a globular cluster to date. We also highlight the scientific
applications that benefit from such MUSE data.
---------------------------------------------------------
Title: VizieR Online Data Catalog: GTC transit light curves of
HAT-P-32b (Nortmann+, 2016)
Authors: Nortmann, L.; Palle, E.; Murgas, F.; Dreizler, S.; Iro, N.;
Cabrera-Lavers, A.
2016yCat..35940065N Altcode:
We provide two transit light curves of the hot Jupiter HAT-P-32b
obtained on the nights of 2012/09/15 and 2012/09/30 using the OSIRIS
instrument at the 10.4-m GTC telescope. The data was obtained by using
OSIRIS in broad slit spectroscopy mode and covering the wavelength
region between 518nm-918nm. For the night of 2012/09/30 we further
provide twenty narrowband light curves which were created by summing
the flux over 20-nm-wide channels instead over the whole wavelength
region. We provide several auxiliary parameters of the observations
which we have used to correct the data from correlated noise. These
auxiliary parameters are the position drift of the stars on the CCD
detector in spatial and dispersion direction, air mass and seeing
(FWHM). <P />(23 data files).
---------------------------------------------------------
Title: Erratum: A detailed census of variable stars in the globular
cluster NGC 6333 (M9) from CCD differential photometry
Authors: Arellano Ferro, A.; Bramich, D. M.; Figuera Jaimes, R.;
Giridhar, Sunetra; Kains, N.; Kuppuswamy, K.; Jørgensen, U. G.;
Alsubai, K. A.; Andersen, J. M.; Bozza, V.; Browne, P.; Calchi Novati,
S.; Damerdji, Y.; Diehl, C.; Dominik, M.; Dreizler, S.; Elyiv, A.;
Giannini, E.; Harpsøe, K.; Hessman, F. V.; Hinse, T. C.; Hundertmark,
M.; Juncher, D.; Kerins, E.; Korhonen, H.; Liebig, C.; Mancini,
L.; Mathiasen, M.; Penny, M. T.; Rabus, M.; Rahvar, S.; Ricci, D.;
Scarpetta, G.; Skottfelt, J.; Snodgrass, C.; Southworth, J.; Surdej,
J.; Tregloan-Reed, J.; Vilela, C.; Wertz, O.; Mindstep Consortium
2016MNRAS.458.1188A Altcode: 2016MNRAS.tmp..123F
No abstract at ADS
---------------------------------------------------------
Title: MUSE crowded field 3D spectroscopy of over 12 000 stars in
the globular cluster NGC 6397. II. Probing the internal dynamics
and the presence of a central black hole
Authors: Kamann, S.; Husser, T. -O.; Brinchmann, J.; Emsellem, E.;
Weilbacher, P. M.; Wisotzki, L.; Wendt, M.; Krajnović, D.; Roth,
M. M.; Bacon, R.; Dreizler, S.
2016A&A...588A.149K Altcode: 2016arXiv160201643K
We present a detailed analysis of the kinematics of the Galactic
globular cluster <ASTROBJ>NGC 6397</ASTROBJ> based on more than ~18 000
spectra obtained with the novel integral field spectrograph MUSE. While
<ASTROBJ>NGC 6397</ASTROBJ> is often considered a core collapse cluster,
our analysis suggests a flattening of the surface brightness profile
at the smallest radii. Although it is among the nearest globular
clusters, the low velocity dispersion of <ASTROBJ>NGC 6397</ASTROBJ>
of < 5 km s<SUP>-1</SUP> imposes heavy demands on the quality of the
kinematical data. We show that despite its limited spectral resolution,
MUSE reaches an accuracy of 1 km s<SUP>-1</SUP> in the analysis of
stellar spectra. We find slight evidence for a rotational component
in the cluster and the velocity dispersion profile that we obtain
shows a mild central cusp. To investigate the nature of this feature,
we calculate spherical Jeans models and compare these models to our
kinematical data. This comparison shows that if a constant mass-to-light
ratio is assumed, the addition of an intermediate-mass black hole
with a mass of 600 M<SUB>⊙</SUB> brings the model predictions into
agreement with our data, and therefore could be at the origin of the
velocity dispersion profile. We further investigate cases with varying
mass-to-light ratios and find that a compact dark stellar component can
also explain our observations. However, such a component would closely
resemble the black hole from the constant mass-to-light ratio models as
this component must be confined to the central ~5″ of the cluster and
must have a similar mass. Independent constraints on the distribution
of stellar remnants in the cluster or kinematic measurements at the
highest possible spatial resolution should be able to distinguish
the two alternatives. <P />Based on observations obtained at the Very
Large Telescope (VLT) of the European Southern Observatory, Paranal,
Chile (ESO Programme ID 60.A-9100(C))
---------------------------------------------------------
Title: MUSE crowded field 3D spectroscopy of over 12 000 stars in
the globular cluster NGC 6397. I. The first comprehensive HRD of a
globular cluster
Authors: Husser, Tim-Oliver; Kamann, Sebastian; Dreizler, Stefan;
Wendt, Martin; Wulff, Nina; Bacon, Roland; Wisotzki, Lutz; Brinchmann,
Jarle; Weilbacher, Peter M.; Roth, Martin M.; Monreal-Ibero, Ana
2016A&A...588A.148H Altcode: 2016arXiv160201649H
<BR /> Aims: We demonstrate the high multiplex advantage of crowded
field 3D spectroscopy with the new integral field spectrograph MUSE
by means of a spectroscopic analysis of more than 12 000 individual
stars in the globular cluster NGC 6397. <BR /> Methods: The stars
are deblended with a point spread function fitting technique, using a
photometric reference catalogue from HST as prior, including relative
positions and brightnesses. This catalogue is also used for a first
analysis of the extracted spectra, followed by an automatic in-depth
analysis via a full-spectrum fitting method based on a large grid
of PHOENIX spectra. <BR /> Results: We analysed the largest sample
so far available for a single globular cluster of 18 932 spectra
from 12 307 stars in <ASTROBJ>NGC 6397</ASTROBJ>. We derived a mean
radial velocity of v<SUB>rad</SUB> = 17.84 ± 0.07 km s<SUP>-1</SUP>
and a mean metallicity of [Fe/H] = -2.120 ± 0.002, with the latter
seemingly varying with temperature for stars on the red giant branch
(RGB). We determine T<SUB>eff</SUB> and [Fe/H] from the spectra,
and log g from HST photometry. This is the first very comprehensive
Hertzsprung-Russell diagram (HRD) for a globular cluster based on the
analysis of several thousands of stellar spectra, ranging from the main
sequence to the tip of the RGB. Furthermore, two interesting objects
were identified; one is a post-AGB star and the other is a possible
millisecond-pulsar companion. <P />Data products are available at <A
href="http://muse-vlt.eu/science">http://muse-vlt.eu/science</A>Based on
observations obtained at the Very Large Telescope (VLT) of the European
Southern Observatory, Paranal, Chile (ESO Programme ID 60.A-9100(C)).
---------------------------------------------------------
Title: Transmission Spectroscopy of HAT-P-32Ab with GTC/OSIRIS
Authors: Nortmann, Lisa; Pallé, Enric; Murgas, Felipe; Dreizler,
Stefan; Iro, Nicolas; Cabrera-Lavers, Antonio
2015ESS.....311120N Altcode:
I will present one of the latest results of our GTC exoplanet transit
spectroscopy survey. Over the last years our group has obtained
ground-based optical (538 nm - 918 nm) spectrophotometric transit
observations for several hot Jupiters including HAT-P-32Ab using
the OSIRIS (Optical System for Imaging and low Resolution Integrated
Spectroscopy) instrument at the Spanish 10-meter telescope GTC.I will
discuss the source, nature and proper correction of instrument specific
systematic noise we found to affect our data. After its correction,
we were able to yield high quality results with a precision between
482 and 1703 ppm depending on the wavelength channel. We measure a
flat optical transmission spectrum for HAT-P-32Ab, consistent with the
results of Gibson et al. (2013, MNRAS, 436, 2974) obtained with GMOS
at Gemini-North. This independent reproduction of consistent results
re-establishes faith in the reliability of ground-based transmission
spectroscopy and emphasizes the high potential of OSIRIS at the GTC
as a tool to complement current and future space-based observations.
---------------------------------------------------------
Title: A temperature inversion in WASP-33b? Large Binocular Telescope
occultation data confirm significant thermal flux at short wavelengths
Authors: von Essen, C.; Mallonn, M.; Albrecht, S.; Antoci, V.; Smith,
A. M. S.; Dreizler, S.; Strassmeier, K. G.
2015A&A...584A..75V Altcode: 2015arXiv150705963V
We observed a secondary eclipse of WASP-33 b quasi-simultaneously
in the optical (~0.55 μm) and the near-infrared (~1.05 μm) using
the 2×8.4 m Large Binocular Telescope. WASP-33 is a δ Scuti star
pulsating with periods comparable to the eclipse duration, making
the determination of the eclipse depth challenging. We use previously
determined oscillation frequencies to model and remove the pulsation
signal from the light curves, isolating the secondary eclipse. The
determined eclipse depth is ΔF = 1.03 ± 0.34 parts per thousand,
corresponding to a brightness temperature of T<SUB>B</SUB> = 3398 ± 302
K. Combining previously published data with our new measurement we find
the equilibrium temperature of WASP-33 b to be T<SUB>B</SUB> = 3358 ±
165 K. We compare all existing eclipse data to a blackbody spectrum,
to a carbon-rich non-inverted model and to a solar composition model
with an inverted temperature structure. We find that current available
data on WASP-33 b's atmosphere can be best represented by a simple
blackbody emission, without the need for more sophisticated atmospheric
models with temperature inversions. Although our data cannot rule out
models with or without a temperature inversion, they do confirm a high
brightness temperature for the planet at short wavelengths. WASP-33 b
is one of the hottest exoplanets known till date, and its equilibrium
temperature is consistent with rapid reradiation of the absorbed stellar
light and a low albedo. <P />The LBT is an international collaboration
among institutions in the United States, Italy and Germany. LBT
Corporation partners are: The University of Arizona on behalf of the
Arizona university system; Instituto Nazionale di Astrofisica, Italy;
LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck
Society, the Leibniz-Institute for Astrophysics Potsdam, and Heidelberg
University; The Ohio State University, and The Research Corporation,
on behalf of The University of Notre Dame, University of Minnesota and
University of Virginia.Appendix A is available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201526202/olm">http://www.aanda.org</A>
---------------------------------------------------------
Title: Planets around post-common envelope binaries
Authors: Dreizler, Stefan; Beuermann, Klaus; Hessman, Frederic;
Husser, Tim-Oliver
2015ESS.....311702D Altcode:
The timing method enables to search planets in extreme conditions,
e.g. as companion to pulsars or as planets in post-common envelope
binaries (PCEB). In both cases, the planetary systems have experience
a dramatic evolution of the primary star.Eclipse time variations in
PCEBs with white dwarfs and subdwarf-B stars as primaries have been
interpreted as signatures from circumbinary planets and planetary
systems. Several of these interpretations have been questioned later
on, either due to dynamical instability of the proposed planetary
systems or due to non-detection of the proposed companions. We will
give an overview of our long-term monitoring of PCEB systems and the
modelling in terms of Keplerian and Newtonian planetary orbits in
order to assess the circumbinary planet scenario for these systems. We
discuss the implications for the first-generation or second-generatoin
planet scenario for these potential planets around these evolved stars.
---------------------------------------------------------
Title: Using Solar Twins to Explore the Planet-Star Connection with
Unparallelled Precision
Authors: Meléndez, J.; Bean, J. L.; Bedell, M.; Ramírez, I.; Asplund,
M.; Dreizler, S.; Alves-Brito, A.; Spina, L.; Casagrande, L.; Monroe,
T.; Maia, M. T.; Freitas, F.
2015Msngr.161...28M Altcode:
This year marks the 20th anniversary of the first definitive
detection of an exoplanet orbiting a Sun-like star by Mayor and
Queloz (1995). Almost 2000 exoplanets have been discovered since this
breakthrough, but many fundamental questions remain open despite the
enormous progress: How common are analogues of the Solar System? How
do planets form and evolve? What is the relationship between stars and
planets? We are observing stars that are near-perfect matches to the
Sun to provide new insights into the above questions, thus exploring
the planet-star connection with unprecedented precision.
---------------------------------------------------------
Title: The Solar Twin Planet Search. II. A Jupiter twin around a
solar twin
Authors: Bedell, M.; Meléndez, J.; Bean, J. L.; Ramírez, I.; Asplund,
M.; Alves-Brito, A.; Casagrande, L.; Dreizler, S.; Monroe, T.; Spina,
L.; Tucci Maia, M.
2015A&A...581A..34B Altcode: 2015arXiv150703998B
Context. With high-precision radial velocity surveys reaching a
sufficiently long time baseline, the domain of long-period planet
detections has recently opened up. The search for Jupiter-like planets
is especially important if we wish to investigate the prevalence
of solar system analogs, but their detection is complicated by the
existence of stellar activity cycles on similar timescales. Radial
velocity data with sufficiently long-term instrumental precision and
robust methods of diagnosing activity are crucial to the detection of
extrasolar Jupiters. <BR /> Aims: Through our HARPS survey for planets
around solar twin stars, we have identified a promising Jupiter twin
candidate around the star HIP11915. We characterize this Keplerian
signal and investigate its potential origins in stellar activity. <BR
/> Methods: We carry out a Markov chain Monte Carlo (MCMC) analysis of
the radial velocity data. To examine the signal's origin, we employ
a variety of statistical tests using activity diagnostics such as
the Ca II H and K lines and line asymmetry tracers. <BR /> Results:
Our analysis indicates that HIP11915 hosts a Jupiter-mass planet with
a 3800-day orbital period and low eccentricity. Although we cannot
definitively rule out an activity cycle interpretation, we find that a
planet interpretation is more likely based on a joint analysis of radial
velocity and activity index data. <BR /> Conclusions: The challenges of
long-period radial velocity signals addressed in this paper are critical
for the ongoing discovery of Jupiter-like exoplanets. If planetary in
nature, the signal investigated here represents a very close analog to
the solar system in terms of both Sun-like host star and Jupiter-like
planet. <P />Table 3 and Fig. 5 are available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201525748/olm">http://www.aanda.org</A>
---------------------------------------------------------
Title: Spectroscopic Surface Brightness Fluctuations: a new method
to analyze the stellar population content of galaxies
Authors: Walcher, C. Jakob; Mitzkus, Martin; Roth, Martin; Dreizler,
Stefan
2015IAUGA..2194398W Altcode:
Rare luminous phases of stellar evolution are important scientific
targets because our understanding of them strongly influences what
physical parameters we can recover from integrated spectra. (TP-)AGB
stars have been the focus of much attention over the last decade,
as their flux contribution to the spectra of intermediate age stellar
populations is highly uncertain. We here present a new approach to this
problem, which relies on Surface Brightness Fluctuations (SBF) with high
spectral resolution - a domain that is opening up for the first time
thanks to the new MUSE integral field unit at the VLT. We will present
the SSBF technique, illustrating its power through simulations. We
will then present the analysis of dedicated data obtained with MUSE,
providing new benchmark constraints on the luminous stellar population
of entire galaxies.
---------------------------------------------------------
Title: Spectroscopic Surface Brightness Fluctuations: Amplifying
Bright Stars in Unresolved Stellar Populations
Authors: Mitzkus, M.; Dreizler, S.; Roth, M. M.
2015ASPC..497..491M Altcode:
We report on our early-stage efforts to resolve the Surface Brightness
Fluctuations (SBFs) in the spectral dimension. Combining the diagnostic
power of SBFs with the physical information content of spectra
seems a tempting possibility to gain new insights into the bright
stars in unresolved stellar populations. The new VLT integral field
spectrograph MUSE is the first instrument that enables spectroscopic
SBFs observationally.
---------------------------------------------------------
Title: Planet formation in post-common-envelope binaries
Authors: Schleicher, D. R. G.; Dreizler, S.; Völschow, M.; Banerjee,
R.; Hessman, F. V.
2015AN....336..458S Altcode: 2015arXiv150101656S
To understand the evolution of planetary systems, it is important to
investigate planets in highly evolved stellar systems, and to explore
the implications of their observed properties with respect to potential
formation scenarios. Observations suggest the presence of giant planets
in post-common-envelope binaries (PCEBs). A particularly well-studied
system with planetary masses of 1.7 M_J and 7.0 M_J is NN Ser. We
show here that a pure first-generation scenario where the planets
form before the common envelope (CE) phase and the orbits evolve due
to the changes in the gravitational potential is inconsistent with
the current data. We propose a second-generation scenario where the
planets are formed from the material that is ejected during the CE,
which may naturally explain the observed planetary masses. In addition,
hybrid scenarios where the planets form before the CE and evolve due
to the accretion of the ejected gas appear as a realistic possibility.
---------------------------------------------------------
Title: Periodicity and eclipse minima timing of CM Draconis.
Authors: Vázquez-Martín, S.; Deeg, H. J.; Dreizler, S.; von Essen,
C.; Kozhevnikov, V. P.
2015hsa8.conf..618V Altcode:
Periodic deviations from a linear ephemeris of a binary star's eclipses
can indicate the presence of a third body in orbit around both. Hints
for such companion around the M4.5/M4.5 binary CMDra were published
by Deeg et al. (2008). The assignment of a planet in the CMDra system
can however only be accepted if the earlier observed periodicity
trends can be verified through further observations over several
years. For eclipsing binary stars of low mass, the method of eclipse
minimum timing allows one to set mass limits for the detection of a
third body. Deeg et al. (2008) concluded that the two possibilities
for the source of CMDra's timing variations that remain valid are
a planet of a few Jupiter masses on a two decade-long orbit, or an
object on a century-to-millenium long orbit with masses 1.5M_J <
M_{p} < 0.1M_{⊙}. However, they concluded that it is necessary
to do continued observations of the timing of CMDra's eclipses to be
decisive regarding the continued viability of the sinusoidal-fit-model,
and hence, about the validity of a Jovian-type planet in a circumbinary
orbiting around the system. Here we update the analysis of Deeg et
al. (2008), including further data presented in Morales et al. (2009r)
and new observations taken at Ural Observatory (2008-2013). Eclipse
minimum times were obtained using the Kwee-van-Woerden method.
---------------------------------------------------------
Title: OGLE-2011-BLG-0265Lb: A Jovian Microlensing Planet Orbiting
an M Dwarf
Authors: Skowron, J.; Shin, I. -G.; Udalski, A.; Han, C.; Sumi,
T.; Shvartzvald, Y.; Gould, A.; Dominis Prester, D.; Street,
R. A.; Jørgensen, U. G.; Bennett, D. P.; Bozza, V.; Szymański,
M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Poleski, R.;
Kozłowski, S.; Pietrukowicz, P.; Ulaczyk, K.; Wyrzykowski, Ł.; OGLE
Collaboration; Abe, F.; Bhattacharya, A.; Bond, I. A.; Botzler, C. S.;
Freeman, M.; Fukui, A.; Fukunaga, D.; Itow, Y.; Ling, C. H.; Koshimoto,
N.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Namba, S.; Ohnishi, K.;
Philpott, L. C.; Rattenbury, N.; Saito, T.; Sullivan, D. J.; Suzuki,
D.; Tristram, P. J.; Yock, P. C. M.; MOA Collaboration; Maoz, D.;
Kaspi, S.; Friedmann, M.; Wise Group; Almeida, L. A.; Batista, V.;
Christie, G.; Choi, J. -Y.; DePoy, D. L.; Gaudi, B. S.; Henderson, C.;
Hwang, K. -H.; Jablonski, F.; Jung, Y. K.; Lee, C. -U.; McCormick,
J.; Natusch, T.; Ngan, H.; Park, H.; Pogge, R. W.; Yee, J. C.;
μFUN Collaboration; Albrow, M. D.; Bachelet, E.; Beaulieu, J. -P.;
Brillant, S.; Caldwell, J. A. R.; Cassan, A.; Cole, A.; Corrales, E.;
Coutures, Ch.; Dieters, S.; Donatowicz, J.; Fouqué, P.; Greenhill,
J.; Kains, N.; Kane, S. R.; Kubas, D.; Marquette, J. -B.; Martin,
R.; Menzies, J.; Pollard, K. R.; Ranc, C.; Sahu, K. C.; Wambsganss,
J.; Williams, A.; Wouters, D.; PLANET Collaboration; Tsapras, Y.;
Bramich, D. M.; Horne, K.; Hundertmark, M.; Snodgrass, C.; Steele,
I. A.; RoboNet Collaboration; Alsubai, K. A.; Browne, P.; Burgdorf,
M. J.; Calchi Novati, S.; Dodds, P.; Dominik, M.; Dreizler, S.; Fang,
X. -S.; Gu, C. -H.; Hardis; Harpsøe, K.; Hessman, F. V.; Hinse, T. C.;
Hornstrup, A.; Jessen-Hansen, J.; Kerins, E.; Liebig, C.; Lund, M.;
Lundkvist, M.; Mancini, L.; Mathiasen, M.; Penny, M. T.; Rahvar, S.;
Ricci, D.; Scarpetta, G.; Skottfelt, J.; Southworth, J.; Surdej, J.;
Tregloan-Reed, J.; Wertz, O.; MiNDSTEp Consortium
2015ApJ...804...33S Altcode: 2014arXiv1410.8252S
We report the discovery of a Jupiter-mass planet orbiting an M-dwarf
star that gave rise to the microlensing event OGLE-2011-BLG-0265. Such
a system is very rare among known planetary systems and thus the
discovery is important for theoretical studies of planetary formation
and evolution. High-cadence temporal coverage of the planetary
signal, combined with extended observations throughout the event,
allows us to accurately model the observed light curve. However, the
final microlensing solution remains degenerate, yielding two possible
configurations of the planet and the host star. In the case of the
preferred solution, the mass of the planet is {{M}<SUB>p</SUB>}=0.9+/-
0.3 {{M}<SUB>J</SUB>}, and the planet is orbiting a star with a mass
M=0.22+/- 0.06 {{M}<SUB>⊙ </SUB>}. The second possible configuration
(2σ away) consists of a planet with {{M}<SUB>p</SUB>}=0.6+/- 0.3
{{M}<SUB>J</SUB>} and host star with M=0.14+/- 0.06 {{M}<SUB>⊙
</SUB>}. The system is located in the Galactic disk 3-4 kpc toward
the Galactic bulge. In both cases, with an orbit size of 1.5-2.0 AU,
the planet is a “cold Jupiter”—located well beyond the “snow
line” of the host star. Currently available data make the secure
selection of the correct solution difficult, but there are prospects
for lifting the degeneracy with additional follow-up observations in
the future, when the lens and source star separate.
---------------------------------------------------------
Title: VizieR Online Data Catalog: MUSE 3D view of HDF-S (Bacon+,
2015)
Authors: Bacon, R.; Brinchmann, J.; Richard, J.; Contini, T.; Drake,
A.; Franx, M.; Tacchella, S.; Vernet, J.; Wisotzki, L.; Blaizot, J.;
Bouche, N.; Bouwens, R.; Cantalupo, S.; Carollo, C. M.; Carton, D.;
Caruana, J.; Clement, B.; Dreizler, S.; Epinat, B.; Guiderdoni, B.;
Herenz, C.; Husser, T. -O.; Kamann, S.; Kerutt, J.; Kollatschny, W.;
Krajnovic, D.; Lilly, S.; Martinsson, T.; Michel-Dansac, L.; Patricio,
V.; Schaye, J.; Shirazi, M.; Soto, K.; Soucail, G.; Steinmetz, M.;
Urrutia, T.; Weilbacher, P.; de Zeeuw, T.
2015yCat..35750075B Altcode:
The HDFS was observed during six nights in July 25-29, 31 and August
2, 3 2014 of the last commissioning run of MUSE. We used the nominal
wavelength range (4750-9300Å) and performed a series of exposures of
30min each. <P />(3 data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: MUSE 3D view of HDF-S (Bacon+,
2015)
Authors: Bacon, R.; Brinchmann, J.; Richard, J.; Contini, T.; Drake,
A.; Franx, M.; Tacchella, S.; Vernet, J.; Wisotzki, L.; Blaizot, J.;
Bouche, N.; Bouwens, R.; Cantalupo, S.; Carollo, C. M.; Carton, D.;
Caruana, J.; Clement, B.; Dreizler, S.; Epinat, B.; Guiderdoni, B.;
Herenz, C.; Husser, T. -O.; Kamann, S.; Kerutt, J.; Kollatschny, W.;
Krajnovic, D.; Lilly, S.; Martinsson, T.; Michel-Dansac, L.; Patricio,
V.; Schaye, J.; Shirazi, M.; Soto, K.; Soucail, G.; Steinmetz, M.;
Urrutia, T.; Weilbacher, P.; de Zeeuw, T.
2015yCat..35759075B Altcode:
The HDFS was observed during six nights in July 25-29, 31 and August
2, 3 2014 of the last commissioning run of MUSE. We used the nominal
wavelength range (4750-9300Å) and performed a series of exposures of
30min each. <P />(3 data files).
---------------------------------------------------------
Title: The MUSE 3D view of the Hubble Deep Field South
Authors: Bacon, R.; Brinchmann, J.; Richard, J.; Contini, T.; Drake,
A.; Franx, M.; Tacchella, S.; Vernet, J.; Wisotzki, L.; Blaizot, J.;
Bouché, N.; Bouwens, R.; Cantalupo, S.; Carollo, C. M.; Carton, D.;
Caruana, J.; Clément, B.; Dreizler, S.; Epinat, B.; Guiderdoni, B.;
Herenz, C.; Husser, T. -O.; Kamann, S.; Kerutt, J.; Kollatschny, W.;
Krajnovic, D.; Lilly, S.; Martinsson, T.; Michel-Dansac, L.; Patricio,
V.; Schaye, J.; Shirazi, M.; Soto, K.; Soucail, G.; Steinmetz, M.;
Urrutia, T.; Weilbacher, P.; de Zeeuw, T.
2015A&A...575A..75B Altcode: 2014arXiv1411.7667B
We observed Hubble Deep Field South with the new panoramic
integral-field spectrograph MUSE that we built and have just
commissioned at the VLT. The data cube resulting from 27 h of
integration covers one arcmin<SUP>2</SUP> field of view at an
unprecedented depth with a 1σ emission-line surface brightness
limit of 1 × 10<SUP>-19</SUP> erg s<SUP>-1</SUP> cm<SUP>-2</SUP>
arcsec<SUP>-2</SUP>, and contains ~90 000 spectra. We present the
combined and calibrated data cube, and we performed a first-pass
analysis of the sources detected in the Hubble Deep Field South
imaging. We measured the redshifts of 189 sources up to a magnitude
I<SUB>814</SUB> = 29.5, increasing the number of known spectroscopic
redshifts in this field by more than an order of magnitude. We
also discovered 26 Lyα emitting galaxies that are not detected
in the HST WFPC2 deep broad-band images. The intermediate spectral
resolution of 2.3 Å allows us to separate resolved asymmetric Lyα
emitters, [O ii]3727 emitters, and C iii]1908 emitters, and the broad
instantaneous wavelength range of 4500 Å helps to identify single
emission lines, such as [O iii]5007, Hβ, and Hα, over a very wide
redshift range. We also show how the three-dimensional information of
MUSE helps to resolve sources that are confused at ground-based image
quality. Overall, secure identifications are provided for 83% of the
227 emission line sources detected in the MUSE data cube and for 32% of
the 586 sources identified in the HST catalogue. The overall redshift
distribution is fairly flat to z = 6.3, with a reduction between z =
1.5 to 2.9, in the well-known redshift desert. The field of view of
MUSE also allowed us to detect 17 groups within the field. We checked
that the number counts of [O ii]3727 and Lyα emitters are roughly
consistent with predictions from the literature. Using two examples, we
demonstrate that MUSE is able to provide exquisite spatially resolved
spectroscopic information on the intermediate-redshift galaxies
present in the field. Thisunique data set can be used for a wide
range of follow-up studies. We release the data cube, the associated
products, and the source catalogue with redshifts, spectra, and
emission-line fluxes. <P />Advanced data products are available at <A
href="http://muse-vlt.eu/science">http://muse-vlt.eu/science</A>. Based
on observations made with ESO telescopes at
the La Silla Paranal Observatory under program ID
60.A-9100(C).Appendices are available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201425419/olm">http://www.aanda.org</A>
---------------------------------------------------------
Title: The Solar Twin Planet Search. I. Fundamental parameters of
the stellar sample
Authors: Ramírez, I.; Meléndez, J.; Bean, J.; Asplund, M.; Bedell,
M.; Monroe, T.; Casagrande, L.; Schirbel, L.; Dreizler, S.; Teske,
J.; Tucci Maia, M.; Alves-Brito, A.; Baumann, P.
2014A&A...572A..48R Altcode: 2014arXiv1408.4130R
Context. We are carrying out a search for planets around a sample
of solar twin stars using the HARPS spectrograph. The goal of this
project is to exploit the advantage offered by solar twins to obtain
chemical abundances of unmatched precision. This survey will enable
new studies of the stellar composition - planet connection. <BR />
Aims: We determine the fundamental parameters of the 88 solar twin
stars that have been chosen as targets for our experiment. <BR />
Methods: We used the MIKE spectrograph on the Magellan Clay Telescope
to acquire high resolution, high signal-to-noise ratio spectra of
our sample stars. We measured the equivalent widths of iron lines
and used strict differential excitation/ionization balance analysis
to determine atmospheric parameters of unprecedented internal
precision: σ(T<SUB>eff</SUB>) = 7 K, σ(log g) = 0.019, σ( [Fe/H]
) = 0.006 dex, σ(v<SUB>t</SUB>) = 0.016 km s<SUP>-1</SUP>. Reliable
relative ages and highly precise masses were then estimated using
theoretical isochrones. <BR /> Results: The spectroscopic parameters
we derived are in good agreement with those measured using other
independent techniques. There is even better agreement if the
sample is restricted to those stars with the most internally precise
determinations of stellar parameters in every technique involved. The
root-mean-square scatter of the differences seen is fully compatible
with the observational errors, demonstrating, as assumed thus far,
that systematic uncertainties in the stellar parameters are negligible
in the study of solar twins. We find a tight activity-age relation
for our sample stars, which validates the internal precision of our
dating method. Furthermore, we find that the solar cycle is perfectly
consistent both with this trend and its star-to-star scatter. <BR />
Conclusions: We present the largest sample of solar twins analyzed
homogeneously using high quality spectra. The fundamental parameters
derived from this work will be employed in subsequent work that aims to
explore the connections between planet formation and stellar chemical
composition. <P />Tables 2-4 are available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201424244/olm">http://www.aanda.org</A>
---------------------------------------------------------
Title: The PLATO 2.0 mission
Authors: Rauer, H.; Catala, C.; Aerts, C.; Appourchaux, T.; Benz,
W.; Brandeker, A.; Christensen-Dalsgaard, J.; Deleuil, M.; Gizon,
L.; Goupil, M. -J.; Güdel, M.; Janot-Pacheco, E.; Mas-Hesse,
M.; Pagano, I.; Piotto, G.; Pollacco, D.; Santos, Ċ.; Smith, A.;
Suárez, J. -C.; Szabó, R.; Udry, S.; Adibekyan, V.; Alibert, Y.;
Almenara, J. -M.; Amaro-Seoane, P.; Eiff, M. Ammler-von; Asplund, M.;
Antonello, E.; Barnes, S.; Baudin, F.; Belkacem, K.; Bergemann, M.;
Bihain, G.; Birch, A. C.; Bonfils, X.; Boisse, I.; Bonomo, A. S.;
Borsa, F.; Brandão, I. M.; Brocato, E.; Brun, S.; Burleigh, M.;
Burston, R.; Cabrera, J.; Cassisi, S.; Chaplin, W.; Charpinet, S.;
Chiappini, C.; Church, R. P.; Csizmadia, Sz.; Cunha, M.; Damasso, M.;
Davies, M. B.; Deeg, H. J.; Díaz, R. F.; Dreizler, S.; Dreyer, C.;
Eggenberger, P.; Ehrenreich, D.; Eigmüller, P.; Erikson, A.; Farmer,
R.; Feltzing, S.; de Oliveira Fialho, F.; Figueira, P.; Forveille,
T.; Fridlund, M.; García, R. A.; Giommi, P.; Giuffrida, G.; Godolt,
M.; Gomes da Silva, J.; Granzer, T.; Grenfell, J. L.; Grotsch-Noels,
A.; Günther, E.; Haswell, C. A.; Hatzes, A. P.; Hébrard, G.; Hekker,
S.; Helled, R.; Heng, K.; Jenkins, J. M.; Johansen, A.; Khodachenko,
M. L.; Kislyakova, K. G.; Kley, W.; Kolb, U.; Krivova, N.; Kupka, F.;
Lammer, H.; Lanza, A. F.; Lebreton, Y.; Magrin, D.; Marcos-Arenal,
P.; Marrese, P. M.; Marques, J. P.; Martins, J.; Mathis, S.; Mathur,
S.; Messina, S.; Miglio, A.; Montalban, J.; Montalto, M.; Monteiro,
M. J. P. F. G.; Moradi, H.; Moravveji, E.; Mordasini, C.; Morel, T.;
Mortier, A.; Nascimbeni, V.; Nelson, R. P.; Nielsen, M. B.; Noack,
L.; Norton, A. J.; Ofir, A.; Oshagh, M.; Ouazzani, R. -M.; Pápics,
P.; Parro, V. C.; Petit, P.; Plez, B.; Poretti, E.; Quirrenbach, A.;
Ragazzoni, R.; Raimondo, G.; Rainer, M.; Reese, D. R.; Redmer, R.;
Reffert, S.; Rojas-Ayala, B.; Roxburgh, I. W.; Salmon, S.; Santerne,
A.; Schneider, J.; Schou, J.; Schuh, S.; Schunker, H.; Silva-Valio,
A.; Silvotti, R.; Skillen, I.; Snellen, I.; Sohl, F.; Sousa, S. G.;
Sozzetti, A.; Stello, D.; Strassmeier, K. G.; Švanda, M.; Szabó,
Gy. M.; Tkachenko, A.; Valencia, D.; Van Grootel, V.; Vauclair,
S. D.; Ventura, P.; Wagner, F. W.; Walton, N. A.; Weingrill, J.;
Werner, S. C.; Wheatley, P. J.; Zwintz, K.
2014ExA....38..249R Altcode: 2014ExA...tmp...41R; 2013arXiv1310.0696R
PLATO 2.0 has recently been selected for ESA's M3 launch opportunity
(2022/24). Providing accurate key planet parameters (radius, mass,
density and age) in statistical numbers, it addresses fundamental
questions such as: How do planetary systems form and evolve? Are there
other systems with planets like ours, including potentially habitable
planets? The PLATO 2.0 instrument consists of 34 small aperture
telescopes (32 with 25 s readout cadence and 2 with 2.5 s candence)
providing a wide field-of-view (2232 deg <SUP>2</SUP>) and a large
photometric magnitude range (4-16 mag). It focusses on bright (4-11
mag) stars in wide fields to detect and characterize planets down to
Earth-size by photometric transits, whose masses can then be determined
by ground-based radial-velocity follow-up measurements. Asteroseismology
will be performed for these bright stars to obtain highly accurate
stellar parameters, including masses and ages. The combination of
bright targets and asteroseismology results in high accuracy for
the bulk planet parameters: 2 %, 4-10 % and 10 % for planet radii,
masses and ages, respectively. The planned baseline observing strategy
includes two long pointings (2-3 years) to detect and bulk characterize
planets reaching into the habitable zone (HZ) of solar-like stars
and an additional step-and-stare phase to cover in total about 50 %
of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect
and characterize hundreds of small planets, and thousands of planets
in the Neptune to gas giant regime out to the HZ. It will therefore
provide the first large-scale catalogue of bulk characterized planets
with accurate radii, masses, mean densities and ages. This catalogue
will include terrestrial planets at intermediate orbital distances,
where surface temperatures are moderate. Coverage of this parameter
range with statistical numbers of bulk characterized planets is unique
to PLATO 2.0. The PLATO 2.0 catalogue allows us to e.g.: - complete
our knowledge of planet diversity for low-mass objects, - correlate the
planet mean density-orbital distance distribution with predictions from
planet formation theories,- constrain the influence of planet migration
and scattering on the architecture of multiple systems, and - specify
how planet and system parameters change with host star characteristics,
such as type, metallicity and age. The catalogue will allow us to study
planets and planetary systems at different evolutionary phases. It
will further provide a census for small, low-mass planets. This will
serve to identify objects which retained their primordial hydrogen
atmosphere and in general the typical characteristics of planets
in such low-mass, low-density range. Planets detected by PLATO 2.0
will orbit bright stars and many of them will be targets for future
atmosphere spectroscopy exploring their atmosphere. Furthermore,
the mission has the potential to detect exomoons, planetary rings,
binary and Trojan planets. The planetary science possible with PLATO
2.0 is complemented by its impact on stellar and galactic science via
asteroseismology as well as light curves of all kinds of variable stars,
together with observations of stellar clusters of different ages. This
will allow us to improve stellar models and study stellar activity. A
large number of well-known ages from red giant stars will probe the
structure and evolution of our Galaxy. Asteroseismic ages of bright
stars for different phases of stellar evolution allow calibrating
stellar age-rotation relationships. Together with the results of ESA's
Gaia mission, the results of PLATO 2.0 will provide a huge legacy to
planetary, stellar and galactic science.
---------------------------------------------------------
Title: Two planets around Kapteyn's star: a cold and a temperate
super-Earth orbiting the nearest halo red dwarf.
Authors: Anglada-Escude, G.; Arriagada, P.; Tuomi, M.; Zechmeister,
M.; Jenkins, J. S.; Ofir, A.; Dreizler, S.; Gerlach, E.; Marvin,
C. J.; Reiners, A.; Jeffers, S. V.; Butler, R. P.; Vogt, S. S.; Amado,
P. J.; Rodriguez-Lopez, C.; Berdinas, Z. M.; Morin, J.; Crane, J. D.;
Shectman, S. A.; Thompson, I. B.; Diaz, M.; Rivera, E.; Sarmiento,
L. F.; Jones, H. R. A.
2014MNRAS.443L..89A Altcode: 2014arXiv1406.0818A
Exoplanets of a few Earth masses can be now detected around
nearby low-mass stars using Doppler spectroscopy. In this Letter,
we investigate the radial velocity variations of Kapteyn's star,
which is both a sub-dwarf M-star and the nearest halo object to the
Sun. The observations comprise archival and new HARPS (High Accuracy
Radial velocity Planet Searcher), High Resolution Echelle Spectrometer
(HIRES) and Planet Finder Spectrograph (PFS) Doppler measurements. Two
Doppler signals are detected at periods of 48 and 120 d using likelihood
periodograms and a Bayesian analysis of the data. Using the same
techniques, the activity indices and archival All Sky Automated
Survey (ASAS-3) photometry show evidence for low-level activity
periodicities of the order of several hundred days. However, there
are no significant correlations with the radial velocity variations on
the same time-scales. The inclusion of planetary Keplerian signals in
the model results in levels of correlated and excess white noise that
are remarkably low compared to younger G, K and M dwarfs. We conclude
that Kapteyn's star is most probably orbited by two super-Earth mass
planets, one of which is orbiting in its circumstellar habitable zone,
becoming the oldest potentially habitable planet known to date. The
presence and long-term survival of a planetary system seem a remarkable
feat given the peculiar origin and kinematic history of Kapteyn's
star. The detection of super-Earth mass planets around halo stars
provides important insights into planet-formation processes in the
early days of the Milky Way.
---------------------------------------------------------
Title: CARMENES ultra-stable cooling system: very promising results
Authors: Mirabet, E.; Carvas, P.; Lizon, J. -L.; Becerril, S.;
Rodríguez, E.; Abril, M.; Cárdenas, M. C.; Morales, R.; Pérez,
D.; Sánchez Carrasco, M. A.; Amado, P. J.; Seifert, W.; Quirrenbach,
A.; Caballero, J. A.; Ribas, I.; Reiners, A.; Dreizler, S.
2014SPIE.9151E..3YM Altcode:
CARMENES is a high resolution spectrograph to detect planets through the
variation of radial velocity, destined for the Calar Alto Observatory
in Almeria, Spain. The optical bench has a working temperature of 140K
with a 24 hours stability of ±0,1K; goal ±0,01K. It is enclosed with
a radiation shield actively cooled with thermalized nitrogen gas that
flows through strategically positioned heat exchangers to remove its
radiative load. The cooling system has an external preparation unit
(N2GPU), which provides the nitrogen gas through actively vaporizing
liquid nitrogen with heating resistances and a three stage circuit
flow, each one controlled by an independent PID. Since CARMENES is
still in the construction phase, a dedicated test facility has been
built in order to simulate the instrument and correctly establish the
N2GPU parameters. Furthermore, the test facility allows a wide range
of configurations set-ups, which enables a full characterization of
the N2GPU and the cooling system. The N2GPU has been designed to offer
a wide temperature range of thermally stabilized nitrogen gas flow,
which apart from CARMENES could also be used to provide ultra-high
thermal stability in other cryogenic instruments. The present paper
shows the testing of the cooling performance, the hardware used and
the very promising results obtained.
---------------------------------------------------------
Title: CARMENES instrument overview
Authors: Quirrenbach, A.; Amado, P. J.; Caballero, J. A.; Mundt,
R.; Reiners, A.; Ribas, I.; Seifert, W.; Abril, M.; Aceituno, J.;
Alonso-Floriano, F. J.; Ammler-von Eiff, M.; Antona Jiménez, R.;
Anwand-Heerwart, H.; Azzaro, M.; Bauer, F.; Barrado, D.; Becerril, S.;
Béjar, V. J. S.; Benítez, D.; Berdiñas, Z. M.; Cárdenas, M. C.;
Casal, E.; Claret, A.; Colomé, J.; Cortés-Contreras, M.; Czesla,
S.; Doellinger, M.; Dreizler, S.; Feiz, C.; Fernández, M.; Galadí,
D.; Gálvez-Ortiz, M. C.; García-Piquer, A.; García-Vargas, M. L.;
Garrido, R.; Gesa, L.; Gómez Galera, V.; González Álvarez, E.;
González Hernández, J. I.; Grözinger, U.; Guàrdia, J.; Guenther,
E. W.; de Guindos, E.; Gutiérrez-Soto, J.; Hagen, H. -J.; Hatzes,
A. P.; Hauschildt, P. H.; Helmling, J.; Henning, T.; Hermann, D.;
Hernández Castaño, L.; Herrero, E.; Hidalgo, D.; Holgado, G.;
Huber, A.; Huber, K. F.; Jeffers, S.; Joergens, V.; de Juan, E.;
Kehr, M.; Klein, R.; Kürster, M.; Lamert, A.; Lalitha, S.; Laun,
W.; Lemke, U.; Lenzen, R.; López del Fresno, Mauro; López Martí,
B.; López-Santiago, J.; Mall, U.; Mandel, H.; Martín, E. L.;
Martín-Ruiz, S.; Martínez-Rodríguez, H.; Marvin, C. J.; Mathar,
R. J.; Mirabet, E.; Montes, D.; Morales Muñoz, R.; Moya, A.; Naranjo,
V.; Ofir, A.; Oreiro, R.; Pallé, E.; Panduro, J.; Passegger, V. -M.;
Pérez-Calpena, A.; Pérez Medialdea, D.; Perger, M.; Pluto, M.;
Ramón, A.; Rebolo, R.; Redondo, P.; Reffert, S.; Reinhardt, S.; Rhode,
P.; Rix, H. -W.; Rodler, F.; Rodríguez, E.; Rodríguez-López, C.;
Rodríguez-Pérez, E.; Rohloff, R. -R.; Rosich, A.; Sánchez-Blanco,
E.; Sánchez Carrasco, M. A.; Sanz-Forcada, J.; Sarmiento, L. F.;
Schäfer, S.; Schiller, J.; Schmidt, C.; Schmitt, J. H. M. M.; Solano,
E.; Stahl, O.; Storz, C.; Stürmer, J.; Suárez, J. C.; Ulbrich,
R. G.; Veredas, G.; Wagner, K.; Winkler, J.; Zapatero Osorio, M. R.;
Zechmeister, M.; Abellán de Paco, F. J.; Anglada-Escudé, G.; del
Burgo, C.; Klutsch, A.; Lizon, J. L.; López-Morales, M.; Morales,
J. C.; Perryman, M. A. C.; Tulloch, S. M.; Xu, W.
2014SPIE.9147E..1FQ Altcode:
This paper gives an overview of the CARMENES instrument and of the
survey that will be carried out with it during the first years of
operation. CARMENES (Calar Alto high-Resolution search for M dwarfs
with Exoearths with Near-infrared and optical Echelle Spectrographs)
is a next-generation radial-velocity instrument under construction
for the 3.5m telescope at the Calar Alto Observatory by a consortium
of eleven Spanish and German institutions. The scientific goal of the
project is conducting a 600-night exoplanet survey targeting ~ 300 M
dwarfs with the completed instrument. The CARMENES instrument consists
of two separate echelle spectrographs covering the wavelength range
from 0.55 to 1.7 μm at a spectral resolution of R = 82,000, fed by
fibers from the Cassegrain focus of the telescope. The spectrographs
are housed in vacuum tanks providing the temperature-stabilized
environments necessary to enable a 1 m/s radial velocity precision
employing a simultaneous calibration with an emission-line lamp
or with a Fabry-Perot etalon. For mid-M to late-M spectral types,
the wavelength range around 1.0 μm (Y band) is the most important
wavelength region for radial velocity work. Therefore, the efficiency
of CARMENES has been optimized in this range. The CARMENES instrument
consists of two spectrographs, one equipped with a 4k x 4k pixel CCD
for the range 0.55 - 1.05 μm, and one with two 2k x 2k pixel HgCdTe
detectors for the range from 0.95 - 1.7μm. Each spectrograph will
be coupled to the 3.5m telescope with two optical fibers, one for
the target, and one for calibration light. The front end contains a
dichroic beam splitter and an atmospheric dispersion corrector, to
feed the light into the fibers leading to the spectrographs. Guiding
is performed with a separate camera; on-axis as well as off-axis
guiding modes are implemented. Fibers with octagonal cross-section
are employed to ensure good stability of the output in the presence
of residual guiding errors. The fibers are continually actuated to
reduce modal noise. The spectrographs are mounted on benches inside
vacuum tanks located in the coudé laboratory of the 3.5m dome. Each
vacuum tank is equipped with a temperature stabilization system
capable of keeping the temperature constant to within +/-0.01°C
over 24 hours. The visible-light spectrograph will be operated near
room temperature, while the near-IR spectrograph will be cooled to
~ 140 K. The CARMENES instrument passed its final design review in
February 2013. The MAIV phase is currently ongoing. First tests at
the telescope are scheduled for early 2015. Completion of the full
instrument is planned for the fall of 2015. At least 600 useable
nights have been allocated at the Calar Alto 3.5m Telescope for the
CARMENES survey in the time frame until 2018. A data base of M stars
(dubbed CARMENCITA) has been compiled from which the CARMENES sample
can be selected. CARMENCITA contains information on all relevant
properties of the potential targets. Dedicated imaging, photometric,
and spectroscopic observations are underway to provide crucial data
on these stars that are not available in the literature.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Kapteyn's star spectroscopic
measurements (Anglada-Escude+ 2014)
Authors: Anglada-Escude, G.; Arriagada, P.; Tuomi, M.; Zechmeister,
M.; Jenkins, J. S.; Ofir, A.; Dreizler, S.; Gerlach, E.; Marvin,
C. J.; Reiners, A.; Jeffers, S. V.; Butler, R. P.; Vogt, S. S.; Amado,
P. J.; Rodriguez-Lopez, C.; Berdinas, Z. M.; Morin, J.; Crane, J. D.;
Shectman, S. A.; Thompson, I. B.; Diaz, M.; Rivera, E.; Sarmiento,
L. F.; Jones, H. R. A.
2014yCat..74439089A Altcode:
Time-series of spectroscopic measurements used in the paper. Median
value and a perspective acceleration were subtracted to each RVs set
(Ins. 1 is HARPS, 2 is HIRES, 3 is PFS). Measurements of the FWHM,
BIS of the cross-correlation profiles and measurements of the S-index
are provided for HARPS data only. Uncertainty in the FWHM is 2.5 times
the uncertainty in BIS. Check (2012ApJS..200...15A), for more detailed
definitions of the measurements and their uses. <P />(1 data file).
---------------------------------------------------------
Title: TRIPP: Time Resolved Imaging Photometry Package
Authors: Geckeler, Ralf D.; Schuh, Sonja; Dreizler, Stefan; Deetjen,
Jochen; Gleissner, Thomas; Risse, Patrick; Rauch, Thomas; Göhler,
Eckart; Hügelmeyer, Simon; Husser, Tim-Oliver; Israel, Holger;
Benlloch-Garcia, Sara; Pottschmidt, Katja; Wilms, Jörn
2014ascl.soft05008G Altcode:
Written in IDL, TRIPP performs CCD time series reduction and
analysis. It provides an on-line check of the incoming frames, performs
relative aperture photometry and provides a set of time series tools,
such as calculation of periodograms including false alarm probability
determination, epoc folding, sinus fitting, and light curve simulations.
---------------------------------------------------------
Title: Hot horizontal branch stars in NGC 288 - effects of diffusion
and stratification on their atmospheric parameters
Authors: Moehler, S.; Dreizler, S.; LeBlanc, F.; Khalack, V.; Michaud,
G.; Richer, J.; Sweigart, A. V.; Grundahl, F.
2014A&A...565A.100M Altcode: 2014arXiv1403.7397M
Context. NGC 288 is a globular cluster with a well-developed blue
horizontal branch (HB) covering the u-jump that indicates the onset of
diffusion. It is therefore well suited to study the effects of diffusion
in blue HB stars. <BR /> Aims: We compare observed abundances with
predictions from stellar evolution models calculated with diffusion
and from stratified atmospheric models. We verify the effect of
using stratified model spectra to derive atmospheric parameters. In
addition, we investigate the nature of the overluminous blue HB stars
around the u-jump. <BR /> Methods: We defined a new photometric
index sz from uvby measurements that is gravity-sensitive between
8000 K and 12 000 K. Using medium-resolution spectra and Strömgren
photometry, we determined atmospheric parameters (T<SUB>eff</SUB>,
log g) and abundances for the blue HB stars. We used both homogeneous
and stratified model spectra for our spectroscopic analyses. <BR />
Results: The atmospheric parameters and masses of the hot HB stars in
NGC 288 show a behaviour seen also in other clusters for temperatures
between 9000 K and 14 000 K. Outside this temperature range, however,
they instead follow the results found for such stars in ω Cen. The
abundances derived from our observations are for most elements (except
He and P) within the abundance range expected from evolutionary models
that include the effects of atomic diffusion and assume a surface mixed
mass of 10<SUP>-7</SUP> M<SUB>⊙</SUB>. The abundances predicted
by stratified model atmospheres are generally significantly more
extreme than observed, except for Mg. When effective temperatures,
surface gravities, and masses are determined with stratified model
spectra, the hotter stars agree better with canonical evolutionary
predictions. <BR /> Conclusions: Our results show definite promise
towards solving the long-standing problem of surface gravity and
mass discrepancies for hot HB stars, but much work is still needed to
arrive at a self-consistent solution. <P />Based on observations with
the ESO Very Large Telescope at Paranal Observatory, Chile (proposal
ID 71.D-0131).Tables 1 and 2 are available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201322953/olm">http://www.aanda.org</A>The
observed abundances plotted in Fig. 8 are
only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/565/A100">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/565/A100</A>
---------------------------------------------------------
Title: On the Current State of Ground-based Transmission Spectroscopy
of Planet Atmospheres
Authors: Nortmann, Lisa; Dreizler, Stefan; Bean, Jacob
2014IAUS..293..315N Altcode:
In response to the large number of exoplanet detections, the
characterization of these planets has become a major focus of exoplanet
science. Transiting planets are of particular interest as they allow
us to investigate the transmission of their atmospheres. Our group uses
ground-based facilities like the ESO/VLT to probe the atmosphere of hot
Jupiters with the technique of spectrophotometry. In our preliminary
results for the hot Jupiters WASP-17b and WASP-31b we find the reachable
precision to be limited by instrumental systematic noise rather than
photon noise. We discuss the source of the noise and suggest two
approaches to correct it.
---------------------------------------------------------
Title: Kepler-9 revisited 60% the mass with six times more data
Authors: Dreizler, Stefan; Ofir, Aviv
2014arXiv1403.1372D Altcode:
Kepler-9 was the first case where transit timing variations have been
used to confirm the planets in this system. Following predictions of
dramatic TTVs - larger than a week - we re-analyse the system based
on the full Kepler data set. We re-processed all available data for
Kepler-9 removing short and long term trends, measured the times of
mid-transit and used those for dynamical analysis of the system. The
newly determined masses and radii of Kepler-9b and -9c change the nature
of these planets relative to the one described in Holman et al. 2010
(hereafter H10) with very low, but relatively well charcterised (to
better than 7%), bulk densities of 0.18 and 0.14 g cm$^3$ (about 1/3
of the H10 value). We constrain the masses (45.1 and 31.0 M$_\oplus$,
for Kepler-9b and -9c respectively) from photometry alone, allowing
us to see possible indications for an outer non-transiting planet in
the radial velocity data. At $2R_\oplus$ Kepler-9d is determined to
be larger than suggested before - suggesting that it is a low-mass
low-density planet. The comparison between the H10 analysis and our
new analysis suggests that small formal error in the TTV inversion
may be misleading if the data does not cover a significant fraction
of the interaction time scale.
---------------------------------------------------------
Title: VizieR Online Data Catalog: NGC 288 hot horizontal branch
stars abundances (Moehler+, 2014)
Authors: Moehler, S.; Dreizler, S.; Leblanc, F.; Khalack, V.; Michaud,
G.; Richer, J.; Sweigart, A. V.; Grundahl, F.
2014yCat..35650100M Altcode: 2014yCat..35659100M
Temperatures, surface gravities, and abundances for hot (Teff>9000K)
horizontal branch stars in NGC 288 as derived from medium-resolution
FLAMES-GIRAFFE spectra (resolution about 0.7Å). Effective temperatures
and surface gravities are derived from line profile fits. The abundances
were derived via spectrum synthesis, using the presviously defined
effective temperature and surface gravity. Errors are about ±5%
in Teff, ±0.1 in logg, ±0.2 (He), ±0.28 (Mg), ±0.34 (Si,
P, Fe), ±0.58 (Ti, Mn, Ni). 0.00 means that no abundance could be
determined. <P />(2 data files).
---------------------------------------------------------
Title: Planet formation from the ejecta of common envelopes
Authors: Schleicher, Dominik R. G.; Dreizler, Stefan
2014A&A...563A..61S Altcode: 2013arXiv1312.3479S
Context. The close binary system NN Serpentis must have gone
through a common envelope phase before the formation of its white
dwarf. During this phase, a substantial amount of mass was lost from
the envelope. The recently detected orbits of circumbinary planets are
probably inconsistent with planet formation before the mass loss. <BR
/> Aims: We explore whether new planets may have formed from the
ejecta of the common envelope and derive the expected planetary mass
as a function of radius. <BR /> Methods: We employed the Kashi &
Soker model to estimate the amount of mass that is retained during
the ejection event and inferred the properties of the resulting disk
from the conservation of mass and angular momentum. The resulting
planetary masses were estimated from models with and without radiative
feedback. <BR /> Results: We show that the observed planetary masses
can be reproduced for appropriate model parameters. Photoheating
can stabilize the disks in the interior, potentially explaining
the observed planetary orbits on scales of a few AU. We compare
the expected mass scale of planets for 11 additional systems with
observational results and find hints of two populations, one consistent
with planet formation from the ejecta of common envelopes and the
other a separate population that may have formed earlier. <BR />
Conclusions: The formation of the observed planets from the ejecta
of common envelopes seems feasible. The model proposed here can be
tested through refined observations of additional post-common envelope
systems. While it appears observationally challenging to distinguish
between the accretion on pre-existing planets and their growth from
new fragments, it may be possible to further constrain the properties
of the protoplanetary disk through additional observations of current
planetary candidates and post-common envelope binary systems.
---------------------------------------------------------
Title: Evidence for an oscillation of the magnetic axis of the white
dwarf in the polar DP Leonis
Authors: Beuermann, K.; Dreizler, S.; Hessman, F. V.; Schwope, A. D.
2014A&A...562A..63B Altcode: 2014arXiv1401.1638B
From 1979 to 2001, the magnetic axis of the white dwarf in the
polar DP Leo slowly rotated by 50° in azimuth, possibly indicating
a small asynchronism between the rotational and orbital periods of
the magnetic white dwarf. Using the MONET/North telescope, we have
obtained phase-resolved orbital light curves between 2009 and 2013,
which show that this trend has not continued in recent years. Our data
are consistent with the theoretically predicted oscillation of the
magnetic axis of the white dwarf about an equilibrium orientation,
which is defined by the competition between the accretion torque and
the magnetostatic interaction of the primary and secondary star. Our
data indicate an oscillation period of ~60 yr, an amplitude of about
25°, and an equilibrium orientation leading the connecting line of
the two stars by about 7°.
---------------------------------------------------------
Title: An independent planet search in the Kepler dataset. II. An
extremely low-density super-Earth mass planet around Kepler-87
Authors: Ofir, Aviv; Dreizler, Stefan; Zechmeister, Mathias; Husser,
Tim-Oliver
2014A&A...561A.103O Altcode: 2013arXiv1310.2064O
Context. The primary goal of the Kepler mission is the measurement of
the frequency of Earth-like planets around Sun-like stars. However,
the confirmation of the smallest of Kepler's candidates in long periods
around FGK dwarfs is extremely difficult or even beyond the limit of
current radial velocity technology. Transit timing variations (TTVs) may
offer the possibility for these confirmations of near-resonant multiple
systems by the mutual gravitational interaction of the planets. <BR />
Aims: We previously detected the second planet candidate in the KOI
1574 system. The two candidates have relatively long periods (about
114 d and 191 d) and are in 5:3 resonance. We therefore searched for
TTVs in this particularly promising system. <BR /> Methods: The full
Kepler data was detrended with the proven SARS pipeline. The entire data
allowed one to search for TTVs of the above signals, and to search for
additional transit-like signals. <BR /> Results: We detected strong
anti-correlated TTVs of the 114 d and 191 d signals, dynamically
confirming them as members of the same system. Dynamical simulations
reproducing the observed TTVs allowed us to also determine the masses
of the planets. We found KOI 1574.01 (hereafter Kepler-87 b) to have
a radius of 13.49 ± 0.55 R<SUB>⊕</SUB> and a mass of 324.2 ± 8.8
M<SUB>⊕</SUB>, and KOI 1574.02 (Kepler-87 c) to have a radius of 6.14
± 0.29 R<SUB>⊕</SUB> and a mass of 6.4 ± 0.8 M<SUB>⊕</SUB>. Both
planets have low densities of 0.729 and 0.152 g cm<SUP>-3</SUP>,
respectively, which is non-trivial for such cold and old (7-8 Gyr)
planets. Specifically, Kepler-87 c is the lowest-density planet
in the super-Earth mass range. Both planets are thus particularly
amenable to modeling and planetary structure studies, and also
present an interesting case where ground-based photometric follow-up
of Kepler planets is very desirable. Finally, we also detected two
more short-period super-Earth sized (<2 R<SUB>⊕</SUB>) planetary
candidates in the system, making the relatively high multiplicity of
this system notable against the general paucity of multiple systems
in the presence of giant planets like Kepler-87 b.
---------------------------------------------------------
Title: VizieR Online Data Catalog: WASP-15 and WASP-16 light curves
(Southworth+, 2013)
Authors: Southworth, J.; Mancini, L.; Browne, P.; Burgdorf, M.; Calchi
Novati, S.; Dominik, M.; Gerner, T.; Hinse, T. C.; Jorgensen, U. G.;
Kains, N.; Ricci, D.; Schafer, S.; Schonebeck, F.; Tregloan-Reed, J.;
Alsubai, K. A.; Bozza, V.; Chen, G.; Dodds, P.; Dreizler, S.; Fang,
X. -S.; Finet, F.; Gu, S. -H.; Hardis, S.; Harpsoe, K.; Henning, T.;
Hundertmark, M.; Jessen-Hansen, J.; Kerins, E.; Kjeldsen, H.; Liebig,
C.; Lund, M. N.; Lundkvist, M.; Mathiasen, M.; Nikolov, N.; Penny,
M. T.; Proft, S.; Rahvar, S.; Sahu, K.; Scarpetta, G.; Skottfelt,
J.; Snodgrass, C.; Surdej, J.; Wertz, O.
2013yCat..74341300S Altcode:
Nine light curves of six transits of the extrasolar planetary systems
WASP-15 and WASP-16 are presented. The data were obtained using the
Danish 1.5m telescope and DFOSC camera, and the ESO/MPI 2.2m telescope
and GROND imager, with substantial telescope defocussing in order to
improve the photometric precision of the observations. A Bessell R
filter was used with DFOSC. The observations with GROND were obtained
simultaneously through four filters: Sloan g, r, i and z. <P />(3
data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: New Kepler planetary candidates
(Ofir+, 2013)
Authors: Ofir, A.; Dreizler, S.
2013yCat..35550058O Altcode: 2013yCat..35559058O
We present first results of our efforts to re-analyze the Kepler
photometric dataset, searching for planetary transits using an
alternative processing pipeline to the one used by the Kepler mission
The SARS pipeline was tried and tested extensively by processing all
available CoRoT mission data. For this first paper of the series we
used this pipeline to search for (additional) planetary transits only
in a small subset of stars - the Kepler objects of interest (KOIs),
which are already known to include at least one promising planet
candidate. <P />(2 data files).
---------------------------------------------------------
Title: The eclipsing post-common envelope binary CSS21055: a white
dwarf with a probable brown-dwarf companion
Authors: Beuermann, K.; Dreizler, S.; Hessman, F. V.; Backhaus, U.;
Boesch, A.; Husser, T. -O.; Nortmann, L.; Schmelev, A.; Springer, R.
2013A&A...558A..96B Altcode: 2013arXiv1312.5088B
We report photometric observations of the eclipsing close binary
CSS21055 (SDSS J141126+200911) that strongly suggest that the
companion to the carbon-oxygen white dwarf is a brown dwarf with a
mass between 0.030 and 0.074 M<SUB>⊙</SUB>. The measured orbital
period is 121.73 min and the totality of the eclipse lasts 125 s. If
confirmed, CSS21055 would be the first detached eclipsing WD+BD
binary. Spectroscopy in the eclipse could provide information about
the companion's evolutionary state and atmospheric structure. <P
/>Light curves are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/558/A96">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/558/A96</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: Vi light curves of NGC6333
variables (Arellano Ferro+, 2013)
Authors: Arellano Ferro, A.; Bramich, D. M.; Figuera Jaimes, R.;
Giridhar, S.; Kains, N.; Kuppuswamy, K.; Jorgensen, U. G.; Alsubai,
K. A.; Andersen, J. M.; Bozza, V.; Browne, P.; Calchi Novati,
S.; Damerdji, Y.; Diehl, C.; Dominik, M.; Dreizler, S.; Elyiv, A.;
Giannini, E.; Harpsoe, K.; Hessman, F. V.; Hinse, T. C.; Hundertmark,
M.; Juncher, D.; Kerins, E.; Korhonen, H.; Liebig, C.; Mancini,
L.; Mathiasen, M.; Penny, M. T.; Rabus, M.; Rahvar, S.; Ricci, D.;
Scarpetta, G.; Skottfelt, J.; Snodgrass, C.; Southworth, J.; Surdej,
J.; Tregloan-Reed, J.; Vilela, C.; Wertz, O.
2013yCat..74341220A Altcode:
V and i time-series photometry for all confirmed variables in NGC
6333. <P />(2 data files).
---------------------------------------------------------
Title: A detailed census of variable stars in the globular cluster
NGC 6333 (M9) from CCD differential photometry
Authors: Arellano Ferro, A.; Bramich, D. M.; Figuera Jaimes, R.;
Giridhar, Sunetra; Kains, N.; Kuppuswamy, K.; Jørgensen, U. G.;
Alsubai, K. A.; Andersen, J. M.; Bozza, V.; Browne, P.; Calchi Novati,
S.; Damerdji, Y.; Diehl, C.; Dominik, M.; Dreizler, S.; Elyiv, A.;
Giannini, E.; Harpsøe, K.; Hessman, F. V.; Hinse, T. C.; Hundertmark,
M.; Juncher, D.; Kerins, E.; Korhonen, H.; Liebig, C.; Mancini,
L.; Mathiasen, M.; Penny, M. T.; Rabus, M.; Rahvar, S.; Ricci, D.;
Scarpetta, G.; Skottfelt, J.; Snodgrass, C.; Southworth, J.; Surdej,
J.; Tregloan-Reed, J.; Vilela, C.; Wertz, O.; Mindstep Consortium
2013MNRAS.434.1220A Altcode: 2013MNRAS.tmp.1768A; 2013arXiv1306.3206A
We report CCD V and I time series photometry of the globular cluster NGC
6333 (M9). The technique of difference image analysis has been used,
which enables photometric precision better than 0.05 mag for stars
brighter than V ∼ 19.0 mag, even in the crowded central regions
of the cluster. The high photometric precision has resulted in the
discovery of two new RRc stars, three eclipsing binaries, seven
long-term variables and one field RRab star behind the cluster. A
detailed identification chart and equatorial coordinates are given for
all the variable stars in the field of our images of the cluster. Our
data together with the literature V-data obtained in 1994 and 1995
allowed us to refine considerably the periods for all RR Lyrae
stars. The nature of the new variables is discussed. We argue that
variable V12 is a cluster member and an Anomalous Cepheid. Secular
period variations, double-mode pulsations and/or the Blazhko-like
modulations in some RRc variables are addressed. Through the light-curve
Fourier decomposition of 12 RR Lyrae stars we have calculated a mean
metallicity of [Fe/H]<SUB>ZW</SUB> = -1.70 ± 0.01(statistical) ±
0.14(systematic) or [Fe/H]_{text{UVES}}=-1.67 ± 0.01(statistical)
± 0.19(systematic). Absolute magnitudes, radii and masses are also
estimated for the RR Lyrae stars. A detailed search for SX Phe stars
in the Blue Straggler region was conducted but none were discovered. If
SX Phe exist in the cluster then their amplitudes must be smaller than
the detection limit of our photometry. The colour-magnitude diagram
has been corrected for heavy differential reddening using the detailed
extinction map of the cluster of Alonso-García et al. This has allowed
us to set the mean cluster distance from two independent estimates;
from the RRab and RRc absolute magnitudes, we find 8.04 ± 0.19 and
7.88 ± 0.30 kpc, respectively.
---------------------------------------------------------
Title: VizieR Online Data Catalog: CSS21055 light curves (Beuermann+,
2013)
Authors: Beuermann, K.; Dreizler, S.; Hessman, F. V.; Backhaus, U.;
Boesch, A.; Husser, T. -O.; Nortmann, L.; Schmelev, A.; Springer, R.
2013yCat..35580096B Altcode: 2013yCat..35589096B
Tables contain the numerical values for the light curves presented in
Figs. 1a, 1b, and 1c. <P />(3 data files).
---------------------------------------------------------
Title: High-precision photometry by telescope defocusing - V. WASP-15
and WASP-16
Authors: Southworth, John; Mancini, L.; Browne, P.; Burgdorf,
M.; Calchi Novati, S.; Dominik, M.; Gerner, T.; Hinse, T. C.;
Jørgensen, U. G.; Kains, N.; Ricci, D.; Schäfer, S.; Schönebeck,
F.; Tregloan-Reed, J.; Alsubai, K. A.; Bozza, V.; Chen, G.; Dodds,
P.; Dreizler, S.; Fang, X. -S.; Finet, F.; Gu, S. -H.; Hardis, S.;
Harpsøe, K.; Henning, Th.; Hundertmark, M.; Jessen-Hansen, J.;
Kerins, E.; Kjeldsen, H.; Liebig, C.; Lund, M. N.; Lundkvist, M.;
Mathiasen, M.; Nikolov, N.; Penny, M. T.; Proft, S.; Rahvar, S.; Sahu,
K.; Scarpetta, G.; Skottfelt, J.; Snodgrass, C.; Surdej, J.; Wertz, O.
2013MNRAS.434.1300S Altcode: 2013MNRAS.tmp.1750S; 2013arXiv1306.3509S
We present new photometric observations of WASP-15 and WASP-16,
two transiting extrasolar planetary systems with measured orbital
obliquities but without photometric follow-up since their discovery
papers. Our new data for WASP-15 comprise observations of one transit
simultaneously in four optical passbands using GROND on the MPG/European
Southern Observatory (ESO) 2.2 m telescope, plus coverage of half
a transit from DFOSC on the Danish 1.54 m telescope, both at ESO La
Silla. For WASP-16 we present observations of four complete transits,
all from the Danish telescope. We use these new data to refine the
measured physical properties and orbital ephemerides of the two
systems. Whilst our results are close to the originally determined
values for WASP-15, we find that the star and planet in the WASP-16
system are both larger and less massive than previously thought.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Transiting planetary system WASP-17
(Southworth+, 2012)
Authors: Southworth, J.; Hinse, T. C.; Dominik, M.; Fang, X. -S.;
Harpsoe, K.; Jorgensen, U. G.; Kerins, E.; Liebig, C.; Mancini, L.;
Skottfelt, J.; Anderson, D. R.; Smalley, B.; Tregloan-Reed, J.; Wertz,
O.; Alsubai, K. A.; Bozza, V.; Calchi Novati, S.; Dreizler, S.; Gu,
S. -H.; Hundertmark, M.; Jessen-Hansen, J.; Kains, N.; Kjeldsen, H.;
Lund, M. N.; Lundkvist, M.; Mathiasen, M.; Penny, M. T.; Rahvar, S.;
Ricci, D.; Scarpetta, G.; Snodgrass, C.; Surdej, J.
2013yCat..74261338S Altcode:
A light curve of four transits of the extrasolar planetary system
WASP-17 is presented. The data were obtained using the Danish 1.5m
telescope and DFOSC camera at ESO La Silla in 2012, with substantial
telescope defocussing in order to improve the photometric precision
of the observations. A Cousins R filter and exposure times of 120s
were used. <P />(1 data file).
---------------------------------------------------------
Title: High angular resolution imaging and infrared spectroscopy of
CoRoT candidates
Authors: Guenther, E. W.; Fridlund, M.; Alonso, R.; Carpano, S.; Deeg,
H. J.; Deleuil, M.; Dreizler, S.; Endl, M.; Gandolfi, D.; Gillon, M.;
Guillot, T.; Jehin, E.; Léger, A.; Moutou, C.; Nortmann, L.; Rouan,
D.; Samuel, B.; Schneider, J.; Tingley, B.
2013A&A...556A..75G Altcode: 2013arXiv1307.1660G
Context. Studies of transiting extrasolar planets are of key
importance for understanding the nature of planets outside our solar
system because their masses, diameters, and bulk densities can be
measured. An important part of transit-search programmes is the removal
of false-positives. In the case of the CoRoT space mission, the majority
of the false-positives are removed by a detailed analysis of the light
curves and by seeing-limited imaging in- and out-of-transit. However,
the critical question is how many of the candidates that passed all
these tests are false-positives. Such false-positives can be caused
by eclipsing binaries, which are either related or unrelated to the
targets. <BR /> Aims: For our study we selected 25 CoRoT candidates
that have already been screened against false-positives using detailed
analysis of the light curves and seeing-limited imaging, which has
transits that are between 0.7 and 0.05% deep. Our aim is to search
for companion candidates that had not been recognized in previous
observations. <BR /> Methods: We observed 20 candidates with the
adaptive optics imager NaCo and 18 with the high-resolution infrared
spectrograph CRIRES. <BR /> Results: We found previously unknown stars
within 2” of the targets in seven of the candidates. All of these are
too faint and too close to the targets to have been previously detected
with seeing-limited telescopes in the optical. Our study thus leads to
the surprising results that if we remove all candidates excluded by the
sophisticated analysis of the light-curve, as well as carrying out deep
imaging with seeing-limited telescopes, still 28-35% of the remaining
candidates are found to possess companions that are bright enough to be
false-positives. <BR /> Conclusions: Given that the companion candidates
cluster around the targets and that the J - K colours are consistent
with physical companions, we conclude that the companion candidates
are more likely to be physical companions rather than unrelated
field stars. <P />Based on observations obtained at the European
Southern Observatory at Paranal, Chile in programmes 282.C-5015A,
282.C-5015B, 282.C-5015C, 285.C-5045A, and 285.C-5045B, 086.C-0235A,
086.C-0235B, 088.C-0707A, 088.C-0707B, 090.C-0251A, 090.C-0251B, and
091.C-203(A).Appendices A and B are available in electronic form at
<A href="http://www.aanda.org">http://www.aanda.org</A>
---------------------------------------------------------
Title: The quest for companions to post-common envelope
binaries. IV. The 2:1 mean-motion resonance of the planets orbiting
NN Serpentis
Authors: Beuermann, K.; Dreizler, S.; Hessman, F. V.
2013A&A...555A.133B Altcode: 2013arXiv1305.6494B
We present 69 new mid-eclipse times of the young post-common envelope
binary (PCEB) <ASTROBJ>NN Ser</ASTROBJ>, which was previously suggested
to possess two circumbinary planets. We have interpreted the observed
eclipse-time variations in terms of the light-travel time effect
caused by two planets, exhaustively covering the multi-dimensional
parameter space by fits in the two binary and ten orbital parameters. We
supplemented the fits by stability calculations for all models with an
acceptable χ<SUP>2</SUP>. An island of secularly stable 2:1 resonant
solutions exists, which coincides with the global χ<SUP>2</SUP>
minimum. Our best-fit stable solution yields current orbital periods
P<SUB>o</SUB> = 15.47 yr and P<SUB>i</SUB> = 7.65 yr and eccentricities
e<SUB>o</SUB> = 0.14 and e<SUB>i</SUB> = 0.22 for the outer and inner
planets, respectively. The companions qualify as giant planets, with
masses of 7.0 M<SUB>Jup</SUB> and 1.7 M<SUB>Jup</SUB> for the case of
orbits coplanar with that of the binary. The two-planet model that
starts from the present system parameters has a lifetime greater
than 10<SUP>8</SUP> yr, which significantly exceeds the age of NN
Ser of 10<SUP>6</SUP> yr as a PCEB. The resonance is characterized by
libration of the resonant variable Θ<SUB>1</SUB> and circulation of ,
the difference between the arguments of periapse of the two planets. No
stable nonresonant solutions were found, and the possibility of a
5:2 resonance suggested previously by us is now excluded at the 99.3%
confidence level. <P />Table 1 is available in electronic form at <A
href="http://www.aanda.org">http://www.aanda.org</A>
---------------------------------------------------------
Title: An independent planet search in the Kepler dataset. I. One
hundred new candidates and revised Kepler objects of interest
Authors: Ofir, A.; Dreizler, S.
2013A&A...555A..58O Altcode: 2012arXiv1206.5347O
<BR /> Aims: We present first results of our efforts to re-analyze the
Kepler photometric dataset, searching for planetary transits using an
alternative processing pipeline to the one used by the Kepler mission
<BR /> Methods: The SARS pipeline was tried and tested extensively by
processing all available CoRoT mission data. For this first paper of
the series we used this pipeline to search for (additional) planetary
transits only in a small subset of stars - the Kepler objects of
interest (KOIs), which are already known to include at least one
promising planet candidate. <BR /> Results: Although less than 1% of the
Kepler dataset are KOIs we are able to significantly update the overall
statistics of planetary multiplicity: we find 84 new transit signals
on 64 systems on these light curves (LCs) only, nearly doubling the
number of transit signals in these systems. Forty-one of the systems
were singly-transiting systems that are now multiply-transiting. This
significantly reduces the chances of false positive in them. Notable
among the new discoveries are KOI 435 as a new six-candidate system
(of which kind only Kepler-11 was known before), KOI 277 (which includes
two candidates in a 6:7 period commensurability that has anti-correlated
transit timing variations) - all but validating the system, KOIs 719,
1574, and 1871 that have small planet candidates (1.15,2.05 and 1.71
R<SUB>⊕</SUB>) in the habitable zone of their host star, and KOI 1843
that exhibits the shortest period (4.25 h) and is among the smallest
(0.63 R<SUB>⊕</SUB>) of all planet candidates. We are also able to
reject 11 KOIs as eclipsing binaries based on photometry alone, update
the ephemeris for five KOIs and otherwise discuss a number of other
objects, which brings the total of new signals and revised KOIs in
this study to more than one hundred. Interestingly, a large fraction,
about ~1/3, of the newly detected candidates participate in period
commensurabilities. Finally, we discuss the possible overestimation of
parameter errors in the current list of KOIs and point out apparent
problems in at least two of the parameters. <BR /> Conclusions: Our
results strengthen previous analyses of the multi-transiting ensemble,
and again highlight the great importance of this dataset. Nevertheless,
we conclude that despite the phenomenal success of the Kepler mission,
parallel analysis of the data by multiple teams is required to make
full use of the data.
---------------------------------------------------------
Title: A new extensive library of PHOENIX stellar atmospheres and
synthetic spectra
Authors: Husser, T. -O.; Wende-von Berg, S.; Dreizler, S.; Homeier,
D.; Reiners, A.; Barman, T.; Hauschildt, P. H.
2013A&A...553A...6H Altcode: 2013arXiv1303.5632H
<BR /> Aims: We present a new library of high-resolution synthetic
spectra based on the stellar atmosphere code PHOENIX that can be used
for a wide range of applications of spectral analysis and stellar
parameter synthesis. <BR /> Methods: The spherical mode of PHOENIX
was used to create model atmospheres and to derive detailed synthetic
stellar spectra from them. We present a new self-consistent way of
describing micro-turbulence for our model atmospheres. <BR /> Results:
The synthetic spectra cover the wavelength range from 500 Å to 5.5 μm
with resolutions of R = 500 000 in the optical and near IR, R = 100 000
in the IR and Δλ = 0.1 Å in the UV. The parameter space covers 2300
K ≤ T<SUB>eff</SUB> ≤ 12 000 K, 0.0 ≤ log g ≤ +6.0, - 4.0 ≤
[Fe/H] ≤ +1.0, and - 0.2 ≤ [α/Fe] ≤ +1.2. The library is a work
in progress and we expect to extend it up to T<SUB>eff</SUB> = 25 000 K.
---------------------------------------------------------
Title: CAFE: Calar Alto Fiber-fed Échelle spectrograph
Authors: Aceituno, J.; Sánchez, S. F.; Grupp, F.; Lillo, J.;
Hernán-Obispo, M.; Benitez, D.; Montoya, L. M.; Thiele, U.; Pedraz,
S.; Barrado, D.; Dreizler, S.; Bean, J.
2013A&A...552A..31A Altcode: 2013arXiv1301.2066A
We present here CAFE, the Calar Alto Fiber-fed Échelle spectrograph,
a new instrument built at the Centro Astronomico Hispano Alemán
(CAHA). CAFE is a single-fiber, high-resolution (R ~ 70 000)
spectrograph, covering the wavelength range between 3650-9800 Å. It was
built on the basis of the common design for Échelle spectrographs. Its
main aim is to measure radial velocities of stellar objects up to V ~
13-14 mag with a precision as good as a few tens of m s<SUP>-1</SUP>. To
achieve this goal the design was simplified at maximum, removing all
possible movable components, the central wavelength is fixed, as is the
wavelength coverage; there is no filter wheel, etc. Particular care
was taken with the thermal and mechanical stability. The instrument
is fully operational and publically accessible at the 2.2 m telescope
of the Calar Alto Observatory. In this article we describe (i) the
design, summarizing its manufacturing phase; (ii) characterize the main
properties of the instrument; (iii) describe the reduction pipeline;
and (iv) show the results from the first light and commissioning
runs. The preliminar results indicate that the instrument fulfills the
specifications and can achieve the planned goals. In particular, the
results show that the instrument is more efficient than anticipated,
reaching a signal-to-noise of ~20 for a stellar object as faint as V ~
14.5 mag in ~2700 s integration time. The instrument is a wonderful
machine for exoplanetary research (by studying large samples of
possible systems cotaining massive planets), galactic dynamics (highly
precise radial velocities in moving groups or stellar associations),
or astrochemistry.
---------------------------------------------------------
Title: A giant planet beyond the snow line in microlensing event
OGLE-2011-BLG-0251
Authors: Kains, N.; Street, R. A.; Choi, J. -Y.; Han, C.; Udalski,
A.; Almeida, L. A.; Jablonski, F.; Tristram, P. J.; Jørgensen,
U. G.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński,
I.; Poleski, R.; Kozłowski, S.; Pietrukowicz, P.; Ulaczyk, K.;
Wyrzykowski, Ł.; Skowron, J.; Alsubai, K. A.; Bozza, V.; Browne, P.;
Burgdorf, M. J.; Calchi Novati, S.; Dodds, P.; Dominik, M.; Dreizler,
S.; Fang, X. -S.; Grundahl, F.; Gu, C. -H.; Hardis, S.; Harpsøe,
K.; Hessman, F. V.; Hinse, T. C.; Hornstrup, A.; Hundertmark, M.;
Jessen-Hansen, J.; Kerins, E.; Liebig, C.; Lund, M.; Lundkvist, M.;
Mancini, L.; Mathiasen, M.; Penny, M. T.; Rahvar, S.; Ricci, D.;
Sahu, K. C.; Scarpetta, G.; Skottfelt, J.; Snodgrass, C.; Southworth,
J.; Surdej, J.; Tregloan-Reed, J.; Wambsganss, J.; Wertz, O.; Bajek,
D.; Bramich, D. M.; Horne, K.; Ipatov, S.; Steele, I. A.; Tsapras,
Y.; Abe, F.; Bennett, D. P.; Bond, I. A.; Botzler, C. S.; Chote,
P.; Freeman, M.; Fukui, A.; Furusawa, K.; Itow, Y.; Ling, C. H.;
Masuda, K.; Matsubara, Y.; Miyake, N.; Muraki, Y.; Ohnishi, K.;
Rattenbury, N.; Saito, T.; Sullivan, D. J.; Sumi, T.; Suzuki, D.;
Suzuki, K.; Sweatman, W. L.; Takino, S.; Wada, K.; Yock, P. C. M.;
Allen, W.; Batista, V.; Chung, S. -J.; Christie, G.; DePoy, D. L.;
Drummond, J.; Gaudi, B. S.; Gould, A.; Henderson, C.; Jung, Y. -K.;
Koo, J. -R.; Lee, C. -U.; McCormick, J.; McGregor, D.; Muñoz, J. A.;
Natusch, T.; Ngan, H.; Park, H.; Pogge, R. W.; Shin, I. -G.; Yee, J.;
Albrow, M. D.; Bachelet, E.; Beaulieu, J. -P.; Brillant, S.; Caldwell,
J. A. R.; Cassan, A.; Cole, A.; Corrales, E.; Coutures, Ch.; Dieters,
S.; Dominis Prester, D.; Donatowicz, J.; Fouqué, P.; Greenhill, J.;
Kane, S. R.; Kubas, D.; Marquette, J. -B.; Martin, R.; Meintjes, P.;
Menzies, J.; Pollard, K. R.; Williams, A.; Wouters, D.; Zub, M.
2013A&A...552A..70K Altcode: 2013arXiv1303.1184K
<BR /> Aims: We present the analysis of the gravitational microlensing
event OGLE-2011-BLG-0251. This anomalous event was observed by several
survey and follow-up collaborations conducting microlensing observations
towards the Galactic bulge. <BR /> Methods: Based on detailed modelling
of the observed light curve, we find that the lens is composed of
two masses with a mass ratio q = 1.9 × 10<SUP>-3</SUP>. Thanks to
our detection of higher-order effects on the light curve due to the
Earth's orbital motion and the finite size of source, we are able
to measure the mass and distance to the lens unambiguously. <BR />
Results: We find that the lens is made up of a planet of mass 0.53 ±
0.21 M<SUB>J</SUB> orbiting an M dwarf host star with a mass of 0.26 ±
0.11 M<SUB>⊙</SUB>. The planetary system is located at a distance of
2.57 ± 0.61 kpc towards the Galactic centre. The projected separation
of the planet from its host star is d = 1.408 ± 0.019, in units of
the Einstein radius, which corresponds to 2.72 ± 0.75 AU in physical
units. We also identified a competitive model with similar planet and
host star masses, but with a smaller orbital radius of 1.50 ± 0.50
AU. The planet is therefore located beyond the snow line of its host
star, which we estimate to be around ~1-1.5 AU.
---------------------------------------------------------
Title: CARMENES: Blue planets orbiting red dwarfs
Authors: Quirrenbach, A.; Amado, P. J.; Caballero, J. A.; Mandel, H.;
Mundt, R.; Reiners, A.; Ribas, I.; Sánchez Carrasco, M. A.; Seifert,
W.; Azzaro, M.; Galadí, D.; Alonso-Floriano, F. J.; Dreizler, S.;
Montes, D.; Rhode, P.; Stürmer, J.
2013EPJWC..4705006Q Altcode:
The CARMENES (Calar Alto high-Resolution search for M dwarfs with
Exo-earths with Near-infrared and optical Echelle Spectrographs)
consortium, consisting of eleven Spanish and German institutions,
has been established to conduct a radial-velocity survey of M dwarfs
with the 3.5 m telescope at the Calar Alto Observatory. This survey
will target ∼300 M stars, with emphasis on spectral types M4V
and later. The CARMENES instrument is currently under construction;
it consists of two independent échelle spectrographs covering the
wavelength ranges 0.55 …1.05 μm and 0.95 …1.7 μm, respectively,
at a spectral resolution of R = 82,000. The spectrographs are fed
by fibers from the Cassegrain focus of the telescope; calibration is
performed simultaneously with emission-line lamps. The optical benches
of the spectrographs are housed in vacuum tanks and climatic chambers,
which provide the temperature-stabilized environments necessary to
enable a 1 m/s radial velocity precision.
---------------------------------------------------------
Title: Flux and color variations of the doubly imaged quasar UM673
Authors: Ricci, D.; Elyiv, A.; Finet, F.; Wertz, O.; Alsubai, K.;
Anguita, T.; Bozza, V.; Browne, P.; Burgdorf, M.; Calchi Novati,
S.; Dodds, P.; Dominik, M.; Dreizler, S.; Gerner, T.; Glitrup, M.;
Grundahl, F.; Hardis, S.; Harpsøe, K.; Hinse, T. C.; Hornstrup, A.;
Hundertmark, M.; Jørgensen, U. G.; Kains, N.; Kerins, E.; Liebig, C.;
Maier, G.; Mancini, L.; Masi, G.; Mathiasen, M.; Penny, M.; Proft,
S.; Rahvar, S.; Scarpetta, G.; Sahu, K.; Schäfer, S.; Schönebeck,
F.; Schmidt, R.; Skottfelt, J.; Snodgrass, C.; Southworth, J.; Thöne,
C. C.; Wambsganss, J.; Zimmer, F.; Zub, M.; Surdej, J.
2013A&A...551A.104R Altcode: 2013arXiv1302.0766R
<BR /> Aims: With the aim of characterizing the flux and color
variations of the multiple components of the gravitationally lensed
quasar <ASTROBJ>UM673</ASTROBJ> as a function of time, we have
performed multiepoch and multiband photometric observations with the
Danish telescope at the La Silla Observatory. <BR /> Methods: The
observations were carried out in the VRi spectral bands during four
seasons (2008-2011). We reduced the data using the point spread function
photometric technique as well as aperture photometry. <BR /> Results:
Our results show for the brightest lensed component some significant
decrease in flux between the first two seasons (+ 0.09/+ 0.11/+ 0.05
mag) and a subsequent increase during the following ones (- 0.11/-
0.11/- 0.10 mag) in the V/R/i spectral bands, respectively. Comparing
our results with previous studies, we find smaller color variations
between these seasons as compared with previous ones. We also separate
the contribution of the lensing galaxy from that of the fainter and
close lensed component. <P />Based on data collected by MiNDSTEp with
the Danish 1.54 m telescope at the ESO La Silla ObservatoryLight curves
are only available in electronic from at the CDS via anonymous ftp
to <A href="http://cdsarc.u-strasbg.fr">cdsarc.u-strasbg.fr</A>
(<A href="http://130.79.128.5">130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/551/A104">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/551/A104</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: Lensed QSO UM673/Q0142-100 VRi
light curves (Ricci+, 2013)
Authors: Ricci, D.; Elyiv, A.; Finet, F.; Wertz, O.; Alsubai, K.;
Anguita, T.; Bozza, V.; Browne, P.; Burgdorf, M.; Calchi Novati,
S.; Dodds, P.; Dominik, M.; Dreizler, S.; Gerner, T.; Glitrup, M.;
Grundahl, F.; Hardis, S.; Harpsoe, K.; Hinse, T. C.; Hornstrup, A.;
Hundertmark, M.; Jorgensen, U. G.; Kains, N.; Kerins, E.; Liebig, C.;
Maier, G.; Mancini, L.; Masi, G.; Mathiasen, M.; Penny, M.; Proft,
S.; Rahvar, S.; Scarpetta, G.; Sahu, K.; Schaefer, S.; Schoenebeck,
F.; Schmidt, R.; Skottfelt, J.; Snodgrass, C.; Southworth, J.; Thoene,
C. C.; Wambsganss, J.; Zimmer, F.; Zub, M.; Surdej, J.
2013yCat..35510104R Altcode: 2013yCat..35519104R
The Table contains the light curves, in the V, R, and i bands, of the
two lensed components of the quasar UM673. The Table also contains
the light curve of the "B+G" component, obtained by superposing the
flux of the fainter B component and the flux of the lens galaxy. <P
/>(1 data file).
---------------------------------------------------------
Title: MOA-2010-BLG-073L: An M-dwarf with a Substellar Companion at
the Planet/Brown Dwarf Boundary
Authors: Street, R. A.; Choi, J. -Y.; Tsapras, Y.; Han, C.; Furusawa,
K.; Hundertmark, M.; Gould, A.; Sumi, T.; Bond, I. A.; Wouters,
D.; Zellem, R.; Udalski, A.; RoboNet Collaboration; Snodgrass, C.;
Horne, K.; Dominik, M.; Browne, P.; Kains, N.; Bramich, D. M.; Bajek,
D.; Steele, I. A.; Ipatov, S.; MOA Collaboration; Abe, F.; Bennett,
D. P.; Botzler, C. S.; Chote, P.; Freeman, M.; Fukui, A.; Harris, P.;
Itow, Y.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Miyake, N.; Muraki,
Y.; Nagayama, T.; Nishimaya, S.; Ohnishi, K.; Rattenbury, N.; Saito,
To.; Sullivan, D. J.; Suzuki, D.; Sweatman, W. L.; Tristram, P. J.;
Wada, K.; Yock, P. C. M.; OGLE Collaboration; Szymański, M. K.;
Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Poleski, R.; Ulaczyk,
K.; Wyrzykowski, Ł.; μFUN Collaboration; Yee, J.; Dong, S.; Shin,
I. -G.; Lee, C. -U.; Skowron, J.; De Almeida, L. Andrade; DePoy,
D. L.; Gaudi, B. S.; Hung, L. -W.; Jablonski, F.; Kaspi, S.; Klein,
N.; Hwang, K. -H.; Koo, J. -R.; Maoz, D.; Muñoz, J. A.; Pogge, R. W.;
Polishhook, D.; Shporer, A.; McCormick, J.; Christie, G.; Natusch, T.;
Allen, B.; Drummond, J.; Moorhouse, D.; Thornley, G.; Knowler, M.;
Bos, M.; Bolt, G.; PLANET Collaboration; Beaulieu, J. -P.; Albrow,
M. D.; Batista, V.; Brillant, S.; Caldwell, J. A. R.; Cassan, A.;
Cole, A.; Corrales, E.; Coutures, Ch.; Dieters, S.; Dominis Prester,
D.; Donatowicz, J.; Fouqué, P.; Bachelet, E.; Greenhill, J.; Kane,
S. R.; Kubas, D.; Marquette, J. -B.; Martin, R.; Menzies, J.; Pollard,
K. R.; Sahu, K. C.; Wambsganss, J.; Williams, A.; Zub, M.; MiNDSTEp;
Alsubai, K. A.; Bozza, V.; Burgdorf, M. J.; Calchi Novati, S.; Dodds,
P.; Dreizler, S.; Finet, F.; Gerner, T.; Hardis, S.; Harpsøe, K.;
Hessman, F.; Hinse, T. C.; Jørgensen, U. G.; Kerins, E.; Liebig,
C.; Mancini, L.; Mathiasen, M.; Penny, M. T.; Proft, S.; Rahvar, S.;
Ricci, D.; Scarpetta, G.; Schäfer, S.; Schönebeck, F.; Southworth,
J.; Surdej, J.
2013ApJ...763...67S Altcode: 2012arXiv1211.3782S
We present an analysis of the anomalous microlensing event,
MOA-2010-BLG-073, announced by the Microlensing Observations in
Astrophysics survey on 2010 March 18. This event was remarkable
because the source was previously known to be photometrically
variable. Analyzing the pre-event source light curve, we demonstrate
that it is an irregular variable over timescales >200 days. Its
dereddened color, (V - I)<SUB> S, 0</SUB>, is 1.221 ± 0.051 mag,
and from our lens model we derive a source radius of 14.7 ± 1.3 R
<SUB>⊙</SUB>, suggesting that it is a red giant star. We initially
explored a number of purely microlensing models for the event but
found a residual gradient in the data taken prior to and after the
event. This is likely to be due to the variability of the source rather
than part of the lensing event, so we incorporated a slope parameter
in our model in order to derive the true parameters of the lensing
system. We find that the lensing system has a mass ratio of q = 0.0654
± 0.0006. The Einstein crossing time of the event, t <SUB>E</SUB> =
44.3 ± 0.1 days, was sufficiently long that the light curve exhibited
parallax effects. In addition, the source trajectory relative to the
large caustic structure allowed the orbital motion of the lens system
to be detected. Combining the parallax with the Einstein radius, we
were able to derive the distance to the lens, D<SUB>L</SUB> = 2.8 ±
0.4 kpc, and the masses of the lensing objects. The primary of the lens
is an M-dwarf with M <SUB> L, 1</SUB> = 0.16 ± 0.03 M <SUB>⊙</SUB>,
while the companion has M <SUB> L, 2</SUB> = 11.0 ± 2.0 M <SUB>J</SUB>,
putting it in the boundary zone between planets and brown dwarfs.
---------------------------------------------------------
Title: Microlensing Binaries with Candidate Brown Dwarf Companions
Authors: Shin, I. -G.; Han, C.; Gould, A.; Udalski, A.; Sumi, T.;
Dominik, M.; Beaulieu, J. -P.; Tsapras, Y.; Bozza, V.; Szymański,
M. K.; Kubiak, M.; Soszyński, I.; Pietrzyński, G.; Poleski,
R.; Ulaczyk, K.; Pietrukowicz, P.; Kozłowski, S.; Skowron, J.;
Wyrzykowski, Ł.; OGLE Collaboration; Abe, F.; Bennett, D. P.;
Bond, I. A.; Botzler, C. S.; Freeman, M.; Fukui, A.; Furusawa, K.;
Hayashi, F.; Hearnshaw, J. B.; Hosaka, S.; Itow, Y.; Kamiya, K.;
Kilmartin, P. M.; Kobara, S.; Korpela, A.; Lin, W.; Ling, C. H.;
Makita, S.; Masuda, K.; Matsubara, Y.; Miyake, N.; Muraki, Y.;
Nagaya, M.; Nishimoto, K.; Ohnishi, K.; Okumura, T.; Omori, K.;
Perrott, Y. C.; Rattenbury, N.; Saito, To.; Skuljan, L.; Sullivan,
D. J.; Suzuki, D.; Sweatman, W. L.; Tristram, P. J.; Wada, K.; Yock,
P. C. M.; MOA Collaboration; Christie, G. W.; Depoy, D. L.; Dong,
S.; Gal-Yam, A.; Gaudi, B. S.; Hung, L. -W.; Janczak, J.; Kaspi, S.;
Maoz, D.; McCormick, J.; McGregor, D.; Moorhouse, D.; Muñoz, J. A.;
Natusch, T.; Nelson, C.; Pogge, R. W.; Tan, T. -G.; Polishook, D.;
Shvartzvald, Y.; Shporer, A.; Thornley, G.; Malamud, U.; Yee, J. C.;
Choi, J. -Y.; Jung, Y. -K.; Park, H.; Lee, C. -U.; Park, B. -G.; Koo,
J. -R.; μFUN Collaboration; Bajek, D.; Bramich, D. M.; Browne, P.;
Horne, K.; Ipatov, S.; Snodgrass, C.; Steele, I.; Street, R.; Alsubai,
K. A.; Burgdorf, M. J.; Calchi Novati, S.; Dodds, P.; Dreizler, S.;
Fang, X. -S.; Grundahl, F.; Gu, C. -H.; Hardis, S.; Harpsøe, K.;
Hinse, T. C.; Hundertmark, M.; Jessen-Hansen, J.; Jørgensen, U. G.;
Kains, N.; Kerins, E.; Liebig, C.; Lund, M.; Lundkvist, M.; Mancini,
L.; Mathiasen, M.; Hornstrup, A.; Penny, M. T.; Proft, S.; Rahvar, S.;
Ricci, D.; Scarpetta, G.; Skottfelt, J.; Southworth, J.; Surdej, J.;
Tregloan-Reed, J.; Wertz, O.; Zimmer, F.; Albrow, M. D.; Batista, V.;
Brillant, S.; Caldwell, J. A. R.; Calitz, J. J.; Cassan, A.; Cole,
A.; Cook, K. H.; Corrales, E.; Coutures, Ch.; Dieters, S.; Dominis
Prester, D.; Donatowicz, J.; Fouqué, P.; Greenhill, J.; Hill, K.;
Hoffman, M.; Kane, S. R.; Kubas, D.; Marquette, J. -B.; Martin, R.;
Meintjes, P.; Menzies, J.; Pollard, K. R.; Sahu, K. C.; Wambsganss,
J.; Williams, A.; Vinter, C.; Zub, M.
2012ApJ...760..116S Altcode: 2012arXiv1208.2323S
Brown dwarfs are important objects because they may provide a missing
link between stars and planets, two populations that have dramatically
different formation histories. In this paper, we present the candidate
binaries with brown dwarf companions that are found by analyzing
binary microlensing events discovered during the 2004-2011 observation
seasons. Based on the low mass ratio criterion of q < 0.2, we
found seven candidate events: OGLE-2004-BLG-035, OGLE-2004-BLG-039,
OGLE-2007-BLG-006, OGLE-2007-BLG-399/MOA-2007-BLG-334,
MOA-2011-BLG-104/OGLE-2011-BLG-0172, MOA-2011-BLG-149, and
MOA-201-BLG-278/OGLE-2011-BLG-012N. Among them, we are able to confirm
that the companions of the lenses of MOA-2011-BLG-104/OGLE-2011-BLG-0172
and MOA-2011-BLG-149 are brown dwarfs by determining the mass of the
lens based on the simultaneous measurement of the Einstein radius and
the lens parallax. The measured masses of the brown dwarf companions are
0.02 ± 0.01 M <SUB>⊙</SUB> and 0.019 ± 0.002 M <SUB>⊙</SUB> for
MOA-2011-BLG-104/OGLE-2011-BLG-0172 and MOA-2011-BLG-149, respectively,
and both companions are orbiting low-mass M dwarf host stars. More
microlensing brown dwarfs are expected to be detected as the number
of lensing events with well-covered light curves increases with
new-generation searches.
---------------------------------------------------------
Title: TMAP: Tübingen NLTE Model-Atmosphere Package
Authors: Werner, Klaus; Dreizler, Stefan; Rauch, Thomas
2012ascl.soft12015W Altcode:
The Tübingen NLTE Model-Atmosphere Package (TMAP) is a tool to
calculate stellar atmospheres in spherical or plane-parallel geometry
in hydrostatic and radiative equilibrium allowing departures from local
thermodynamic equilibrium (LTE) for the population of atomic levels. It
is based on the Accelerated Lambda Iteration (ALI) method and is able
to account for line blanketing by metals. All elements from hydrogen
to nickel may be included in the calculation with model atoms which
are tailored for the aims of the user.
---------------------------------------------------------
Title: A brown dwarf orbiting an M-dwarf: MOA 2009-BLG-411L
Authors: Bachelet, E.; Fouqué, P.; Han, C.; Gould, A.; Albrow,
M. D.; Beaulieu, J. -P.; Bertin, E.; Bond, I. A.; Christie, G. W.;
Heyrovský, D.; Horne, K.; Jørgensen, U. G.; Maoz, D.; Mathiasen,
M.; Matsunaga, N.; McCormick, J.; Menzies, J.; Nataf, D.; Natusch, T.;
Oi, N.; Renon, N.; Tsapras, Y.; Udalski, A.; Yee, J. C.; Batista, V.;
Bennett, D. P.; Brillant, S.; Caldwell, J. A. R.; Cassan, A.; Cole,
A.; Cook, K. H.; Coutures, C.; Dieters, S.; Dominik, M.; Dominis
Prester, D.; Donatowicz, J.; Greenhill, J.; Kains, N.; Kane, S. R.;
Marquette, J. -B.; Martin, R.; Pollard, K. R.; Sahu, K. C.; Street,
R. A.; Wambsganss, J.; Williams, A.; Zub, M.; PLANET Collaboration;
Bos, M.; Dong, Subo; Drummond, J.; Gaudi, B. S.; Graff, D.; Janczak,
J.; Kaspi, S.; Kozłowski, S.; Lee, C. -U.; Monard, L. A. G.; Muñoz,
J. A.; Park, B. -G.; Pogge, R. W.; Polishook, D.; Shporer, A.; Fun
Collaboration; Abe, F.; Botzler, C. S.; Fukui, A.; Furusawa, K.;
Hearnshaw, J. B.; Itow, Y.; Korpela, A. V.; Ling, C. H.; Masuda,
K.; Matsubara, Y.; Miyake, N.; Muraki, Y.; Ohnishi, K.; Rattenbury,
N. J.; Saito, To.; Sullivan, D.; Sumi, T.; Suzuki, D.; Sweatman,
W. L.; Tristram, P. J.; Wada, K.; MOA Collaboration; Allan, A.; Bode,
M. F.; Bramich, D. M.; Clay, N.; Fraser, S. N.; Hawkins, E.; Kerins,
E.; Lister, T. A.; Mottram, C. J.; Saunders, E. S.; Snodgrass, C.;
Steele, I. A.; Wheatley, P. J.; ROBONET-II Collaboration; Bozza, V.;
Browne, P.; Burgdorf, M. J.; Calchi Novati, S.; Dreizler, S.; Finet,
F.; Glitrup, M.; Grundahl, F.; HarpsøE, K.; Hessman, F. V.; Hinse,
T. C.; Hundertmark, M.; Liebig, C.; Maier, G.; Mancini, L.; Rahvar,
S.; Ricci, D.; Scarpetta, G.; Skottfelt, J.; Southworth, J.; Surdej,
J.; Zimmer, F.; Mindstep Consortium
2012A&A...547A..55B Altcode:
Context. Caustic crossing is the clearest signature of binary lenses
in microlensing. In the present context, this signature is diluted
by the large source star but a detailed analysis has allowed the
companion signal to be extracted. <BR /> Aims: MOA 2009-BLG-411
was detected on August 5, 2009 by the MOA-Collaboration. Alerted as
a high-magnification event, it was sensitive to planets. Suspected
anomalies in the light curve were not confirmed by a real-time model,
but further analysis revealed small deviations from a single lens
extended source fit. <BR /> Methods: Thanks to observations by all
the collaborations, this event was well monitored. We first decided to
characterize the source star properties by using a more refined method
than the classical one: we measure the interstellar absorption along the
line of sight in five different passbands (VIJHK). Secondly, we model
the lightcurve by using the standard technique: make (s,q,α) grids
to look for local minima and refine the results by using a downhill
method (Markov chain Monte Carlo). Finally, we use a Galactic model
to estimate the physical properties of the lens components. <BR />
Results: We find that the source star is a giant G star with radius
9 R<SUB>⊙</SUB>. The grid search gives two local minima, which
correspond to the theoretical degeneracy s ≡ s<SUP>-1</SUP>. We
find that the lens is composed of a brown dwarf secondary of mass
M<SUB>S</SUB> = 0.05 M<SUB>⊙</SUB> orbiting a primary M-star
of mass M<SUB>P</SUB> = 0.18 M<SUB>⊙</SUB>. We also reveal a new
mass-ratio degeneracy for the central caustics of close binaries. <BR />
Conclusions: As far as we are aware, this is the first detection using
the microlensing technique of a binary system in our Galaxy composed of
an M-star and a brown dwarf. <P />Appendix is available in electronic
form at <A href="http://www.aanda.org">http://www.aanda.org</A>
---------------------------------------------------------
Title: High-precision photometry by telescope defocusing -
IV. Confirmation of the huge radius of WASP-17 b
Authors: Southworth, John; Hinse, T. C.; Dominik, M.; Fang, X. -S.;
Harpsøe, K.; Jørgensen, U. G.; Kerins, E.; Liebig, C.; Mancini, L.;
Skottfelt, J.; Anderson, D. R.; Smalley, B.; Tregloan-Reed, J.; Wertz,
O.; Alsubai, K. A.; Bozza, V.; Calchi Novati, S.; Dreizler, S.; Gu,
S. -H.; Hundertmark, M.; Jessen-Hansen, J.; Kains, N.; Kjeldsen, H.;
Lund, M. N.; Lundkvist, M.; Mathiasen, M.; Penny, M. T.; Rahvar, S.;
Ricci, D.; Scarpetta, G.; Snodgrass, C.; Surdej, J.
2012MNRAS.426.1338S Altcode: 2012arXiv1207.5797S
We present photometric observations of four transits in the WASP-17
planetary system, obtained using telescope defocusing techniques and
with scatters reaching 0.5 mmag per point. Our revised orbital period is
4.0 ± 0.6 s longer than previous measurements, a difference of 6.6σ,
and does not support the published detections of orbital eccentricity
in this system. We model the light curves using the JKTEBOP code and
calculate the physical properties of the system by recourse to five
sets of theoretical stellar model predictions. The resulting planetary
radius, R<SUB>b</SUB> = 1.932 ± 0.052 ± 0.010 R<SUB>Jup</SUB>
(statistical and systematic errors, respectively), provides confirmation
that WASP-17 b is the largest planet currently known. All 14 planets
with radii measured to be greater than 1.6 R<SUB>Jup</SUB> are found
around comparatively hot (T<SUB>eff</SUB> > 5900 K) and massive
(M<SUB>A</SUB> > 1.15 M<SUB>⊙</SUB>) stars. Chromospheric activity
indicators are available for eight of these stars, and all imply a low
activity level. The planets have small or zero orbital eccentricities,
so tidal effects struggle to explain their large radii. The observed
dearth of large planets around small stars may be natural but could
also be due to observational biases against deep transits, if these are
mistakenly labelled as false positives and so not followed up. Based
on data collected by MiNDSTEp with the Danish 1.54-m telescope at the
ESO La Silla Observatory.Royal Society University Research Fellow.
---------------------------------------------------------
Title: A New Type of Ambiguity in the Planet and Binary
Interpretations of Central Perturbations of High-magnification
Gravitational Microlensing Events
Authors: Choi, J. -Y.; Shin, I. -G.; Han, C.; Udalski, A.; Sumi, T.;
Gould, A.; Bozza, V.; Dominik, M.; Fouqué, P.; Horne, K.; Szymański,
M. K.; Kubiak, M.; Soszyński, I.; Pietrzyński, G.; Poleski,
R.; Ulaczyk, K.; Pietrukowicz, P.; Kozłowski, S.; Skowron, J.;
Wyrzykowski, Ł.; OGLE Collaboration; Abe, F.; Bennett, D. P.; Bond,
I. A.; Botzler, C. S.; Chote, P.; Freeman, M.; Fukui, A.; Furusawa,
K.; Itow, Y.; Kobara, S.; Ling, C. H.; Masuda, K.; Matsubara, Y.;
Miyake, N.; Muraki, Y.; Ohmori, K.; Ohnishi, K.; Rattenbury, N. J.;
Saito, To.; Sullivan, D. J.; Suzuki, D.; Suzuki, K.; Sweatman,
W. L.; Takino, S.; Tristram, P. J.; Wada, K.; Yock, P. C. M.;
MOA Collaboration; Bramich, D. M.; Snodgrass, C.; Steele, I. A.;
Street, R. A.; Tsapras, Y.; RoboNet Collaboration; Alsubai, K. A.;
Browne, P.; Burgdorf, M. J.; Calchi Novati, S.; Dodds, P.; Dreizler,
S.; Fang, X. -S.; Grundahl, F.; Gu, C. -H.; Hardis, S.; Harpsøe,
K.; Hinse, T. C.; Hornstrup, A.; Hundertmark, M.; Jessen-Hansen,
J.; Jørgensen, U. G.; Kains, N.; Kerins, E.; Liebig, C.; Lund, M.;
Lunkkvist, M.; Mancini, L.; Mathiasen, M.; Penny, M. T.; Rahvar, S.;
Ricci, D.; Scarpetta, G.; Skottfelt, J.; Southworth, J.; Surdej, J.;
Tregloan-Reed, J.; Wambsganss, J.; Wertz, O.; MiNDSTEp Consortium;
Almeida, L. A.; Batista, V.; Christie, G.; DePoy, D. L.; Dong, Subo;
Gaudi, B. S.; Henderson, C.; Jablonski, F.; Lee, C. -U.; McCormick,
J.; McGregor, D.; Moorhouse, D.; Natusch, T.; Ngan, H.; Pogge, R. W.;
Tan, T. -G.; Thornley, G.; Yee, J. C.; μFUN Collaboration; Albrow,
M. D.; Bachelet, E.; Beaulieu, J. -P.; Brillant, S.; Cassan, A.; Cole,
A. A.; Corrales, E.; Coutures, C.; Dieters, S.; Dominis Prester, D.;
Donatowicz, J.; Greenhill, J.; Kubas, D.; Marquette, J. -B.; Menzies,
J. W.; Sahu, K. C.; Zub, M.; PLANET Collaboration
2012ApJ...756...48C Altcode: 2012arXiv1204.4789C
High-magnification microlensing events provide an important channel to
detect planets. Perturbations near the peak of a high-magnification
event can be produced either by a planet or a binary companion. It
is known that central perturbations induced by both types of
companions can be generally distinguished due to the essentially
different magnification pattern around caustics. In this paper, we
present a case of central perturbations for which it is difficult to
distinguish the planetary and binary interpretations. The peak of a
lensing light curve affected by this perturbation appears to be blunt
and flat. For a planetary case, this perturbation occurs when the
source trajectory passes the negative perturbation region behind the
back end of an arrowhead-shaped central caustic. For a binary case,
a similar perturbation occurs for a source trajectory passing through
the negative perturbation region between two cusps of an astroid-shaped
caustic. We demonstrate the degeneracy for two high-magnification events
of OGLE-2011-BLG-0526 and OGLE-2011-BLG-0950/MOA-2011-BLG-336. For
OGLE-2011-BLG-0526, the χ<SUP>2</SUP> difference between the planetary
and binary model is ~3, implying that the degeneracy is very severe. For
OGLE-2011-BLG-0950/MOA-2011-BLG-336, the stellar binary model is
formally excluded with Δχ<SUP>2</SUP> ~ 105 and the planetary model is
preferred. However, it is difficult to claim a planet discovery because
systematic residuals of data from the planetary model are larger than
the difference between the planetary and binary models. Considering
that two events observed during a single season suffer from such a
degeneracy, it is expected that central perturbations experiencing
this type of degeneracy is common.
---------------------------------------------------------
Title: CARMENES. I: instrument and survey overview
Authors: Quirrenbach, Andreas; Amado, Pedro J.; Seifert, Walter;
Sánchez Carrasco, Miguel A.; Mandel, Holger; Caballero, Jose A.;
Mundt, Reinhard; Ribas, Ignasi; Reiners, Ansgar; Abril, Miguel;
Aceituno, Jesus; Alonso-Floriano, Javier; Ammler-von Eiff, Matthias;
Anglada-Escude, Guillem; Antona Jiménez, Regina; Anwand-Heerwart,
Heiko; Barrado y Navascués, David; Becerril, Santiago; Bejar,
Victor; Benitez, Daniel; Cardenas, Concepcion; Claret, Antonio;
Colome, Josep; Cortés-Contreras, Miriam; Czesla, Stefan; del Burgo,
Carlos; Doellinger, Michaela; Dorda, R.; Dreizler, Stefan; Feiz,
Carmen; Fernandez, Matilde; Galadi, David; Garrido, Rafael; González
Hernández, Jonay; Guardia, Josep; Guenther, Eike; de Guindos, Enrique;
Gutiérrez-Soto, Juan; Hagen, Hans J.; Hatzes, Artie; Hauschildt,
Peter; Helmling, Jens; Henning, Thomas; Herrero, Enrique; Huber,
Armin; Huber, Klaus; Jeffers, Sandra; Joergens, Viki; de Juan,
Enrique; Kehr, M.; Klutsch, Alexis; Kürster, Martin; Lalitha, S.;
Laun, Werner; Lemke, Ulrike; Lenzen, Rainer; Lizon, Jean-Louis; López
del Fresno, Mauro; López-Morales, Mercedes; López-Santiago, Javier;
Mall, Ulrich; Martin, Eduardo; Martín-Ruiz, Susana; Mirabet, Eduard;
Montes, David; Morales, Juan Carlos; Morales Muñoz, Rafael; Moya,
Andres; Naranjo, Vianak; Oreiro, Raquel; Pérez Medialdea, David;
Pluto, Michael; Rabaza, Ovidio; Ramon, Alejandro; Rebolo, Rafael;
Reffert, Sabine; Rhode, Petra; Rix, Hans-Walter; Rodler, Florian;
Rodríguez, Eloy; Rodríguez López, Cristina; Rodríguez Pérez,
Emilio; Rodriguez Trinidad, A.; Rohloff, Ralf-Reiner; Sánchez-Blanco,
Ernesto; Sanz-Forcada, Jorge; Schäfer, Sebastian; Schiller, Jörg;
Schmidt, Christof; Schmitt, Jürgen; Solano, Enrique; Stahl, Otmar;
Storz, Clemens; Stürmer, Julian; Suarez, Juan Carlos; Thiele, Ulrich;
Ulbrich, Rainer; Vidal-Dasilva, Manuela; Wagner, Karl; Winkler,
Johannes; Xu, Wenli; Zapatero Osorio, Maria Rosa; Zechmeister, Mathias
2012SPIE.8446E..0RQ Altcode:
CARMENES (Calar Alto high-Resolution search for M dwarfs with
Exo-earths with Near-infrared and optical Echelle Spectrographs)
is a next-generation instrument for the 3.5m telescope at the Calar
Alto Observatory, built by a consortium of eleven Spanish and German
institutions. The CARMENES instrument consists of two separate
échelle spectrographs covering the wavelength range from 0.55 μm
to 1.7 μm at a spectral resolution of R = 82, 000, fed by fibers
from the Cassegrain focus of the telescope. Both spectrographs are
housed in temperature-stabilized vacuum tanks, to enable a long-term
1 m/s radial velocity precision employing a simultaneous calibration
with Th-Ne and U-Ne emission line lamps. CARMENES has been optimized
for a search for terrestrial planets in the habitable zones (HZs)
of low-mass stars, which may well provide our first chance to study
environments capable of supporting the development of life outside the
Solar System. With its unique combination of optical and near-infrared
´echelle spectrographs, CARMENES will provide better sensitivity for
the detection of low-mass planets than any comparable instrument, and
a powerful tool for discriminating between genuine planet detections
and false positives caused by stellar activity. The CARMENES survey
will target 300 M dwarfs in the 2014 to 2018 time frame.
---------------------------------------------------------
Title: CARMENES. II: optical and opto-mechanical design
Authors: Seifert, W.; Sánchez Carrasco, M. A.; Xu, W.; Cárdenas,
M. C.; Sánchez-Blanco, E.; Becerril, S.; Feiz, C.; Ramón, A.;
Dreizler, S.; Rohde, P.; Quirrenbach, A.; Amado, P. J.; Ribas, I.;
Reiners, A.; Mandel, H.; Caballero, J. A.
2012SPIE.8446E..33S Altcode:
CARMENES is a fiber-fed high-resolution échelle spectrograph for the
Calar Alto 3.5m telescope. The instrument is built by a German-Spanish
consortium under the lead of the Landessternwarte Heidelberg. The
search for planets around M dwarfs with a radial velocity accuracy of
1 m/s is the main focus of the planned science. Two channels, one for
the visible, another for the near-infrared, will allow observations
in the complete wavelength range from 550 to 1700 nm. To ensure the
stability, the instrument is working in vacuum in a thermally controlled
environment. The optical design of both channels of the instrument
and the front-end, as well as the opto-mechanical design, are described.
---------------------------------------------------------
Title: Characterizing Low-mass Binaries from Observation of
Long-timescale Caustic-crossing Gravitational Microlensing Events
Authors: Shin, I. -G.; Han, C.; Choi, J. -Y.; Udalski, A.; Sumi, T.;
Gould, A.; Bozza, V.; Dominik, M.; Fouqué, P.; Horne, K.; Szymański,
M. K.; Kubiak, M.; Soszyński, I.; Pietrzyński, G.; Poleski,
R.; Ulaczyk, K.; Pietrukowicz, P.; Kozłowski, S.; Skowron, J.;
Wyrzykowski, Ł.; OGLE Collaboration; Abe, F.; Bennett, D. P.; Bond,
I. A.; Botzler, C. S.; Chote, P.; Freeman, M.; Fukui, A.; Furusawa, K.;
Itow, Y.; Kobara, S.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Miyake,
N.; Muraki, Y.; Ohmori, K.; Ohnishi, K.; Rattenbury, N. J.; Saito,
To.; Sullivan, D. J.; Suzuki, D.; Suzuki, K.; Sweatman, W. L.; Takino,
S.; Tristram, P. J.; Wada, K.; Yock, P. C. M.; MOA Collaboration;
Bramich, D. M.; Snodgrass, C.; Steele, I. A.; Street, R. A.; Tsapras,
Y.; RoboNet Collaboration; Alsubai, K. A.; Browne, P.; Burgdorf,
M. J.; Calchi Novati, S.; Dodds, P.; Dreizler, S.; Fang, X. -S.;
Grundahl, F.; Gu, C. -H.; Hardis, S.; Harpsøe, K.; Hinse, T. C.;
Hornstrup, A.; Hundertmark, M.; Jessen-Hansen, J.; Jørgensen, U. G.;
Kains, N.; Kerins, E.; Liebig, C.; Lund, M.; Lunkkvist, M.; Mancini,
L.; Mathiasen, M.; Penny, M. T.; Rahvar, S.; Ricci, D.; Scarpetta,
G.; Skottfelt, J.; Southworth, J.; Surdej, J.; Tregloan-Reed, J.;
Wambsganss, J.; Wertz, O.; MiNDSTEp Consortium; Almeida, L. A.;
Batista, V.; Christie, G.; DePoy, D. L.; Dong, Subo; Gaudi, B. S.;
Henderson, C.; Jablonski, F.; Lee, C. -U.; McCormick, J.; McGregor,
D.; Moorhouse, D.; Natusch, T.; Ngan, H.; Park, S. -Y.; Pogge, R. W.;
Tan, T. -G.; Thornley, G.; Yee, J. C.; μFUN Collaboration; Albrow,
M. D.; Bachelet, E.; Beaulieu, J. -P.; Brillant, S.; Cassan, A.; Cole,
A. A.; Corrales, E.; Coutures, C.; Dieters, S.; Dominis Prester, D.;
Donatowicz, J.; Greenhill, J.; Kubas, D.; Marquette, J. -B.; Menzies,
J. W.; Sahu, K. C.; Zub, M.; PLANET Collaboration
2012ApJ...755...91S Altcode: 2012arXiv1204.2869S
Despite the astrophysical importance of binary star systems,
detections are limited to those located in small ranges of separations,
distances, and masses and thus it is necessary to use a variety of
observational techniques for a complete view of stellar multiplicity
across a broad range of physical parameters. In this paper, we
report the detections and measurements of two binaries discovered
from observations of microlensing events MOA-2011-BLG-090 and
OGLE-2011-BLG-0417. Determinations of the binary masses are possible by
simultaneously measuring the Einstein radius and the lens parallax. The
measured masses of the binary components are 0.43 M <SUB>⊙</SUB> and
0.39 M <SUB>⊙</SUB> for MOA-2011-BLG-090 and 0.57 M <SUB>⊙</SUB>
and 0.17 M <SUB>⊙</SUB> for OGLE-2011-BLG-0417 and thus both lens
components of MOA-2011-BLG-090 and one component of OGLE-2011-BLG-0417
are M dwarfs, demonstrating the usefulness of microlensing in
detecting binaries composed of low-mass components. From modeling of
the light curves considering full Keplerian motion of the lens, we
also measure the orbital parameters of the binaries. The blended light
of OGLE-2011-BLG-0417 comes very likely from the lens itself, making
it possible to check the microlensing orbital solution by follow-up
radial-velocity observation. For both events, the caustic-crossing parts
of the light curves, which are critical for determining the physical
lens parameters, were resolved by high-cadence survey observations
and thus it is expected that the number of microlensing binaries with
measured physical parameters will increase in the future.
---------------------------------------------------------
Title: MOA 2010-BLG-477Lb: Constraining the Mass of a Microlensing
Planet from Microlensing Parallax, Orbital Motion, and Detection of
Blended Light
Authors: Bachelet, E.; Shin, I. -G.; Han, C.; Fouqué, P.; Gould, A.;
Menzies, J. W.; Beaulieu, J. -P.; Bennett, D. P.; Bond, I. A.; Dong,
Subo; Heyrovský, D.; Marquette, J. -B.; Marshall, J.; Skowron, J.;
Street, R. A.; Sumi, T.; Udalski, A.; Abe, L.; Agabi, K.; Albrow,
M. D.; Allen, W.; Bertin, E.; Bos, M.; Bramich, D. M.; Chavez, J.;
Christie, G. W.; Cole, A. A.; Crouzet, N.; Dieters, S.; Dominik, M.;
Drummond, J.; Greenhill, J.; Guillot, T.; Henderson, C. B.; Hessman,
F. V.; Horne, K.; Hundertmark, M.; Johnson, J. A.; Jørgensen, U. G.;
Kandori, R.; Liebig, C.; Mékarnia, D.; McCormick, J.; Moorhouse,
D.; Nagayama, T.; Nataf, D.; Natusch, T.; Nishiyama, S.; Rivet,
J. -P.; Sahu, K. C.; Shvartzvald, Y.; Thornley, G.; Tomczak, A. R.;
Tsapras, Y.; Yee, J. C.; Batista, V.; Bennett, C. S.; Brillant, S.;
Caldwell, J. A. R.; Cassan, A.; Corrales, E.; Coutures, C.; Dominis
Prester, D.; Donatowicz, J.; Kubas, D.; Martin, R.; Williams, A.;
Zub, M.; PLANET Collaboration; de Almeida, L. Andrade; DePoy, D. L.;
Gaudi, B. S.; Hung, L. -W.; Jablonski, F.; Kaspi, S.; Klein, N.;
Lee, C. -U.; Lee, Y.; Koo, J. -R.; Maoz, D.; Muñoz, J. A.; Pogge,
R. W.; Polishook, D.; Shporer, A.; μFUN Collaboration; Abe, F.;
Botzler, C. S.; Chote, P.; Freeman, M.; Fukui, A.; Furusawa, K.;
Harris, P.; Itow, Y.; Kobara, S.; Ling, C. H.; Masuda, K.; Matsubara,
Y.; Miyake, N.; Ohmori, K.; Ohnishi, K.; Rattenbury, N. J.; Saito,
To.; Sullivan, D. J.; Suzuki, D.; Sweatman, W. L.; Tristram, P. J.;
Wada, K.; Yock, P. C. M.; MOA Collaboration; Szymański, M. K.;
Soszyński, I.; Kubiak, M.; Poleski, R.; Ulaczyk, K.; Pietrzyński,
G.; Wyrzykowski, Ł.; OGLE Collaboration; Kains, N.; Snodgrass, C.;
Steele, I. A.; RoboNet Collaboration; Alsubai, K. A.; Bozza, V.;
Browne, P.; Burgdorf, M. J.; Calchi Novati, S.; Dodds, P.; Dreizler,
S.; Finet, F.; Gerner, T.; Hardis, S.; Harpsøe, K.; Hinse, T. C.;
Kerins, E.; Mancini, L.; Mathiasen, M.; Penny, M. T.; Proft, S.;
Rahvar, S.; Ricci, D.; Scarpetta, G.; Schäfer, S.; Schönebeck, F.;
Southworth, J.; Surdej, J.; Wambsganss, J.; MiNDSTEp Consortium
2012ApJ...754...73B Altcode: 2012arXiv1205.6323B
Microlensing detections of cool planets are important for the
construction of an unbiased sample to estimate the frequency of planets
beyond the snow line, which is where giant planets are thought to
form according to the core accretion theory of planet formation. In
this paper, we report the discovery of a giant planet detected from
the analysis of the light curve of a high-magnification microlensing
event MOA 2010-BLG-477. The measured planet-star mass ratio is q =
(2.181 ± 0.004) × 10<SUP>-3</SUP> and the projected separation is
s = 1.1228 ± 0.0006 in units of the Einstein radius. The angular
Einstein radius is unusually large θ<SUB>E</SUB> = 1.38 ± 0.11
mas. Combining this measurement with constraints on the "microlens
parallax" and the lens flux, we can only limit the host mass to
the range 0.13 < M/M <SUB>⊙</SUB> < 1.0. In this particular
case, the strong degeneracy between microlensing parallax and planet
orbital motion prevents us from measuring more accurate host and planet
masses. However, we find that adding Bayesian priors from two effects
(Galactic model and Keplerian orbit) each independently favors the
upper end of this mass range, yielding star and planet masses of M
<SUB>*</SUB> = 0.67<SUP>+0.33</SUP> <SUB>- 0.13</SUB> M <SUB>⊙</SUB>
and m<SUB>p</SUB> = 1.5<SUP>+0.8</SUP> <SUB>- 0.3</SUB> M <SUB>JUP</SUB>
at a distance of D = 2.3 ± 0.6 kpc, and with a semi-major axis of
a = 2<SUP>+3</SUP> <SUB>- 1</SUB> AU. Finally, we show that the lens
mass can be determined from future high-resolution near-IR adaptive
optics observations independently from two effects, photometric and
astrometric.
---------------------------------------------------------
Title: The quest for companions to post-common envelope
binaries. III. A reexamination of <ASTROBJ>HW Virginis</ASTROBJ>
Authors: Beuermann, K.; Dreizler, S.; Hessman, F. V.; Deller, J.
2012A&A...543A.138B Altcode: 2012arXiv1206.3080B
We report new mid-eclipse times of the short-period sdB/dM binary
<ASTROBJ>HW Virginis</ASTROBJ>, which differ substantially from the
times predicted by a previous model. The proposed orbits of the two
planets in that model are found to be unstable. We present a new
secularly stable solution, which involves two companions orbiting
<ASTROBJ>HW Vir</ASTROBJ> with periods of 12.7 yr and 55 ± 15 yr. For
orbits coplanar with the binary, the inner companion is a giant planet
with mass M<SUB>3</SUB> sin i<SUB>3</SUB> ≃ 14 M<SUB>Jup</SUB> and the
outer one a brown dwarf or low-mass star with a mass of M<SUB>4</SUB>
sin i<SUB>4</SUB> = 30-120 M<SUB>Jup</SUB>. Using the mercury6 code, we
find that such a system would be stable over more than 10<SUP>7</SUP>
yr, in spite of the sizeable interaction. Our model fits the observed
eclipse-time variations by the light-travel time effect alone, without
invoking any additional process, and provides support for the planetary
hypothesis of the eclipse-time variations in close binaries. The
signature of non-Keplerian orbits may be visible in the data.
---------------------------------------------------------
Title: Characterizing Lenses and Lensed Stars of High-magnification
Single-lens Gravitational Microlensing Events with Lenses Passing
over Source Stars
Authors: Choi, J. -Y.; Shin, I. -G.; Park, S. -Y.; Han, C.; Gould,
A.; Sumi, T.; Udalski, A.; Beaulieu, J. -P.; Street, R.; Dominik, M.;
Allen, W.; Almeida, L. A.; Bos, M.; Christie, G. W.; Depoy, D. L.;
Dong, S.; Drummond, J.; Gal-Yam, A.; Gaudi, B. S.; Henderson, C. B.;
Hung, L. -W.; Jablonski, F.; Janczak, J.; Lee, C. -U.; Mallia, F.;
Maury, A.; McCormick, J.; McGregor, D.; Monard, L. A. G.; Moorhouse,
D.; Muñoz, J. A.; Natusch, T.; Nelson, C.; Park, B. -G.; Pogge, R. W.;
"TG" Tan, T. -G.; Thornley, G.; Yee, J. C.; μFUN Collaboration; Abe,
F.; Barnard, E.; Baudry, J.; Bennett, D. P.; Bond, I. A.; Botzler,
C. S.; Freeman, M.; Fukui, A.; Furusawa, K.; Hayashi, F.; Hearnshaw,
J. B.; Hosaka, S.; Itow, Y.; Kamiya, K.; Kilmartin, P. M.; Kobara, S.;
Korpela, A.; Lin, W.; Ling, C. H.; Makita, S.; Masuda, K.; Matsubara,
Y.; Miyake, N.; Muraki, Y.; Nagaya, M.; Nishimoto, K.; Ohnishi, K.;
Okumura, T.; Omori, K.; Perrott, Y. C.; Rattenbury, N.; Saito, To.;
Skuljan, L.; Sullivan, D. J.; Suzuki, D.; Suzuki, K.; Sweatman,
W. L.; Takino, S.; Tristram, P. J.; Wada, K.; Yock, P. C. M.;
MOA Collaboration; Szymański, M. K.; Kubiak, M.; Pietrzyński,
G.; Soszyński, I.; Poleski, R.; Ulaczyk, K.; Wyrzykowski, Ł.;
Kozłowski, S.; Pietrukowicz, P.; OGLE Collaboration; Albrow, M. D.;
Bachelet, E.; Batista, V.; Bennett, C. S.; Bowens-Rubin, R.; Brillant,
S.; Cassan, A.; Cole, A.; Corrales, E.; Coutures, Ch.; Dieters, S.;
Dominis Prester, D.; Donatowicz, J.; Fouqué, P.; Greenhill, J.;
Kane, S. R.; Menzies, J.; Sahu, K. C.; Wambsganss, J.; Williams, A.;
Zub, M.; PLANET Collaboration; Allan, A.; Bramich, D. M.; Browne, P.;
Clay, N.; Fraser, S.; Horne, K.; Kains, N.; Mottram, C.; Snodgrass,
C.; Steele, I.; Tsapras, Y.; RoboNet Collaboration; Alsubai, K. A.;
Bozza, V.; Burgdorf, M. J.; Calchi Novati, S.; Dodds, P.; Dreizler,
S.; Finet, F.; Gerner, T.; Glitrup, M.; Grundahl, F.; Hardis, S.;
Harpsøe, K.; Hinse, T. C.; Hundertmark, M.; Jørgensen, U. G.;
Kerins, E.; Liebig, C.; Maier, G.; Mancini, L.; Mathiasen, M.; Penny,
M. T.; Proft, S.; Rahvar, S.; Ricci, D.; Scarpetta, G.; Schäfer, S.;
Schönebeck, F.; Skottfelt, J.; Surdej, J.; Southworth, J.; Zimmer,
F.; MiNDSTEp Consortium
2012ApJ...751...41C Altcode: 2011arXiv1111.4032C
We present the analysis of the light curves of nine high-magnification
single-lens gravitational microlensing events with lenses passing
over source stars, including OGLE-2004-BLG-254, MOA-2007-BLG-176,
MOA-2007-BLG-233/OGLE-2007-BLG-302, MOA-2009-BLG-174, MOA-2010-BLG-436,
MOA-2011-BLG-093, MOA-2011-BLG-274, OGLE-2011-BLG-0990/MOA-2011-BLG-300,
and OGLE-2011-BLG-1101/MOA-2011-BLG-325. For all of the events, we
measure the linear limb-darkening coefficients of the surface brightness
profile of source stars by measuring the deviation of the light curves
near the peak affected by the finite-source effect. For seven events,
we measure the Einstein radii and the lens-source relative proper
motions. Among them, five events are found to have Einstein radii
of less than 0.2 mas, making the lenses very low mass star or brown
dwarf candidates. For MOA-2011-BLG-274, especially, the small Einstein
radius of θ<SUB>E</SUB> ~ 0.08 mas combined with the short timescale
of t <SUB>E</SUB> ~ 2.7 days suggests the possibility that the lens
is a free-floating planet. For MOA-2009-BLG-174, we measure the lens
parallax and thus uniquely determine the physical parameters of the
lens. We also find that the measured lens mass of ~0.84 M <SUB>⊙</SUB>
is consistent with that of a star blended with the source, suggesting
that the blend is likely to be the lens. Although we did not find
planetary signals for any of the events, we provide exclusion diagrams
showing the confidence levels excluding the existence of a planet as
a function of the separation and mass ratio.
---------------------------------------------------------
Title: KIC 4247791: a SB4 system with two eclipsing binaries (2EBs). A
quadruple system?
Authors: Lehmann, H.; Zechmeister, M.; Dreizler, S.; Schuh, S.;
Kanzler, R.
2012A&A...541A.105L Altcode: 2012arXiv1202.6552L
Context. KIC 4247791 is an eclipsing binary observed by the Kepler
satellite mission. <BR /> Aims: We wish to determine the nature of
its components and in particular the origin of a shallow dip in its
Kepler light curve that previous investigations have been unable to
explain in a unique way. <BR /> Methods: We analyse newly obtained
high-resolution spectra of the star using synthetic spectra based
on atmosphere models, derive the radial velocities of the stellar
components from cross-correlation with a synthetic template, and
calculate the orbital solution. We use the JKTEBOP program to model the
Kepler light curve of KIC 4247791. <BR /> Results: We find KIC 4247791
to be a SB4 star. The radial velocity variations of its four components
can be explained by two separate eclipsing binaries. In contradiction
to previous photometric findings, we show that the observed composite
spectrum as well as the derived masses of all four of its components
correspond to spectral type F. <BR /> Conclusions: The observed small
dip in the light curve is not caused by a transit-like phenomenon but
by the eclipses of the second binary system. We find evidence that
KIC 4247791 might belong to the very rare hierarchical SB4 systems
with two eclipsing binaries. <P />Based on observations with the 2-m
Alfred-Jensch-Telescope of the Thüringer Landessternwarte Tautenburg.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Planetary transit candidates in
CoRoT LRa01 field (Carone+, 2012)
Authors: Carone, L.; Gandolfi, D.; Cabrera, J.; Hatzes, A. P.; Deeg,
H. J.; Csizmadia, Sz.; Paetzold, M.; Weingrill, J.; Aigrain, S.;
Alonso, R.; Alapini, A.; Almenara, J. -M.; Auvergne, M.; Baglin, A.;
Barge, P.; Bonomo, A. S.; Borde, P.; Bouchy, F.; Bruntt, H.; Carpano,
S.; Cochran, W. D.; Deleuil, M.; Diaz, R. F.; Dreizler, S.; Dvorak, R.;
Eisloeffel, J.; Eigmueller, P.; Endl, M.; Erikson, A.; Ferraz-Mello,
S.; Fridlund, M.; Gazzano, J. -C.; Gibson, N.; Gillon, M.; Gondoin,
P.; Grziwa, S.; Guenther, E. W.; Guillot, T.; Hartmann, M.; Havel, M.;
Hebrard, G.; Jorda, L.; Kabath, P.; Leger, A.; Llebaria, A.; Lammer,
H.; Lovis, C.; MacQueen, P. J.; Mayor, M.; Mazeh, T.; Moutou, C.;
Nortmann, L.; Ofir, A.; Ollivier, M.; Parviainen, H.; Pepe, F.; Pont,
F.; Queloz, D.; Rabus, M.; Rauer, H.; Regulo, C.; Renner, S.; de La,
Reza R.; Rouan, D.; Santerne, A.; Samuel, B.; Schneider, J.; Shporer,
A.; Stecklum, B.; Tal-Or, L.; Tingley, B.; Udry, S.; Wuchterl, G.
2012yCat..35380112C Altcode: 2012yCat..35389112C
We present the list of planetary transit candidates from the CoRoT
LRa01 star field in the Monoceros constellation toward the Galactic
anti-center direction. The CoRoT observations of LRa01 lasted from
24 October 2007 to 3 March 2008. <P />We acquired and analyzed 7470
chromatic and 3938 monochromatic lightcurves. Instrumental noise
and stellar variability were treated with several filtering tools by
different teams from the CoRoT community. Different transit search
algorithms were applied to the lightcurves. <P />(4 data files).
---------------------------------------------------------
Title: The quest for companions to post-common envelope
binaries. II. NSVS14256825 and HS0705+6700
Authors: Beuermann, K.; Breitenstein, P.; Debski, B.; Diese, J.;
Dubovsky, P. A.; Dreizler, S.; Hessman, F. V.; Hornoch, K.; Husser,
T. -O.; Pojmanski, G.; Wolf, M.; Woźniak, P. R.; Zasche, P.; Denk,
B.; Langer, M.; Wagner, C.; Wahrenberg, D.; Bollmann, T.; Habermann,
F. N.; Haustovich, N.; Lauser, M.; Liebing, F.; Niederstadt, F.
2012A&A...540A...8B Altcode: 2012arXiv1202.5990B
We report new mid-eclipse times of the two close binaries NSVS14256825
and HS0705+6700, harboring an sdB primary and a low-mass main-sequence
secondary. Both objects display clear variations in their measured
orbital period, which can be explained by the action of a third object
orbiting the binary. If this interpretation is correct, the third
object in NSVS14256825 is a giant planet with a mass of roughly 12
M<SUB>Jup</SUB>. For HS0705+6700, we provide evidence that strengthens
the case for the suggested periodic nature of the eclipse time variation
and reduces the uncertainties in the parameters of the brown dwarf
implied by that model. The derived period is 8.4 yr and the mass is
31 M<SUB>Jup</SUB>, if the orbit is coplanar with the binary. This
research is part of the PlanetFinders project, an ongoing collaboration
between professional astronomers and student groups at high schools.
---------------------------------------------------------
Title: News of the MUSE
Authors: Bacon, R.; Accardo, M.; Adjali, L.; Anwand, H.; Bauer, S. -M.;
Blaizot, J.; Boudon, D.; Brinchmann, J.; Brotons, L.; Caillier, P.;
Capoani, L.; Carollo, M.; Comin, M.; Contini, T.; Cumani, C.; Daguis,
E.; Deiries, S.; Delabre, B.; Dreizler, S.; Dubois, J. -P.; Dupieux,
M.; Dupuy, C.; Emsellem, E.; Fleischmann, A.; François, M.; Gallou,
G.; Gharsa, T.; Girard, N.; Glindemann, A.; Guiderdoni, B.; Hahn,
T.; Hansali, G.; Hofmann, D.; Jarno, A.; Kelz, A.; Kiekebusch, M.;
Knudstrup, J.; Koehler, C.; Kollatschny, W.; Kosmalski, J.; Laurent,
F.; Le Floch, M.; Lilly, S.; Lizon à L'Allemand, J. -L.; Loupias,
M.; Manescau, A.; Monstein, C.; Nicklas, H.; Niemeyer, J.; Olaya,
J. -C.; Palsa, R.; Parès, L.; Pasquini, L.; Pécontal-Rousset, A.;
Pello, R.; Petit, C.; Piqueras, L.; Popow, E.; Reiss, R.; Remillieux,
A.; Renault, E.; Rhode, P.; Richard, J.; Roth, J.; Rupprecht, G.;
Schaye, J.; Slezak, E.; Soucail, G.; Steinmetz, M.; Streicher, O.;
Stuik, R.; Valentin, H.; Vernet, J.; Weilbacher, P.; Wisotzki, L.;
Yerle, N.; Zins, G.
2012Msngr.147....4B Altcode:
We report on progress of the Multi Unit Spectroscopic Explorer (MUSE),
a second generation VLT panoramic integral field spectrograph. MUSE
is now in its final phase of integration, testing and validation in
Europe. The instrument is described and some results of its measured
performance are shown.
---------------------------------------------------------
Title: Microlensing Binaries Discovered through High-magnification
Channel
Authors: Shin, I. -G.; Choi, J. -Y.; Park, S. -Y.; Han, C.; Gould, A.;
Sumi, T.; Udalski, A.; Beaulieu, J. -P.; Dominik, M.; Allen, W.; Bos,
M.; Christie, G. W.; Depoy, D. L.; Dong, S.; Drummond, J.; Gal-Yam,
A.; Gaudi, B. S.; Hung, L. -W.; Janczak, J.; Kaspi, S.; Lee, C. -U.;
Mallia, F.; Maoz, D.; Maury, A.; McCormick, J.; Monard, L. A. G.;
Moorhouse, D.; Muñoz, J. A.; Natusch, T.; Nelson, C.; Park, B. -G.;
Pogge, R. W.; Polishook, D.; Shvartzvald, Y.; Shporer, A.; Thornley,
G.; Yee, J. C.; μFUN Collaboration; Abe, F.; Bennett, D. P.; Bond,
I. A.; Botzler, C. S.; Fukui, A.; Furusawa, K.; Hayashi, F.; Hearnshaw,
J. B.; Hosaka, S.; Itow, Y.; Kamiya, K.; Kilmartin, P. M.; Kobara, S.;
Korpela, A.; Lin, W.; Ling, C. H.; Makita, S.; Masuda, K.; Matsubara,
Y.; Miyake, N.; Muraki, Y.; Nagaya, M.; Nishimoto, K.; Ohnishi, K.;
Okumura, T.; Omori, K.; Perrott, Y. C.; Rattenbury, N.; Saito, To.;
Skuljan, L.; Sullivan, D. J.; Suzuki, D.; Sweatman, W. L.; Tristram,
P. J.; Wada, K.; Yock, P. C. M.; MOA Collaboration; Szymański,
M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Poleski, R.;
Ulaczyk, K.; Wyrzykowski, Ł.; Kozłowski, S.; Pietrukowicz, P.; OGLE
Collaboration; Albrow, M. D.; Batista, V.; Bramich, D. M.; Brillant,
S.; Caldwell, J. A. R.; Calitz, J. J.; Cassan, A.; Cole, A.; Cook,
K. H.; Corrales, E.; Coutures, Ch.; Dieters, S.; Dominis Prester, D.;
Donatowicz, J.; Fouqué, P.; Greenhill, J.; Hoffman, M.; Jørgensen,
U. G.; Kane, S. R.; Kubas, D.; Marquette, J. -B.; Martin, R.; Meintjes,
P.; Menzies, J.; Pollard, K. R.; Sahu, K. C.; Wambsganss, J.; Williams,
A.; Vinter, C.; Zub, M.; PLANET Collaboration; Allan, A.; Browne, P.;
Horne, K.; Snodgrass, C.; Steele, I.; Street, R.; Tsapras, Y.; RoboNet
Collaboration; Alsubai, K. A.; Bozza, V.; Browne, P.; Burgdorf, M. J.;
Calchi Novati, S.; Dodds, P.; Dreizler, S.; Finet, F.; Gerner, T.;
Glitrup, M.; Grundahl, F.; Hardis, S.; Harpsøe, K.; Hessman, F. V.;
Hinse, T. C.; Hundertmark, M.; Kains, N.; Kerins, E.; Liebig, C.;
Maier, G.; Mancini, L.; Mathiasen, M.; Penny, M. T.; Proft, S.; Rahvar,
S.; Ricci, D.; Scarpetta, G.; Schäfer, S.; Schönebeck, F.; Skottfelt,
J.; Surdej, J.; Southworth, J.; Zimmer, F.; MiNDSTEp Consortium
2012ApJ...746..127S Altcode: 2011arXiv1109.3295S
Microlensing can provide a useful tool to probe binary distributions
down to low-mass limits of binary companions. In this paper, we analyze
the light curves of eight binary-lensing events detected through the
channel of high-magnification events during the seasons from 2007 to
2010. The perturbations, which are confined near the peak of the light
curves, can be easily distinguished from the central perturbations
caused by planets. However, the degeneracy between close and wide binary
solutions cannot be resolved with a 3σ confidence level for three
events, implying that the degeneracy would be an important obstacle
in studying binary distributions. The dependence of the degeneracy on
the lensing parameters is consistent with a theoretical prediction
that the degeneracy becomes severe as the binary separation and the
mass ratio deviate from the values of resonant caustics. The measured
mass ratio of the event OGLE-2008-BLG-510/MOA-2008-BLG-369 is q ~ 0.1,
making the companion of the lens a strong brown dwarf candidate.
---------------------------------------------------------
Title: The quest for companions to post-common envelope
binaries. I. Searching a sample of stars from the CSS and SDSS
Authors: Backhaus, U.; Bauer, S.; Beuermann, K.; Diese, J.; Dreizler,
S.; Hessman, F. V.; Husser, T. -O.; Klapdohr, K. -H.; Möllmanns, J.;
Schünecke, R.; Dette, J.; Dubbert, J.; Miosga, T.; Rochus Vogel,
A. L.; Simons, S.; Biriuk, S.; Debrah, M.; Griemens, M.; Hahn, A.;
Möller, T.; Pawlowski, M.; Schweizer, M.; Speck, A. -L.; Zapros, C.;
Bollmann, T.; Habermann, F. N.; Haustovich, N.; Lauser, M.; Liebing,
F.; Niederstadt, F.; Hoppen, K.; Kindermann, D.; Küppers, F.; Rauch,
B.; Althoff, F.; Horstmann, M.; Kellerman, J. N.; Kietz, R.; Nienaber,
T.; Sauer, M.; Secci, A.; Wüllner, L.
2012A&A...538A..84B Altcode: 2012arXiv1201.2098B
As part of an ongoing collaboration between student groups at high
schools and professional astronomers, we have searched for the presence
of circum-binary planets in a bona-fide unbiased sample of twelve
post-common envelope binaries (PCEBs) from the Catalina Sky Survey
(CSS) and the Sloan Digital Sky Survey (SDSS). Although the present
ephemerides are significantly more accurate than previous ones, we
find no clear evidence for orbital period variations between 2005 and
2011 or during the 2011 observing season. The sparse long-term coverage
still permits O-C variations with a period of years and an amplitude of
tens of seconds, as found in other systems. Our observations provide the
basis for future inferences about the frequency with which planet-sized
or brown-dwarf companions have either formed in these evolved systems
or survived the common envelope (CE) phase.
---------------------------------------------------------
Title: Planetary transit candidates in the CoRoT LRa01 field
Authors: Carone, L.; Gandolfi, D.; Cabrera, J.; Hatzes, A. P.; Deeg,
H. J.; Csizmadia, Sz.; Pätzold, M.; Weingrill, J.; Aigrain, S.;
Alonso, R.; Alapini, A.; Almenara, J. -M.; Auvergne, M.; Baglin,
A.; Barge, P.; Bonomo, A. S.; Bordé, P.; Bouchy, F.; Bruntt, H.;
Carpano, S.; Cochran, W. D.; Deleuil, M.; Díaz, R. F.; Dreizler,
S.; Dvorak, R.; Eislöffel, J.; Eigmüller, P.; Endl, M.; Erikson,
A.; Ferraz-Mello, S.; Fridlund, M.; Gazzano, J. -C.; Gibson, N.;
Gillon, M.; Gondoin, P.; Grziwa, S.; Günther, E. W.; Guillot, T.;
Hartmann, M.; Havel, M.; Hébrard, G.; Jorda, L.; Kabath, P.; Léger,
A.; Llebaria, A.; Lammer, H.; Lovis, C.; MacQueen, P. J.; Mayor,
M.; Mazeh, T.; Moutou, C.; Nortmann, L.; Ofir, A.; Ollivier, M.;
Parviainen, H.; Pepe, F.; Pont, F.; Queloz, D.; Rabus, M.; Rauer,
H.; Régulo, C.; Renner, S.; de La Reza, R.; Rouan, D.; Santerne,
A.; Samuel, B.; Schneider, J.; Shporer, A.; Stecklum, B.; Tal-Or,
L.; Tingley, B.; Udry, S.; Wuchterl, G.
2012A&A...538A.112C Altcode: 2011arXiv1110.2384C
Context. CoRoT is a pioneering space mission whose primary goals are
stellar seismology and extrasolar planets search. Its surveys of large
stellar fields generate numerous planetary candidates whose lightcurves
have transit-like features. An extensive analytical and observational
follow-up effort is undertaken to classify these candidates. <BR
/> Aims: We present the list of planetary transit candidates from
the CoRoT LRa01 star field in the Monoceros constellation toward the
Galactic anti-center direction. The CoRoT observations of LRa01 lasted
from 24 October 2007 to 3 March 2008. <BR /> Methods: We acquired and
analyzed 7470 chromatic and 3938 monochromatic lightcurves. Instrumental
noise and stellar variability were treated with several filtering
tools by different teams from the CoRoT community. Different transit
search algorithms were applied to the lightcurves. <BR /> Results:
Fifty-one stars were classified as planetary transit candidates
in LRa01. Thirty-seven (i.e., 73% of all candidates) are "good"
planetary candidates based on photometric analysis only. Thirty-two
(i.e., 87% of the "good" candidates) have been followed-up. At the
time of writing twenty-two cases were solved and five planets were
discovered: three transiting hot-Jupiters (CoRoT-5b, CoRoT-12b,
and CoRoT-21b), the first terrestrial transiting planet (CoRoT-7b),
and another planet in the same system (CoRoT-7c, detected by radial
velocity survey only). Evidence of another non-transiting planet in
the CoRoT-7 system, namely CoRoT-7d, was recently found as well. <P
/>The CoRoT space mission, launched on December 27, 2006, has been
developed and is operated by CNES, with contributions of Austria,
Belgium, Brazil, ESA (RSSD and Science Program), Germany and Spain.
---------------------------------------------------------
Title: Transiting exoplanets from the CoRoT space
mission. XXI. CoRoT-19b: a low density planet orbiting an old
inactive F9V-star
Authors: Guenther, E. W.; Díaz, R. F.; Gazzano, J. -C.; Mazeh,
T.; Rouan, D.; Gibson, N.; Csizmadia, Sz.; Aigrain, S.; Alonso, R.;
Almenara, J. M.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.;
Bordé, P.; Bouchy, F.; Bruntt, H.; Cabrera, J.; Carone, L.; Carpano,
S.; Cavarroc, C.; Deeg, H. J.; Deleuil, M.; Dreizler, S.; Dvorak, R.;
Erikson, A.; Ferraz-Mello, S.; Fridlund, M.; Gandolfi, D.; Gillon, M.;
Guillot, T.; Hatzes, A.; Havel, M.; Hébrard, G.; Jehin, E.; Jorda,
L.; Lammer, H.; Léger, A.; Moutou, C.; Nortmann, L.; Ollivier, M.;
Ofir, A.; Pasternacki, Th.; Pätzold, M.; Parviainen, H.; Queloz,
D.; Rauer, H.; Samuel, B.; Santerne, A.; Schneider, J.; Tal-Or, L.;
Tingley, B.; Weingrill, J.; Wuchterl, G.
2012A&A...537A.136G Altcode: 2011arXiv1112.1035G
Context. Observations of transiting extrasolar planets are of key
importance to our understanding of planets because their mass, radius,
and mass density can be determined. These measurements indicate that
planets of similar mass can have very different radii. For low-density
planets, it is generally assumed that they are inflated owing to their
proximity to the host-star. To determine the causes of this inflation,
it is necessary to obtain a statistically significant sample of planets
with precisely measured masses and radii. <BR /> Aims: The CoRoT space
mission allows us to achieve a very high photometric accuracy. By
combining CoRoT data with high-precision radial velocity measurements,
we derive precise planetary radii and masses. We report the discovery
of CoRoT-19b, a gas-giant planet transiting an old, inactive F9V-type
star with a period of four days. <BR /> Methods: After excluding
alternative physical configurations mimicking a planetary transit
signal, we determine the radius and mass of the planet by combining
CoRoT photometry with high-resolution spectroscopy obtained with the
echelle spectrographs SOPHIE, HARPS, FIES, and SANDIFORD. To improve
the precision of its ephemeris and the epoch, we observed additional
transits with the TRAPPIST and Euler telescopes. Using HARPS spectra
obtained during the transit, we then determine the projected angle
between the spin of the star and the orbit of the planet. <BR />
Results: We find that the host star of CoRoT-19b is an inactive
F9V-type star close to the end of its main-sequence life. The host star
has a mass M<SUB>∗</SUB> = 1.21 ± 0.05 M<SUB>⊙</SUB> and radius
R<SUB>∗</SUB> = 1.65 ± 0.04 R<SUB>⊙</SUB>. The planet has a mass of
M<SUB>P</SUB> = 1.11 ± 0.06 M<SUB>Jup</SUB> and radius of R<SUB>P</SUB>
= 1.29 ± 0.03 R<SUB>Jup</SUB>. The resulting bulk density is only ρ
= 0.71 ± 0.06 g cm<SUP>-3</SUP>, which is much lower than that for
Jupiter. <BR /> Conclusions: The exoplanet CoRoT-19b is an example of
a giant planet of almost the same mass as Jupiter but a ≈30% larger
radius. <P />The CoRoT space mission, launched on December 27, 2006,
has been developed and is operated by the CNES, with the contribution of
Austria, Belgium, Brazil, ESA (RSSD and Science Program), Germany and
Spain. Partly based on observations obtained at the European Southern
Observatory at Paranal, Chile in program 184.C-0639, and partly based
on observations conducted at McDonald Observatory.
---------------------------------------------------------
Title: A new extensive library of synthetic stellar spectra from
PHOENIX atmospheres and its application to fitting VLT MUSE spectra
Authors: Husser, T. -O.; Kamann, S.; Dreizler, S.; Hauschildt, Peter H.
2012ASInC...6...71H Altcode: 2012arXiv1203.1941H
We present a new library of synthetic spectra based on the stellar
atmosphere code phx. It covers the wavelength range from 500 Å to
55 000 Å with a resolution of R=500 000 in the optical and near IR,
R=100 000 in the IR and &Delta&;lambda;=0.1 Å in the UV. The
parameter space covers 2 300 K ≤ T_{eff} ≤ 8 000 K, 0.0 ≤ log(g)
≤ +6.0, -4.0 ≤ [Fe/H] ≤ +1.0 and -0.3 ≤ [α/Fe] ≤ +0.8. The
library is work-in-progress and going to be extended to at least
T_{eff}=25 000 K. We use a new self-consistent way of describing
the microturbulence for our model atmospheres. The entire library
of synthetic spectra will be available for download. Furthermore we
present a method for fitting spectra, especially designed to work
with the new 2nd generation VLT instrument muse. We show that we can
determine stellar parameters (T_{eff}, log(g), [Fe/H] and [α/Fe])
and even single element abundances.
---------------------------------------------------------
Title: Evidence for planets in post-common envelope binaries
Authors: Dreizler, S.; Beuermann, K.; Hesman, F. V.
2012MmSAI..83..498D Altcode:
In the recent years, several circum-binary planets orbiting post-common
envelope systems have been announced. Some of the derived planetary
parameters have been questioned by others. We therefore present an
investigation of the current status in this dynamically evolving
field. False positive scenarios for the eclipse time variations are
therefore discussed. We also present an update on new measurements on
NN Ser and shortly address the quest for the frequency of planets in
post-common envelope systems.
---------------------------------------------------------
Title: Discovery and Mass Measurements of a Cold, 10 Earth Mass
Planet and Its Host Star
Authors: Muraki, Y.; Han, C.; Bennett, D. P.; Suzuki, D.; Monard,
L. A. G.; Street, R.; Jorgensen, U. G.; Kundurthy, P.; Skowron, J.;
Becker, A. C.; Albrow, M. D.; Fouqué, P.; Heyrovský, D.; Barry,
R. K.; Beaulieu, J. -P.; Wellnitz, D. D.; Bond, I. A.; Sumi, T.;
Dong, S.; Gaudi, B. S.; Bramich, D. M.; Dominik, M.; Abe, F.; Botzler,
C. S.; Freeman, M.; Fukui, A.; Furusawa, K.; Hayashi, F.; Hearnshaw,
J. B.; Hosaka, S.; Itow, Y.; Kamiya, K.; Korpela, A. V.; Kilmartin,
P. M.; Lin, W.; Ling, C. H.; Makita, S.; Masuda, K.; Matsubara, Y.;
Miyake, N.; Nishimoto, K.; Ohnishi, K.; Perrott, Y. C.; Rattenbury,
N. J.; Saito, To.; Skuljan, L.; Sullivan, D. J.; Sweatman, W. L.;
Tristram, P. J.; Wada, K.; Yock, P. C. M.; MOA Collaboration;
Christie, G. W.; DePoy, D. L.; Gorbikov, E.; Gould, A.; Kaspi, S.;
Lee, C. -U.; Mallia, F.; Maoz, D.; McCormick, J.; Moorhouse, D.;
Natusch, T.; Park, B. -G.; Pogge, R. W.; Polishook, D.; Shporer, A.;
Thornley, G.; Yee, J. C.; μFUN Collaboration; Allan, A.; Browne,
P.; Horne, K.; Kains, N.; Snodgrass, C.; Steele, I.; Tsapras, Y.;
RoboNet Collaboration; Batista, V.; Bennett, C. S.; Brillant, S.;
Caldwell, J. A. R.; Cassan, A.; Cole, A.; Corrales, R.; Coutures,
Ch.; Dieters, S.; Dominis Prester, D.; Donatowicz, J.; Greenhill,
J.; Kubas, D.; Marquette, J. -B.; Martin, R.; Menzies, J.; Sahu,
K. C.; Waldman, I.; Williams, A.; Zub, M.; PLANET Collaboration;
Bourhrous, H.; Matsuoka, Y.; Nagayama, T.; Oi, N.; Randriamanakoto,
Z.; IRSF Observers; Bozza, V.; Burgdorf, M. J.; Calchi Novati, S.;
Dreizler, S.; Finet, F.; Glitrup, M.; Harpsøe, K.; Hinse, T. C.;
Hundertmark, M.; Liebig, C.; Maier, G.; Mancini, L.; Mathiasen, M.;
Rahvar, S.; Ricci, D.; Scarpetta, G.; Skottfelt, J.; Surdej, J.;
Southworth, J.; Wambsganss, J.; Zimmer, F.; MiNDSTEp Consortium;
Udalski, A.; Poleski, R.; Wyrzykowski, Ł.; Ulaczyk, K.; Szymański,
M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; OGLE Collaboration
2011ApJ...741...22M Altcode: 2011arXiv1106.2160M
We present the discovery and mass measurement of the cold,
low-mass planet MOA-2009-BLG-266Lb, performed with the gravitational
microlensing method. This planet has a mass of m<SUB>p</SUB> = 10.4 ±
1.7 M<SUB>⊕</SUB> and orbits a star of mass M <SUB>sstarf</SUB> = 0.56
± 0.09 M<SUB>sun</SUB> at a semimajor axis of a = 3.2{+1.9\atop -0.5}
AU and an orbital period of P = 7.6{+7.7\atop -1.5} yrs. The planet
and host star mass measurements are enabled by the measurement of the
microlensing parallax effect, which is seen primarily in the light curve
distortion due to the orbital motion of the Earth. But the analysis
also demonstrates the capability to measure the microlensing parallax
with the Deep Impact (or EPOXI) spacecraft in a heliocentric orbit. The
planet mass and orbital distance are similar to predictions for the
critical core mass needed to accrete a substantial gaseous envelope,
and thus may indicate that this planet is a "failed" gas giant. This
and future microlensing detections will test planet formation theory
predictions regarding the prevalence and masses of such planets.
---------------------------------------------------------
Title: CAFE: Calar Alto Fiber-fed Echelle spectrograph
Authors: Sánchez, S. F.; Aceituno, J.; Thiele, U.; Grupp, F.;
Dreizler, S.; Bean, J.; Benitez, D.
2011hsa6.conf..783S Altcode:
The Calar Alto Fiber-fed Echelle spectrograph (CAFE) is an instrument
underconstruction at CAHA to replace FOCES, the high-resolution
echellespectrograph at the 2.2 m telescope of the observatory. FOCES
is a property ofthe Observatory of the Munich University, and it
was recalled it from Calar Altoin 2009. The instrument comprised
a substantial fraction of thetelescope time during its operational
life-time, and it is due to that it wastaken the decision to build
a replacement.CAFE shares its basic characteristics with those of
FOCES. However, significantimprovements have been introduced in
the original design, the quality of thematerials, and the overall
stability of the system. In particular: (i) a newcalibration Iodine
cell is foreseen to operate together with the standard ThArlamps;
(ii) the optical quality of all the components has been selected to
belambda/20, instead of the original lambda/10; (iii) an isolated room
hasbeen selected to place the instrument, termalized and stabilized
againstvibrations (extensive tests have been performed to grant the
stability); (iv)most of the mobile parts in FOCES has been substituted
by fixed elements, toincrease the stability of the system; and finally
(v) a new more efficientCCD, with a smaller pixel has been acquired. It
is expected that the overallefficiency and the quality of the data will
be significantly improved withrespect to its precesor. In particular,
CAFE is design and built to achieveresolutions of R ∼ 70000, which
will be kept in the final acquired data,allowing it to compete with
current operational extrasolar planets hunters.After two years of work
all the components are in place. The instrument is nowfinally assembled,
and we are performing the the first alignment tests. It isexpected that
the commissioning on the laboratory will finish at the end of2010,
followed by the commissioning on telescope along the first semester
of2011. If everything goes well, we will offer the instrument in a
shared-riskmode for the second semester of 2011.
---------------------------------------------------------
Title: MOA-2009-BLG-387Lb: a massive planet orbiting an M dwarf
Authors: Batista, V.; Gould, A.; Dieters, S.; Dong, S.; Bond, I.;
Beaulieu, J. P.; Maoz, D.; Monard, B.; Christie, G. W.; McCormick,
J.; Albrow, M. D.; Horne, K.; Tsapras, Y.; Burgdorf, M. J.; Calchi
Novati, S.; Skottfelt, J.; Caldwell, J.; Kozłowski, S.; Kubas, D.;
Gaudi, B. S.; Han, C.; Bennett, D. P.; An, J.; MOA Collaboration; Abe,
F.; Botzler, C. S.; Douchin, D.; Freeman, M.; Fukui, A.; Furusawa,
K.; Hearnshaw, J. B.; Hosaka, S.; Itow, Y.; Kamiya, K.; Kilmartin,
P. M.; Korpela, A.; Lin, W.; Ling, C. H.; Makita, B. S.; Masuda, K.;
Matsubara, Y.; Miyake, N.; Muraki, Y.; Nagaya, M.; Nishimoto, K.;
Ohnishi, K.; Okumura, T.; Perrott, Y. C.; Rattenbury, N.; Saito,
To.; Sullivan, D. J.; Sumi, T.; Sweatman, W. L.; Tristram, P. J.;
von Seggern, E.; Yock, P. C. M.; PLANET Collaboration; Brillant, S.;
Calitz, J. J.; Cassan, A.; Cole, A.; Cook, K.; Coutures, C.; Dominis
Prester, D.; Donatowicz, J.; Greenhill, J.; Hoffman, M.; Jablonski,
F.; Kane, S. R.; Kains, N.; Marquette, J. -B.; Martin, R.; Martioli,
E.; Meintjes, P.; Menzies, J.; Pedretti, E.; Pollard, K.; Sahu, K. C.;
Vinter, C.; Wambsganss, J.; Watson, R.; Williams, A.; Zub, M.; FUN
Collaboration; Allen, W.; Bolt, G.; Bos, M.; DePoy, D. L.; Drummond,
J.; Eastman, J. D.; Gal-Yam, A.; Gorbikov, E.; Higgins, D.; Janczak,
J.; Kaspi, S.; Lee, C. -U.; Mallia, F.; Maury, A.; Monard, L. A. G.;
Moorhouse, D.; Morgan, N.; Natusch, T.; Ofek, E. O.; Park, B. -G.;
Pogge, R. W.; Polishook, D.; Santallo, R.; Shporer, A.; Spector, O.;
Thornley, G.; Yee, J. C.; MiNDSTEp Consortium; Bozza, V.; Browne,
P.; Dominik, M.; Dreizler, S.; Finet, F.; Glitrup, M.; Grundahl,
F.; Harpsøe, K.; Hessman, F. V.; Hinse, T. C.; Hundertmark, M.;
Jørgensen, U. G.; Liebig, C.; Maier, G.; Mancini, L.; Mathiasen,
M.; Rahvar, S.; Ricci, D.; Scarpetta, G.; Southworth, J.; Surdej,
J.; Zimmer, F.; RoboNet Collaboration; Allan, A.; Bramich, D. M.;
Snodgrass, C.; Steele, I. A.; Street, R. A.
2011A&A...529A.102B Altcode: 2011arXiv1102.0558B
<BR /> Aims: We report the discovery of a planet with a high
planet-to-star mass ratio in the microlensing event MOA-2009-BLG-387,
which exhibited pronounced deviations over a 12-day interval, one
of the longest for any planetary event. The host is an M dwarf,
with a mass in the range 0.07 M<SUB>⊙</SUB> < M<SUB>host</SUB>
< 0.49 M<SUB>⊙</SUB> at 90% confidence. The planet-star mass
ratio q = 0.0132 ± 0.003 has been measured extremely well, so at
the best-estimated host mass, the planet mass is m<SUB>p</SUB> = 2.6
Jupiter masses for the median host mass, M = 0.19 M<SUB>⊙</SUB>. <BR
/> Methods: The host mass is determined from two "higher order"
microlensing parameters. One of these, the angular Einstein radius
θ<SUB>E</SUB> = 0.31 ± 0.03 mas has been accurately measured,
but the other (the microlens parallax π<SUB>E</SUB>, which is
due to the Earth's orbital motion) is highly degenerate with the
orbital motion of the planet. We statistically resolve the degeneracy
between Earth and planet orbital effects by imposing priors from a
Galactic model that specifies the positions and velocities of lenses
and sources and a Kepler model of orbits. <BR /> Results: The 90%
confidence intervals for the distance, semi-major axis, and period
of the planet are 3.5 kpc < D<SUB>L</SUB> < 7.9 kpc, 1.1 AU
< a < 2.7 AU, and 3.8 yr < P < 7.6 yr, respectively. <P
/>Photometric data is only available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/529/A102">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/529/A102</A>
---------------------------------------------------------
Title: XMM-Newton observations of the X-ray soft polar QS Telescopii
Authors: Traulsen, I.; Reinsch, K.; Schwope, A. D.; Burwitz, V.;
Dreizler, S.; Schwarz, R.; Walter, F. M.
2011A&A...529A.116T Altcode: 2011arXiv1103.4575T
Context. On the basis of XMM-Newton observations, we investigate
the energy balance of selected magnetic cataclysmic variables,
which have shown an extreme soft-to-hard X-ray flux ratio in the
ROSAT All-Sky Survey. <BR /> Aims: We intend to establish the X-ray
properties of the system components, their flux contributions, and the
accretion geometry of the X-ray soft polar QS Tel. In the context of
high-resolution X-ray analyses of magnetic cataclysmic variables, this
study will contribute to better understanding the accretion processes
on magnetic white dwarfs. <BR /> Methods: During an intermediate high
state of accretion of QS Tel, we have obtained 20 ks of XMM-Newton
data, corresponding to more than two orbital periods, accompanied by
simultaneous optical photometry and phase-resolved spectroscopy. We
analyze the multi-wavelength spectra and light curves and compare
them to former high- and low-state observations. <BR /> Results:
Soft emission at energies below 2 keV dominates the X-ray light
curves. The complex double-peaked maxima are disrupted by a sharp
dip in the very soft energy range (0.1-0.5 keV), where the count rate
abruptly drops to zero. The EPIC spectra are described by a minimally
absorbed black body at 20 eV and two partially absorbed mekal plasma
models with temperatures around 0.2 and 3 keV. The black-body-like
component arises from one mainly active, soft X-ray bright accretion
region nearly facing the mass donor. Parts of the plasma emission
might be attributed to the second, virtually inactive pole. High
soft-to-hard X-ray flux ratios and hardness ratios demonstrate that the
high-energy emission of QS Tel is substantially dominated by its X-ray
soft component. <P />Based on observations obtained with XMM-Newton,
an ESA science mission with instruments and contributions directly
funded by ESA Member States and NASA.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Hot HB stars in ω Cen (Moehler+,
2011)
Authors: Moehler, S.; Dreizler, S.; Lanz, T.; Bono, G.; Sweigart,
A. V.; Calamida, A.; Nonino, M.
2011yCat..35260136M Altcode: 2011yCat..35269136M
Moderately high resolution spectra of hot HB stars in the globular
cluster omega Cen were analysed for radial velocity variations,
atmospheric parameters, and abundances using LTE and non-LTE model
atmospheres. <P />The spectroscopic data were obtained in 2005 (4
observations) and in 2006 (5 observations) in Service Mode using the
MEDUSA mode of the multi-object fiber spectrograph FLAMES + GIRAFFE on
the UT2 Telescope of the VLT. We used the low spectroscopic resolution
mode with the spectral range 3964Å-4567Å (LR2, R=6400) and observed
spectra for a total of 109 blue hook and canonical blue HB/EHB star
candidates (see Table 1) and for 17 sky background positions. Each
observation had an exposure time of 2550s to keep the total execution
time of the observing block shorter than one hour. <P />(3 data files).
---------------------------------------------------------
Title: Flux and color variations of the quadruply imaged quasar
HE 0435-1223
Authors: Ricci, D.; Poels, J.; Elyiv, A.; Finet, F.; Sprimont, P. G.;
Anguita, T.; Bozza, V.; Browne, P.; Burgdorf, M.; Calchi Novati, S.;
Dominik, M.; Dreizler, S.; Glitrup, M.; Grundahl, F.; Harpsøe, K.;
Hessman, F.; Hinse, T. C.; Hornstrup, A.; Hundertmark, M.; Jørgensen,
U. G.; Liebig, C.; Maier, G.; Mancini, L.; Masi, G.; Mathiasen, M.;
Rahvar, S.; Scarpetta, G.; Skottfelt, J.; Snodgrass, C.; Southworth,
J.; Teuber, J.; Thöne, C. C.; Wambsganß, J.; Zimmer, F.; Zub, M.;
Surdej, J.
2011A&A...528A..42R Altcode: 2011arXiv1101.3664R
<BR /> Aims: We present VRi photometric observations of the quadruply
imaged quasar<ASTROBJ>HE0435-1223</ASTROBJ>, carried out with the
Danish 1.54 m telescope at the La Silla Observatory. Our aim was to
monitor and study the magnitudes and colors of each lensed component
as a function of time. <BR /> Methods: We monitored the object during
two seasons (2008 and 2009) in the VRi spectral bands, and reduced the
data with two independent techniques: difference imaging and point
spread function (PSF) fitting. <BR /> Results: Between these two
seasons, our results show an evident decrease in flux by ≈ 0.2-0.4
magnitudes of the four lensed components in the three filters. We also
found a significant increase ( ≈ 0.05-0.015) in their V - R and R -
i color indices. <BR /> Conclusions: These flux and color variations
are very likely caused by intrinsic variations of the quasar between
the observed epochs. Microlensing effects probably also affect
the brightest "A" lensed component. <P />Based on data collected
by MiNDSTEp with the Danish 1.54 m telescope at the ESO La Silla
Observatory. Tables 5-7 are only available in electronic form at the
CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/528/A42">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/528/A42</A>
---------------------------------------------------------
Title: VizieR Online Data Catalog: MOA-2007-BLG-387Lb light curve
I band (Batista+, 2011)
Authors: Batista, V.; Gould, A.; Dieters, S.; Dong, Subo; Bond, I.;
Beaulieu, J. P.; Maoz, D.; Monard, B.; Christie, G. W.; McCormick,
J.; Albrow, M. D.; Horne, K.; Tsapras, Y.; Burgdorf, M. J.; Calchi
Novati, S.; Skottfelt, J.; Caldwell, J.; Kozlowski, S.; Kubas, D.;
Gaudi, B. S.; Han, C.; Bennett1, D. P.; An, J.; Abe, F.; Botzler,
C. S.; Douchin, D.; Freeman, M.; Fukui, A.; Furusawa, K.; Hearnshaw,
J. B.; Hosaka, S.; Itow, Y.; Kamiya, K.; Kilmartin, P. M.; Korpela, A.;
Lin, W.; Ling, C. H.; Makita, S.; Masuda, K.; Matsubara, Y.; Miyake,
N.; Muraki, Y.; Nagaya, M.; Nishimoto, K.; Ohnishi, K.; Okumura, T.;
Perrott, Y. C.; Rattenbury, N.; Saito, To.; Sullivan, D. J.; Sumi,
T.; Sweatman, W. L.; Tristram, P. J.; von Seggern, E.; Yock P. C. M.;
MOA Collaboration; Brillant, S.; Calitz, J. J.; Cassan, A.; Cole,
A.; Cook, K.; Coutures, C.; Dominis Prester, D.; Donatowicz, J.;
Greenhill, J.; Hoffman, M.; Jablonski, F.; Kane, S. R.; Kains, N.;
Marquette, J. -B.; Martin, R.; Martioli, E.; Meintjes, P.; Menzies,
J.; Pedretti, E.; Pollard, K.; Sahu, K. C.; Vinter, C.; Wambsganss,
J.; Watson, R.; Williams, A.; Zub, M.; PLANET Collaboration; Allen,
W.; Bolt, G.; Bos, M.; DePoy, D. L.; Drummond, J.; Eastman, J. D.;
Gal-Yam, A.; Gorbikov, E.; Higgins, D.; Janczak, J.; Kaspi, S.; Lee,
C. -U.; Mallia, F.; Maury, A.; Monard, L. A. G.; Moorhouse, D.; Morgan,
N.; Natusch, T.; Ofek, E. O.; Park, B. -G.; Pogge, R. W.; Polishook,
D.; Santallo, R.; Shporer, A.; Spector, O.; Thornley, G.; Yee, J. C.;
μ Collaboration; Bozza, V.; Browne, P.; Dominik, M.; Dreizler, S.;
Finet, F.; Glitrup, M.; Grundah, F.; Harpsoe, K.; Hessman, F. V.;
Hinse, T. C.; Hundertmark, M.; Jorgensen, U. G.; Liebig, C.; Maier,
G.; Mancini, L.; Mathiasen, M.; Rahvar, S.; Ricci, D.; Scarpetta,
G.; Southworth, J.; Surdej, J.; Zimmer, F.
2011yCat..35290102B Altcode: 2011yCat..35299102B
The RoboNet collaboration also followed the event with their three
2m robotic telescopes : the Faulkes Telescopes The microlensing event
MOA-2009-BLG-387 was alerted North (FTN) and South (FTS) in Hawaii and
Australia by the MOA collaboration (Microlensing Observations in (Siding
Springs Observatory) respectively, and the Liverpool Astrophysics)
on 24 July 2009 at 15:08 UT, HJD'=HJD-24500000=5037.13, a few days
before the first caustic entry. Many observatories obtained data of
the event. The celestial coordinates of the event are RA=17:53:50.79
and DE=-33:59:25 (J2000.0) corresponding to Galactic coordinates:
l=+356.56, b=-4.097. <P />(1 data file).
---------------------------------------------------------
Title: The Planets around the post-Common Envelope Binary NN Serpentis
Authors: Hessman, Frederic V.; Beuermann, Klaus; Dreizler, Stefan;
Marsh, Tom R.; Parsons, Steven G.; Copperwheat, Chris M.; Winget,
Don E.; Miller, George F.; Hermes, James J.; Schreiber, Matthias R.;
Kley, Wilhelm; Dhillon, Vik S.; Littlefair, Stuart P.
2011AIPC.1331..281H Altcode: 2011arXiv1102.0508H
We have detected 2 circumbinary planets around the close binary system
NN Serpentis using the orbital time delay effect measured via the sharp
eclipses of the white dwarf primary. The present pre-cataclysmic binary
was formed when the original ~2 M<SUB>solar</SUB> primary expanded into
a red giant, causing the secondary star to drop from its original orbit
at a separation of about 1.4 A.U. down to its current separation at
0.0043 A.U. A quasi-adiabatic evolution of the circumbinary planets'
orbits during the common-envelope phase would have placed them in
unstable configurations, suggesting that they may have suffered
significant orbital drag effects and were originally in much larger
orbits. Alternatively, they may have been created as 2nd-generation
planets during the last million years from the substantial amount
of material lost during the creation of the binary, making them the
youngest planets known. Either solution shows how little we actually
understand about planetary formation.
---------------------------------------------------------
Title: A much lower density for the transiting extrasolar planet
WASP-7
Authors: Southworth, J.; Dominik, M.; Jørgensen, U. G.; Rahvar,
S.; Snodgrass, C.; Alsubai, K.; Bozza, V.; Browne, P.; Burgdorf, M.;
Calchi Novati, S.; Dodds, P.; Dreizler, S.; Finet, F.; Gerner, T.;
Hardis, S.; Harpsøe, K.; Hellier, C.; Hinse, T. C.; Hundertmark, M.;
Kains, N.; Kerins, E.; Liebig, C.; Mancini, L.; Mathiasen, M.; Penny,
M. T.; Proft, S.; Ricci, D.; Sahu, K.; Scarpetta, G.; Schäfer, S.;
Schönebeck, F.; Surdej, J.
2011A&A...527A...8S Altcode: 2010arXiv1012.5181S
We present the first high-precision photometry of the transiting
extrasolar planetary system WASP-7, obtained using telescope defocussing
techniques and reaching a scatter of 0.68 mmag per point. We find that
the transit depth is greater and that the host star is more evolved
than previously thought. The planet has a significantly larger
radius (1.330 ± 0.093 R<SUB>Jup</SUB> versus ; R<SUB>Jup</SUB>)
and much lower density (0.41 ± 0.10 ρ<SUB>Jup</SUB> versus ;
ρ<SUB>Jup</SUB>) and surface gravity (13.4 ± 2.6 m s<SUP>-2</SUP>
versus ; m s<SUP>-2</SUP>) than previous measurements showed. Based
on the revised properties it is no longer an outlier in planetary
mass-radius and period-gravity diagrams. We also obtain a more precise
transit ephemeris for the WASP-7 system. <P />Based on data collected
by MiNDSTEp with the Danish 1.54 m telescope at the ESO La Silla
Observatory.Lightcurves data is only available in electronic form at the
CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/527/A8">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/527/A8</A>
---------------------------------------------------------
Title: A Sub-Saturn Mass Planet, MOA-2009-BLG-319Lb
Authors: Miyake, N.; Sumi, T.; Dong, Subo; Street, R.; Mancini, L.;
Gould, A.; Bennett, D. P.; Tsapras, Y.; Yee, J. C.; Albrow, M. D.;
Bond, I. A.; Fouqué, P.; Browne, P.; Han, C.; Snodgrass, C.; Finet,
F.; Furusawa, K.; Harpsøe, K.; Allen, W.; Hundertmark, M.; Freeman,
M.; Suzuki, D.; Abe, F.; Botzler, C. S.; Douchin, D.; Fukui, A.;
Hayashi, F.; Hearnshaw, J. B.; Hosaka, S.; Itow, Y.; Kamiya, K.;
Kilmartin, P. M.; Korpela, A.; Lin, W.; Ling, C. H.; Makita, S.;
Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagayama, T.; Nishimoto, K.;
Ohnishi, K.; Perrott, Y. C.; Rattenbury, N.; Saito, To.; Skuljan, L.;
Sullivan, D. J.; Sweatman, W. L.; Tristram, P. J.; Wada, K.; Yock,
P. C. M.; MOA Collaboration; Bolt, G.; Bos, M.; Christie, G. W.; DePoy,
D. L.; Drummond, J.; Gal-Yam, A.; Gaudi, B. S.; Gorbikov, E.; Higgins,
D.; Hwang, K. -H.; Janczak, J.; Kaspi, S.; Lee, C. -U.; Koo, J. -R.;
Kozłowski, S.; Lee, Y.; Mallia, F.; Maury, A.; Maoz, D.; McCormick,
J.; Monard, L. A. G.; Moorhouse, D.; Muñoz, J. A.; Natusch, T.;
Ofek, E. O.; Pogge, R. W.; Polishook, D.; Santallo, R.; Shporer, A.;
Spector, O.; Thornley, G.; μFUN Collaboration; Allan, A.; Bramich,
D. M.; Horne, K.; Kains, N.; Steele, I.; RoboNet Collaboration; Bozza,
V.; Burgdorf, M. J.; Calchi Novati, S.; Dominik, M.; Dreizler, S.;
Glitrup, M.; Hessman, F. V.; Hinse, T. C.; Jørgensen, U. G.; Liebig,
C.; Maier, G.; Mathiasen, M.; Rahvar, S.; Ricci, D.; Scarpetta, G.;
Skottfelt, J.; Southworth, J.; Surdej, J.; Wambsganss, J.; Zimmer,
F.; MiNDSTEp Consortium; Batista, V.; Beaulieu, J. P.; Brillant,
S.; Cassan, A.; Cole, A.; Corrales, E.; Coutures, Ch.; Dieters, S.;
Greenhill, J.; Kubas, D.; Menzies, J.; PLANET Collaboration
2011ApJ...728..120M Altcode: 2010arXiv1010.1809M
We report the gravitational microlensing discovery of a sub-Saturn
mass planet, MOA-2009-BLG-319Lb, orbiting a K- or M-dwarf star in the
inner Galactic disk or Galactic bulge. The high-cadence observations
of the MOA-II survey discovered this microlensing event and enabled
its identification as a high-magnification event approximately 24
hr prior to peak magnification. As a result, the planetary signal at
the peak of this light curve was observed by 20 different telescopes,
which is the largest number of telescopes to contribute to a planetary
discovery to date. The microlensing model for this event indicates a
planet-star mass ratio of q = (3.95 ± 0.02) × 10<SUP>-4</SUP> and a
separation of d = 0.97537 ± 0.00007 in units of the Einstein radius. A
Bayesian analysis based on the measured Einstein radius crossing
time, t <SUB>E</SUB>, and angular Einstein radius, θ<SUB>E</SUB>,
along with a standard Galactic model indicates a host star mass of M
<SUB>L</SUB> = 0.38<SUP>+0.34</SUP> <SUB>-0.18</SUB> M <SUB>sun</SUB>
and a planet mass of M <SUB>p</SUB> = 50<SUP>+44</SUP> <SUB>-24</SUB>
M <SUB>⊕</SUB>, which is half the mass of Saturn. This analysis
also yields a planet-star three-dimensional separation of a =
2.4<SUP>+1.2</SUP> <SUB>-0.6</SUB> AU and a distance to the planetary
system of D <SUB>L</SUB> = 6.1<SUP>+1.1</SUP> <SUB>-1.2</SUB> kpc. This
separation is ~2 times the distance of the snow line, a separation
similar to most of the other planets discovered by microlensing.
---------------------------------------------------------
Title: The hot horizontal-branch stars in ω Centauri
Authors: Moehler, S.; Dreizler, S.; Lanz, T.; Bono, G.; Sweigart,
A. V.; Calamida, A.; Nonino, M.
2011A&A...526A.136M Altcode: 2010arXiv1009.3191M
Context. UV observations of some massive globular clusters have revealed
a significant population of stars hotter and fainter than the hot end of
the horizontal branch (HB), the so-called blue hook stars. This feature
might be explained either by the late hot flasher scenario where stars
experience the helium flash while on the white dwarf cooling curve
or by the progeny of the helium-enriched sub-population postulated to
exist in some clusters. Previous spectroscopic analyses of blue hook
stars in ω Cen and NGC 2808 support the late hot flasher scenario,
but the stars contain much less helium than expected and the predicted
C and N enrichment cannot be verified. <BR /> Aims: We compare the
observed effective temperatures, surface gravities, helium abundances,
and carbon line strengths (where detectable) of our targets stars
with the predictions of the two aforementioned scenarios. <BR />
Methods: Moderately high resolution spectra of hot HB stars in the
globular cluster ω Cen were analysed for radial velocity variations,
atmospheric parameters, and abundances using LTE and non-LTE model
atmospheres. <BR /> Results: We find no evidence of close binaries
among our target stars. All stars below 30 000 K are helium-poor and
very similar to HB stars observed in that temperature range in other
globular clusters. In the temperature range 30 000 K to 50 000 K,
we find that 28% of our stars are helium-poor ({log{n_He}/{n_H}} <
-1.6), while 72% have roughly solar or super-solar helium abundance
({log{n_He}/{n_H}} ≥ -1.5). We also find that carbon enrichment
is strongly correlated with helium enrichment, with a maximum carbon
enrichment of 3% by mass. <BR /> Conclusions: A strong carbon enrichment
in tandem with helium enrichment is predicted by the late hot flasher
scenario, but not by the helium-enrichment scenario. We conclude that
the helium-rich HB stars in ω Cen cannot be explained solely by the
helium-enrichment scenario invoked to explain the blue main sequence. <P
/>Based on observations with the ESO Very Large Telescope at Paranal
Observatory, Chile (proposal IDs 075.D-0280(A) and 077.D-0021(A)).
---------------------------------------------------------
Title: The giant planet orbiting the cataclysmic binary DP Leonis
Authors: Beuermann, K.; Buhlmann, J.; Diese, J.; Dreizler, S.; Hessman,
F. V.; Husser, T. -O.; Miller, G. F.; Nickol, N.; Pons, R.; Ruhr,
D.; Schmülling, H.; Schwope, A. D.; Sorge, T.; Ulrichs, L.; Winget,
D. E.; Winget, K. I.
2011A&A...526A..53B Altcode: 2010arXiv1011.3905B
Planets orbiting post-common envelope binaries provide fundamental
information on planet formation and evolution, especially for the
yet nearly unexplored class of circumbinary planets. We searched for
such planets in DP Leo, an eclipsing short-period binary, which shows
long-term eclipse-time variations. Using published, reanalysed, and
new mid-eclipse times of the white dwarf in DP Leo, obtained between
1979 and 2010, we find agreement with the light-travel-time effect
produced by a third body in an elliptical orbit. In particular, the
measured binary period in 2009/2010 and the implied radial velocity
coincide with the values predicted for the motion of the binary and
the third body around the common center of mass. The orbital period,
semi-major axis, and eccentricity of the third body are P<SUB>c</SUB>
= 28.0 ± 2.0 yrs, a<SUB>c</SUB> = 8.2 ± 0.4 AU, and e<SUB>c</SUB>
= 0.39 ± 0.13. Its mass of sin i_ c M_c = 6.1 ± 0.5 M<SUB>Jup</SUB>
qualifies it as a giant planet. It formed either as a first generation
object in a protoplanetary disk around the original binary or as a
second generation object in a disk formed in the common envelope shed
by the progenitor of the white dwarf. Even a third generation origin
in matter lost from the present accreting binary can not be entirely
excluded. We searched for, but found no evidence for a fourth body.
---------------------------------------------------------
Title: Giant Transiting Planets Observations with LAIWO
Authors: Nikolov, N.; Moyano, M.; Henning, T.; Dreizler, S.; Mundt, R.
2011EPJWC..1106004N Altcode:
We present preliminary single field results on a search for transiting
extrasolar planets with the LAIWO wide field optical CCD camera,
attached to the 1-m telescope at the Wise Observatory. With a 3 min
integration time, the system achieved a few mmag precision for the
brightest stars in a field of view of one square degree. We detect
several periodic variables and a few transit-like events. The promising
candidates will be followed-up in the near future.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Transiting planetary system WASP-7
(Southworth+, 2011)
Authors: Southworth, J.; Dominik, M.; Jorgensen, U. G.; Rahvar, S.;
Snodgrass, C.; Alsubai, K.; Bozza, V.; Browne, P.; Burgdorf, M.;
Calchi Novati, S.; Dodds, P.; Dreizler, S.; Finet, F.; Gerner, T.;
Hardis, S.; Harpsoe, K.; Hellier, C.; Hinse, T. C.; Hundertmark, M.;
Kains, N.; Kerins, E.; Liebig, C.; Mancini, L.; Mathiasen, M.; Penny,
M. T.; Proft, S.; Ricci, D.; Scarpetta, G.; Schaefer, S.; Schoenebeck,
F.; Surdej, J.
2011yCat..35270008S Altcode: 2011yCat..35279008S
A light curve of one transit of the extrasolar planetary system
WASP-7 is presented. The data were obtained using the Danish 1.5m
telescope and DFOSC camera at ESO La Silla in 2010, with substantial
telescope defocussing in order to improve the photometric precision
of the observations. A Johnson I filter and exposure times of 60s were
used. <P />(1 data file).
---------------------------------------------------------
Title: VizieR Online Data Catalog: VRi light curves of the lensed
QSO HE 0435-1223 (Ricci+, 2011)
Authors: Ricci, D.; Poels, J.; Elyiv, A.; Finet, F.; Sprimont, P. G.;
Anguita, T.; Bozza, V.; Browne, P.; Burgdorf, M.; Calchi Novati,
S.; Dominik, M.; Dreizler, S.; Glitrup, M.; Grundahl, F.; Harps, K.;
Hessman, F.; Hinse, T. C.; Hornstrup, A.; Hundertmark, M.; Jorgensen,
U. G.; Liebig, C.; Maier, G.; Mancini, L.; Masi, G.; Mathiasen, M.;
Rahvar, S.; Scarpetta, G.; Skottfelt, J.; Snodgrass, C.; Southworth,
J.; Teuber, J.; Thone, C. C.; Wambsganss, J.; Zimmer, F.; Zub, M.;
Surdej, J.
2011yCat..35280042R Altcode: 2011yCat..35289042R
Tables contain the light curves of the 4 components of the quasar,
in the V, R, and i bands. <P />(3 data files).
---------------------------------------------------------
Title: Asteroseismology of solar-type stars with Kepler:
III. Ground-based data
Authors: Molenda-Żakowicz, J.; Bruntt, H.; Sousa, S.; Frasca,
A.; Biazzo, K.; Huber, D.; Ireland, M.; Bedding, T.; Stello, D.;
Uytterhoeven, K.; Dreizler, S.; De Cat, P.; Briquet, M.; Catanzaro,
G.; Karoff, C.; Frandsen, S.; Spezzi, L.
2010AN....331..981M Altcode: 2010arXiv1005.0986M
We report on the ground-based follow-up program of spectroscopic and
photometric observations of solar-like asteroseismic targets for
the Kepler space mission. These stars constitute a large group of
more than a thousand objects which are the subject of an intensive
study by the Kepler Asteroseismic Science Consortium Working Group 1
(KASC WG-1). In the current work we will discuss the methods we use
to determine the fundamental stellar atmospheric parameters using
high-quality stellar spectra. These provide essential constraints
for the asteroseismic modelling and make it possible to verify the
parameters in the Kepler Input Catalogue (KIC).
---------------------------------------------------------
Title: ERRATUM: "Physical Properties of the 0.94 Day Period Transiting
Planetary System WASP-18" <A href="/abs/2009ApJ...707..167S">(2009,
ApJ, 707, 167)</A>
Authors: Southworth, John; Hinse, T. C.; Dominik, M.; Glitrup, M.;
Jørgensen, U. G.; Liebig, C.; Mathiasen, M.; Anderson, D. R.; Bozza,
V.; Browne, P.; Burgdorf, M.; Calchi Novati, S.; Dreizler, S.; Finet,
F.; Harpsøe, K.; Hessman, F.; Hundertmark, M.; Maier, G.; Mancini,
L.; Maxted, P. F. L.; Rahvar, S.; Ricci, D.; Scarpetta, G.; Skottfelt,
J.; Snodgrass, C.; Surdej, J.; Zimmer, F.
2010ApJ...723.1829S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: OGLE-2009-BLG-092/MOA-2009-BLG-137: A Dramatic Repeating
Event with the Second Perturbation Predicted by Real-time Analysis
Authors: Ryu, Y. -H.; Han, C.; Hwang, K. -H.; Street, R.; Udalski,
A.; Sumi, T.; Fukui, A.; Beaulieu, J. -P.; Gould, A.; Dominik, M.;
Abe, F.; Bennett, D. P.; Bond, I. A.; Botzler, C. S.; Furusawa, K.;
Hayashi, F.; Hearnshaw, J. B.; Hosaka, S.; Itow, Y.; Kamiya, K.;
Kilmartin, P. M.; Korpela, A.; Lin, W.; Ling, C. H.; Makita, S.;
Masuda, K.; Matsubara, Y.; Miyake, N.; Muraki, Y.; Nishimoto, K.;
Ohnishi, K.; Perrott, Y. C.; Rattenbury, N.; Saito, To.; Skuljan, L.;
Sullivan, D. J.; Suzuki, D.; Sweatman, W. L.; Tristram, P. J.; Wada,
K.; Yock, P. C. M.; MOA Collaboration; Szymański, M. K.; Kubiak,
M.; Pietrzyński, G.; Poleski, R.; Soszyński, I.; Szewczyk, O.;
Wyrzykowski, Ł.; Ulaczyk, K.; OGLE Collaboration; Bos, M.; Christie,
G. W.; Depoy, D. L.; Gal-Yam, A.; Gaudi, B. S.; Kaspi, S.; Lee,
C. -U.; Maoz, D.; McCormick, J.; Monard, B.; Moorhouse, D.; Pogge,
R. W.; Polishook, D.; Shvartzvald, Y.; Shporer, A.; Thornley, G.; Yee,
J. C.; μFUN Collaboration; Albrow, M. D.; Batista, V.; Brillant,
S.; Cassan, A.; Cole, A.; Corrales, E.; Coutures, Ch.; Dieters, S.;
Fouqué, P.; Greenhill, J.; Menzies, J.; PLANET Collaboration; Allan,
A.; Bramich, D. M.; Browne, P.; Horne, K.; Kains, N.; Snodgrass, C.;
Steele, I.; Tsapras, Y.; RoboNet Collaboration; Bozza, V.; Burgdorf,
M. J.; Calchi Novati, S.; Dreizler, S.; Finet, F.; Glitrup, M.;
Grundahl, F.; Harpsøe, K.; Hessman, F. V.; Hinse, T. C.; Hundertmark,
M.; Jørgensen, U. G.; Liebig, C.; Maier, G.; Mancini, L.; Mathiasen,
M.; Rahvar, S.; Ricci, D.; Scarpetta, G.; Skottfelt, J.; Surdej, J.;
Southworth, J.; Wambsganss, J.; Zimmer, F.; MiNDSTEp Collaboration
2010ApJ...723...81R Altcode: 2010arXiv1009.0338R
We report the result of the analysis of a dramatic repeating
gravitational microlensing event OGLE-2009-BLG-092/MOA-2009-BLG-137,
for which the light curve is characterized by two distinct peaks with
perturbations near both peaks. We find that the event is produced by
the passage of the source trajectory over the central perturbation
regions associated with the individual components of a wide-separation
binary. The event is special in the sense that the second perturbation,
occurring ~100 days after the first, was predicted by the real-time
analysis conducted after the first peak, demonstrating that real-time
modeling can be routinely done for binary and planetary events. With
the data obtained from follow-up observations covering the second peak,
we are able to uniquely determine the physical parameters of the lens
system. We find that the event occurred on a bulge clump giant and it
was produced by a binary lens composed of a K- and M-type main-sequence
stars. The estimated masses of the binary components are M <SUB>1</SUB>
= 0.69 ± 0.11 M <SUB>sun</SUB> and M <SUB>2</SUB> = 0.36 ± 0.06 M
<SUB>sun</SUB>, respectively, and they are separated in projection by
r <SUB>bottom</SUB> = 10.9 ± 1.3 AU. The measured distance to the
lens is D <SUB>L</SUB> = 5.6 ± 0.7 kpc. We also detect the orbital
motion of the lens system.
---------------------------------------------------------
Title: A Precise Asteroseismic Age and Radius for the Evolved Sun-like
Star KIC 11026764
Authors: Metcalfe, T. S.; Monteiro, M. J. P. F. G.; Thompson, M. J.;
Molenda-Żakowicz, J.; Appourchaux, T.; Chaplin, W. J.; Doǧan, G.;
Eggenberger, P.; Bedding, T. R.; Bruntt, H.; Creevey, O. L.; Quirion,
P. -O.; Stello, D.; Bonanno, A.; Silva Aguirre, V.; Basu, S.; Esch,
L.; Gai, N.; Di Mauro, M. P.; Kosovichev, A. G.; Kitiashvili, I. N.;
Suárez, J. C.; Moya, A.; Piau, L.; García, R. A.; Marques, J. P.;
Frasca, A.; Biazzo, K.; Sousa, S. G.; Dreizler, S.; Bazot, M.; Karoff,
C.; Frandsen, S.; Wilson, P. A.; Brown, T. M.; Christensen-Dalsgaard,
J.; Gilliland, R. L.; Kjeldsen, H.; Campante, T. L.; Fletcher, S. T.;
Handberg, R.; Régulo, C.; Salabert, D.; Schou, J.; Verner, G. A.;
Ballot, J.; Broomhall, A. -M.; Elsworth, Y.; Hekker, S.; Huber, D.;
Mathur, S.; New, R.; Roxburgh, I. W.; Sato, K. H.; White, T. R.;
Borucki, W. J.; Koch, D. G.; Jenkins, J. M.
2010ApJ...723.1583M Altcode: 2010arXiv1010.4329M
The primary science goal of the Kepler Mission is to provide
a census of exoplanets in the solar neighborhood, including the
identification and characterization of habitable Earth-like planets. The
asteroseismic capabilities of the mission are being used to determine
precise radii and ages for the target stars from their solar-like
oscillations. Chaplin et al. published observations of three bright
G-type stars, which were monitored during the first 33.5 days of science
operations. One of these stars, the subgiant KIC 11026764, exhibits a
characteristic pattern of oscillation frequencies suggesting that it
has evolved significantly. We have derived asteroseismic estimates of
the properties of KIC 11026764 from Kepler photometry combined with
ground-based spectroscopic data. We present the results of detailed
modeling for this star, employing a variety of independent codes and
analyses that attempt to match the asteroseismic and spectroscopic
constraints simultaneously. We determine both the radius and the age
of KIC 11026764 with a precision near 1%, and an accuracy near 2%
for the radius and 15% for the age. Continued observations of this
star promise to reveal additional oscillation frequencies that will
further improve the determination of its fundamental properties.
---------------------------------------------------------
Title: Evidence for planets orbiting the post-common envelope binary
NN Serpentis
Authors: Dreizler, S.; Beuermann, K.; Hessman, F. V.; Marsh, T. R.;
Parsons, S. G.; Dhillon, V. S.; Schreiber, M. R.; Kley, W.; Miller,
G. F.
2010AIPC.1273..450D Altcode:
From published and new mid-eclipse times obtained between 1988 and 2010
we find long-term eclipse time variations in the post-common envelope
eclipsing binary NN Ser. We find strong evidence for two circum-binary
planets in this system with orbital periods of P<SUB>c</SUB> = 15.5
and P<SUB>d</SUB> = 7.7 yrs, small eccentricities of e<SUB>c</SUB>~0
and e<SUB>d</SUB>~0.2 and lower mass limits of M<SUB>c</SUB>
sin i<SUB>c</SUB> = 6.9 and M<SUB>c</SUB> sin i<SUB>c</SUB> = 2.2
M<SUB>Jup</SUB>. The periods suggest that the planets are locked in
a 2:1 resonance. A second solution with a 5:2 resonance and slightly
modified planetary parameters results in a nearly equal reduced
χ<SUP>2</SUP>. The progenitor system is estimated to consists of a ~2
M<SUB>solar</SUB> primary and the present M dwarf secondary at ~1.5 AU
distance. The first generation formation of planets and their survival
in the later evolutionary stages or the second generation formation
in the common envelope shed new light on planet formation and evolution.
---------------------------------------------------------
Title: Pathways towards Neptune-mass Planets around Very Low-mass
Stars
Authors: Dreizler, S.; Bean, J.; Seifahrt, A.; Hartman, H.; Nilsson,
H.; Wiedemann, G.; Reiners, A.; Henry, T. J.
2010ASPC..430..127D Altcode:
Radial velocities measured from near-infrared spectra are a potentially
powerful tool to search for planets around low-mass stars. The radial
velocity precision routinely obtained in the visible can, however,
not be achieved in the NIR with existing techniques. In this paper,
we describe a method for measuring high-precision radial velocities
of a sample of the lowest-mass M dwarfs using CRIRES on the VLT. Our
project makes use of a gas cell filled with ammonia to calibrate the
instrument response similar to the iodine cell technique that has
been used so successfully in the visible. Tests of the method based
on the analysis of hundreds of spectra obtained for late M dwarfs
over six months demonstrate that precisions of ∼5 m s<SUP>-1</SUP>
are obtainable over long timescales, and precisions better than 3 m
s<SUP>-1</SUP> can be obtained over timescales up to a week. This
allows to search for low-mass planets, i.e., Neptune-mass or even
Super-Earth planets around very low-mass stars or sub-stellar objects.
---------------------------------------------------------
Title: Two planets orbiting the recently formed post-common envelope
binary NN Serpentis
Authors: Beuermann, K.; Hessman, F. V.; Dreizler, S.; Marsh, T. R.;
Parsons, S. G.; Winget, D. E.; Miller, G. F.; Schreiber, M. R.; Kley,
W.; Dhillon, V. S.; Littlefair, S. P.; Copperwheat, C. M.; Hermes,
J. J.
2010A&A...521L..60B Altcode: 2010arXiv1010.3608B
Planets orbiting post-common envelope binaries provide fundamental
information on planet formation and evolution. We searched for such
planets in NN Ser ab, an eclipsing short-period binary that shows
long-term eclipse time variations. Using published, reanalysed, and
new mid-eclipse times of NN Ser ab obtained between 1988 and 2010, we
find excellent agreement with the light-travel-time effect produced
by two additional bodies superposed on the linear ephemeris of the
binary. Our multi-parameter fits accompanied by N-body simulations
yield a best fit for the objects NN Ser (ab)c and d locked in the 2:1
mean motion resonance, with orbital periods P<SUB>c</SUB> ≃ 15.5 yrs
and P<SUB>d</SUB> ≃ 7.7 yrs, masses M<SUB>c</SUB> sin i<SUB>c</SUB>
≃ 6.9 M<SUB>Jup</SUB> and M<SUB>d</SUB> sin i<SUB>d</SUB> ≃ 2.2
M<SUB>Jup</SUB> and eccentricities e<SUB>c</SUB> ≃ 0 and e<SUB>d</SUB>
≃ 0.20. A secondary χ<SUP>2</SUP> minimum corresponds to an
alternative solution with a period ratio of 5:2. We estimate that the
progenitor binary consisted of an A star with ~2 M_⊙ and the present
M dwarf secondary at an orbital separation of ~1.5 AU. The survival of
two planets through the common-envelope phase that created the present
white dwarf requires fine tuning between the gravitational force
and the drag force experienced by them in the expanding envelope. The
alternative is a second-generation origin in a circumbinary disk created
at the end of this phase. In that case, the planets would be extremely
young with ages not exceeding the cooling age of the white dwarf of
10<SUP>6</SUP> yrs. <P />Table 3 is only available in electronic form
at <A href="http://www.aanda.org">http://www.aanda.org</A>
---------------------------------------------------------
Title: Ground-based Multisite Observations of Two Transits of
HD 80606b
Authors: Shporer, A.; Winn, J. N.; Dreizler, S.; Colón, K. D.;
Wood-Vasey, W. M.; Choi, P. I.; Morley, C.; Moutou, C.; Welsh, W. F.;
Pollaco, D.; Starkey, D.; Adams, E.; Barros, S. C. C.; Bouchy, F.;
Cabrera-Lavers, A.; Cerutti, S.; Coban, L.; Costello, K.; Deeg, H.;
Díaz, R. F.; Esquerdo, G. A.; Fernandez, J.; Fleming, S. W.; Ford,
E. B.; Fulton, B. J.; Good, M.; Hébrard, G.; Holman, M. J.; Hunt, M.;
Kadakia, S.; Lander, G.; Lockhart, M.; Mazeh, T.; Morehead, R. C.;
Nelson, B. E.; Nortmann, L.; Reyes, F.; Roebuck, E.; Rudy, A. R.;
Ruth, R.; Simpson, E.; Vincent, C.; Weaver, G.; Xie, J. -W.
2010ApJ...722..880S Altcode: 2010arXiv1008.4129S
We present ground-based optical observations of the 2009 September
and 2010 January transits of HD 80606b. Based on three partial light
curves of the 2009 September event, we derive a midtransit time of
T<SUB>c</SUB> [HJD] = 2455099.196 ± 0.026, which is about 1σ away
from the previously predicted time. We observed the 2010 January event
from nine different locations, with most phases of the transit being
observed by at least three different teams. We determine a midtransit
time of T<SUB>c</SUB> [HJD] = 2455210.6502 ± 0.0064, which is within
1.3σ of the time derived from a Spitzer observation of the same event.
---------------------------------------------------------
Title: EXOTIME: searching for planets around pulsating subdwarf
B stars
Authors: Schuh, Sonja; Silvotti, Roberto; Lutz, Ronny; Loeptien,
Björn; Green, Elizabeth M.; Østensen, Roy H.; Leccia, Silvio;
Kim, Seung-Lee; Fontaine, Gilles; Charpinet, Stéphane; Francœur,
Myriam; Randall, Suzanna; Rodríguez-López, Cristina; Van Grootel,
Valerie; Odell, Andrew P.; Paparó, Margit; Bognár, Zsófia; Pápics,
Péter; Nagel, Thorsten; Beeck, Benjamin; Hundertmark, Markus; Stahn,
Thorsten; Dreizler, Stefan; Hessman, Frederic V.; Dall'Ora, Massimo;
Mancini, Dario; Cortecchia, Fausto; Benatti, Serena; Claudi, Riccardo;
Janulis, Rimvydas
2010Ap&SS.329..231S Altcode: 2010arXiv1005.3461S; 2010Ap&SS.tmp..130S
In 2007, a companion with planetary mass was found around
the pulsating subdwarf B star V391 Pegasi with the timing
method, indicating that a previously undiscovered population
of substellar companions to apparently single subdwarf B stars
might exist. Following this serendipitous discovery, the EXOTIME
(<ExternalRef> <RefSource>http://www.na.astro.it/
silvotti/exotime/</RefSource> <RefTarget
Address="http://www.na.astro.it/ silvotti/exotime/"
TargetType="URL"/> </ExternalRef>) monitoring program has
been set up to follow the pulsations of a number of selected rapidly
pulsating subdwarf B stars on time scales of several years with two
immediate observational goals: <P />(1) <P />determine dot{P} of the
pulsational periods P
---------------------------------------------------------
Title: CARMENES: Calar Alto high-resolution search for M dwarfs with
exo-earths with a near-infrared Echelle spectrograph
Authors: Quirrenbach, A.; Amado, P. J.; Mandel, H.; Caballero, J. A.;
Mundt, R.; Ribas, I.; Reiners, A.; Abril, M.; Aceituno, J.; Afonso,
C.; Barrado y Navascues, D.; Bean, J. L.; Béjar, V. J. S.; Becerril,
S.; Böhm, A.; Cárdenas, M. C.; Claret, A.; Colomé, J.; Costillo,
L. P.; Dreizler, S.; Fernández, M.; Francisco, X.; Galadí, D.;
Garrido, R.; González Hernández, J. I.; Guàrdia, J.; Guenther,
E. W.; Gutiérrez-Soto, F.; Joergens, V.; Hatzes, A. P.; Helmling,
J.; Henning, T.; Herrero, E.; Kürster, M.; Laun, W.; Lenzen, R.;
Mall, U.; Martin, E. L.; Martín-Ruiz, S.; Mirabet, E.; Montes, D.;
Morales, J. C.; Morales Muñoz, R.; Moya, A.; Naranjo, V.; Rabaza,
O.; Ramón, A.; Rebolo, R.; Reffert, S.; Rodler, F.; Rodríguez, E.;
Rodríguez Trinidad, A.; Rohloff, R. R.; Sánchez Carrasco, M. A.;
Schmidt, C.; Seifert, W.; Setiawan, J.; Solano, E.; Stahl, O.; Storz,
C.; Suárez, J. C.; Thiele, U.; Wagner, K.; Wiedemann, G.; Zapatero
Osorio, M. R.; del Burgo, C.; Sánchez-Blanco, E.; Xu, W.
2010SPIE.7735E..13Q Altcode: 2010SPIE.7735E..37Q
CARMENES (Calar Alto high-Resolution search for M dwarfs with
Exo-earths with Near-infrared and optical Echelle Spectrographs)
is a next-generation instrument to be built for the 3.5m telescope
at the Calar Alto Observatory by a consortium of Spanish and German
institutions. Conducting a five-year exoplanet survey targeting ~
300 M stars with the completed instrument is an integral part of the
project. The CARMENES instrument consists of two separate spectrographs
covering the wavelength range from 0.52 to 1.7 μm at a spectral
resolution of R = 85, 000, fed by fibers from the Cassegrain focus of
the telescope. The spectrographs are housed in a temperature-stabilized
environment in vacuum tanks, to enable a 1m/s radial velocity precision
employing a simultaneous ThAr calibration.
---------------------------------------------------------
Title: The MUSE second-generation VLT instrument
Authors: Bacon, R.; Accardo, M.; Adjali, L.; Anwand, H.; Bauer, S.;
Biswas, I.; Blaizot, J.; Boudon, D.; Brau-Nogue, S.; Brinchmann, J.;
Caillier, P.; Capoani, L.; Carollo, C. M.; Contini, T.; Couderc,
P.; Daguisé, E.; Deiries, S.; Delabre, B.; Dreizler, S.; Dubois,
J.; Dupieux, M.; Dupuy, C.; Emsellem, E.; Fechner, T.; Fleischmann,
A.; François, M.; Gallou, G.; Gharsa, T.; Glindemann, A.; Gojak, D.;
Guiderdoni, B.; Hansali, G.; Hahn, T.; Jarno, A.; Kelz, A.; Koehler,
C.; Kosmalski, J.; Laurent, F.; Le Floch, M.; Lilly, S. J.; Lizon,
J. -L.; Loupias, M.; Manescau, A.; Monstein, C.; Nicklas, H.; Olaya,
J. -C.; Pares, L.; Pasquini, L.; Pécontal-Rousset, A.; Pelló, R.;
Petit, C.; Popow, E.; Reiss, R.; Remillieux, A.; Renault, E.; Roth,
M.; Rupprecht, G.; Serre, D.; Schaye, J.; Soucail, G.; Steinmetz, M.;
Streicher, O.; Stuik, R.; Valentin, H.,; Vernet, J.; Weilbacher, P.;
Wisotzki, L.; Yerle, N.
2010SPIE.7735E..08B Altcode: 2010SPIE.7735E...7B
Summary: The Multi Unit Spectroscopic Explorer (MUSE) is a
second-generation VLT panoramic integral-field spectrograph currently
in manufacturing, assembly and integration phase. MUSE has a field of
1x1 arcmin<SUP>2</SUP> sampled at 0.2x0.2 arcsec<SUP>2</SUP> and is
assisted by the VLT ground layer adaptive optics ESO facility using
four laser guide stars. The instrument is a large assembly of 24
identical high performance integral field units, each one composed
of an advanced image slicer, a spectrograph and a 4kx4k detector. In
this paper we review the progress of the manufacturing and report the
performance achieved with the first integral field unit.
---------------------------------------------------------
Title: X-ray spectroscopy and photometry of the long-period polar
AI Trianguli with XMM-Newton
Authors: Traulsen, I.; Reinsch, K.; Schwarz, R.; Dreizler, S.;
Beuermann, K.; Schwope, A. D.; Burwitz, V.
2010A&A...516A..76T Altcode: 2010arXiv1004.1629T
Context. The energy balance of cataclysmic variables with strong
magnetic fields is a central subject in understanding accretion
processes on magnetic white dwarfs. With XMM-Newton, we perform a
spectroscopic and photometric study of soft X-ray selected polars
during their high states of accretion. <BR /> Aims: On the basis of
X-ray and optical observations of the magnetic cataclysmic variable
AI Tri, we derive the properties of the spectral components, their
flux contributions, and the physical structure of the accretion
region in soft polars. <BR /> Methods: We use multi-temperature
approaches in our xspec modeling of the X-ray spectra to describe the
physical conditions and the structures of the post-shock accretion
flow and the accretion spot on the white-dwarf surface. In addition,
we investigate the accretion geometry of the system by completing a
timing analysis of the photometric data. <BR /> Results: Flaring
soft X-ray emission from the heated surface of the white dwarf
dominates the X-ray flux during roughly 70% of the binary cycle. This
component deviates from a single black body and can be described by
a superimposition of mildly absorbed black bodies with a Gaussian
temperature distribution between kT<SUB>bb,low</SUB> := 2 eV and
kT<SUB>bb,high</SUB> = 43.9<SUP>+3.3</SUP><SUB>-3.2</SUB> eV, and
{N}_H,ISM = 1.5<SUP>+0.8</SUP><SUB>-0.7</SUB>× 10<SUP>20</SUP>
cm<SUP>-2</SUP>. In addition, weaker hard X-ray emission is visible
nearly all the time. The spectrum from the cooling post-shock accretion
flow is most closely fitted by a combination of thermal plasma
mekal models with temperature profiles adapted from prior stationary
two-fluid hydrodynamic calculations. The resulting plasma temperatures
lie between kT_MEKAL,{low} = 0.8<SUP>+0.4</SUP><SUB>-0.2</SUB>
keV and kT_MEKAL,{high} = 20.0<SUP>+9.9</SUP><SUB>-6.1</SUB> keV;
additional intrinsic, partial-covering absorption is on the order of
N<SUB>H,int</SUB> = 3.3<SUP>+2.5</SUP><SUB>-1.2</SUB>× 10<SUP>23</SUP>
cm<SUP>-2</SUP>. The soft X-ray light curves show a dip during the
bright phase, which can be interpreted as self-absorption in the
accretion stream. Phase-resolved spectral modeling supports the picture
of one-pole accretion and self-eclipse. One of the optical light curves
corresponds to an irregular mode of accretion. During a short XMM-Newton
observation at the same epoch, the X-ray emission of the system is
clearly dominated by the soft component. <P />Based on observations
obtained with XMM-Newton, an ESA science mission with instruments and
contributions directly funded by ESA Member States and NASA.
---------------------------------------------------------
Title: The CRIRES Search for Planets at the Bottom of the Main
Sequence
Authors: Bean, J.; Seifahrt, A.; Hartman, H.; Nilsson, H.; Wiedemann,
G.; Reiners, A.; Dreizler, S.; Henry, T.
2010Msngr.140...41B Altcode:
We present the first results obtained from our ongoing search
for planets around very low-mass stars and brown dwarfs using
radial velocities measured with the CRIRES spectrograph on the
VLT. High-precision radial velocity measurements for a large sample
of these previously neglected stars are enabled by observing at
near-infrared wavelengths and using a new type of gas cell that we
have developed. Unprecedented long-term near-infrared radial velocity
precisions of ~ 5 ms-1 have been demonstrated using CRIRES with the
cell. As a first scientific result, data obtained for the very low-mass
star VB 10 have been used to refute a claimed planet detection based
on astrometry. These results demonstrate the unique sensitivity of
our methodology, and confirm its power to detect planets, including
potentially habitable ones, around the most numerous stars in the
Galaxy.
---------------------------------------------------------
Title: Discovery of a nearby young brown dwarf binary candidate
Authors: Reiners, A.; Seifahrt, A.; Dreizler, S.
2010A&A...513L...9R Altcode: 2010arXiv1003.1715R
In near-infrared NaCo observations of the young brown dwarf 2MASS
J0041353-562112, we discovered a companion a little less than
a magnitude fainter than the primary. The binary candidate has a
separation of 143 mas, and the spectral types of the two components
are M 6.5 and M 9.0. Colors and flux ratios of the components are
consistent with their locations being at the same distance minimizing
the probability of the secondary being a background object. The
brown dwarf is known to exhibit Li absorption constraining the age
to be younger than ~ 200 Myr, and has been suspected of experiencing
ongoing accretion, which implies an age as young as ~ 10 Myr. We
estimate distance and orbital parameters of the binary as a function
of age. For an age of 10 Myr, the distance to the system is 50 pc,
the orbital period is 126 yr, and the masses of the components are ~
30 and ~ 15 M<SUB>Jup</SUB>. The binary brown dwarf fills a so far
unoccupied region in the parameters mass and age; it is a valuable
new benchmark object for brown dwarf atmospheric and evolutionary
models. <P />Emmy Noether Fellow.
---------------------------------------------------------
Title: The CRIRES Search for Planets Around the Lowest-mass
Stars. I. High-precision Near-infrared Radial Velocities with an
Ammonia Gas Cell
Authors: Bean, Jacob L.; Seifahrt, Andreas; Hartman, Henrik; Nilsson,
Hampus; Wiedemann, Günter; Reiners, Ansgar; Dreizler, Stefan; Henry,
Todd J.
2010ApJ...713..410B Altcode: 2009arXiv0911.3148B
Radial velocities measured from near-infrared (NIR) spectra are a
potentially powerful tool to search for planets around cool stars
and sub-stellar objects. However, no technique currently exists that
yields NIR radial velocity precision comparable to that routinely
obtained in the visible. We are carrying out an NIR radial velocity
planet search program targeting a sample of the lowest-mass M dwarfs
using the CRIRES instrument on the Very Large Telescope. In this first
paper in a planned series about the project, we describe a method for
measuring high-precision relative radial velocities of these stars from
K-band spectra. The method makes use of a glass cell filled with ammonia
gas to calibrate the spectrograph response similar to the "iodine cell"
technique that has been used very successfully in the visible. Stellar
spectra are obtained through the ammonia cell and modeled as the product
of a Doppler-shifted template spectrum of the object and a spectrum of
the cell, convolved with a variable instrumental profile (IP) model. A
complicating factor is that a significant number of telluric absorption
lines are present in the spectral regions containing useful stellar and
ammonia lines. The telluric lines are modeled simultaneously as well
using spectrum synthesis with a time-resolved model of the atmosphere
over the observatory. The free parameters in the complete model are
the wavelength scale of the spectrum, the IP, adjustments to the water
and methane abundances in the atmospheric model, telluric spectrum
Doppler shift, and stellar Doppler shift. Tests of the method based
on the analysis of hundreds of spectra obtained for late-M dwarfs
over 6 months demonstrate that precisions of ~ 5 m s<SUP>-1</SUP>
are obtainable over long timescales, and precisions of better than
3 m s<SUP>-1</SUP> can be obtained over timescales up to a week. The
obtained precision is comparable to the predicted photon-limited errors,
but primarily limited over long timescales by the imperfect modeling of
the telluric lines. <P />Based on observations made with ESO Telescopes
at the Paranal Observatories under program ID 182.C-0748.
---------------------------------------------------------
Title: The Asteroseismic Potential of Kepler: First Results for
Solar-Type Stars
Authors: Chaplin, W. J.; Appourchaux, T.; Elsworth, Y.; García,
R. A.; Houdek, G.; Karoff, C.; Metcalfe, T. S.; Molenda-Żakowicz,
J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Brown, T. M.;
Christensen-Dalsgaard, J.; Gilliland, R. L.; Kjeldsen, H.; Borucki,
W. J.; Koch, D.; Jenkins, J. M.; Ballot, J.; Basu, S.; Bazot, M.;
Bedding, T. R.; Benomar, O.; Bonanno, A.; Brandão, I. M.; Bruntt,
H.; Campante, T. L.; Creevey, O. L.; Di Mauro, M. P.; Doǧan,
G.; Dreizler, S.; Eggenberger, P.; Esch, L.; Fletcher, S. T.;
Frandsen, S.; Gai, N.; Gaulme, P.; Handberg, R.; Hekker, S.; Howe,
R.; Huber, D.; Korzennik, S. G.; Lebrun, J. C.; Leccia, S.; Martic,
M.; Mathur, S.; Mosser, B.; New, R.; Quirion, P. -O.; Régulo, C.;
Roxburgh, I. W.; Salabert, D.; Schou, J.; Sousa, S. G.; Stello, D.;
Verner, G. A.; Arentoft, T.; Barban, C.; Belkacem, K.; Benatti, S.;
Biazzo, K.; Boumier, P.; Bradley, P. A.; Broomhall, A. -M.; Buzasi,
D. L.; Claudi, R. U.; Cunha, M. S.; D'Antona, F.; Deheuvels, S.;
Derekas, A.; García Hernández, A.; Giampapa, M. S.; Goupil, M. J.;
Gruberbauer, M.; Guzik, J. A.; Hale, S. J.; Ireland, M. J.; Kiss,
L. L.; Kitiashvili, I. N.; Kolenberg, K.; Korhonen, H.; Kosovichev,
A. G.; Kupka, F.; Lebreton, Y.; Leroy, B.; Ludwig, H. -G.; Mathis, S.;
Michel, E.; Miglio, A.; Montalbán, J.; Moya, A.; Noels, A.; Noyes,
R. W.; Pallé, P. L.; Piau, L.; Preston, H. L.; Roca Cortés, T.;
Roth, M.; Sato, K. H.; Schmitt, J.; Serenelli, A. M.; Silva Aguirre,
V.; Stevens, I. R.; Suárez, J. C.; Suran, M. D.; Trampedach, R.;
Turck-Chièze, S.; Uytterhoeven, K.; Ventura, R.; Wilson, P. A.
2010ApJ...713L.169C Altcode: 2010arXiv1001.0506C
We present preliminary asteroseismic results from Kepler on three G-type
stars. The observations, made at one-minute cadence during the first
33.5 days of science operations, reveal high signal-to-noise solar-like
oscillation spectra in all three stars: about 20 modes of oscillation
may be clearly distinguished in each star. We discuss the appearance of
the oscillation spectra, use the frequencies and frequency separations
to provide first results on the radii, masses, and ages of the stars,
and comment in the light of these results on prospects for inference
on other solar-type stars that Kepler will observe.
---------------------------------------------------------
Title: Discovery of a Red Giant with Solar-like Oscillations in an
Eclipsing Binary System from Kepler Space-based Photometry
Authors: Hekker, S.; Debosscher, J.; Huber, D.; Hidas, M. G.; De
Ridder, J.; Aerts, C.; Stello, D.; Bedding, T. R.; Gilliland, R. L.;
Christensen-Dalsgaard, J.; Brown, T. M.; Kjeldsen, H.; Borucki, W. J.;
Koch, D.; Jenkins, J. M.; Van Winckel, H.; Beck, P. G.; Blomme,
J.; Southworth, J.; Pigulski, A.; Chaplin, W. J.; Elsworth, Y. P.;
Stevens, I. R.; Dreizler, S.; Kurtz, D. W.; Maceroni, C.; Cardini,
D.; Derekas, A.; Suran, M. D.
2010ApJ...713L.187H Altcode: 2010arXiv1001.0399H
Oscillating stars in binary systems are among the most interesting
stellar laboratories, as these can provide information on the stellar
parameters and stellar internal structures. Here we present a red
giant with solar-like oscillations in an eclipsing binary observed
with the NASA Kepler satellite. We compute stellar parameters of the
red giant from spectra and the asteroseismic mass and radius from
the oscillations. Although only one eclipse has been observed so far,
we can already determine that the secondary is a main-sequence F star
in an eccentric orbit with a semi-major axis larger than 0.5 AU and
orbital period longer than 75 days.
---------------------------------------------------------
Title: The Proposed Giant Planet Orbiting VB 10 Does Not Exist
Authors: Bean, Jacob L.; Seifahrt, Andreas; Hartman, Henrik; Nilsson,
Hampus; Reiners, Ansgar; Dreizler, Stefan; Henry, Todd J.; Wiedemann,
Günter
2010ApJ...711L..19B Altcode:
We present high-precision relative radial velocities of the very low
mass star VB 10 that were obtained over a time span of 0.61 years as
part of an ongoing search for planets around stars at the end of the
main sequence. The radial velocities were measured from high-resolution
near-infrared spectra obtained using the CRIRES instrument on the
Very Large Telescope with an ammonia gas cell. The typical internal
precision of the measurements is 10 m s<SUP>-1</SUP>. These data do
not exhibit significant variability and are essentially constant at a
level consistent with the measurement uncertainties. Therefore, we do
not detect the radial velocity variations of VB 10 expected due to the
presence of an orbiting giant planet similar to that recently proposed
by Pravdo & Shaklan based on apparent astrometric perturbations. In
addition, we do not confirm the ~1 km s<SUP>-1</SUP> radial velocity
variability of the star tentatively detected by Zapatero Osorio and
colleagues with lower precision measurements. Our measurements rule out
planets with M <SUB> p </SUB> > 3 M <SUB>Jup</SUB> and the orbital
period and inclination suggested by Pravdo & Shaklan at better than
5σ confidence. We conclude that the planet detection claimed by Pravdo
& Shaklan is spurious on the basis of this result. Although the
outcome of this work is a non-detection, it illustrates the potential
of using ammonia cell radial velocities to detect planets around very
low mass stars. <P />Based on observations made with ESO Telescopes
at the Paranal Observatories under program ID 182.C-0748.
---------------------------------------------------------
Title: Detecting Planets Around Very Low Mass Stars with the Radial
Velocity Method
Authors: Reiners, A.; Bean, J. L.; Huber, K. F.; Dreizler, S.;
Seifahrt, A.; Czesla, S.
2010ApJ...710..432R Altcode: 2009arXiv0909.0002R
The detection of planets around very low-mass stars with the radial
velocity (RV) method is hampered by the fact that these stars are very
faint at optical wavelengths where the most high-precision spectrometers
operate. We investigate the precision that can be achieved in RV
measurements of low mass stars in the near-infrared (NIR) Y-, J-,
and H-bands, and we compare it to the precision achievable in the
optical assuming comparable telescope and instrument efficiencies. For
early-M stars, RV measurements in the NIR offer no or only marginal
advantage in comparison with optical measurements. Although they emit
more flux in the NIR, the richness of spectral features in the optical
outweighs the flux difference. We find that NIR measurement can be
as precise as optical measurements in stars of spectral type ~M4,
and from there the NIR gains in precision toward cooler objects. We
studied potential calibration strategies in the NIR finding that a
stable spectrograph with a ThAr calibration can offer enough wavelength
stability for m s<SUP>-1</SUP> precision. Furthermore, we simulate
the wavelength-dependent influence of activity (cool spots) on RV
measurements from optical to NIR wavelengths. Our spot simulations
reveal that the RV jitter does not decrease as dramatically toward
longer wavelengths as often thought. The jitter strongly depends on
the details of the spots, i.e., on spot temperature and the spectral
appearance of the spot. At low temperature contrast (~200 K), the jitter
shows a decrease toward the NIR up to a factor of 10, but it decreases
substantially less for larger temperature contrasts. Forthcoming NIR
spectrographs will allow the search for planets with a particular
advantage in mid- and late-M stars. Activity will remain an issue,
but simultaneous observations at optical and NIR wavelengths can
provide strong constraints on spot properties in active stars.
---------------------------------------------------------
Title: The CRIRES Search for Planets Around the Lowest-Mass Stars:
Introduction and First Results
Authors: Bean, Jacob; Seifahrt, A.; Reiners, A.; Dreizler, S.; Hartman,
H.; Nilsson, H.; Wiedemann, G.; Henry, T.
2010AAS...21534807B Altcode: 2010BAAS...42..530B
We are currently carrying out a search for planets around the
lowest-mass stars using the CRIRES instrument at the VLT under the
auspices of an ESO Large Programme. The main purposes of this work are
to illuminate the correlation between stellar mass and planet formation,
improve the census of planets, and identify new planets that can be
followed-up for detailed study. We have developed, and are utilizing
a new type of gas cell for obtaining high-precision radial velocities
of late-type stars in the nIR spectral region. Observations in the
nIR offer the advantages in that the targetted stars are bright enough
for high-precision spectroscopy, and that the noise contribution from
stellar activity is significantly reduced. We will give an introduction
to the survey and present some preliminary results.
---------------------------------------------------------
Title: The CRIRES Search for Planets Around the Lowest-Mass Stars:
High-Precision nIR Radial Velocities with a New Gas Cell
Authors: Seifahrt, Andreas; Bean, J.; Hartman, H.; Nilsson, H.;
Wiedemann, G.; Reiners, A.; Dreizler, S.; Henry, T.
2010AAS...21542114S Altcode: 2010BAAS...42..288S
We are currently carrying out a search for planets around the
lowest-mass stars using the CRIRES instrument at the VLT under the
auspices of an ESO Large Programme. The main purposes of this work are
to illuminate the correlation between stellar mass and planet formation,
improve the census of planets, and identify new planets that can be
followed-up for detailed study. We have developed, and are utilizing
a new type of gas cell for obtaining high-precision radial velocities
of late-type stars in the nIR spectral region. Observations in the
nIR offer the advantages in that the targeted stars are bright enough
for high-precision spectroscopy, and that the noise contribution from
stellar activity is significantly reduced. We will describe the new
gas cell and our radial velocity measurement algorithm, and present
extensive tests of the obtained precision.
---------------------------------------------------------
Title: The CRIRES Search for Planets Around the Lowest-Mass
Stars. II. The Proposed Giant Planet Orbiting VB10 Does Not Exist
Authors: Bean, Jacob L.; Seifahrt, Andreas; Hartman, Henrik; Nilsson,
Hampus; Reiners, Ansgar; Dreizler, Stefan; Henry, Todd J.; Wiedemann,
Guenter
2009arXiv0912.0003B Altcode:
We present high-precision relative radial velocities of the very
low-mass star VB10 that were obtained over a time span of 0.61 yr as
part of an ongoing search for planets around stars at the end of the
main sequence. The radial velocities were measured from high-resolution
near-infrared spectra obtained using the CRIRES instrument on the
VLT with an ammonia gas cell. The typical internal precision of
the measurements is 10 m/s. These data do not exhibit significant
variability and are essentially constant at a level consistent
with the measurement uncertainties. Therefore, we do not detect the
radial velocity variations of VB10 expected due to the presence of
an orbiting giant planet similar to that recently proposed by Pravdo
and Shaklan based on apparent astrometric perturbations. In addition,
we do not confirm the ~1 km/s radial velocity variability of the star
tentatively detected by Zapatero Osorio and colleagues with lower
precision measurements. Our measurements rule out planets with M_p >
3 M_Jup and the orbital period and inclination suggested by Pravdo and
Shaklan at better than 5 sigma confidence. We conclude that the planet
detection claimed by Pravdo and Shaklan is spurious on the basis of
this result. Although the outcome of this work is a non-detection,
it illustrates the potential of using ammonia cell radial velocities
to detect planets around very low-mass stars.
---------------------------------------------------------
Title: Physical Properties of the 0.94-Day Period Transiting Planetary
System WASP-18
Authors: Southworth, John; Hinse, T. C.; Dominik, M.; Glitrup, M.;
Jørgensen, U. G.; Liebig, C.; Mathiasen, M.; Anderson, D. R.; Bozza,
V.; Browne, P.; Burgdorf, M.; Calchi Novati, S.; Dreizler, S.; Finet,
F.; Harpsøe, K.; Hessman, F.; Hundertmark, M.; Maier, G.; Mancini,
L.; Maxted, P. F. L.; Rahvar, S.; Ricci, D.; Scarpetta, G.; Skottfelt,
J.; Snodgrass, C.; Surdej, J.; Zimmer, F.
2009ApJ...707..167S Altcode: 2009arXiv0910.4875S
We present high-precision photometry of five consecutive transits
of WASP-18, an extrasolar planetary system with one of the shortest
orbital periods known. Through the use of telescope defocusing we
achieve a photometric precision of 0.47-0.83 mmag per observation over
complete transit events. The data are analyzed using the JKTEBOP code
and three different sets of stellar evolutionary models. We find the
mass and radius of the planet to be M <SUB>b</SUB> = 10.43 ± 0.30 ±
0.24 M <SUB>Jup</SUB> and R <SUB>b</SUB> = 1.165 ± 0.055 ± 0.014 R
<SUB>Jup</SUB> (statistical and systematic errors), respectively. The
systematic errors in the orbital separation and the stellar and
planetary masses, arising from the use of theoretical predictions,
are of a similar size to the statistical errors and set a limit on
our understanding of the WASP-18 system. We point out that seven of
the nine known massive transiting planets (M <SUB>b</SUB> > 3 M
<SUB>Jup</SUB>) have eccentric orbits, whereas significant orbital
eccentricity has been detected for only four of the 46 less-massive
planets. This may indicate that there are two different populations
of transiting planets, but could also be explained by observational
biases. Further radial velocity observations of low-mass planets will
make it possible to choose between these two scenarios. <P />Based
on data collected by MiNDSTEp with the Danish 1.54 m telescope at the
ESO La Silla Observatory.
---------------------------------------------------------
Title: A hot white dwarf luminosity function from the Sloan Digital
Sky Survey
Authors: Krzesinski, J.; Kleinman, S. J.; Nitta, A.; Hügelmeyer,
S.; Dreizler, S.; Liebert, J.; Harris, H.
2009A&A...508..339K Altcode:
Aims. We present a hot white dwarf (WD) luminosity function (LF) using
data taken from the Sloan Digital Sky Survey (SDSS) Data Release 4. We
present and discuss a combined LF, along with separate DA and non-DA
as LFs. We explore the completeness of our LFs and interpret a sudden
drop in the non-DA LF near 2 M_bol as a transition of the non-DA WD
atmosphere into the DA one during WD evolution. Our LF extends roughly
between -0.5 < M_bol < 7 or equivalently, ∼ 120 000 K >
T_eff > ∼25 000 K. Our LF should now be useful for estimates of
recent star formation and for studies of neutrino and other potential
particle emission losses in hot WDs. <BR /> Methods: To create a
sample whose completeness can be characterized fully, we used stars
whose spectra were obtained via the SDSS's “hot standard” target
selection criteria. The hot standard stars were purposefully targeted to
a high level of completeness by the SDSS for calibration purposes. We
are fortunate that many of them are hot white dwarfs stars. We further
limited the sample to stars with fitted temperatures exceeding 23
500 K and log{g} > 7.0. We determined stellar distances for our
sample based on their absolute SDSS g filter magnitudes, derived from
WD stellar atmosphere model fits to the SDSS stellar spectra. <BR />
Results: We compared our LF with those of other researchers where
overlap occurs; however, our LFs are unique in their extension to the
most luminous/hottest WDs. The cool end of our LF connects with the
hot end of previously determined SDSS WD LFs and agreement here is
quite good. It is also good with previous non-SDSS WD LFs. We note
distinct differences between the DA and non-DA LFs and discuss the
reliability of the DA LF at its hot end. We have extended the range
of luminosities covered in the most recent WD LFs. The SDSS sample
is understood quite well and its exploration should contribute to a
number of new insights into early white dwarf evolution. <BR />
---------------------------------------------------------
Title: The Transit Ingress and the Tilted Orbit of the Extraordinarily
Eccentric Exoplanet HD 80606b
Authors: Winn, Joshua N.; Howard, Andrew W.; Johnson, John Asher;
Marcy, Geoffrey W.; Gazak, J. Zachary; Starkey, Donn; Ford, Eric B.;
Colón, Knicole D.; Reyes, Francisco; Nortmann, Lisa; Dreizler, Stefan;
Odewahn, Stephen; Welsh, William F.; Kadakia, Shimonee; Vanderbei,
Robert J.; Adams, Elisabeth R.; Lockhart, Matthew; Crossfield, Ian J.;
Valenti, Jeff A.; Dantowitz, Ronald; Carter, Joshua A.
2009ApJ...703.2091W Altcode: 2009arXiv0907.5205W
We present the results of a transcontinental campaign to observe the
2009 June 5 transit of the exoplanet HD 80606b. We report the first
detection of the transit ingress, revealing the transit duration to be
11.64 ± 0.25 hr and allowing more robust determinations of the system
parameters. Keck spectra obtained at midtransit exhibit an anomalous
blueshift, giving definitive evidence that the stellar spin axis and
planetary orbital axis are misaligned. The Keck data show that the
projected spin-orbit angle λ is between 32° and 87° with 68.3%
confidence and between 14° and 142° with 99.73% confidence. Thus,
the orbit of this planet is not only highly eccentric (e = 0.93) but is
also tilted away from the equatorial plane of its parent star. A large
tilt had been predicted, based on the idea that the planet's eccentric
orbit was caused by the Kozai mechanism. Independently of the theory,
it is worth noting that all three exoplanetary systems with known
spin-orbit misalignments have massive planets on eccentric orbits,
suggesting that those systems migrate through a different channel than
lower mass planets on circular orbits.
---------------------------------------------------------
Title: 1D and 3D radiative transfer in circumstellar disks
Authors: Hügelmeyer, S. D.; Dreizler, S.; Homeier, D.; Hauschildt,
P. H.; Barman, T.
2009AIPC.1171...93H Altcode:
We present our code for the calculation of the 1D structure and
synthetic spectra of accretion disks. The code is an extension of the
well-tested stellar atmosphere code PHOENIX and is therefore capable
of including large lists of atomic and molecular lines as well as
a large set of dust species. We assume the standard accretion disk
model for geometrically thin disks and solve the radiative transfer
equation in the vertical direction for a number of disk rings with
different radii. The combination of these rings yields the total disk
spectrum. Comparison to observations of the T Tauri star GQ Lup shows
the capability of our code. Additionally, we will show first results of
3D radiative transfer calculations. We plan to investigate the effect
of rotating disks on the line profile by means of a two-level atom.
---------------------------------------------------------
Title: Detecting circumstellar disks around gravitational microlenses
Authors: Hundertmark, M.; Hessman, F. V.; Dreizler, S.
2009A&A...500..929H Altcode: 2009arXiv0904.1117H
Aims: We investigate the chance of detecting proto-planetary or debris
disks in stars that induce microlensing event (lenses), and consider
the modification of the light curve shapes due to occultation and
extinction by the disks, as well as the gravitational deflection
caused by the additional mass. <BR />Methods: The magnification
of gravitational microlensing events is calculated using the ray
shooting method. The occultation is taken into account by neglecting
or weighting the images on the lens plane according to a transmission
map of the corresponding disk for a point source point lens (PSPL)
model. The estimated frequency of events is obtained by considering the
possible inclinations and optical depths of the disk. <BR />Results:
We conclude that gravitational microlensing can be used, in principle,
as a tool for detecting debris disks beyond 1 kpc, but estimate that
each year around 1 debris disk is expected for lens stars of F, G, or
K spectral type and about 10 debris disks might have shown signatures
in existing datasets.
---------------------------------------------------------
Title: Spectral synthesis of circumstellar disks - application to
white dwarf debris disks
Authors: Hügelmeyer, S. D.; Dreizler, S.; Homeier, D.; Hauschildt, P.
2009JPhCS.172a2060H Altcode: 2009arXiv0905.0329H
Gas and dust disks are common objects in the universe and can be
found around various objects, e.g. young stars, cataclysmic variables,
active galactic nuclei, or white dwarfs. The light that we receive from
disks provides us with clues about their composition, temperature,
and density. In order to better understand the physical and chemical
dynamics of these disks, self-consistent radiative transfer simulations
are inevitable. Therefore, we have developed a 1+1D radiative transfer
code as an extension to the well-established model atmosphere code
PHOENIX. We will show the potential of the application of our code to
model the spectra of white dwarf debris disks.
---------------------------------------------------------
Title: Spectral analysis of 636 WD - M star binaries from the Sloan
Digital Sky Survey (Data Release 6)
Authors: Heller, R.; Homeier, D.; Dreizler, S.; Østensen, R.
2009JPhCS.172a2023H Altcode:
We present a catalog of 857 WD (WD)-M star binaries from the sixth
data release of the Sloan Digital Sky Survey (SDSS), most of them
known before. For 636 of them, we give a spectral analysis and derive
the basic parameters of the stellar constituents and their distances
from Earth. Our purpose is to test the modeled spectra applied in
the fitting procedure on the one hand and to confine the respective
evolutionary scenarios on the other hand. We use a χ<SUP>2</SUP>
minimization technique in order to decompose each combined spectrum
and yield independent parameter estimates for the components. 41 of the
stellar duets in our spectroscopic sample are optically resolved on the
respective SDSS images. Despite various selection effects, the fraction
of 6.4 % of WD-M star binaries with orbital separation around 500 AU and
orbital perdiods of ~ 10<SUP>4</SUP> yr is a criterion for evolutionary
models of stellar binary systems. We find 20 out of 636 WDs being
fitted as DOs, with 16 of them indicating T<SUB>ef</SUB><SUP>WD</SUP>
around 40000K. This excess of cool DOs is most likely due to additional
WDs in the DB-DO T<SUB>eff</SUB> range, for which no detailed fitting
was done. Furthermore, we identify 70 very low-mass objects, meaning
secondaries with masses smaller than about 0.1 M<SUB>odot</SUB>, as
candidate substellar companions. A trend of WD masses towards higher
values in a binary constellation compared to those of field WDs is
compatible with our results.
---------------------------------------------------------
Title: SDSS DR4: Progress on the hot white dwarf luminosity function
Authors: Krzesinski, J.; Nitta, A.; Kleinman, S. J.; Hügelmeyer,
S.; Dreizler, S.; Liebert, J.; Harris, H.
2009JPhCS.172a2002K Altcode:
A large collection of white dwarf (WD) spectra from Sloan Digital
Sky Survey (SDSS) data release 4 (DR4) WD catalog data allowed us
to obtain a luminosity function (LF) for the hottest WDs. The LF was
calculated basing on spectra of the WDs from a special class of SDSS
objects called hot standards (HS), for which the WD sample completeness
can be estimated. WD distances were determined from the observed and
absolute SDSS g filter magnitudes derived from WD stellar atmosphere
model fits to the SDSS spectra. The result LF covers -0.5 up to 7
absolute bolometric magnitude range. It shows a slight disagreement
at the cold end comparing to the literature LFs but it can be due
to some problems with HS WD sample completeness estimations. It is
clearly visible that the LF has unexpected plateau between 1.5 and
4 absolute bolometric magnitudes. There is nothing similar visible
in a LF built only for non-DA WDs. The plateau might be real but we
are concern that its existence can be connected to the problems with
spectra calibration of the blue objects in SDSS DR4 data and lack of
good stellar atmosphere models for the hottest DA white dwarfs.
---------------------------------------------------------
Title: Non-LTE spectral analyses of the lately discovered DB-gap
white dwarfs from the SDSS
Authors: Hügelmeyer, S. D.; Dreizler, S.
2009JPhCS.172a2048H Altcode: 2009arXiv0905.0331H
For a long time, no hydrogen-deficient white dwarfs have been
known that have effective temperature between 30 kK and < 45 kK,
i. e. exceeding those of DB white dwarfs and having lower ones than DO
white dwarfs. Therefore, this temperature range was long known as the
DB-gap. Only recently, the SDSS provided spectra of several candidate
DB-gap stars. First analyses based on model spectra calculated under
the assumption of local thermodynamic equilibrium (LTE) confirmed that
these stars had 30 kK < T<SUB>eff</SUB> < 45 kK (Eisenstein et
al. 2006). It has been shown for DO white dwarfs that the relaxation
of LTE is necessary to account for non local effects in the atmosphere
caused by the intense radiation field. Therefore, we calculated a
non-LTE model grid and re-analysed the aforementioned set of SDSS
spectra. Our results confirm the existence of DB-gap white dwarfs.
---------------------------------------------------------
Title: On the possibility of detecting extrasolar planets' atmospheres
with the Rossiter-McLaughlin effect
Authors: Dreizler, S.; Reiners, A.; Homeier, D.; Noll, M.
2009A&A...499..615D Altcode: 2009arXiv0903.2217D
Context: The detection of extrasolar planets' atmospheres requires
very demanding observations. For planets that cannot be spatially
separated from their host stars, i.e. the vast majority of planets,
the transiting planets are the only ones to allow their atmospheres
to be probed. This is possible from transmission spectroscopy
or from measurements taken during the secondary eclipse. An
alternative is to measure of the Rossiter-McLaughlin effect, which
is sensitive to the size of the planetary radius. Since the radius
is wavelength-dependent due to contributions of strong planetary
absorption lines, this opens a path toward also probing planetary
atmospheres with ground-based high-resolution spectroscopy. <BR
/>Aims: The major goal of our numerical simulations is to provide
a reliable estimate of the amplitude of the wavelength-dependent
Rossiter-McLaughlin effect. <BR />Methods: Our numerical simulations
provide detailed phase-resolved synthetic spectra modeling the partly
eclipsed stellar surface during the transit. With these spectra
we can obtain Rossiter-McLaughlin curves for different wavelength
regions and for a wavelength-dependent planetary radius. Curves from
regions with high and low contributions of absorption lines within
the planetary atmosphere can be compared. Observable quantities are
derived from these differential effects. <BR />Results: We applied
our simulations to HD 209458. Our numerical simulations show that a
detailed treatment of the limb-darkening for the synthetic spectra
is important for a precise analysis. Compared to a parameterized
limb-darkening law, systematic errors of 6 m s<SUP>-1</SUP> occur. The
wavelength dependency of the planetary atmospheres over the NaD-doublet
produces a differential effect in the Rossiter-McLaughlin curve of
1.5 m s<SUP>-1</SUP> for a star with a rotation velocity of 4.5 km
s<SUP>-1</SUP>, which increases to 4 m s<SUP>-1</SUP> for twice the
rotation velocity. <BR />Conclusions: As a tool for probing planetary
atmospheres the Rossiter-McLaughlin effect requires phase-resolved,
high signal-to-noise, high-resolution spectra taken with a stabilized
spectrograph in order to obtain reliable results for slowly rotating
(<10 m s<SUP>-1</SUP>) planet host stars. Stars with spectral type
earlier than about F5 are a bit less demanding since the typically
higher rotation velocity increases the amplitude of the effect to about
15 m s<SUP>-1</SUP> for a star with v sin i = 25 km s<SUP>-1</SUP>.
---------------------------------------------------------
Title: Radiative transfer in circumstellar disks. I. 1D models for
GQ Lupi
Authors: Hügelmeyer, S. D.; Dreizler, S.; Hauschildt, P. H.; Seifahrt,
A.; Homeier, D.; Barman, T.
2009A&A...498..793H Altcode: 2009arXiv0903.2381H
We present a new code for the calculation of the 1D structure and
synthetic spectra of accretion disks. The code is an extension of the
general purpose stellar atmosphere code PHOENIX and is therefore capable
of including extensive lists of atomic and molecular lines as well as
dust in the calculations. We assume that the average viscosity can be
represented by a critical Reynolds number in a geometrically thin disk
and solve the structure and radiative transfer equations for a number
of disk rings in the vertical direction. The combination of these
rings provides the total disk structure and spectrum. Since the warm
inner regions of protoplanetary disks show a rich molecular spectrum,
they are well suited for a spectral analysis with our models. In this
paper we test our code by comparing our models with high-resolution
VLT CRIRES spectra of the T Tauri star GQ Lup.
---------------------------------------------------------
Title: OGLE2-TR-L9b: an exoplanet transiting a rapidly rotating
F3 star
Authors: Snellen, I. A. G.; Koppenhoefer, J.; van der Burg, R. F. J.;
Dreizler, S.; Greiner, J.; de Hoon, M. D. J.; Husser, T. O.; Krühler,
T.; Saglia, R. P.; Vuijsje, F. N.
2009A&A...497..545S Altcode: 2008arXiv0812.0599S
Context: The photometric observations of the OGLE-II microlens
monitoring campaign have been taken in the period 1997-2000. All light
curves of this campaign have recently become public. Our analysis of
these data has revealed 13 low-amplitude transiting objects among
15 700 stars in three Carina fields towards the Galactic disk. One
of these objects, OGLE2-TR-L9 (P∼2.5 days), turned out to be an
excellent transiting-planet candidate. <BR />Aims: We report on our
investigation of the true nature of OGLE2-TR-L9. By re-observing the
photometric transit, we attempt to determine the transit parameters to
high precision, and, by spectroscopic observations, to estimate the
properties of the host star and determine the mass of the transiting
object by means of radial-velocity measurements. <BR />Methods:
High precision photometric observations were obtained in g',
r', i', and z' band simultaneously, using the new GROND detector,
mounted on the MPI/ESO 2.2 m telescope at La Silla. Eight epochs of
high-dispersion spectroscopic observations were obtained using the
fiber-fed FLAMES/UVES Echelle spectrograph, mounted on ESO's Very Large
Telescope at Paranal. <BR />Results: The photometric transit, now more
than 7 years after the last OGLE-II observations, was re-discovered
only 8 min from its predicted time. The primary object is a rapidly
rotating F3 star with v sin i=39.33±0.38 km s<SUP>-1</SUP>, T=6933±58
K, log g = 4.25±0.01, and [Fe/H] = -0.05±0.20. The transiting object
is an extrasolar planet with M<SUB>{p</SUB>}=4.5±1.5 M<SUB>{Jup</SUB>}
and R<SUB>{p</SUB>}=1.61±0.04 R<SUB>{Jup</SUB>}. Since this is the
first planet detected orbiting a fast rotating star, the uncertainties
in both the radial-velocity measurements and the planetary mass are
larger than for most other planets discovered to date. The rejection
of possible blend scenarios was based on a quantitative analysis of
the multi-color photometric data. A stellar-blend scenario of an early
F-star with a faint eclipsing-binary system is excluded, due to 1) the
consistency between the spectroscopic parameters of the star and the
mean density of the transited object as determined from the photometry,
and 2) the excellent agreement between the transit signal as observed
at four different wavelengths. <P />Based on observations collected
at the European Organisation for Astronomical Research in the Southern
Hemisphere, Chile (280.C-5036(A)).
---------------------------------------------------------
Title: VizieR Online Data Catalog: Spectral analysis of 636 SDSS
WD-M binaries (Heller+, 2009)
Authors: Heller, R.; Homeier, D.; Dreizler, S.; Oestensen, R.
2009yCat..34960191H Altcode:
We present a catalog of 857 WD-M star binaries from the Sloan Digital
Sky Survey (SDSS), most of which were previously identified by other
authors, and the results of our spectral analysis for a subsample of
636 WD-M composite spectra. Our automatic fitting procedure bases on a
chi<SUP>2</SUP> minimization technique, yielding a decomposition of each
combined spectrum and a derivation of independent parameter estimates
for both components. On the respective photometric data from the SDSS,
we also find 41 optically resolved binaries. We also investigated the
spectra for hydrogen and helium emission. <P />(3 data files).
---------------------------------------------------------
Title: The planet-hosting subdwarf B star <ASTROBJ>V 391
Pegasi</ASTROBJ> is a hybrid pulsator
Authors: Lutz, R.; Schuh, S.; Silvotti, R.; Bernabei, S.; Dreizler,
S.; Stahn, T.; Hügelmeyer, S. D.
2009A&A...496..469L Altcode: 2009arXiv0901.4523L
Context: A noticeable fraction of subdwarf B stars shows either
short-period (p-mode) or long-period (g-mode) luminosity variations,
with two objects so far known to exhibit hybrid behaviour, i.e. showing
both types of modes at the same time. The pulsating subdwarf B star
<ASTROBJ>V 391 Pegasi</ASTROBJ> (or <ASTROBJ>HS 2201+2610</ASTROBJ>),
which is close to the two known hybrid pulsators in the log
g-T_eff plane, has recently been discovered to host a planetary
companion. <BR />Aims: In order to learn more about the planetary
companion and its possible influence on the evolution of its host star
(subdwarf B star formation is still not well understood), an accurate
characterisation of the host star is required. As part of an ongoing
effort to significantly improve the asteroseismic characterisation
of the host star, we investigate the low-frequency behaviour of
<ASTROBJ>HS 2201+2610</ASTROBJ>. <BR />Methods: We obtained rapid high
signal-to-noise photometric CCD (B-filter) and PMT (clear-filter)
data at 2 m-class telescopes and carried out a careful frequency
analysis of the light curves. <BR />Results: In addition to the
previously known short-period luminosity variations in the range 342
s-367 s, we find a long-period variation with a period of 54 mn and an
amplitude of 0.15 per cent. This can most plausibly be identified with
a g-mode pulsation, so that <ASTROBJ>HS 2201+2610</ASTROBJ> is a new
addition to the short list of hybrid sdB pulsators. <BR />Conclusions:
Along with the previously known pulsating subdwarf B stars <ASTROBJ>HS
0702+6043</ASTROBJ> and <ASTROBJ>Balloon 090100001</ASTROBJ> showing
hybrid behaviour, the new hybrid <ASTROBJ>HS 2201+2610</ASTROBJ> is
the third member of this class. This important property of <ASTROBJ>HS
2201+2610</ASTROBJ> can lead to a better characterisation of this
planet-hosting star, helping the characterisation of its planetary
companion as well. Current pulsation models cannot yet reproduce
hybrid sdBV stars particularly well and improved pulsation models
for this object have to include the hybrid behaviour. <P />Based
on observations collected at the Centro Astronómico Hispano Alemán
(CAHA) at Calar Alto, <P />operated jointly by the Max-Planck Institut
für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).
---------------------------------------------------------
Title: Spectral analysis of 636 white dwarf-M star binaries from
the sloan digital sky survey
Authors: Heller, R.; Homeier, D.; Dreizler, S.; Østensen, R.
2009A&A...496..191H Altcode:
Context: We present a catalog of 857 white dwarf (WD)-M binaries from
the sixth data release (DR6) of the Sloan Digital Sky Survey (SDSS),
most of which were previously identified. For 636 of them, we complete
a spectral analysis and derive the basic parameters of their stellar
constituents and their distances from Earth. <BR />Aims: We attempt to
measure fundamental parameters of these systems by completing spectral
analyses. We propose to test models typically applied in fitting
procedures and constrain likely and appropriate evolutionary scenarios
for the systems. <BR />Methods: We use a χ<SUP>2</SUP> minimization
technique to decompose each combined spectrum and derive independent
parameter estimates for its components. The possibility of alignment by
chance is demoted to statistical insignificance, hence, we use physical
interaction of the binary constituents as input parameter. Additionally,
we check the corresponding photometric data from the SDSS to find
optically resolved systems. <BR />Results: Forty-one of the stellar
duets in our spectroscopic sample are optically resolved in their
respective SDSS images. For these systems, we also derive a minimum
true spatial separation and a lower limit to their orbital periods,
typically which are some 10<SUP>4</SUP> yr. Spectra of 167 stellar duets
show significant hydrogen emission and in most cases no additional He
i or He ii features. We also find that 20 of the 636 WDs are fitted to
be DOs, with 16 measured to have T<SUB>eff</SUB><SUP>WD</SUP> around
40 000 K. Furthermore, we identify 70 very low-mass objects (VLMOs),
which are secondaries of masses smaller than about 0.1 M<SUB>⊙</SUB>,
to be candidate substellar companions. <BR />Conclusions: Although
various selection effects may play a role, the fraction 6.4% of WD-M
star binaries with orbital separations of around 500 AU is a criterion
for evolutionary models of stellar binary systems. Of the 167 spectra
with hydrogen emission, 8 had already been found to be post-common
envelope binaries (PCEBs) and 4 are systems with strong irradiation
processes on the M dwarf. The remaining 155 Balmer-emitting binaries
probably harbor an active M dwarf (dM), corresponding to a fraction
of 24.4%. The excess of cool DOs is most likely due to additional WDs
in the DB-DO T<SUB>eff</SUB> range, for which no detailed fitting was
completed. The trend of the M stars being closer to Earth than the WD
component is probably due to an underestimation of the theoretical M
star radii.
---------------------------------------------------------
Title: Long-term EXOTIME photometry and follow-up spectroscopy of
the sdB pulsator HS 0702+6043
Authors: Lutz, R.; Schuh, S.; Silvotti, R.; Kruspe, R.; Dreizler, S.
2009CoAst.159...94L Altcode: 2009arXiv0901.4514L
Pulsating subdwarf B (sdB) stars oscillate in short-period p modes or
long-period g modes. HS 0702+6043 (DW Lyn) is one of a few objects to
show characteristics of both types and is hence classified as a hybrid
pulsator. It is one of our targets in the EXOTIME program to search
for planetary companions around extreme horizontal branch objects. In
addition to the standard exercise in asteroseismology to probe the
instantaneous inner structure of a star, measured changes in the
pulsation frequencies as derived from an O--C diagram can be compared
to theoretical evolutionary time scales. Based on the photometric data
available so far, we are able to derive a high-resolution frequency
spectrum and to report our efforts to construct a multi-season O--C
diagram. Additionally, we have gathered time-resolved spectroscopic
data in order to constrain stellar parameters and to derive mode
parameters as well as radial and rotational velocities.
---------------------------------------------------------
Title: Spectral synthesis of inner gaseous protoplanetary disks
with PHOENIX
Authors: Hügelmeyer, S. D.; Dreizler, S.; Homeier, D.; Hauschildt,
P. H.; Barman, T.
2009AIPC.1094..389H Altcode: 2009csss...15..389H
The inner gaseous regions of protoplanetary disks are of special
interest in the formation and evolution of planets and stars because
they are the likely birthplaces of planets and serve as the accretion
reservoir for young stars. The study of inner disks may give rise to a
better understanding of the dynamics, physical and chemical structure,
and gas content of the region. As a first step, we have developed a 1+1D
disk radiative transfer package as an extension to the well established
multipurpose stellar atmosphere program PHOENIX. The solution of
the equations of momentum and energy conservation as well as the
radiative transfer equation is adopted for the physical conditions in
and the geometry of disks. Irradiation by the central star is treated in
detail. Comparison of our models with high-resolution infrared spectra
will enable us to constrain the structure, dynamics, and gas content of
disks, and thus give new insights on the physical processes governing
star and planet formation. Additionally, we present our current
construction site: a 3D radiative transfer code for accretion disks.
---------------------------------------------------------
Title: Spectral Analysis of 636 White Dwarf-M Star Binaries from
the Sloan Digital Sky Survey
Authors: Heller, R.; Homeier, D.; Dreizler, S.; Østensen, R.
2009AIPC.1094..931H Altcode: 2009csss...15..931H; 2008arXiv0811.1508H
We present a catalog of 857 white dwarf-M binaries from the sixth data
release of the Sloan Digital Sky Survey (SDSS), most of them known
before. For 636 of them, we give a spectral analysis and derive the
basic parameters of the stellar constituents and their distances from
Earth. The analysis shall give a statistically relevant statement about
the fundamental parameters of such systems. Our purpose is to test
the models applied in the fitting procedure on the one hand and to
confine the respective evolutionary scenarios on the other hand. The
χ<SUP>2</SUP> minimization technique we use, in order to decompose
each combined spectrum and yield independent parameter estimates for the
components, differs from that typically applied to break down combined
spectra. In the corresponding SDSS photometric data we find 41 optically
resolved systems. For these we also derive a minimum real spatial
separation and a lower limit for the orbital periods-typically some
10<SUP>4</SUP> yr. 167 spectra show significant hydrogen emission and
mostly no additional He I or He II features. Furthermore, we identify
70 very low-mass objects, meaning secondaries with masses smaller than
about 0.1 M<SUB>solar</SUB>, as candidate substellar companions.
---------------------------------------------------------
Title: New Science Opportunities Offered by MUSE
Authors: Bacon, R.; Bauer, S.; Brau-Nogué, S.; Caillier, P.; Capoani,
L.; Carollo, M.; Contini, T.; Daguisé, E.; Delabre, B.; Dreizler,
S.; Dubois, J. P.; Dupieux, M.; Dupin, J.; Emsellem, E.; Ferruit,
P.; Francois, M.; Franx, M.; Gallou, G.; Gerssen, J.; Guiderdoni,
B.; Hansali, G.; Hofmann, D.; Jarno, A.; Kelz, A.; Koehler, C.;
Kollatschny, W.; Kosmalski, J.; Laurent, F.; Lilly, S.; Lizon, J.;
Loupias, M.; Monstein, C.; Moultaka, J.; Nicklas, H.; Parés, L.;
Pasquini, L.; Pecontal, A.; Pello, R.; Petit, C.; Manescau, A.; Reiss,
R.; Remillieux, A.; Renault, E.; Roth, M.; Schaye, J.; Steinmetz,
M.; Ströbele, S.; Stuik, R.; Weilbacher, P.; Wisotzki, L.; Wozniak, H.
2009ASSP....9..331B Altcode: 2009svlt.conf..331B
The Multi Unit Spectroscopic Explorer MUSE [MUSE public web site:
http://muse.univ-lyon1.fr] is one of the second generation VLT
instruments. MUSE is a wide-field optical integral field spectrograph
operating in the visible wavelength range with improved spatial
resolution. The MUSE Consortium consists of groups at Lyon (PI
institute, CRAL), Gottingen (IAG), Potsdam (AIP), Leiden (NOVA),
Toulouse (LATT), Zurich (ETH) and ESO. The project is currently in its
final design phase. Manufacturing, assembly and integration will start
after the Final Design Review which is foreseen for late 2008. The
Preliminary acceptance in Europe is scheduled for mid 2011 and the
instrument shall be in operation at Paranal in 2012.
---------------------------------------------------------
Title: Multi-wavelength photometric variation of PG 1605+072
Authors: Schuh, S.; Dreizler, S.; Heber, U.; Jeffery, C. S.; O'Toole,
S. J.; Cordes, O.; Stahn, T.; Lutz, R.; Tillich, A.; Wet and MSST
Collaborations
2008CoAst.157...35S Altcode: 2008arXiv0812.4857S
In a large coordinated attempt to further our understanding of the
p-mode pulsating sdB star PG 1605+072, the Multi-Site Spectroscopic
Telescope (MSST) collaboration has obtained simultaneous time-resolved
spectroscopic and photometric observations. The photometry was extended
by additional WET data which increased the time base. This contribution
outlines the analysis of the MSST photometric light curve, including
the four-colour BUSCA data from which chromatic amplitudes have been
derived, as well as supplementary FUV spectra and light curves from
two different epochs. These results have the potential to complement
the interpretation of the published spectroscopic information.
---------------------------------------------------------
Title: Long-term photometric monitoring of the hybrid subdwarf B
pulsator HS 0702+6043
Authors: Lutz, R.; Schuh, S.; Silvotti, R.; Kruspe, R.; Dreizler, S.
2008CoAst.157..185L Altcode: 2008arXiv0812.4859L
Pulsating subdwarf B stars oscillate in short-period p-modes or
long-period g-modes. HS 0702 +6043 is one of the three objects currently
known to show characteristics of both types and hence is classified
as hybrid pulsator. We briefly present our analysis of the g-mode
domain of this star, but focus on the first results from long-term
photometric monitoring in particular of the p-mode oscillations. We
present a high-resolution frequency spectrum, and report on our
efforts to construct a multi-season O C diagram. Additionally to the
standard (although nontrivial) exercise in asteroseismology to probe
the instantaneous inner structure of a star, measured changes in the
pulsation frequencies as derived from an O C diagram can be compared
to theoretical evolutionary timescales. Within the EXOTIME program,
we also use this same data to search for planetary companions around
extreme horizontal branch objects (”asteroseismic planets”).
---------------------------------------------------------
Title: A Hubble Space Telescope transit light curve for GJ 436b
Authors: Bean, J. L.; Benedict, G. F.; Charbonneau, D.; Homeier, D.;
Taylor, D. C.; McArthur, B.; Seifahrt, A.; Dreizler, S.; Reiners, A.
2008A&A...486.1039B Altcode: 2008arXiv0806.0851B
We present time series photometry for six partial transits
of GJ 436b obtained with the Fine Guidance Sensor instrument
on the Hubble Space Telescope (HST). Our analysis of these
data yields independent estimates of the host star's radius
R<SUB>star</SUB> = 0.505<SUP>+0.029</SUP><SUB>-0.020</SUB>
R<SUB>⊙</SUB>, and the planet's orbital period P =
2.643882^+0.000060<SUB>-0.000058</SUB> d, orbital inclination i =
85.80° <SUP>+0.21°</SUP><SUB>-0.25°</SUB>, mean central transit time
T<SUB>c</SUB> = 2 454 455.279241<SUP>+0.00026</SUP><SUB>-0.00025</SUB>
HJD, and radius R<SUB>p</SUB> = 4.90<SUP>+0.45</SUP><SUB>-0.33</SUB>
R<SUB>⊕</SUB>. The radius we determine for the planet is larger than
the previous findings from analyses of an infrared light curve obtained
with the Spitzer Space Telescope. Although this discrepancy has a 92%
formal significance (1.7σ), it might be indicative of systematic errors
that still influence the analyses of even the highest-precision transit
light curves. Comparisons of all the measured radii to theoretical
models suggest that GJ 436b has a H/He envelope of 10% by mass. We point
out the similarities in structure between this planet and Uranus and
Neptune and discuss possible parallels between these planets' formation
environments and dynamical evolution. We also find that the transit
times for GJ 436b are constant to within 10 s over the 11 planetary
orbits that the HST data span. However, the ensemble of published
values exhibits a long-term drift and our mean transit time is 128 s
later than that expected from the Spitzer ephemeris. The sparseness of
the currently available data hinders distinguishing between an error in
the orbital period or perturbations arising from an additional object
in the system as the cause of the apparent trend. Assuming the drift is
due to an error in the orbital period we obtain an improved estimate
for it of P = 2.643904 ± 0.000005 d. This value and our measured
transit times will serve as important benchmarks in future studies of
the GJ 436 system. <P />Table 2 is only available in electronic form
at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5)
or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/486/1039
---------------------------------------------------------
Title: VizieR Online Data Catalog: HST transit light curve for GJ436b
(Bean+, 2008)
Authors: Bean, J. L.; Benedict, G. F.; Charbonneau, D.; Homeier, D.;
Taylor, D. C.; McArthur, B.; Seifahrt, A.; Dreizler, S.; Reiners, A.
2008yCat..34861039B Altcode:
This is Table 2 from the above paper. It contains photometric time
series of 6 partial transits for GJ436b obtained with the FGS instrument
on HST. The first column gives the visit number, the second one gives
the date as Heliocentric Julian Days (HJD), the third one gives the
flux in 60 second bins normalized by the reference star observations,
and the fourth one gives the statistical noise for each measurement. <P
/>(1 data file).
---------------------------------------------------------
Title: Hot DO and DB White Dwarfs from the Sloan Digital Sky Survey
Authors: Liebert, J.; Krzesinski, J.; Hügelmeyer, S.; Dreizler, S.
2008ASPC..391..227L Altcode:
Hot DB and DO stars found in the Sloan Digital Sky Survey are
analyzed. We note first that the mass distribution of DB stars
determined by others has a very similar mean to that for samples of DA
stars, but lacks low and high mass outliers. Our working hypothesis
is that the missing high mass DB stars may simply be observed as hot
DQ white dwarfs. The recent discovery of DB stars in the alleged “DB
gap” at 30,000 - 45,000 K is discussed. Temperatures are estimated from
both fits to the spectra and to the energy distributions. A deficit of
stars in this range still seems likely, which would imply that about
10% of DA evolve into DB stars below 30,000 K. We are working towards
a preliminary luminosity function of DO-DB white dwarfs.
---------------------------------------------------------
Title: XMM-Newton Observations of Two Soft X-Ray Selected Magnetic CVs
Authors: Traulsen, I.; Reinsch, K.; Dreizler, S.
2008ASPC..391..287T Altcode:
The two AM Her type systems AI Tri and QS Tel have been monitored
with the X-ray satellite XMM-Newton with 20 ksec exposures each
and additional optical photometry at several sites during high and
intermediate high states of accretion. The light curves are dominated
by highly variable soft X-ray emission arising from the accretion
heated surface of the white dwarf primary in addition to a weaker
hard component reflecting the contribution of the multi-temperature
thermal plasma emission from the post-shock accretion column. A mildly
absorbed blackbody plus MEKAL plasma emission with variable element
abundances describe the associated spectra. Evident discrepancies
between the observed X-ray spectrum and the blackbody approximation
emphasize the need for accurate models including radiative transfer
to reproduce the white dwarf's contribution in a more realistic way.
---------------------------------------------------------
Title: New Views of the Horizontal Branch in ω Centauri
Authors: Moehler, S.; Dreizler, S.; Lanz, T.; Bono, G.; Sweigart,
A. V.; Calamida, A.; Monelli, M.; Nonino, M.
2008ASPC..392...47M Altcode:
UV observations of some massive globular clusters uncovered a
significant population of very hot stars below the hot end of the
horizontal branch, the so-called blue hook stars. This feature might
be explained either by the late hot flasher scenario where stars
experience the helium flash while on the white dwarf cooling curve
or by the helium-rich sub-population recently postulated to exist in
some clusters. Previous spectroscopic analyses of blue hook stars in
ω Cen and NGC 2808 support the late hot flasher scenario, but the
stars were found to contain much less helium than expected and the
predicted carbon and nitrogen enrichment could not be verified. New
moderately high resolution spectra of stars at the hot end of the blue
horizontal branch in ω Cen were analysed for atmospheric parameters
( T<SUB>eff</SUB>, log g, and log{n<SUB>He</SUB>}/{n<SUB>H</SUB>})
and abundances using LTE and non-LTE model atmospheres. In the
temperature range 30,000 K to 50,000 K we find that 35% of our
stars are helium-poor (log{n<SUB>He</SUB>/{n<SUB>H</SUB>} <
-2), 51% have solar helium abundance within a factor of 3 (-1.5 ≤
log{n<SUB>He</SUB>}/{n<SUB>H</SUB>} ≤ -0.5) and 14% are helium-rich
(log{n<SUB>He</SUB>/{n<SUB>H</SUB>} > -0.4). We also find carbon
enrichment along with helium enrichment, with a maximum carbon abundance
of 3% by mass. At least 14% of the hottest horizontal branch stars
in ωCen show helium abundances well above the highest predictions
from the helium enrichment scenario (Y≈ 0.42, corresponding to
log{n<SUB>He</SUB>}/{n<SUB>H</SUB>} ≈ -0.74). In addition, the most
helium-rich stars show high carbon abundances as predicted by the late
hot flasher scenario. We conclude that the helium-rich horizontal branch
stars in ω Cen cannot be explained solely by the helium-enrichment
scenario invoked to explain the blue main sequence.
---------------------------------------------------------
Title: MUSE: A Second-Generation Integral-Field Spectrograph for
the VLT
Authors: McDermid, R. M.; Bacon, R.; Bauer, S.; Boehm, P.; Boudon,
D.; Brau-Nogué, S.; Caillier, P.; Capoani, L.; Carollo, C. M.;
Champavert, N.; Contini, T.; Daguisé, E.; Delabre, B.; Devriendt,
J.; Dreizler, S.; Dubois, J.; Dupieux, M.; Dupin, J. P.; Emsellem, E.;
Ferruit, P.; Franx, M.; Gallou, G.; Gerssen, J.; Guiderdoni, B.; Hahn,
T.; Hofmann, D.; Jarno, A.; Kelz, A.; Koehler, C.; Kollatschny, W.;
Kosmalski, J.; Laurent, F.; Lilly, S. J.; Lizon, J. L.; Loupias, M.;
Manescau, A.; Monstein, C.; Nicklas, H.; Parès, L.; Pasquini, L.;
Pécontal-Rousset, A.; Pécontal, E.; Pello, R.; Petit, C.; Picat,
J. -P.; Popow, E.; Quirrenbach, A.; Reiss, R.; Renault, E.; Roth,
M.; Schaye, J.; Soucail, G.; Steinmetz, M.; Stroebele, S.; Stuik,
R.; Weilbacher, P.; Wisotzki, L.; Wozniak, H.; de Zeeuw, P. T.
2008eic..work..325M Altcode:
The Multi Unit Spectroscopic Explorer (MUSE) is a second-generation
instrument in development for the Very Large Telescope (VLT) of
the European Southern Observatory (ESO), due to begin operation in
2011/12. MUSE will be an extremely powerful integral-field spectrograph
fed by a new multiple-laser adaptive optics system on the VLT. In its
usual operating mode, MUSE will, in a single observation, produce
a 3-dimensional data cube consisting of 90,000 R 3000 spectra,
each covering a full spectral octave (480-930 nm), and fully
sampling a contiguous 1×1 arcmin<SUP>2</SUP> field with 0.2×0.2
arcsec<SUP>2</SUP> apertures. A high-resolution mode will increase
the spatial sampling to 0.025 arcsec per pixel. MUSE is built around
a novel arrangement of 24 identical spectrographs (each comparable
to a 1st generation VLT instrument), which are fed by a set of 24
precision image slicers. MUSE is designed for stability, with only 2
modes, and virtually no moving parts, allowing very long exposures to
be accumulated. Together with high throughput, this ensures that MUSE
will have extreme sensitivity for observing faint objects. We overview
the technical and scientific aspects of MUSE, highlighting the key
challenges for dealing with the unprecedented quantity and complexity
of the data, and the integration with the VLT adaptive optics facility
(AOF) - a key development on the path to extremely large telescopes
(ELTs).
---------------------------------------------------------
Title: The pulsation modes of the pre-white dwarf PG 1159-035
Authors: Costa, J. E. S.; Kepler, S. O.; Winget, D. E.; O'Brien, M. S.;
Kawaler, S. D.; Costa, A. F. M.; Giovannini, O.; Kanaan, A.; Mukadam,
A. S.; Mullally, F.; Nitta, A.; Provençal, J. L.; Shipman, H.; Wood,
M. A.; Ahrens, T. J.; Grauer, A.; Kilic, M.; Bradley, P. A.; Sekiguchi,
K.; Crowe, R.; Jiang, X. J.; Sullivan, D.; Sullivan, T.; Rosen, R.;
Clemens, J. C.; Janulis, R.; O'Donoghue, D.; Ogloza, W.; Baran, A.;
Silvotti, R.; Marinoni, S.; Vauclair, G.; Dolez, N.; Chevreton, M.;
Dreizler, S.; Schuh, S.; Deetjen, J.; Nagel, T.; Solheim, J. -E.;
Gonzalez Perez, J. M.; Ulla, A.; Barstow, M.; Burleigh, M.; Good,
S.; Metcalfe, T. S.; Kim, S. -L.; Lee, H.; Sergeev, A.; Akan, M. C.;
Çakırlı, Ö.; Paparo, M.; Viraghalmy, G.; Ashoka, B. N.; Handler,
G.; Hürkal, Ö.; Johannessen, F.; Kleinman, S. J.; Kalytis, R.;
Krzesinski, J.; Klumpe, E.; Larrison, J.; Lawrence, T.; Meištas,
E.; Martinez, P.; Nather, R. E.; Fu, J. -N.; Pakštienė, E.; Rosen,
R.; Romero-Colmenero, E.; Riddle, R.; Seetha, S.; Silvestri, N. M.;
Vučković, M.; Warner, B.; Zola, S.; Althaus, L. G.; Córsico, A. H.;
Montgomery, M. H.
2008A&A...477..627C Altcode: 2007arXiv0711.2244C
Context: <ASTROBJ>PG 1159-035</ASTROBJ>, a pre-white dwarf with
T<SUB>eff</SUB>≃ 140 000 K, is the prototype of both two classes:
the PG 1159 spectroscopic class and the DOV pulsating class. Previous
studies of <ASTROBJ>PG 1159-035</ASTROBJ> photometric data obtained
with the Whole Earth Telescope (WET) showed a rich frequency spectrum
allowing the identification of 122 pulsation modes. Analyzing the
periods of pulsation, it is possible to measure the stellar mass, the
rotational period and the inclination of the rotation axis, to estimate
an upper limit for the magnetic field, and even to obtain information
about the inner stratification of the star. <BR />Aims: We have three
principal aims: to increase the number of detected and identified
pulsation modes in <ASTROBJ>PG 1159-035</ASTROBJ>, study trapping of the
star's pulsation modes, and to improve or constrain the determination of
stellar parameters. <BR />Methods: We used all available WET photometric
data from 1983, 1985, 1989, 1993 and 2002 to identify the pulsation
periods. <BR />Results: We identified 76 additional pulsation modes,
increasing to 198 the number of known pulsation modes in <ASTROBJ>PG
1159-035</ASTROBJ>, the largest number of modes detected in any star
besides the Sun. From the period spacing we estimated a mass M/M_⊙ =
0.59 ± 0.02 for <ASTROBJ>PG 1159-035</ASTROBJ>, with the uncertainty
dominated by the models, not the observation. Deviations in the regular
period spacing suggest that some of the pulsation modes are trapped,
even though the star is a pre-white dwarf and the gravitational
settling is ongoing. The position of the transition zone that causes
the mode trapping was calculated at r_c/R_star = 0.83 ± 0.05. From
the multiplet splitting, we calculated the rotational period P_rot =
1.3920 ± 0.0008 days and an upper limit for the magnetic field, B <
2000 G. The total power of the pulsation modes at the stellar surface
changed less than 30% for ℓ = 1 modes and less than 50% for ℓ =
2 modes. We find no evidence of linear combinations between the 198
pulsation mode frequencies. <ASTROBJ>PG 1159-035</ASTROBJ> models have
not significative convection zones, supporting the hypothesis that
nonlinearity arises in the convection zones in cooler pulsating white
dwarf stars. <P />Tables [see full textsee full text]-[see full textsee
full text] are only available in electronic form at http://www.aanda.org
---------------------------------------------------------
Title: An Implementation of the Ray Shooting Method
Authors: Hundertmark, M.; Hessman, F.; Dreizler, S.
2008mmc..confE..53H Altcode: 2008PoS....54E..53H
No abstract at ADS
---------------------------------------------------------
Title: Light Curve Analysis of the Hybrid SdB PulsatorsHS 0702+6043
and HS 2201+2610
Authors: Lutz, R.; Schuh, S.; Silvotti, R.; Dreizler, S.; Green,
E. M.; Fontaine, G.; Stahn, T.; Hügelmeyer, S. D.; Husser, T. -O.
2008ASPC..392..339L Altcode: 2007arXiv0710.4871L
We present the detection of low-amplitude, long-period g-modes in two
individual sdBV stars which are known to be p-mode pulsators. Only
few of these hybrid objects, showing both p- and g-modes, are known
today. We resolve the g-mode domain in HS 0702+6043 and add HS 2201+2610
to the list of hybrid pulsators. To discover the low-amplitude g-modes,
a filtering algorithm based on wavelet transformations was applied to
denoise observational data.
---------------------------------------------------------
Title: Testing the Tidal Heating Hypothesis for the Transiting
Exoplanets HAT-P-1b and TrES-4b
Authors: Armstrong, Amber; Bean, J. L.; McArthur, B.; Reiners, A.;
Dreizler, S.; Benedict, G. F.
2007AAS...21113409A Altcode: 2007BAAS...39..969A
One of the most interesting results that has emerged from the detection
and study of transiting exoplanets is that some Hot Jupiters have
larger radii, and thus lower densities, than models predict. A few
mechanisms have been suggested as the cause of this, including one
hypothesis that there is an unknown source of internal heat inflating
these planets. Such a source of heat could be the dissipation of
energy arising from the ongoing tidal circularization of the planets'
eccentric orbits. However, the tidal circularization timescale
for such close in planets is predicted to be at least an order of
magnitude shorter than the putative ages of the systems. Therefore,
if an inflated Hot Jupiter's orbital eccentricity is truly non-zero,
there must be a perturber - possibly an additional undiscovered
planet - in the system to regularly excite its eccentricity. We are
currently carrying out high cadence and high precision radial velocity
measurements of the host stars to inflated Hot Jupiters with the <P
/>Hobby-Eberly-Telescope to constrain their orbital eccentricities,
search for additional planets in the systems, and ultimately test
the tidal heating hypothesis. We present here preliminary results for
the systems HAT-P-1 and TrES-4. At the time of this writing, TrES-4b
is by far the lowest density exoplanet and the most discrepant from
theoretical models. <P />Support for this work was provided by NASA
through grants GO-10103, GO-10610, and GO-10989 from the Space Telescope
Science Institute, which is operated by the Association of Universities
for Research in Astronomy, Inc., under NASA <P />contract NAS5-26555.
---------------------------------------------------------
Title: The hottest horizontal-branch stars in ω Centauri. Late hot
flasher vs. helium enrichment
Authors: Moehler, S.; Dreizler, S.; Lanz, T.; Bono, G.; Sweigart,
A. V.; Calamida, A.; Monelli, M.; Nonino, M.
2007A&A...475L...5M Altcode: 2007arXiv0709.2839M
Context: UV observations of some massive globular clusters have revealed
a significant population of very hot stars below the hot end of the
horizontal branch (HB), the so-called blue hook stars. This feature
might be explained either as a result of the late hot flasher scenario
where stars experience the helium flash while on the white dwarf cooling
curve or by the progeny of the helium-enriched sub-population recently
postulated to exist in some clusters. Previous spectroscopic analyses
of blue hook stars in ω Cen and NGC 2808 support the late hot flasher
scenario, but the stars contain much less helium than expected and the
predicted C, N enrichment could not be verified. <BR />Aims: We compare
observed effective temperatures, surface gravities, and abundances of
He, C, and N of blue hook and canonical extreme horizontal branch (EHB)
star candidates to the predictions of the two scenarios. <BR />Methods:
Moderately high resolution spectra of stars at the hot end of the
blue HB in the globular cluster ω Cen were analysed for atmospheric
parameters and abundances using LTE and non-LTE model atmospheres. <BR
/>Results: In the temperature range 30 000 K to 50 000 K we find that
35% of our stars are helium-poor (log{{n_He}/{n_H}} < -2), 51% have
solar helium abundance within a factor of 3 (-1.5 ⪉ log{{n_He}/{n_H}}
⪉ -0.5) and 14% are helium-rich (log{{n_He}/{n_H}}} > -0.4). We
also find carbon enrichment strongly correlated with helium enrichment,
with a maximum carbon enrichment of 3% by mass. <BR />Conclusions: At
least 14% of the hottest HB stars in ω Cen show helium abundances well
above the highest predictions from the helium enrichment scenario (Y =
0.42 corresponding to log{{n_He}/{n_H}} ≈ -0.74). In addition, the
most helium-rich stars show strong carbon enrichment, as predicted by
the late hot flasher scenario. We conclude that the helium-rich HB stars
in ω Cen cannot be explained solely by the helium-enrichment scenario
invoked to explain the blue main sequence. <P />Based on observations
<P />with the ESO Very Large Telescope at Paranal Observatory, Chile
<P />(proposal IDs 075.D-0280(A) and 077.D-0021(A)).
---------------------------------------------------------
Title: XMM-Newton Observations of Soft X-Ray Selected Magnetic CVs
Authors: Traulsen, Iris; Reinsch, Klaus; Dreizler, Stefan
2007AN....328..712T Altcode:
No abstract at ADS
---------------------------------------------------------
Title: SDSS DR4: Hot White Dwarf Luminosity Function
Authors: Krzesinski, J.; Kleinman, S. J.; Nitta, A.; Hügelmeyer,
S. D.; Dreizler, S.
2007ASPC..372...65K Altcode:
A large, nearly complete, magnitude-limited,
spectroscopically-identified sample of hot white dwarf stars presented
in the Sloan Digital Sky Survey (SDSS) Data Release 4 White Dwarf
Catalog tep{p8_eis06} allowed us to construct the hot end of a SDSS
white dwarf luminosity function (LF). The LF covers an approximate
temperature range of 23,000 K to 100,000 K and is based on the distances
and absolute bolometric magnitudes determined from stellar models. The
sample is dominated by DA type white dwarfs, but it also contains DB,
DAO, DO and PG 1159 type stars. We present our new LF, compare it to
previous work tep{p8_har06}, and comment on sample completeness.
---------------------------------------------------------
Title: X-Ray Spectroscopy and Photometry of the Accreting White
Dwarf in AI Tri
Authors: Traulsen, I.; Reinsch, K.; Dreizler, S.; Schwarz, R.
2007ASPC..372..553T Altcode:
Based on recent X-ray observations with the XMM-Newton satellite, we
present first results of our spectroscopic and photometric analysis of
the accretion region on the white dwarf in the long-period magnetic
cataclysmic variable AI Tri. Our XMM-Newton observation covers for
the first time uninterruptedly a complete binary orbital period. The
shape of the X-ray light curve is highly variable with strong flares,
occurring mainly in the soft energy range over about 70% of the binary
orbit. Weaker hard X-ray emission is visible nearly all the time. The
ultraviolet light curve, obtained in the UVM2 filter at an effective
wavelength of 231 nm, has a similar shape but higher amplitude than
the optical and near UV light curves reported during high states of
accretion. The X-ray spectrum is dominated by soft X-ray emission which
can be described in good approximation by a mildly absorbed blackbody
component with kT<SUB>bb</SUB> = 36.8<SUP>+1.8</SUP><SUB>-1.4</SUB>
{eV} and N<SUB>H</SUB> = 3.08<SUP>+0.51</SUP><SUB>-0.42</SUB> \cdot
10<SUP>20</SUP> {cm}<SUP>-2</SUP>. In addition, weak emission from a
thermal plasma is present and iron Kα at 6.4 keV and iron L emission
around 0.9 keV can be identified.
---------------------------------------------------------
Title: Abell 43 and PG 0122+200: a Look at the Beginning and at the
End of the PG 1159 Instability Strip
Authors: Vauclair, G.; Solheim, J. -E.; Fu, J. -N.; Chevreton, M.;
Dolez, N.; O'Brien, M. S.; Mukadam, A. S.; Kim, S. -L.; Park, B. -G.;
Handler, G.; Medupe, R.; Wood, M.; González Perez, J.; Hashimoto,
O.; Kinugasa, K.; Taguchi, H.; Kambe, E.; Dobrovolskas, V.; Provencal,
J. L.; Dreizler, S.; Schuh, S.; Leibowitz, E. M.; Lipkin, Y.; Zhang,
X. -B.; Paparo, M.; Szeidl, B.; Virághalmy, G.; Zsuffa, D.
2007ASPC..372..641V Altcode:
While Abell 43 is entering the PG 1159 instability strip, in fact
as an "hybrid-PG 1159" nucleus of a planetary nebula, PG 0122+200
presently defines its red edge. So these two stars define the limits
of the instability strip along the evolutionary sequence from the
planetary nebula nuclei to the pre-white dwarf PG 1159 stars. We
describe the new observations that have been obtained recently on
these two extreme PG 1159 pulsators. Abell 43, the second discovered
"hybrid-PG 1159" pulsator after HS 2324+3944, is a multi-periodic low
amplitude pulsator with the longest period observed so far in PG 1159
pulsators. As it shows amplitude variations, follow-up observations
are needed to obtain a sufficient number of frequencies to start an
asteroseismological analysis. We summarize the status of the presently
available data. On PG 0122+200, new observations were obtained in
2001 and 2002. Together with previous data, they allow us to detect 23
frequencies, including seven triplets and two single frequencies. We
interpret the triplets as ℓ=1 modes split by rotation and confirm an
average rotation period of 1.55 days. From the up-dated average period
spacing of 22.9 s, we derive a mass of 0.59 ± 0.02 M<SUB>⊙</SUB>,
in better agreement with the spectroscopically derived mass than from
previous estimates, and a luminosity log(L/L<SUB>⊙</SUB>)= 1.3 ±
0.5. The uncertainty on the luminosity is dominated by the poorly
determined surface gravity. We discuss the impact of that new mass
determination on the predicted neutrino luminosity.
---------------------------------------------------------
Title: Spectral Analyses of 16 DAO White Dwarfs from the Sloan
Digital Sky Survey
Authors: Hügelmeyer, S. D.; Dreizler, S.; Rauch, T.; Krzesiński, J.
2007ASPC..372..187H Altcode: 2006astro.ph.10744H
We present a spectral analysis of 16 DAO from the Sloan Digital Sky
Survey Data Release 4. With our NLTE H+He model grid, we derived
photospheric parameters for these objects. We compare our new results
to literature values and divide the DAOs into two distinct groups:
post-AGB and EHB progenitors.
---------------------------------------------------------
Title: Observational Constraints on the Evolutionary Connection
between PG 1159 Stars and DO White Dwarfs
Authors: Hügelmeyer, S. D.; Dreizler, S.; Werner, K.; Krzesinski,
J.; Nitta, A.; Kleinman, S. J.
2007ASPC..372..249H Altcode: 2006astro.ph.10746H
The Sloan Digital Sky Survey has provided spectra of a large number
of new PG 1159 stars and DO white dwarfs. This increase in known hot
H-deficient compact objects significantly improves the statistics and
helps to investigate late stages of stellar evolution. We have finished
our analyses of nine PG 1159 stars and 23 DO white dwarfs by means
of detailed NLTE model atmospheres. From the optical SDSS spectra,
effective temperatures, surface gravities, and element abundances are
derived by using our new automated χ^2--fitting in order to place the
observed objects in an evolutionary context. Especially the connection
between PG 1159 stars and DO white dwarfs has been investigated.
---------------------------------------------------------
Title: BMBF funded projects at Göttingen
Authors: Kollatschny, Wolfram; Hofmann, Denni; Dreizler, Stefan;
Nicklas, Harald; Zetzl, Matthias; Köhler, Christof
2007AN....328..710K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Spectral Analysis and Constraints on the Nature of the
Ultra-Compact Binary RX J0806.3+1527
Authors: Reinsch, K.; Steiper, J.; Dreizler, S.
2007ASPC..372..419R Altcode:
RX J0806.3+1527 has been discovered as a luminous soft X-ray
source during the ROSAT All-Sky Survey and is suspected to be a
double-degenerate white dwarf binary with the shortest known orbital
period of 321 s. We have performed the first NLTE analysis of its
optical spectrum which consists of a blue continuum with weak emission
lines superimposed. Using a grid of hot white dwarf atmospheres
including illumination effects we have derived an abundance ratio
(He/H) ≈ 0.1 (by number) and a comparably low surface gravity log{g}
= 6 of the irradiated system component. The observed flux implies
a distance d ≈ 2.0 kpc to the system. Our findings provide new
constrains for the different models proposed for the nature of this
peculiar binary. The donor must have about solar composition. If line
emission arises from its irradiated side it could be either a low-mass
white dwarf or a substellar object. Alternatively, line emission could
arise from an accretion column standing several white dwarf radii above
the photosphere of the accretor. Such conditions are encountered in
systems with comparably low field strengths and high mass-flow rates.
---------------------------------------------------------
Title: Investigation of transit-selected exoplanet candidates from
the MACHO survey
Authors: Hügelmeyer, S. D.; Dreizler, S.; Homeier, D.; Reiners, A.
2007A&A...469.1163H Altcode: 2007arXiv0704.1366H
Context: Planets outside our solar system transiting their host
star, i.e. those with an orbital inclination near 90°, are
of special interest to derive physical properties of extrasolar
planets. With the knowledge of the host star's physical parameters,
the planetary radius can be determined. Combined with spectroscopic
observations the mass and therefore the density can be derived from
Doppler-measurements. Depending on the brightness of the host star,
additional information, e.g. about the spin-orbit alignment between the
host star and planetary orbit, can be obtained. <BR />Aims: The last few
years have witnessed a growing success of transit surveys. Among other
surveys, the MACHO project provided nine potential transiting planets,
several of them with relatively bright parent stars. The photometric
signature of a transit event is, however, insufficient to confirm the
planetary nature of the faint companion. The aim of this paper therefore
is a determination of the spectroscopic parameters of the host stars as
well as a dynamical mass determination through Doppler-measurements. <BR
/>Methods: We obtained follow-up high-resolution spectra for five stars
selected from the MACHO sample, which are consistent with transits
of low-luminosity objects. Radial velocities were determined by means
of cross-correlation with model spectra. The MACHO light-curves were
compared to simulations based on the physical parameters of the system
derived from the radial velocities and spectral analyses. <BR />Results:
We show that all transit light-curves of the exoplanet candidates
analysed in this work can be explained by eclipses of stellar objects,
hence none of the five transiting objects is a planet. <P />Based on
observations made with ESO Telescopes <P />at the La Silla or Paranal
Observatories under programme ID <P />075.C-0526(A).
---------------------------------------------------------
Title: Analyzing <ASTROBJ>SN 2003Z</ASTROBJ> with PHOENIX
Authors: Knop, S.; Hauschildt, P. H.; Baron, E.; Dreizler, S.
2007A&A...469.1077K Altcode: 2009arXiv0902.1867K
Aims:We present synthetic spectra around maximum for the type
II supernova SN 2003Z, which was first detected on January 29.7
2003. Comparison with observed spectra aim at the determination of
physical parameters for SN 2003Z. <BR />Methods: Synthetic spectra
are calculated with our stellar atmosphere code PHOENIX. It solves the
special relativistic equation of radiative transfer, including large
NLTE-calculations and line blanketing by design, in 1-dimensional
spherical symmetry. The observed spectra were obtained at the 3.5
m telescope at Calar Alto. The TWIN instrument was used so that a
spectral range from about 3600 to 7500 Å was covered. The spectra
were taken on Feb. 4, 5, 9, and 11, 2003. <BR />Results: The physical
parameters of the models give the luminosities, a range of possible
velocity profiles for the SN, an estimate of the colour excess, and
the observed metalicity. <P />Based on observations collected at the
Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated
jointly by the Max-Planck Institut für Astronomie and the Instituto
de Astrofísica de Andalucía (CSIC).
---------------------------------------------------------
Title: X-Ray Spectroscopy and Photometry of the long-period Polar
AI Tri with XMM-Newton
Authors: Traulsen, I.; Reinsch, K.; Dreizler, S.
2007xnnd.confP...4T Altcode:
No abstract at ADS
---------------------------------------------------------
Title: MONET, HET and SALT and asteroseismological observations and
theory in Göttingen
Authors: Schuh, S.; Hessman, F. V.; Dreizler, S.; Kollatschny, W.;
Glatzel, W.
2007CoAst.150..317S Altcode:
The Göttingen stellar astrophysics group, headed by Stefan Dreizler,
conducts research on extrasolar planets and their host stars,
on lower-main sequence stars, and on evolved compact objects, in
particular hot white dwarfs (including PG 1159 objects, magnetic
WDs and cataclysmic variables), and subdwarf B stars. In addition to
sophisticated NLTE spectral analyses of these stars, which draw on
the extensive stellar atmosphere modelling experience of the group,
we actively develop and apply a variety of photometric monitoring
and time-resolved spectroscopic techniques to address time-dependent
phenomena. With the new instrumentational developments described
below, we plan to continue the study of variable white dwarfs (GW Vir,
DB and ZZ Ceti variables) and in particular sdB EC 14026 and PG 1617
pulsators which already constitute a main focus, partly within the Whole
Earth Telescope (WET/DARC), http://www.physics.udel.edu/~jlp/darc/)
collaboration, on a new level. Additional interest is directed towards
strange mode instabilities in Wolf Rayet stars.
---------------------------------------------------------
Title: Asteroseismology of the PG 1159 star PG 0122+200
Authors: Fu, J. -N.; Vauclair, G.; Solheim, J. -E.; Chevreton, M.;
Dolez, N.; O'Brien, M. S.; Kim, S. -L.; Park, B. -G.; Handler, G.;
Medupe, R.; Wood, M.; Gonzalez Perez, J.; Hashimoto, O.; Kinugasa,
K.; Taguchi, H.; Kambe, E.; Provencal, J.; Dreizler, S.; Schuh, S.;
Leibowitz, E.; Lipkin, Y.; Zhang, X. -B.; Paparo, M.; Szeidl, B.;
Virághalmy, G.; Zsuffa, D.
2007A&A...467..237F Altcode:
Context: The variable pre-white dwarf PG 1159 stars (GW Vir) are
g-mode non-radial pulsators. Asteroseismology puts strong constraints
on their global parameters and internal structure. PG 0122+200 defines
the red edge of the instability strip and its evolutionary timescale
is predicted to be dominated by neutrino emission. Its study offers
the opportunity to better understand the instability mechanism and to
validate the physics of the neutrino production in dense plasma. <BR
/>Aims: To achieve such a goal requires determining precisely its
fundamental parameters. This is the goal of this paper. <BR />Methods:
We present new multi-site photometric observations obtained in 2001
and 2002. Together with previous data, they allow us to detect
23 frequencies, composed of 7 triplets and 2 single frequencies,
which are used to constrain its internal structure and derive its
fundamental parameters. <BR />Results: All the observed frequencies
correspond to ℓ=1 g-modes. The period distribution shows a signature
of mode trapping from which we constrain the He-rich envelope mass
fraction to be -6.0≤ log(q<SUB>y</SUB>) ≤ -5.3. The comparison
of the mode trapping amplitudes among GW Vir stars suggests that the
mass-loss efficiency must decrease significantly below T_eff≤ 140
kK. We measure an average period spacing of 22.9 s from which we
derive a mass of 0.59±0.02 M<SUB>⊙</SUB>. From the triplets we
measure a mean rotational splitting of 3.74 μHz and a rotational
period of 1.55 days. We derive an upper limit to the magnetic field
of B≤4×10<SUP>3</SUP> G. The luminosity (log L/L<SUB>⊙</SUB> =
1.3±0.5) and the distance (D = 0.7^+1.0_-0.4 kpc) are only weakly
constrained due to the large uncertainty on the spectroscopically
derived surface gravity and the absence of a measured parallax. <BR
/>Conclusions: From the asteroseismic mass, the ratio of the
neutrino luminosity on the photon luminosity is 1.6±0.2 confirming
that the PG 0122+200 evolutionary time scale should be dominated by
neutrino cooling. A measurement of dot{P} for the largest amplitude
untrapped modes should verify this prediction. <P />Based on data
obtained at the Haute-Provence Observatory, INSU/CNRS, France; the
Nordic Optical Telescope, La Palma, Spain; the Xinglong station of
National Astronomical Observatories, China; the Bohyunsan Observatory,
South-Korea; the Gunma Astrophysical Observatory, Japan; the Teide
Observatory, Tenerife, Spain; the Calar Alto Observatory, Spain; the
Kitt Peak National Observatory, Arizona, USA; the McDonald Observatory,
Texas, USA; the South Africa Astronomical Observatory, South Africa;
the Wise Observatory, Israel and the Piszkéstető Observatory, Hungary.
---------------------------------------------------------
Title: Spectral types of planetary host star candidates from OGLE III
Authors: Dreizler, S.; Schuh, S.; Homeier, D.
2007A&A...464..367D Altcode: 2007astro.ph..1718D
Context: The Optical Gravitational Lensing Experiment project has
recently provided the OGLE III list of low-luminosity object transits
from campaigns #3 and #4, reporting 40 new objects exhibiting the
low-amplitude photometric eclipses expected for exoplanets. Compared
to previous OGLE targets, these OGLE III candidates have been
more restrictively selected and may contain low-mass planets. <BR
/>Aims: We have secured follow-up low-resolution spectroscopy for 28
candidates out of this list (and one from the OGLE Carina fields)
to obtain an independent characterization of the primary stars by
spectral classification and thus better constrain the parameters of
their companions. <BR />Methods: We fed the constraints from these
results back into an improved light curve solution. Together with the
radius ratios from the transit measurements, we derived the radii of
the low-luminosity companions. This allows us to examine the possible
sub-stellar nature of these objects. <BR />Results: Sixteen of the
companions can be clearly identified as low-mass stars orbiting a main
sequence primary, while 10 more objects are likely to have red giant
primaries and therefore also host a stellar companion; 3 possibly
have a sub-stellar nature (R≤ 0.15 R_⊙). <BR />Conclusions: .The
planetary nature of these objects should therefore be confirmed by
dynamical mass determinations.
---------------------------------------------------------
Title: Hot subdwarfs from the ESO supernova Ia progenitor
survey. II. Atmospheric parameters of subdwarf O stars
Authors: Stroeer, A.; Heber, U.; Lisker, T.; Napiwotzki, R.; Dreizler,
S.; Christlieb, N.; Reimers, D.
2007A&A...462..269S Altcode: 2006astro.ph..9718S
Aims: We address the origin and evolutionary status of hot subdwarf
stars by studying the optical spectral properties of 58 subdwarf O
(sdO) stars. Combining them with the results of our previously studied
subdwarf B (sdB) stars, we aim at investigating possible evolutionary
links. <BR />Methods: We analyse high-resolution (R > 18 000),
high-quality optical spectra of sdO stars obtained with the ESO
VLT UVES echelle spectrograph in the course of the ESO Supernova Ia
Progenitor Survey (SPY). Effective temperatures, surface gravities,
and photospheric helium abundances are determined simultaneously by
fitting the profiles of hydrogen and helium lines using dedicated
synthetic spectra calculated from an extensive grid of NLTE model
atmospheres. <BR />Results: We find spectroscopic or photometric
evidence for cool companions to eight sdO stars, as well as a binary
consisting of two sdO stars. A clear correlation between helium
abundances and the presence of carbon and/or nitrogen lines is found:
below solar helium abundance, no sdO star shows C or N lines. In
contrast, C and/or N lines are present in the spectra of all sdO
stars with supersolar helium abundance. We thus use the solar helium
abundance to divide our sample into helium-deficient and helium-enriched
sdO stars. While helium-deficient sdO stars are scattered in a wide
range of the {T_eff}-log(g)-diagram, most of the helium-enriched sdO
stars cluster in a narrow region at temperatures between 40 000 and 50
000 K and gravities between log g=5.5 and 6.0. <BR />Conclusions: . An
evolutionary link between sdB stars and sdO stars appears plausible only
for the helium-deficient sdO stars. They probably have evolved away from
the extreme horizontal branch; i.e., they are the likely successors to
sdB stars. In contrast, the atmospheric properties of helium-enriched
sdO stars cannot be explained with canonical single-star evolutionary
models. Alternative scenarios for both single-star (late hot flasher)
and binary evolution (white-dwarf merger; post-RGB evolution) fail
to reproduce the observed properties of helium-enriched sdO stars
in detail. While we regard the post-RGB scenario as inappropriate,
the white-dwarf merger and the late hot-flasher scenarios remain
viable to explain the origin of helium-enriched sdO stars. <P />Based
<P />on observations collected at the Paranal Observatory of the
European <P />Southern Observatory for programme No. 165.H-0588(A)
and 167.D-0407(A).
---------------------------------------------------------
Title: Spectral analyses of eighteen hot H-deficient (pre-) white
dwarfs from the Sloan Digital Sky Survey Data Release 4
Authors: Hügelmeyer, S. D.; Dreizler, S.; Homeier, D.; Krzesiński,
J.; Werner, K.; Nitta, A.; Kleinman, S. J.
2006A&A...454..617H Altcode: 2006astro.ph..5551H
Context: .The Sloan Digital Sky Survey Data Release 4 has provided
spectra of several new PG 1159 stars and DO white dwarfs. This increase
in known hot H-deficient compact objects significantly improves the
statistics and helps to investigate late stages of stellar evolution.<BR
/> Aims: .From the optical SDSS spectra, effective temperatures and
surface gravities are derived in order to place the observed objects
in an evolutionary context. Especially the connection between PG 1159
stars and DO white dwarfs shall be investigated.<BR /> Methods: .Using
our non-LTE model atmospheres and applying χ<SUP>2</SUP>-fitting
techniques, we determine stellar parameters and their errors. We
derive total stellar masses for the DO white dwarfs using model
evolutionary tracks.<BR /> Results: .We confirm three PG 1159 stars,
with one showing ultra-high excitation ion features, and one sdO which
we originally classified as a PG 1159 star. Additionally, we re-analysed
the known PG 1159 star, PG 1424+535, with our new models. Furthermore,
we present the first spectral analyses of thirteen DO white dwarfs,
three of which show M-star features in their spectra, while two display
ultra-high excitation ion features.<BR />
---------------------------------------------------------
Title: The D/H Ratio towards PG 0038+199
Authors: Williger, G. M.; Oliveira, C.; Hébrard, G.; Dupuis, J.;
Dreizler, S.
2006ASPC..348...97W Altcode:
We determine the D/H ratio in the interstellar medium toward the
DO white dwarf PG 0038+199 using spectra from the Far Ultraviolet
Spectroscopic Explorer (FUSE), with ground-based support from Keck H
IRES. We employ curve of growth, apparent optical depth and profile
fitting techniques to measure column densities and limits of many
other species which allow us to determine related ratios such as
D/O, D/N and the H<SUB>2</SUB> fraction. We estimate a distance to PG
0038+199 of 297<SUP>+164</SUP><SUB>-104</SUB> pc (1σ). We find column
densities log N(H I) = 20.41± 0.08, log N(D I) = 15.75± 0.08 and log
N(H<SUB>2</SUB>) = 19.33± 0.04, yielding a molecular hydrogen fraction
of 14± 2% (all 2σ errors). [D I + HD]/[H I + 2H<SUB>2</SUB>] toward
PG 0038+199 is 1.91<SUP>+0.52</SUP><SUB>-0.42</SUB>× 10<SUP>-5</SUP>
(2σ). There is no evidence of component structure on the scale of Δ v
> 8 km s<SUP>-1</SUP> based on Na I, but there is marginal evidence
for structure on smaller scales. The D/H value is high compared to the
majority of recent D/H measurements, but consistent with the values
for two other measurements at similar distances. D/O is in agreement
with other distant measurements. The scatter in D/H values beyond ∼
100 pc remains a challenge for Galactic chemical evolution.
---------------------------------------------------------
Title: Probing unexplored territories with MUSE: a second generation
instrument for the VLT
Authors: Bacon, R.; Bauer, S.; Boehm, P.; Boudon, D.; Brau-Nogué, S.;
Caillier, P.; Capoani, L.; Carollo, C. M.; Champavert, N.; Contini,
T.; Daguisé, E.; Dallé, D.; Delabre, B.; Devriendt, J.; Dreizler,
S.; Dubois, J.; Dupieux, M.; Dupin, J. P.; Emsellem, E.; Ferruit, P.;
Franx, M.; Gallou, G.; Gerssen, J.; Guiderdoni, B.; Hahn, T.; Hofmann,
D.; Jarno, A.; Kelz, A.; Koehler, C.; Kollatschny, W.; Kosmalski,
J.; Laurent, F.; Lilly, S. J.; Lizon, J.; Loupias, M.; Lynn, S.;
Manescau, A.; McDermid, R. M.; Monstein, C.; Nicklas, H.; Parès, L.;
Pasquini, L.; Pécontal-Rousset, A.; Pécontal, E.; Pello, R.; Petit,
C.; Picat, J. -P.; Popow, E.; Quirrenbach, A.; Reiss, R.; Renault,
E.; Roth, M.; Schaye, J.; Soucail, G.; Steinmetz, M.; Stroebele, S.;
Stuik, R.; Weilbacher, P.; Wozniak, H.; de Zeeuw, P. T.
2006SPIE.6269E..0JB Altcode: 2006astro.ph..6329B; 2006SPIE.6269E..17B
The Multi Unit Spectroscopic Explorer (MUSE) is a second-generation
VLT panoramic integral-field spectrograph under preliminary design
study. MUSE has a field of 1x1 arcmin<SUP>2</SUP> sampled at 0.2x0.2
arcsec<SUP>2</SUP> and is assisted by the VLT ground layer adaptive
optics ESO facility using four laser guide stars. The simultaneous
spectral range is 0.465-0.93 μm, at a resolution of R~3000. MUSE
couples the discovery potential of a large imaging device to the
measuring capabilities of a high-quality spectrograph, while taking
advantage of the increased spatial resolution provided by adaptive
optics. This makes MUSE a unique and tremendously powerful instrument
for discovering and characterizing objects that lie beyond the reach
of even the deepest imaging surveys. MUSE has also a high spatial
resolution mode with 7.5x7.5 arcsec<SUP>2</SUP> field of view sampled at
25 milli-arcsec. In this mode MUSE should be able to obtain diffraction
limited data-cubes in the 0.6-0.93 μm wavelength range. Although the
MUSE design has been optimized for the study of galaxy formation and
evolution, it has a wide range of possible applications; e.g. monitoring
of outer planets atmosphere, environment of young stellar objects,
super massive black holes and active nuclei in nearby galaxies or
massive spectroscopic surveys of stellar fields in the Milky Way and
nearby galaxies.
---------------------------------------------------------
Title: Probing Unexplored Territories with MUSE: a Second-Generation
Instrument for the VLT
Authors: Bacon, Roland; Bauer, Svend; Böhm, Petra; Boudon, Didier;
Brau-Nogue, Sylvie; Caillier, Patrick; Capoani, Lionel; Carollo,
C. Marcella; Champavert, Nicolas; Contini, Thierry; Daguise, Eric;
Dalle, Didier; Delabre, Bernard; Devriendt, Julien; Dreizler, Stefan;
Dubois, Jean-Pierre; Dupieux, Michel; Dupin, Jean-Pierre; Emsellem,
Eric; Ferruit, Pierre; Franx, Marijn; Gallou, Gérard; Gerssen, Joris;
Guiderdoni, Bruno; Hahn, Thomas; Hofmann, Denni; Jarno, Aurélien;
Kelz, Andreas; Koehler, Christof; Kollatschny, Wolfram; Kosmalski,
Johan; Laurent, Florence; Lilly, Simon J.; Lizon, Jean-Louis; Loupias,
Magali; Lynn, Stéphanie; Manescau, Antonio; McDermid, Richard M.;
Monstein, Christian; Nicklas, Harals; Perès, Laurent; Pasquini,
Luca; Pécontal, Emmanuel; Pécontal-Rousset, Arlette; Pello, Roser;
Petit, Chantal; Picat, Jean-Pierre; Popow, Emil; Quirrenbach, Andreas;
Reiss, Roland; Renault, Edgar; Roth, Martin; Schaye, Joop; Soucail,
Geneviève; Steinmetz, Matthias; Ströbele, Stefan; Stuik, Remko;
Weilbacher, Peter; Wozniak, Herve; de Zeeuw, P. Tim
2006Msngr.124....5B Altcode:
The Multi Unit Spectroscopic Explorer (MUSE) is a second-generation
VLT panoramic integral-field spectrograph presently under preliminary
design study. MUSE has a field of 1 × 1 arcmin2 sampled at 0.2 ×
0.2 arcsec2 and is assisted by the VLT ground layer adaptive optics
ESO facility using four laser guide stars. The simultaneous spectral
range is 0.465-0.93 μm, at a resolution of R ~ 3000. MUSE couples
the discovery potential of a large imaging device to the measuring
capabilities of a high-quality spectrograph, while taking advantage of
the increased spatial resolution provided by adaptive optics. MUSE has
also a high spatial resolution mode with 7.5 × 7.5 arcsec2 field of
view sampled at 25 milli-arcsec. In this mode MUSE should be able to
obtain diffraction-limited data cubes in the 0.6-0.93 μm wavelength
range.
---------------------------------------------------------
Title: VLT spectroscopy and non-LTE modeling of the C/O-dominated
accretion disks in two ultracompact X-ray binaries
Authors: Werner, K.; Nagel, T.; Rauch, T.; Hammer, N. J.; Dreizler, S.
2006A&A...450..725W Altcode: 2006astro.ph..1546W
Aims.We present new medium-resolution high-S/N optical spectra of
the ultracompact low-mass X-ray binaries 4U 0614+091 and 4U 1626-67,
taken with the ESO Very Large Telescope. They are pure emission line
spectra and the lines are identified as due to CII-IV and OII-III.<BR
/> Methods: .Line identification is corroborated by first results from
modeling the disk spectra with detailed non-LTE radiation transfer
calculations. Hydrogen and helium lines are lacking in the observed
spectra.<BR /> Results: .Our models confirm the deficiency of H and He
in the disks. The lack of neon lines suggests an Ne abundance of less
than about 10 percent (by mass), however, this result is uncertain due
to possible shortcomings in the model atom. These findings suggest
that the donor stars are eroded cores of C/O white dwarfs with no
excessive neon overabundance. This would contradict earlier claims of Ne
enrichment concluded from X-ray observations of circumbinary material,
which was explained by crystallization and fractionation of the white
dwarf core.<BR />
---------------------------------------------------------
Title: SDSS J212531.92-010745.9 - the first definite PG 1159 close
binary system
Authors: Nagel, T.; Schuh, S.; Kusterer, D. -J.; Stahn, T.;
Hügelmeyer, S. D.; Dreizler, S.; Gänsicke, B. T.; Schreiber, M. R.
2006A&A...448L..25N Altcode: 2006astro.ph..1512N
Aims.The archival spectrum of SDSS J212531.92-010745.9 shows not
only the typical signature of a PG 1159 star, but also indicates the
presence of a companion. Our aim was the proof of the binary nature
of this object and the determination of its orbital period.Methods.We
performed time-series photometry of SDSS J212531.92-010745.9. We
observed the object during 10 nights, spread over one month, with
the Tübingen 80 cm and the Göttingen 50 cm telescopes. We fitted
the observed light curve with a sine and simulated the light curve of
this system with the nightfall program. Furthermore, we compared the
spectrum of SDSS J212531.92-010745.9 with NLTE models, the results
of which also constrain the light curve solution. Results.An orbital
period of 6.95616(33) h with an amplitude of 0.354(3) mag is derived
from our observations. A pulsation period could not be detected. For
the PG 1159 star we found, as preliminary results from comparison
with our NLTE models, T<SUB>eff</SUB> ~ 90 000 K, log g ~ 7.60, and
the abundance ratio C/He ~ 0.05 by number fraction. For the companion
we obtained with a mean radius of 0.4 ± 0.1~R<SUB>⊙</SUB>, a mass
of 0.4 ± 0.1~M<SUB>⊙</SUB>, and a temperature of 8200 K on the
irradiated side, good agreement between the observed light curve and
the nightfall simulation, but we do not regard those values as final.
---------------------------------------------------------
Title: Giant Transiting Planets Observations GITPO
Authors: Afonso, C.; Henning, Th.; Weldrake, D.; Mazeh, T.; Dreizler,
S.
2006dies.conf...79A Altcode: 2006IAUCo.200...79A
The search for extrasolar planets is nowadays one of the most promising
science drivers in Astronomy. The radial velocity technique proved
to be successful in planet hunting, harvesting more than a hundred
planets to date. In these last recent years, the transit method has
come to fruition, with the detection of seven Jupiter-mass extrasolar
transiting planets in close-in orbits ({ AU). Currently, the radius of
planets can only be determined from transiting planets, representing
the principal motivation and strength of this technique. The MPIA is
presently building the Large Area Imager (LAIWO) for the 1m telescope
in the Wise Observatory, Israel. LAIWO will have a field of view of
one square degree. An intensive search for extra-solar planets will
be performed with the 1m Wise telescope, together with the 1.2m MONET
telescope in Texas. We will monitor three fields at a given time during
three years and more than 200 nights per year. We expect several dozens
of extra-solar planets.
---------------------------------------------------------
Title: The Msst Campaign: 4 M Spectroscopy of PG 1605+072
Authors: Jeffery, C. S.; Heber, U.; Dreizler, S.; O'Toole, S. J.;
Schuh, S. L.; Woolf, V. M.; Falter, S.; Nitta, A.; Kleinman, S.;
Krzesinski, J.; Billères, M.
2006BaltA..15..321J Altcode: 2006OAst...15..321J
The MultiSite Spectroscopic Telescope (MSST) campaign aimed to provide
a detailed view of the short-period pulsating subdwarf B star PG 1605+
072. We present results from the part of the campaign undertaken on
4 m telescopes in 2002 May and June.
---------------------------------------------------------
Title: Exciting new features in the frequency spectrum of the EC 14026
star HS 0702+6043. Simultaneous g-modes and p-modes in a sdB pulsator
Authors: Schuh, S.; Huber, J.; Dreizler, S.; Green, E. M.; Stahn,
T.; Randall, S.; Husser, T. -O.; Heber, U.; O'Toole, S.; Fontaine, G.
2006MmSAI..77..480S Altcode: 2005astro.ph.10832S
The discovery of a long-period g-mode oscillation in the previously
known short-period p-mode sdB pulsator HS 0702+6043 makes this star an
extraordinary object, unique as a member of the family of sdB pulsators,
and one of the very few known pulsating stars overall exhibiting excited
modes along both the acoustic and gravity branches of the nonradial
pulsation spectrum. Because p-modes and g-modes probe different regions
of a pulsating star, HS 0702+6043 holds a tremendous potential for
asteroseismological investigations. We present preliminary results
from the first extended campaign on this object.
---------------------------------------------------------
Title: Subluminous O Stars
Authors: Heber, U.; Hirsch, H.; Ströer, A.; O'Toole, S.; Haas, S.;
Dreizler, S.
2006BaltA..15...91H Altcode: 2006OAst...15...91H
We report results of spectral analyses of sdO stars selected from
the Supernova Ia Progenitor Survey, the Hamburg Quasar Survey and
the Sloan Digital Sky Survey and based on state-of-the-art NLTE model
atmospheres. By combining the sdO with the sdB samples we discuss trends
of the atmospheric parameters in order to search for evidence for
possible evolutionary linkage. The He-sdO stars are found to cluster
near Teff = 45 000 K, log g = 5.5, whereas the number of sdO stars
in this area is very small. The “cooler” sdO stars seem to form an
extension to the sdB sequences. A couple of sdO stars are obviously
evolved from the extended horizontal branch and reach temperatures
as high as 80 000 K. We conjecture that the He-sdO stars and sdO/sdB
stars have a different evolutionary origin. This is corroborated by
the much lower binary frequency of the former. Strong enrichments
of iron group elements are discovered for hydrogen-rich sdO stars
as well as for sdB stars from high resolution UV spectra and have
severe implications for the temperature scale. We finally highlight
the discovery of a hyper-velocity He-sdO star with a radial velocity
of 708 kms unbound to the Galaxy.
---------------------------------------------------------
Title: An Approach to a Stability Analysis of a SDO Star
Authors: Rodríguez-López, C.; Moya, A.; Garrido, R.; MacDonald,
J.; Ulla, A.; Dreizler, S.; Hügelmeyer, S. D.; Manteiga, M.
2006BaltA..15..313R Altcode: 2006OAst...15..313R
A stability analysis of a structural model of an sdO star is
presented. A non-adiabatic code of oscillations is used to search
for modes in the frequency range 0.4 to 15 mHz. All of the computed
modes were found to be stable. We draw attention, however, to three
different stability regions.
---------------------------------------------------------
Title: <ASTROBJ>HS 0702+6043</ASTROBJ>: a star showing both
short-period p-mode and long-period g-mode oscillations
Authors: Schuh, S.; Huber, J.; Dreizler, S.; Heber, U.; O'Toole,
S. J.; Green, E. M.; Fontaine, G.
2006A&A...445L..31S Altcode: 2005astro.ph.10831S
Context: .The hot subdwarf B star <ASTROBJ>HS 0702+6043</ASTROBJ>
is known as a large-amplitude, short-period p-mode pulsator of the
<ASTROBJ>EC 14026</ASTROBJ> type. Its atmospheric parameters place it
at the common boundary between the empirical instability regions of
the <ASTROBJ>EC 14026</ASTROBJ> variables and the typically cooler
long-period g-mode pulsators of the <ASTROBJ>PG 1716</ASTROBJ>
kind.<BR /> Aims: .We analyse and interpret the photometric
variability of <ASTROBJ>HS 0702+6043</ASTROBJ> in order to explore
its asteroseismological potential.<BR /> Methods: .We report on
rapid wide band CCD photometric observations to follow up on and
confirm the serendipitous discovery of multiperiodic long-period
luminosity variations with typical time scales of ~1 h in <ASTROBJ>HS
0702+6043</ASTROBJ>, in addition to the two previously known pulsations
at 363 s and 383 s. In particular, we isolate a relatively low-amplitude
(~4 mmag), long-period (3538±130 s) light variation.<BR /> Results:
.We argue that the most likely origin for this luminosity variation is
the presence of an excited g-mode pulsation. If confirmed, <ASTROBJ>HS
0702+6043</ASTROBJ> would constitute a rare addition to the very select
class of pulsating stars showing simultaneously parts of their pressure
and gravity mode pulsation spectra. The asteroseismological potential of
such stars is immense, and <ASTROBJ>HS 0702+6043</ASTROBJ> thus becomes
a target of choice for future investigations. While our discovery
appears consistent with the location of <ASTROBJ>HS 0702+6043</ASTROBJ>
at the common boundary between the two families of pulsating sdB stars,
it does challenge theory's current description of stability and driving
mechanisms in pulsating B subdwarfs.<BR /> Conclusions: .
---------------------------------------------------------
Title: Light and Heavy Metal Abundances in Hot Central Stars of
Planetary Nebulae
Authors: Werner, Klaus; Hoffmann, Agnes I. D.; Jahn, Dorothee; Rauch,
Thomas; Reiff, Elke; Traulsen, Iris; Kruk, Jeffrey W.; Dreizler, Stefan
2005AIPC..804..129W Altcode: 2005astro.ph..8108W
We present new results from our spectral analyses of very hot central
stars achieved since the last IAU Symposium on planetary nebulae held
in Canberra 2001. The analyses are mainly based on UV and far-UV
spectroscopy performed with the Hubble Space Telescope and the Far
Ultraviolet Spectroscopic Explorer but also on ground-based observations
performed at the Very Large Telescope and other observatories. We
report on temperature, gravity, and abundance determinations for the
CNO elements of hydrogen-rich central stars. In many hydrogen-deficient
central stars (spectral type PG1159) we discovered particular neon
and fluorine lines, which are observed for the very first time in
any astrophysical object. Their analysis strongly confirms the idea
that these stars exhibit intershell matter as a consequence of a late
helium-shell flash.
---------------------------------------------------------
Title: On the most metal-poor PN and its binary central star
Authors: Napiwotzki, R.; Tovmassian, G.; Richer, M. G.; Stasińska,
G.; Peña, M.; Drechsel, H.; Dreizler, S.; Rauch, T.
2005AIPC..804..173N Altcode: 2005astro.ph..9801N
PN G135.9+55.9 is the most metal-poor PN known in our Galaxy. The
central star resides in a short-period binary system with a compact
component, probably a white dwarf. We describe new observations, which
allowed us to determine the orbital period. The lower limit for the
combined mass of both stars is close to the Chandrasekhar limit for
white dwarfs, making this binary a possible progenitor of a supernova
type Ia. The binary system must have recently emerged from a common
envelope phase.
---------------------------------------------------------
Title: High-resolution extreme ultraviolet spectroscopy of G191-B2B:
structure of the stellar photosphere and the surrounding interstellar
medium
Authors: Barstow, M. A.; Cruddace, R. G.; Kowalski, M. P.; Bannister,
N. P.; Yentis, D.; Lapington, J. S.; Tandy, J. A.; Hubeny, I.; Schuh,
S.; Dreizler, S.; Barbee, T. W.
2005MNRAS.362.1273B Altcode: 2005MNRAS.tmp..749B
We have continued our detailed analysis of the high-resolution (R=
4000) spectroscopic observation of the DA white dwarf G191-B2B,
obtained by the Joint Astrophysical Plasmadynamic Experiment (J-PEX)
normal incidence sounding rocket-borne telescope, comparing the
observed data with theoretical predictions for both homogeneous and
stratified atmosphere structures. We find that the former models
give the best agreement over the narrow waveband covered by J-PEX,
in conflict with what is expected from previous studies of the lower
resolution but broader wavelength coverage Extreme Ultraviolet Explorer
spectra. We discuss the possible limitations of the atomic data and
our understanding of the stellar atmospheres that might give rise to
this inconsistency. In our earlier study, we obtained an unusually
high ionization fraction for the ionized HeII present along the line
of sight to the star. In the present paper, we obtain a better fit
when we assume, as suggested by Space Telescope Imaging Spectrograph
results, that this HeII resides in two separate components. When one
of these is assigned to the local interstellar cloud, the implied He
ionization fraction is consistent with measurements along other lines
of sight. However, the resolving power and signal-to-noise available
from the instrument configuration used in this first successful J-PEX
flight are not sufficient to clearly identify and prove the existence
of the two components.
---------------------------------------------------------
Title: Spectral analyses of DO white dwarfs and PG 1159 stars from
the Sloan Digital Sky Survey
Authors: Hügelmeyer, S. D.; Dreizler, S.; Werner, K.; Krzesiński,
J.; Nitta, A.; Kleinman, S. J.
2005A&A...442..309H Altcode: 2005astro.ph..8101H
We present a model atmosphere analysis of ten new DO white dwarfs and
five new PG 1159 stars discovered in the Sloan Digital Sky Survey DR1,
DR2 and DR3. This is a significant increase in the number of known
DOs and PG 1159 stars. DO white dwarfs are situated on the white
dwarf cooling sequence from the upper hot end (T_eff ≈ 120 000 K)
down to the DB gap (T_eff ≈ 45 000 K). PG 1159 stars on the other
hand feature effective temperatures which exceed T_eff = 65 000 K with
an upper limit of T_eff = 200 000 K and are the proposed precursors
of DO white dwarfs. Improved statistics are necessary to investigate
the evolutionary link between these two types of stars. From optical
SDSS spectra effective temperatures, surface gravities and element
abundances are determined by means of non-LTE model atmospheres.
---------------------------------------------------------
Title: The MultiSite Spectroscopic Telescope campaign: 2 m
spectroscopy of the V361 Hya variable PG 1605+072
Authors: O'Toole, S. J.; Heber, U.; Jeffery, C. S.; Dreizler, S.;
Schuh, S. L.; Woolf, V. M.; Falter, S.; Green, E. M.; For, B. -Q.;
Hyde, E. A.; Kjeldsen, H.; Mauch, T.; White, B. A.
2005A&A...440..667O Altcode: 2005astro.ph..6722O
We present results and analysis for the 2 m spectroscopic part of the
MultiSite Spectroscopic Telescope (MSST) campaign undertaken in May/June
2002. The goal of the project was to observe the pulsating subdwarf
B star PG 1605+072 simultaneously in velocity and photometry and to
resolve as many of the >50 known modes as possible, which will allow
a detailed asteroseismological analysis. We have obtained over 150 h
of spectroscopy, leading to an unprecedented noise level of only 207
m s<SUP>-1</SUP>. We report here the detection of 20 frequencies in
velocity, with two more likely just below our detection threshold. In
particular, we detect 6 linear combinations, making PG 1605+072
only the second star known to show such frequencies in velocity. We
investigate the phases of these combinations and their parent modes
and find relationships between them that cannot be easily understood
based on current theory. These observations, when combined with our
simultaneous photometry, should allow asteroseismology of this most
complicated of sdB pulsators.
---------------------------------------------------------
Title: Modelling C/O/Ne dominated accretion discs in ultra-compact
X-ray binaries
Authors: Hammer, N. J.; Kusterer, D. -J.; Nagel, T.; Rauch, T.;
Werner, K.; Dreizler, S.
2005ASPC..330..333H Altcode:
We present synthetic UV/optical NLTE spectra for the accretion disc
in the ultra-compact LMXB 4U 1626-67. By assuming a radial α-disc
structure, we perform full non-LTE radiative transfer calculations
to compute the detailed vertical structure of the disc. Comparing our
results with HST spectra confirms that the disc is H and He depleted,
but mainly composed of C and O.
---------------------------------------------------------
Title: Detection of planetary transits using wavelet analysis and
genetic algorithms.
Authors: Husser, T. -O.; Dreizler, S.; Solanki, S.; Thomas, R.
2005AN....326R.628H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Automated Difference Imaging for extrasolar planet searches.
Authors: Israel, H.; Hessman, F. V.; Dreizler, S.; Schuh, S.
2005AN....326..629I Altcode:
No abstract at ADS
---------------------------------------------------------
Title: NLTE Spectral Analysis of Accretion Discs in Ultracompact
X-ray Binaries
Authors: Nagel, T.; Hammer, N. J.; Rauch, T.; Werner, K.; Dreizler, S.
2005ASPC..330...73N Altcode:
We present first results of a NLTE spectral analysis of the accretion
discs in the ultracompact X-ray binaries 4U 0614+091 and 4U 1626-67,
performed with our accretion disc code AcDc. We show, that it is
possible to give an upper limit for the abundances of hydrogen. The
emission line features seen in the spectrum of 4U 1626-67 can be
modeled qualitatively with irradiation of the accretion disc by the
central neutron star.
---------------------------------------------------------
Title: The Spectral Variability of Pulsating Stars: PG 1159-035
Authors: Stahn, T.; Dreizler, S.; Werner, K.
2005ASPC..334..545S Altcode: 2005astro.ph..2013S
With 10m class telescopes as well as with time-tagging detectors
on board of HST and FUSE, the analysis of time-resolved spectra
for pulsating white dwarfs becomes feasible. We present simulated
time-resolved spectra for the hot pulsating white dwarf PG 1159-035
and compare these models with observational data of the 516 s mode
based on HST-STIS spectroscopy. A determination of the pulsation mode
by the spectral variability of PG 1159-035 seems to be impossible for
the moment.
---------------------------------------------------------
Title: Spectral Analyses of DO White Dwarfs and PG1159 Stars from
the Sloan Digital Sky Survey
Authors: Huegelmeyer, S. D.; Dreizler, S.; Werner, K.; Nitta, A.;
Kleinman, S. J.; Krzesiński, J.
2005ASPC..334..233H Altcode: 2005astro.ph..1252H
SDSS (DR1 and DR2) has recently proposed 7 new DO white dwarfs as
well as 6 new PG1159 stars. This is a significant increase in the
known number of DOs and PG1159 stars. Our spectral analyses provide
stellar parameters which can then be used to derive constraints for the
evolution of H-deficient white dwarfs. A comprehensive understanding
of these objects is still severely hampered by low-number statistics.
---------------------------------------------------------
Title: Investigation of the Spectral Variability of PG 1159-035
Authors: Dreizler, S.; Werner, K.; Stahn, T.
2005ASPC..334..512D Altcode:
Based on HST-STIS spectra of PG 1159-035, a hot, variable white dwarf,
we investigate the response of the stellar atmosphere to pulsations. The
observations are compared to theoretical model atmospheres which
allows to derive an amplitude for the variation of the effective
temperature of about 1 250 K. Additionally, we derive amplitudes for
radial velocity variations with 4.5 km s<SUP>-1</SUP> for the second
strongest optical mode.
---------------------------------------------------------
Title: NLTE Analysis of the Ultra-short Period White-Dwarf Binary
RX J0806.3+1527
Authors: Steiper, J.; Reinsch, K.; Dreizler, S.
2005ASPC..334..399S Altcode: 2005astro.ph..1255S
RX J0806.3+1527 is suspected to be a double-degenerate white dwarf
binary. We present first results of our NLTE analysis of its optical
spectrum. The VLT/FORS1 data show a composite spectrum consisting of a
blue continuum and superimposed emission lines of the He II Pickering
series and, possibly, the H Balmer series. Our models are based on
hot white dwarf atmospheres and include illumination effects onto
the secondary star. The physical parameters and chemical abundances
derived from the comparison of the observed spectrum with a grid
of model atmospheres provide constraints on the true nature of this
enigmatic binary and on the models proposed so far.
---------------------------------------------------------
Title: HST and FUSE Spectroscopy of Hot Hydrogen-Rich Central Stars
of Planetary Nebulae
Authors: Traulsen, I.; Hoffmann, A. I. D.; Rauch, T.; Werner, K.;
Dreizler, S.; Kruk, J. W.
2005ASPC..334..325T Altcode: 2004astro.ph.11403T
High-resolution UV spectra, obtained with HST and FUSE, enable us
to analyse hot hydrogen-rich central stars in detail. Up to now,
optical hydrogen and helium lines have been used to derive temperature
and surface gravity. Those lines, however, are rather insensitive; in
particular, neutral helium lines have completely vanished in the hottest
central stars. Therefore, we have concentrated on ionization balances
of metals, which have a rich line spectrum in the UV, to establish a
new temperature scale for our sample. Furthermore, we have determined
abundances of light metals, which had been poorly known before. They
show considerable variation from star to star. We present results of
quantitative spectral analyses performed with non-LTE model atmospheres.
---------------------------------------------------------
Title: Subluminous O Stars from the ESO Supernova Progenitor Survey -
Observation versus Theory
Authors: Ströer, A.; Heber, U.; Lisker, T.; Napiwotzki, R.;
Dreizler, S.
2005ASPC..334..309S Altcode: 2004astro.ph.10433S
The ESO Supernova Progenitor Survey (SPY) has identified 58 (mostly
helium-rich) subluminous O stars. We use the Balmer line strength to
distinguish sdO from He-sdO (no Balmer lines) and present the results
of the analyses of high resolution optical VLT-UVES spectra using an
extensive grid of NLTE atmosphere models covering a large range in
T<SUB>eff</SUB>, log{g} and helium abundances. The stellar atmospheric
parameters are derived from line profile fits using a χ<SUP>2</SUP>
technique. The resulting distribution in the (T<SUB>eff</SUB>, log{g})
diagram as well as the luminosity function are discussed in the context
of stellar evolution scenarios. By combining our results with those for
the sdB stars from SPY (Lisker et al. 2004) we discuss the implications
for binary population synthesis models of Han et al. (2003). Models with
a low CEE efficiency and a constant mass ratio distribution provide a
reasonable explanation of the observed properties of the SPY sample
of sdB and sdO stars indicating that the sdO stars form the hot and
luminous extension of the sdB sequence. However, for the He-sdO stars
none of the considered evolution scenarios are in agreement with the
measured parameters of our programme stars. We conclude that He-sdO
stars are formed by a different process than the sdB and sdO stars.
---------------------------------------------------------
Title: Successors of White Dwarfs -- Blue Hook Stars and the Late
Hot Flasher Scenario
Authors: Moehler, S.; Sweigart, A. V.; Landsman, W. B.; Hammer, N. J.;
Dreizler, S.
2005ASPC..334...73M Altcode:
Recent UV observations of massive globular clusters show a significant
population of hot stars fainter than the zero-age horizontal branch
(“blue hook” stars), which cannot be explained by canonical stellar
evolution. Stars which experience unusually large mass loss on the
red giant branch and which subsequently undergo the helium core
flash while descending the white dwarf cooling curve could populate
this region. Such objects should show higher temperatures than the
hottest canonical horizontal branch stars and should have helium- and
carbon-rich atmospheres. As a test of this late hot flasher scenario,
we have obtained and analysed medium resolution spectra of a sample of
blue hook stars to derive their atmospheric parameters. While these
parameters generally support the late hot flasher scenario there
remain important differences between our observational results and
theoretical predictions.
---------------------------------------------------------
Title: Metal Abundances in Hot DA White Dwarfs
Authors: Schuh, S.; Barstow, M. A.; Dreizler, S.
2005ASPC..334..237S Altcode: 2004astro.ph.11643S
We compare measured element abundances in hot DA white dwarfs from
UV observations to predictions from our self-consistent non-LTE model
atmosphere diffusion calculations.
---------------------------------------------------------
Title: Iron Abundance in Hydrogen-Rich Central Stars of Planetary
Nebulae
Authors: Hoffmann, A. I. D.; Traulsen, I.; Rauch, T.; Werner, K.;
Dreizler, S.; Kruk, J. W.
2005ASPC..334..321H Altcode: 2004astro.ph.11404H
We report on an on-going analysis of high-resolution UV spectra
of hot hydrogen-rich central stars of planetary nebulae (CSPN),
obtained with the Hubble Space Telescope and FUSE. Since UV spectra
of many CSPN are dominated by Fe and Ni lines, we intend to use them
as temperature indicators to check the CSPN temperature scale we have
derived earlier from CNO ionization balances. Furthermore, the observed
line strengths of heavy metals show large variations between different
objects suggesting a possible spread in abundances. We will determine
abundances of iron group elements by quantitative spectral analyses
with non-LTE model atmospheres.
---------------------------------------------------------
Title: On Possible Oxygen/Neon White Dwarfs: H1504+65 and the White
Dwarf Donors in Ultracompact X-ray Binaries
Authors: Werner, K.; Hammer, N. J.; Nagel, T.; Rauch, T.; Dreizler, S.
2005ASPC..334..165W Altcode: 2004astro.ph.10690W
We discuss the possibility to detect O/Ne white dwarfs by evidence
for Ne overabundances. The hottest known WD, H1504+65, could be the
only single WD for which we might be able to prove its O/Ne nature
directly. Apart from this, strong Ne abundances are known or suspected
only from binary systems, namely from a few novae, and from a handful
of LMXBs. We try to verify the hypothesis that the latter might host
strongly ablated O/Ne WD donors, by abundance analyses of the accretion
disks in these systems. In any case, to conclude on O/Ne WDs just by
strong Ne overabundances is problematic, because Ne enrichment also
occurs by settling of this species into the core of C/O WDs.
---------------------------------------------------------
Title: Discovery of a Long-Period Photometric Variation in the V361
Hya Star HS 0702+6043
Authors: Schuh, S.; Huber, J.; Green, E. M.; O'Toole, S. J.; Dreizler,
S.; Heber, U.; Fontaine, G.
2005ASPC..334..530S Altcode: 2004astro.ph.11640S
We report the discovery of a long-period g-mode oscillation in the
previously known short-period p-mode sdB pulsator HS 0702+6043. This
makes this star an extraordinary object, unique as a member of the
family of sdB pulsators, and one of the very few known pulsating
stars overall exhibiting excited modes along both the acoustic and
gravity branches of the nonradial pulsation spectrum. Because p-modes
and g-modes probe different regions of a pulsating star, HS 0702+6043
holds a tremendous potential for future detailed asteroseismological
investigations.
---------------------------------------------------------
Title: Rotation Velocities of DA White Dwarfs with Convective
Atmospheres}
Authors: Karl, C.; Heber, U.; Napiwotzki, R.; Dreizler, S.; Koester,
D.; Reid, I. N.
2005ASPC..334..241K Altcode:
The sharp H{α} NLTE line cores of hydrogen rich (DA) white dwarfs
allow their projected rotational velocities to be determined. High
resolution optical spectra of 22 stars obtained with the Keck I
telescope are matched by synthetic spectra computed from a grid of NLTE
model atmospheres. We concentrate preferentially on hydrogen-rich white
dwarfs with convective atmospheres, i.e. with T<SUB>eff</SUB> < 14
000 K. Previous analyses found DA white dwarfs hotter than 14 000 K to
be very slow rotators and rarely show any spectroscopically detectable
rotation. For 19 of our program stars we were able to derive projected
rotational velocities or upper limits. Combining our results with
those from two similar studies (Heber et al 1997, paper I and Koester
et al. 1998, paper II), we have obtained information of 56 DA white
dwarfs. The fraction of rotating DA white dwarfs whose line profiles can
be matched for a vanishing projected rotation velocities is high for
hot white dwarfs with radiative atmospheres (25 out of 28) with upper
limits ranging from 1 kms<SUP>-1</SUP> to 24 kms<SUP>-1</SUP>, whereas
amongst the cool white dwarfs with presumably convective atmospheres
only for a few stars (8 out of 22) no additional line broadening has
to be invoked to explain their observed Hα line profiles resulting
in upper limits to v sin i of 7 kms<SUP>-1</SUP> to 35 kms<SUP>-1</SUP>.
---------------------------------------------------------
Title: Rotation velocities of white dwarfs. III. DA stars with
convective atmospheres
Authors: Karl, C. A.; Napiwotzki, R.; Heber, U.; Dreizler, S.; Koester,
D.; Reid, I. N.
2005A&A...434..637K Altcode:
The sharp Hα NLTE line cores of hydrogen-rich (DA) white dwarfs
allow their projected rotational velocities to be determined. High
resolution optical spectra of 22 stars obtained with the Keck I
telescope are matched by synthetic spectra computed from a grid of
NLTE model atmospheres. In this paper, the third in a series on white
dwarf rotation, we concentrate preferentially on DA white dwarfs
with convective atmospheres, i.e. with T<SUB>eff</SUB> < 14 000
K. Previous analyses found DA white dwarfs hotter than 14 000 K to be
very slow rotators and rarely show any spectroscopically detectable
rotation. For 19 of our programme stars we were able to derive projected
rotational velocities or upper limits. No rotation could be detected for
seven stars in our sample. However twelve stars show significant line
broadening. In the case of the ZZ Ceti star G 117-B15A, the observed
Hα line profile cannot be matched by a rotationally broadened profile
as its line core is too narrow. Combining our results with those from
two similar studies, we have obtained information on the rotation or
other line broadening mechanisms (such as caused by magnetic fields)
of 56 DA white dwarfs. The fraction of rotating DA white dwarfs
whose line profiles can be matched for a vanishing projected rotation
velocity is high for hot white dwarfs with radiative atmospheres (25
out of 28). Amongst the cool white dwarfs with presumedly convective
atmospheres, only for a few stars (8 out of 22) has no additional line
broadening to be invoked to explain their observed Hα line profiles. We
conjecture that the physics of Hα line formation in convective DA
white dwarf atmospheres is not yet sufficiently well understood and
additional observational and theoretical efforts have to be made.
---------------------------------------------------------
Title: The D/H Ratio toward PG 0038+199
Authors: Williger, Gerard M.; Oliveira, Cristina; Hébrard, Guillaume;
Dupuis, Jean; Dreizler, Stefan; Moos, H. Warren
2005ApJ...625..210W Altcode: 2005astro.ph..1320W
We determine the D/H ratio in the interstellar medium toward the
DO white dwarf PG 0038+199 using spectra from the Far Ultraviolet
Spectroscopic Explorer (FUSE), with ground-based support from
Keck HIRES. We employ curve-of-growth, apparent optical depth,
and profile-fitting techniques to measure the column densities
and limits of many other species (H<SUB>2</SUB>, Na I, C I, C II,
C III, N I, N II, O I, Si II, P II, S III, Ar I, and Fe II),
which allows us to determine related ratios such as D/O, D/N,
and the H<SUB>2</SUB> fraction. Our efforts are concentrated on
measuring gas-phase D/H, which is key to understanding Galactic
chemical evolution, and comparing it to predictions from big bang
nucleosynthesis. We find column densities logN(HI)=20.41+/-0.08,
logN(DI)=15.75+/-0.08, and logN(H<SUB>2</SUB>)=19.33+/-0.04,
yielding a molecular hydrogen fraction of 0.14+/-0.02 (2 σ errors),
with an excitation temperature of 143+/-5 K. The high H I column
density implies that PG 0038+199 lies outside of the Local Bubble;
we estimate its distance to be 297<SUP>+164</SUP><SUB>-104</SUB>
pc (1 σ). [DI+HD]/[HI+2H<SUB>2</SUB>] toward PG 0038+199 is
1.91<SUP>+0.52</SUP><SUB>-0.42</SUB>×10<SUP>-5</SUP> (2 σ). There
is no evidence of component structure on the scale of Δv>8 km
s<SUP>-1</SUP>, based on Na I, but there is marginal evidence for
structure on smaller scales. The D/H value is high compared to the
majority of recent D/H measurements but consistent with the values
for two other measurements at similar distances. D/O is in agreement
with other distant measurements. The scatter in D/H values beyond
~100 pc remains a challenge for Galactic chemical evolution. <P />This
paper is dedicated in memory of Ervin J. Williger, father of the first
author, who passed away on 2003 September 13. His enthusiastic support
and encouragement were essential to its successful completion. <P
/>Based on data from the Far Ultraviolet Spectroscopic Explorer and
the W. M. Keck Observatory.
---------------------------------------------------------
Title: Whole Earth Telescope observations of BPM 37093: A
seismological test of crystallization theory in white dwarfs
Authors: Kanaan, A.; Nitta, A.; Winget, D. E.; Kepler, S. O.;
Montgomery, M. H.; Metcalfe, T. S.; Oliveira, H.; Fraga, L.; da
Costa, A. F. M.; Costa, J. E. S.; Castanheira, B. G.; Giovannini, O.;
Nather, R. E.; Mukadam, A.; Kawaler, S. D.; O'Brien, M. S.; Reed,
M. D.; Kleinman, S. J.; Provencal, J. L.; Watson, T. K.; Kilkenny,
D.; Sullivan, D. J.; Sullivan, T.; Shobbrook, B.; Jiang, X. J.;
Ashoka, B. N.; Seetha, S.; Leibowitz, E.; Ibbetson, P.; Mendelson,
H.; Meištas, E. G.; Kalytis, R.; Ališauskas, D.; O'Donoghue, D.;
Buckley, D.; Martinez, P.; van Wyk, F.; Stobie, R.; Marang, F.; van
Zyl, L.; Ogloza, W.; Krzesinski, J.; Zola, S.; Moskalik, P.; Breger,
M.; Stankov, A.; Silvotti, R.; Piccioni, A.; Vauclair, G.; Dolez, N.;
Chevreton, M.; Deetjen, J.; Dreizler, S.; Schuh, S.; Gonzalez Perez,
J. M.; Østensen, R.; Ulla, A.; Manteiga, M.; Suarez, O.; Burleigh,
M. R.; Barstow, M. A.
2005A&A...432..219K Altcode: 2004astro.ph.11199K
BPM 37093 is the only hydrogen-atmosphere white dwarf currently known
which has sufficient mass (~1.1 M<SUB>⊙</SUB>) to theoretically
crystallize while still inside the ZZ Ceti instability strip
(T<SUB>eff</SUB>∼12 000 K). As a consequence, this star represents
our first opportunity to test crystallization theory directly. If the
core is substantially crystallized, then the inner boundary for each
pulsation mode will be located at the top of the solid core rather
than at the center of the star, affecting mainly the average period
spacing. This is distinct from the “mode trapping” caused by
the stratified surface layers, which modifies the pulsation periods
more selectively. In this paper we report on Whole Earth Telescope
observations of BPM 37093 obtained in 1998 and 1999. Based on a simple
analysis of the average period spacing we conclude that a large fraction
of the total stellar mass is likely to be crystallized. <P />Based
on observations obtained at: Observatório do Pico dos Dias (OPD)
Brazil, the European Southern Observatory (ESO) Chile, South African
Astronomical Observatory (SAAO), Mt. John University Observatory
(MJUO) New Zealand, Siding Spring Observatory (SSO) Australia, and
Cerro Tololo Inter-American Observatory (CTIO), a division of the
National Optical Astronomy Observatories, which is operated by the
Association of Universities for Research in Astronomy, Inc. under
cooperative agreement with the National Science Foundation.
---------------------------------------------------------
Title: Stellar atmosphere modeling in the era of 10m class telescopes
Authors: Dreizler, S.
2005AIPC..752...13D Altcode:
In this paper, I briefly summarize the basic ingredients for modeling
stellar atmospheres. The progress in the numerical solution techniques
has evolved in parallel to the rapid development of observing
facilities. The modeling of stellar atmospheres in particular and
stellar astrophysics in general are therefore important ingredients
for our understanding of stellar, galactic and cosmic evolution.
---------------------------------------------------------
Title: Giant Transiting Planets Observations - GITPO
Authors: Afonso, C.; Henning, Th.; Weldrake, D.; Mazeh, T.; Dreizler,
S.
2005prpl.conf.8047A Altcode: 2005LPICo1286.8047A
No abstract at ADS
---------------------------------------------------------
Title: AcDc - A new code for the NLTE spectral analysis of accretion
discs: application to the helium CV AM CVn
Authors: Nagel, T.; Dreizler, S.; Rauch, T.; Werner, K.
2004A&A...428..109N Altcode: 2004astro.ph..8352N
We present a recently developed code for detailed NLTE calculations
of accretion disc spectra of cataclysmic variables and compact X-ray
binaries. Assuming a radial structure of a standard α-disc, the disc
is divided into concentric rings. For each disc ring the solution
of the radiation transfer equation and the structure equations,
comprising the hydrostatic and radiative equilibrium, the population
of the atomic levels as well as charge and particle conservation,
is done self-consistently. Metal-line blanketing and irradiation by
the central object are taken into account. As a first application, we
show the influence of different disc parameters on the disc spectrum
for the helium cataclysmic variable AM CVn.
---------------------------------------------------------
Title: Modeling He-rich Disks in AM CVn Binaries
Authors: Nagel, T.; Rauch, T.; Dreizler, S.; Werner, K.
2004RMxAC..20..228N Altcode: 2004IAUCo.194..228N
We have developed a new code for the calculation of synthetic spectra
and vertical structures of accretion disks in cataclysmic variables
and compact X-ray binaries. Here we present results for the CV system
AM CVn.
---------------------------------------------------------
Title: Modeling of Oxygen-Neon Dominated Accretion Disks in
Ultracompact X-ray Binaries: 4U 1626-67
Authors: Werner, K.; Nagel, T.; Dreizler, S.; Rauch, T.
2004RMxAC..20..146W Altcode: 2003astro.ph.12561W; 2004IAUCo.194..146W
We report on first results of computing synthetic spectra from H/He-poor
accretion disks in ultracompact LMXBs. We aim at the determination
of the chemical composition of the very low-mass donor star, which is
the core of a former C/O white dwarf. The abundance analysis allows to
draw conclusions on gravitational settling in WDs which is an important
process affecting cooling times and pulsational g-mode periods.
---------------------------------------------------------
Title: HS 2237+8154: A new pre-CV just above the period gap
Authors: Gänsicke, B. T.; Araujo-Betancor, S.; Hagen, H. -J.;
Harlaftis, E. T.; Kitsionas, S.; Dreizler, S.; Engels, D.
2004RMxAC..20..271G Altcode: 2004IAUCo.194..271G
We report follow-up observations of the new pre-cataclysmic variable
HS 2237+8154, identified from the Hamburg Quasar Survey. The orbital
period derived from ellipsoidal modulation observed in the R-band as
well as from the Hα radial velocity variation is [orb] = 178.10±0.08
min. We briefly discuss the evolutionary state of this system.
---------------------------------------------------------
Title: The Rotational Velocity of Helium-rich Pre-White Dwarfs
Authors: Rauch, T.; Köper, S.; Dreizler, S.; Werner, K.; Heber, U.;
Reid, I. Neill
2004IAUS..215..573R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: MSST observations of the pulsating sdB star PG 1605+072
Authors: O'Toole, S. J.; Falter, S.; Heber, U.; Jeffery, C. S.;
Dreizler, S.; Schuh, S. L.; MSST + Wet Teams,
2004Ap&SS.291..457O Altcode: 2003astro.ph..9061O
We present the first results from the MultiSite Spectroscopic Telescope
(MSST) observations of the sdBV star PG 1605+072. Pulsating sdB stars
(also known as EC 14026 stars) offer the chance to gain new insights
into the formation and evolution of extreme Horizontal Branch stars
using the tools of asteroseismology. PG 1605+072 is an outstanding
object in its class, with the richest frequency spectrum, the longest
periods, and the largest variations.
---------------------------------------------------------
Title: Helium-rich EHB Stars in Globular Clusters
Authors: Moehler, S.; Sweigart, A. V.; Landsman, W. B.; Dreizler, S.
2004Ap&SS.291..231M Altcode: 2003astro.ph..9768M
Recent UV observations of the most massive Galactic globular clusters
show a significant population of hot stars below the zero-age HB
(“blue hook” stars), which cannot be explained by canonical stellar
evolution. Stars which suffer unusually large mass loss on the red giant
branch and thus experience the helium-core flash while descending the
white dwarf cooling curve could populate this region. They should
show higher temperatures than the hottest canonical HB stars and
their atmospheres should be helium-rich and probably C/N-rich. We
have obtained spectra of blue hook stars in ω Cen and NGC 2808 to
test this possibility. Our analysis shows that the blue hook stars in
these clusters reach effective temperatures well beyond the hot end of
the canonical EHB and have higher helium abundances than canonical EHB
stars. These results support the hypothesis that the blue hook stars
arise from stars which ignite helium on the white dwarf cooling curve.
---------------------------------------------------------
Title: Discovery of Gravity-Mode Pulsators among Subdwarf B Stars:
PG 1716+426, the Class Prototype
Authors: Reed, M. D.; Green, E. M.; Callerame, K.; Seitenzahl, I. R.;
White, B. A.; Hyde, E. A.; Giovanni, M. K.; Østensen, R.; Bronowska,
A.; Jeffery, E. J.; Cordes, O.; Falter, S.; Edelmann, H.; Dreizler,
S.; Schuh, S. L.
2004ApJ...607..445R Altcode:
A new class of pulsating subdwarf B stars has recently been announced
by Green and coworkers. Here we present a follow-up paper describing
our observations and the pulsation structure of the class prototype
PG 1716+426. The oscillations are multiperiodic with periods between
0.8 and 1.4 hr (180-340 μHz) and semiamplitudes less than 0.2%. We
also observe that the periods and amplitudes appear variable, making
the pulsation structure of PG 1716 complicated. The periods are an
order of magnitude longer than those seen in EC 14026 (sdBV) stars,
implying that they are gravity modes rather than pressure modes. As
such, they represent a new class of variable star.
---------------------------------------------------------
Title: Multisite spectroscopic and photometric observations of the
pulsating sdB star PG 1605+072
Authors: O'Toole, S. J.; Falter, S.; Heber, U.; Jeffery, C. S.;
Dreizler, S.; Schuh, S. L.; Msst, The; Wet Teams
2004ASPC..310..230O Altcode: 2004IAUCo.193..230O; 2004vslg.conf..230O
We present the first results from the MultiSite Spectroscopic Telescope
(MSST) observations ofthe sd BV star PG 1605+072. Pulsating sdB stars
(V361 Hya stars) offer the chance to gain new insights into the
formation and evolution of extreme Horizontal Branch stars using the
tools of asteroseismology. PG 1605+072 is an outstanding object in
its class, with the richest frequency spectrum, the longest periods,
and the largest variations. The MSST campaign took place in 2002
May/June and we present here the massive data set, madeup of 399 hr of
photometry and 151 hr of spectroscopy. The overall aims of the project
are to examine light/velocity amplitude ratios and phase differences,
changes in equivalent width/line index, and λ-dependence of photometric
amplitudes, and to use these properties for mode identification.
---------------------------------------------------------
Title: HS 2237+8154: On the onset of mass transfer or entering the
period gap?
Authors: Gänsicke, B. T.; Araujo-Betancor, S.; Hagen, H. -J.;
Harlaftis, E. T.; Kitsionas, S.; Dreizler, S.; Engels, D.
2004A&A...418..265G Altcode: 2004astro.ph..2189G
We report follow-up observations of a new white dwarf/red dwarf binary
HS 2237+8154, identified as a blue variable star from the Hamburg
Quasar Survey. Ellipsoidal modulation observed in the R band as well
as the Hα radial velocity variations measured from time-resolved
spectroscopy determine the orbital period to be P<SUB>orb</SUB>=178.10
± 0.08 min. The optical spectrum of HS 2237+8154 is well described
by a combination of a T<SUB>eff</SUB>=11 500 ± 1500 K white dwarf
(assuming log g=8) and a dM 3.5 ± 0.5 secondary star. The distance
implied from the flux scaling factors of both stellar components is
d=105 ± 25 pc. Combining the constraints obtained from the radial
velocity of the secondary and from the ellipsoidal modulation, we
derive a binary inclination of i≃50<SUP>°</SUP>-70<SUP>°</SUP>
and stellar masses of M<SUB>wd</SUB>=0.47-0.67 M<SUB>⊙</SUB> and
M<SUB>sec</SUB>=0.2-0.4 M<SUB>⊙</SUB>. All observations imply that
the secondary star must be nearly Roche-lobe filling. Consequently, HS
2237+8154 may be either a pre-cataclysmic variable close to the start
of mass transfer, or - considering its orbital period - a cataclysmic
variable that terminated mass transfer and entered the period gap, or
a hibernating nova. <P />Based in part on observations made at the 1.2
m telescope, located at Kryoneri Korinthias, and owned by the National
Observatory of Athens, Greece, and with the Isaac Newton Telescope,
which is operated on the island of La Palma by the Isaac Newton Group
in the Spanish Observatorio del Roque de los Muchachos of the Instituto
de Astrofisica de Canarias.
---------------------------------------------------------
Title: Observations of the pulsating subdwarf B star Feige 48:
Constraints on evolution and companions
Authors: Reed, M. D.; Kawaler, S. D.; Zola, S.; Jiang, X. J.; Dreizler,
S.; Schuh, S. L.; Deetjen, J. L.; Kalytis, R.; Meištas, E.; Janulis,
R.; Ališauskas, D.; Krzesiński, J.; Vuckovic, M.; Moskalik, P.;
Ogłoza, W.; Baran, A.; Stachowski, G.; Kurtz, D. W.; González Pérez,
J. M.; Mukadam, A.; Watson, T. K.; Koen, C.; Bradley, P. A.; Cunha,
M. S.; Kilic, M.; Klumpe, E. W.; Carlton, R. F.; Handler, G.; Kilkenny,
D.; Riddle, R.; Dolez, N.; Vauclair, G.; Chevreton, M.; Wood, M. A.;
Grauer, A.; Bromage, G.; Solheim, J. E.; Østensen, R.; Ulla, A.;
Burleigh, M.; Good, S.; Hürkal, Ö.; Anderson, R.; Pakstiene, E.
2004MNRAS.348.1164R Altcode: 2003astro.ph.11476R
Since pulsating subdwarf B (sdBV or EC14026) stars were first
discovered, observational efforts have tried to realize their potential
for constraining the interior physics of extreme horizontal branch
stars. Difficulties encountered along the way include uncertain mode
identifications and a lack of stable pulsation mode properties. Here we
report on Feige 48, an sdBV star for which follow-up observations have
been obtained spanning more than four years. These observations show
some stable pulsation modes. <P />We resolve the temporal spectrum into
five stable pulsation periods in the range 340-380 s with amplitudes
less than 1 per cent, and two additional periods that appear in one
data set each. The three largest amplitude periodicities are nearly
equally spaced, and we explore the consequences of identifying them as
a rotationally split l= 1 triplet by consulting a representative stellar
model. <P />The general stability of the pulsation amplitudes and phases
allows us to use the pulsation phases to constrain the time-scale
of evolution for this sdBV star. Additionally, we are able to place
interesting limits on any stellar or planetary companion to Feige 48.
---------------------------------------------------------
Title: Spectroscopic analyses of the blue hook stars in NGC 2808:
A more stringent test of the late hot flasher scenario
Authors: Moehler, S.; Sweigart, A. V.; Landsman, W. B.; Hammer, N. J.;
Dreizler, S.
2004A&A...415..313M Altcode: 2003astro.ph.11215M
Recent UV observations of the globular cluster NGC 2808 (Brown et
al. \cite{brsw01}) show a significant population of hot stars fainter
than the zero-age horizontal branch (“blue hook” stars), which
cannot be explained by canonical stellar evolution. Their results
suggest that stars which experience unusually large mass loss on
the red giant branch and which subsequently undergo the helium core
flash while descending the white dwarf cooling curve could populate
this region. Theory predicts that these “late hot flashers” should
show higher temperatures than the hottest canonical horizontal branch
stars and should have helium- and carbon-rich atmospheres. As a test
of this late hot flasher scenario, we have obtained and analysed
medium resolution spectra of a sample of blue hook stars in NGC 2808
to derive their atmospheric parameters. Using the same procedures,
we have also re-analyzed our earlier spectra of the blue hook stars in
ω Cen (Moehler et al. \cite{mosw02}) for comparison with the present
results for NGC 2808. The blue hook stars in these two clusters are both
hotter (T<SUB>eff</SUB> ≥35 000 K) and more helium-rich than canonical
extreme horizontal branch stars in agreement with the late hot flasher
scenario. Moreover, we find indications for carbon enhancement in the
three most helium-enriched stars in NGC 2808. However, the blue hook
stars still show some hydrogen in their atmospheres, perhaps indicating
that some residual hydrogen survives a late hot flash and then later
diffuses to the surface during the horizontal branch phase. We note
that the presence of blue hook stars apparently depends mostly on the
total mass of the globular cluster and not so much on its horizontal
branch morphology. <P />Based on observations collected at the European
Southern Observatory, Chile (ESO proposal 68.D-0248).
---------------------------------------------------------
Title: 2MASS J0516288+260738: a new low-mass eclipsing binary system.
Authors: Schuh, S.; Drechsel, H.; Hauschildt, P.; Handler, G.; Endl,
M.; Dreizler, S.
2004ANS...325R..84S Altcode: 2004ANS...325a..84S; 2004ANS...325..P09S
No abstract at ADS
---------------------------------------------------------
Title: Asteroseismology of the β Cephei star ν Eridani -
II. Spectroscopic observations and pulsational frequency analysis
Authors: Aerts, C.; De Cat, P.; Handler, G.; Heiter, U.; Balona, L. A.;
Krzesinski, J.; Mathias, P.; Lehmann, H.; Ilyin, I.; De Ridder, J.;
Dreizler, S.; Bruch, A.; Traulsen, I.; Hoffmann, A.; James, D.;
Romero-Colmenero, E.; Maas, T.; Groenewegen, M. A. T.; Telting,
J. H.; Uytterhoeven, K.; Koen, C.; Cottrell, P. L.; Bentley, J.;
Wright, D. J.; Cuypers, J.
2004MNRAS.347..463A Altcode:
We undertook a multisite spectroscopic campaign for the β Cephei star
ν Eridani. A total of 2294 high-resolution spectra were obtained
from telescopes at 11 different observatories around the world. The
time base of dedicated multisite observations is 88 d. To this
data set we have added 148 older, previously unpublished spectra,
such that the overall time-span of the 2442 spectra is 430 d. The
analysis of the radial velocity variations derived from the SiIII
triplet centred on 4560Å leads to 19 significant frequencies, of
which seven correspond to independent pulsation frequencies. Five of
these are members of multiplets with an average spacing of 0.018 +/-
0.002 cd<SUP>-1</SUP>. Our spectroscopic results agree well with
those derived from a simultaneous multisite photometric campaign of
the star, albeit that we do not recover their low frequency at 0.43218
cd<SUP>-1</SUP>. We find three different candidate frequencies below
1 cd<SUP>-1</SUP> instead. We also find that the radial velocity
amplitude of the main mode has increased by some 30 per cent over
the last 15 years, which is consistent with the photometry data. We
derive a relative equivalent width variation of 6.5 per cent, which
is completely dominated by the main radial mode. The phase difference
between the radial velocity and light variations for the main frequency
is , which is clearly deviant from the adiabatic value and confirms the
radial nature of the dominant mode. The spectral line broadening leads
to an upper limit of 20 km s<SUP>-1</SUP> for vsini, which is consistent
with the long rotation period derived from the frequency splittings.
---------------------------------------------------------
Title: Time resolved spectroscopy of the sdB variable PG1605+072
Authors: Dreizler, Stefan
2004fuse.prop.C020D Altcode:
The recent discovery of radial and nonradial mode pulsations in more
than 20 sdB stars make them primary targets for asteroseismology
to probe their internal structure and discern their evolutionary
status; the latter is crucial for reasons as diverse as understanding
the late stages of stellar evolution and the calibration of the
observed ultraviolet upturn in giant elliptical galaxies as an age
indicator. Central to any asteroseismological study is an identification
of the pulsation modes. Photometric studies have failed to identify
modes from optical light curves. Line profile and flux variations in
the far ultraviolet offer a promising way to disentangle the pulsation
modes by comparison with detailed model predictions. PG1605+072 is
an outstanding target among the sdB variables because it displays
the richest period spectrum (>50 pulsation periods), largest
amplitudes and longest periods, which makes it the primary target for
a spectroscopic FUV study.
---------------------------------------------------------
Title: <ASTROBJ>2MASS J0516288+260738</ASTROBJ>: Discovery of the
first eclipsing late K + Brown dwarf binary system?
Authors: Schuh, S. L.; Handler, G.; Drechsel, H.; Hauschildt, P.;
Dreizler, S.; Medupe, R.; Karl, C.; Napiwotzki, R.; Kim, S. -L.; Park,
B. -G.; Wood, M. A.; Paparó, M.; Szeidl, B.; Virághalmy, G.; Zsuffa,
D.; Hashimoto, O.; Kinugasa, K.; Taguchi, H.; Kambe, E.; Leibowitz,
E.; Ibbetson, P.; Lipkin, Y.; Nagel, T.; Göhler, E.; Pretorius, M. L.
2003A&A...410..649S Altcode: 2003astro.ph..8329S
We report the discovery of a new eclipsing system less than
one arcminute south of the pulsating DB white dwarf <ASTROBJ>KUV
05134+2605</ASTROBJ>. The object could be identified with the point
source <ASTROBJ>2MASS J0516288+260738</ASTROBJ> published by the Two
Micron All Sky Survey. We present and discuss the first light curves
as well as some additional colour and spectral information. The
eclipse period of the system is 1.29 d, and, assuming this to be
identical to the orbital period, the best light curve solution yields
a mass ratio of m<SUB>2</SUB>/m<SUB>1</SUB>=0.11, a radius ratio of
r<SUB>2</SUB>/r<SUB>1</SUB>~ 1 and an inclination of 74<SUP>o</SUP>. The
spectral anaylsis results in a T<SUB>eff</SUB>=4200 K for the
primary. On this basis, we suggest that the new system probably consists
of a late K + Brown dwarf (which would imply a system considerably
younger than ~0.01 Gyr to have r<SUB>2</SUB>/r<SUB>1</SUB>~ 1), and
outline possible future observations. <P />This paper uses observations
made at the Bohyunsan Optical Astronomy Observatory of Korea Astronomy
Observatory, at the South African Astronomical Observatory (SAAO), at
the 0.9 m telescope at Kitt Peak National Observatory recommissioned
by the Southeastern Association for Research in Astronomy (SARA),
at Gunma Astronomical Observatory established by Gunma prefecture,
Japan, at the Florence and George Wise Observatory, operated by the
Tel-Aviv University, Israel and at Piszkésteto, the mountain station
of Konkoly Observatory of the Hungarian Academy of Science, Hungary. <P
/>This publication makes use of data products from the Two Micron All
Sky Survey, a joint project of the University of Massachusetts and
the Infrared Processing and Analysis Center / California Institute of
Technology, funded by the National Aeronautics and Space Administration
and the National Science Foundation. <P />The Digitized Sky Survey was
produced at the Space Telescope Science Institute under US Government
grant NAG W-2166. The images of these surveys are based on photographic
data obtained using the Oschin Schmidt Telescope on Palomar Mountain
and the UK Schmidt Telescope. The plates were processed into the present
compressed digital form with the permission of these institutions.
---------------------------------------------------------
Title: A Whole Earth Telescope campaign on the pulsating subdwarf
B binary system PG 1336-018 (NY Vir)
Authors: Kilkenny, D.; Reed, M. D.; O'Donoghue, D.; Kawaler, S. D.;
Mukadam, A.; Kleinman, S. J.; Nitta, A.; Metcalfe, T. S.; Provencal,
J. L.; Watson, T. K.; Sullivan, D. J.; Sullivan, T.; Shobbrook, R.;
Jiang, X. J.; Joshi, S.; Ashoka, B. N.; Seetha, S.; Leibowitz, E.;
Ibbetson, P.; Mendelson, H.; Meištas, E.; Kalytis, R.; Ališauskas,
D.; Martinez, P.; van Wyk, F.; Stobie, R. S.; Marang, F.; Zola, S.;
Krzesinski, J.; Ogłoza, W.; Moskalik, P.; Silvotti, R.; Piccioni,
A.; Vauclair, G.; Dolez, N.; Chevreton, M.; Dreizler, S.; Schuh,
S. L.; Deetjen, J. L.; Solheim, J. -E.; Gonzalez Perez, J. M.; Ulla,
A.; Østensen, R.; Manteiga, M.; Suarez, O.; Burleigh, M.; Kepler,
S. O.; Kanaan, A.; Giovannini, O.
2003MNRAS.345..834K Altcode:
We present results from a multisite (`Whole Earth Telescope')
photometric campaign on PG 1336-018, the close eclipsing binary system
containing a pulsating subdwarf B (sdB) star. The main part of the
campaign (1999 April) resulted in ~172 h of observations, representing a
coverage of about 47 per cent, and additional data were obtained outside
the core campaign. Periodogram analysis shows that the light variations
are dominated by three frequencies near 5757, 5585 and 5369 μHz (~174,
179 and 186 s, respectively), although many frequencies are present,
particularly in the range 5000-6000 μHz (~200-170 s). We identify,
with some confidence, 28 frequencies down to a semi-amplitude of
0.0005 in fractional intensity (equivalent to about 0.5 mmag). It
is clear that the pulsation frequencies of PG 1336-018 have changed
substantially since the 1996 discovery observations were made, and that
amplitude changes occur, at least in the dominant three frequencies, on
relatively short time-scales (of the order of a day). On the assumption
that the pulsating star is phase-locked in the binary system, we have
searched for rotational splitting of frequencies near the orbital and
half of the orbital period, but the results are confused by aliasing
at those frequencies (due to the data gaps caused by the eclipses). A
preliminary model qualitatively matches the distribution of frequencies
in PG 1336-018, with some good individual correspondences, but cannot
be considered adequate because geometric cancellation should hide some
of the modes which are apparently detected. Analysis of the pulsations
during eclipse recovers three of the strongest modes, but the limited
eclipse data - which can, at best, be only about 9 per cent of the total
- do not allow mode identification at this stage. Simulations indicate
that an overall coverage of about 80 per cent would be required for
this to be viable. An attempt was made to determine phase shifts in
the pulsation frequencies as a way of directly measuring the size of
the binary orbit, but the uncertainties in the method are comparable
to the light travel time across the orbit (probably less than a second).
---------------------------------------------------------
Title: Synthetic Spectra of Accretion Disks
Authors: Nagel, T.; Dreizler, S.; Werner, K.
2003ANS...324...64N Altcode: 2003ANS...324..P31N; 2003ANS...324b..64N
No abstract at ADS
---------------------------------------------------------
Title: Analysis of the FUSE spectrum of the sdOB EC11481-2303
Authors: Hammer, N.; Deetjen, J. L.; Dreizler, S.; Werner, K.; Kruk,
J. W.
2003ANS...324...72H Altcode: 2003ANS...324b..72H; 2003ANS...324..P51H
No abstract at ADS
---------------------------------------------------------
Title: Spectral Types of Planetary Host Star Candidates: New
Transiting Planets?
Authors: Dreizler, S.; Rauch, T.; Hauschildt, P.; Schuh, S. L.; Kley,
W.; Werner, K.
2003ANS...324....2D Altcode: 2003ANS...324..A03D; 2003ANS...324b...2D
No abstract at ADS
---------------------------------------------------------
Title: HST UV-spectroscopy of Hot Central Stars of Planetary Nebulae
Authors: Traulsen, I.; Hoffmann, A.; Dreizler, S.; Rauch, T.;
Werner, K.
2003ANS...324..144T Altcode: 2003ANS...324c.144T; 2003ANS...324..P60T
No abstract at ADS
---------------------------------------------------------
Title: Population Membership of White Dwarfs from the SPY Project
Authors: Pauli, E. -M.; Napiwotzki, R.; Altmann, M.; Heber, U.;
Dreizler, S.; Kerber, F.; Odenkirchen, M.; Spy Consortium
2003ANS...324...36P Altcode: 2003ANS...324b..36P; 2003ANS...324..G04P
No abstract at ADS
---------------------------------------------------------
Title: Improved Results for Equilibrium Abundances from Diffusion
Calculations
Authors: Schuh, S. L.; Dreizler, S.
2003ANS...324...72S Altcode: 2003ANS...324..P50S; 2003ANS...324b..72S
No abstract at ADS
---------------------------------------------------------
Title: To be or Not to Be a Late Hot Flasher
Authors: Moehler, S.; Sweigart, A. V.; Landsman, W. B.; Dreizler, S.
2003ANS...324...79M Altcode: 2003ANS...324b..79M; 2003ANS...324..P66M
No abstract at ADS
---------------------------------------------------------
Title: OGLE-TR-3: A possible new transiting planet
Authors: Dreizler, S.; Hauschildt, P. H.; Kley, W.; Rauch, T.; Schuh,
S. L.; Werner, K.; Wolff, B.
2003A&A...402..791D Altcode: 2003astro.ph..3183D
Recently, 59 low-luminosity object transits were reported from
the Optical Gravitational Lensing Experiment (OGLE). Our follow-up
low-resolution spectroscopy of 16 candidates provided two objects,
<ASTROBJ>OGLE-TR-3</ASTROBJ> and <ASTROBJ>OGLE-TR-10</ASTROBJ>,
which have companions with radii compatible with those of gas-giant
planets. Further high-resolution spectroscopy revealed a very low
velocity variation (<500 m s<SUP>-1</SUP>) of the host star
<ASTROBJ>OGLE-TR-3</ASTROBJ> which may be caused by its unseen
companion. An analysis of the radial velocity and light curve results
in M<2.5 M<SUB>Jup</SUB>, R<1.6 R<SUB>Jup</SUB>, and an orbital
separation of about 5 R<SUB>sun</SUB>, which makes it the planet with
the shortest period known. This allows to identify the low-luminosity
companion of <ASTROBJ>OGLE-TR-3</ASTROBJ> as a possible new gas-giant
planet. If confirmed, this makes <ASTROBJ>OGLE-TR-3</ASTROBJ> together
with <ASTROBJ>OGLE-TR-56</ASTROBJ> the first extrasolar planets
detected via their transit light curves. <P />Based on observations
collected at the European Southern Observatory, Paranal, Chile (ESO
Programme 269.C-5034).
---------------------------------------------------------
Title: Simultaneous time-series spectroscopy and multi-band photometry
of the sdBV PG 1605+072
Authors: Falter, S.; Heber, U.; Dreizler, S.; Schuh, S. L.; Cordes,
O.; Edelmann, H.
2003A&A...401..289F Altcode: 2003astro.ph..1604F
We present time-series spectroscopy and multi-band photometry of the
sdBV PG 1605+072 carried out simultaneously at the Calar Alto 2.2-m
and 3.5-m telescopes. The periodogram analysis of the radial velocity
curves reveals three frequencies at 2.078, 2.756, and 1.985 mHz for
H<SUB>beta </SUB> and at 2.076, 2.753, and 1.978 mHz for H<SUB>gamma
</SUB>. The corresponding radial velocity amplitudes are 12.7, 8.0,
and 7.9 km s<SUP>-1</SUP> for H<SUB>beta </SUB> and 14.3, 6.5, and 7.2
km s<SUP>-1</SUP> for H<SUB>gamma </SUB>. Furthermore, we found five
frequencies that are present in all wavelength bands of the BUSCA
photometer. The frequencies detected in the radial velocity curves
are recovered by the photometric measurements. Moreover, additional
frequencies were present in the periodograms which could not be
identified in all four bands simultaneously. The comparison of the
amplitudes presented here with previous results from radial velocity
and photometric observations of PG 1605+072 shows a significant change
or even switch in the power of the modes within short time scales,
i.e. about one year. No changes in frequency were registered and
the phases of the modes show no wavelength dependency within our
multi-band photometry. <P />Based on observations obtained at the
German-Spanish Astronomical Center (DSAZ), Calar Alto, operated by
the Max-Planck-Institut für Astronomie Heidelberg jointly with the
Spanish National Commission for Astronomy.
---------------------------------------------------------
Title: The everchanging pulsating white dwarf GD358
Authors: Kepler, S. O.; Nather, R. E.; Winget, D. E.; Nitta,
A.; Kleinman, S. J.; Metcalfe, T.; Sekiguchi, K.; Jiang, Xiaojun;
Sullivan, D.; Sullivan, T.; Janulis, R.; Meistas, E.; Kalytis, R.;
Krzesinski, J.; Ogoza, W.; Zola, S.; O'Donoghue, D.; Romero-Colmenero,
E.; Martinez, P.; Dreizler, S.; Deetjen, J.; Nagel, T.; Schuh,
S. L.; Vauclair, G.; Ning, Fu Jian; Chevreton, M.; Solheim, J. -E.;
Gonzalez Perez, J. M.; Johannessen, F.; Kanaan, A.; Costa, J. E.;
Murillo Costa, A. F.; Wood, M. A.; Silvestri, N.; Ahrens, T. J.; Jones,
A. K.; Collins, A. E.; Boyer, M.; Shaw, J. S.; Mukadam, A.; Klumpe,
E. W.; Larrison, J.; Kawaler, S.; Riddle, R.; Ulla, A.; Bradley, P.
2003A&A...401..639K Altcode: 2003astro.ph..1477K
We report 323 hours of nearly uninterrupted time series photometric
observations of the DBV star GD 358 acquired with the Whole Earth
Telescope (WET) during May 23rd to June 8th, 2000. We acquired more
than 232,000 independent measurements. We also report on 48 hours of
time-series photometric observations in Aug 1996. We detected the
non-radial g-modes consistent with degree ℓ=1 and radial order 8
to 20 and their linear combinations up to 6th order. We also detect,
for the first time, a high amplitude ℓ=2 mode, with a period of 796
s. In the 2000 WET data, the largest amplitude modes are similar to
those detected with the WET observations of 1990 and 1994, but the
highest combination order previously detected was 4th order. At one
point during the 1996 observations, most of the pulsation energy
was transferred into the radial order k=8 mode, which displayed a
sinusoidal pulse shape in spite of the large amplitude. The multiplet
structure of the individual modes changes from year to year, and
during the 2000 observations only the k=9 mode displays clear normal
triplet structure. Even though the pulsation amplitudes change on
timescales of days and years, the eigenfrequencies remain essentially
the same, showing the stellar structure is not changing on any dynamical
timescale. <P />Tables \ref{j96} to \ref{journal2} and \ref{combination}
and Figs. \ref{gd358lc1}, \ref{dftchange}, \ref{an34dft}, \ref{pkh},
\ref{k16} and \ref{deltap8} are available only in the electronic form
at http://www.edpsciences.org
---------------------------------------------------------
Title: Spectral analysis of sdB stars from the Hamburg Quasar Survey
Authors: Edelmann, H.; Heber, U.; Hagen, H. -J.; Lemke, M.; Dreizler,
S.; Napiwotzki, R.; Engels, D.
2003A&A...400..939E Altcode: 2003astro.ph..1602E
We present the results of a spectral analysis of a large sample of
subdwarf B stars selected from follow-up observations of candidates
from the Hamburg Quasar Survey. Fundamental parameters (effective
temperature, gravity, and helium abundance) were determined by
matching synthetic line profiles calculated from model atmospheres
to all hydrogen and helium absorption lines present in the observed
optical spectra. The derived helium abundances are compared with the
atmospheric parameters to search for possible trends. We discovered a
correlation between the helium abundance and the effective temperature:
the larger the temperature, the larger the photospheric helium content
of sdB stars. Additionally, a separation into two sequences of sdB stars
in the effective temperature - helium abundance plane is detected. We
compared our analysis results with data from the literature. The
stars from our sample are found to be somewhat more luminous. This can
only partly be explained by NLTE effects. Three apparently normal B
stars were discovered, which could be massive stars far away from the
galactic plane (7-19 kpc). Radial velocities were measured for 23 stars
from which we discovered a new radial velocity variable sdB star. <P
/>Based on Observations collected at the German-Spanish Astronomical
Center (DSAZ), Calar Alto, operated by the Max-Planck-Institut für
Astronomie Heidelberg jointly with the Spanish National Commission
for Astronomy. <P />Table 4 is only available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or
via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/400/939
---------------------------------------------------------
Title: VizieR Online Data Catalog: Stellar parameters of 115 HQS
sdB stars (Edelmann+, 2003)
Authors: Edelmann, H.; Heber, U.; Hagen, H. -J.; Lemke, M.; Dreizler,
S.; Napiwotzki, R.; Engels, D.
2003yCat..34000939E Altcode:
We present the results of a spectral analysis of a large sample of
subdwarf B stars selected from follow-up observations of candidates
from the Hamburg Quasar Survey. Table 4 summarizes the results
(effective temperatures, gravities, and helium abundances) of our
analysis. Additionally, the equatorial and galactical coordinates,
the B magnitudes and extinctions, the derived radial velocities,
the absolute visual magnitudes, the distances from earth and from
the galactic plane, and the references are given for all programme
stars. <P />(3 data files).
---------------------------------------------------------
Title: FUSE Spectroscopy of the Two Prototype White Dwarfs With
Signatures of a Super-hot Wind
Authors: Werner, K.; Dreizler, S.; Kruk, J. W.; Sitko, M. L.
2003ASIB..105..171W Altcode: 2003whsw.conf..171W; 2002astro.ph..8506W; 2003whdw.conf..171W
The O VIII phenomenon describes the occurrence of ultra-high ionization
absorption lines of the CNO elements (e.g. O VIII, N VII, C VI, and
even Ne X) in the optical spectra hot of DO WDs.
---------------------------------------------------------
Title: Temperature Correction Schemes
Authors: Dreizler, S.
2003ASPC..288...69D Altcode: 2003sam..conf...69D
The pro and contra for using temperature correction are discussed
on the basis of our linearization scheme and our implementation of
an Unsöld-Lucy temperature correction. I will show the improvements
which partly overcome the typical weakness of the UL-scheme as well
as our generalization to non-LTE.
---------------------------------------------------------
Title: FUSE Observations of the Central Star of Abell 78
Authors: Werner, K.; Dreizler, S.; Koesterke, L.; Kruk, J. W.
2003IAUS..209..239W Altcode: 2002astro.ph..1280W
FUSE high resolution spectra of two PG1159 type central stars (K1-16
and NGC 7094) have revealed an unexpected iron deficiency of at least
1 or 2 dex (Miksa et al. 2002). Here we present early results of FUSE
spectroscopy of the CSPN Abell 78. It is shown that iron is strongly
deficient in this star, too.
---------------------------------------------------------
Title: TRIPP: An Aperture Photometry Package for the Reduction of
CCD Time Series Images
Authors: Schuh, S. L.; Dreizler, S.; Deetjen, J. L.; Göhler, E.
2003BaltA..12..167S Altcode: 2003OAst...12..167S
TRIPP is an aperture photometry program designed with the purpose of
extracting light curves from large sets of similar CCD frames typically
obtained during time-resolved photometric monitoring campaigns such
as, for example, WET runs. We describe its properties and usage
with an emphasis on where the functionality of TRIPP may differ from
similar programs, and try to outline both its strengths as well as
the non-trivial issues where difficulties may arise.
---------------------------------------------------------
Title: NLTE Spectral Analysis of Iron Group Elements in the Hot
Subluminous O-star BD+28° 4211
Authors: Ramspeck, M.; Haas, S.; Napiwotzki, R.; Heber, U.; Deetjen,
J.; Dreizler, S.
2003ASPC..288..161R Altcode: 2003sam..conf..161R
An analysis of UV spectra of BD+28<SUP>circ</SUP>4211 obtained with
the STIS spectrograph onboard the HST is presented. The spectral
analysis is based on NLTE model calculation, which deal with the
lineblanketing of iron group elements in great detail. Improved model
atoms for iron group elements were set up and new interband cross
sections were calculated. Comparison with observation allowed, Mn and
Cr lines to be identified for the first time. The abundances of Fe,
Ni, Cr and Mn are determined and point to the presence of diffusion
processes in the atmosphere of BD+28<SUP>circ</SUP>4211.
---------------------------------------------------------
Title: Analysis of FUSE and IUE spectra of the sdOB star EC11481-2303
Authors: Hammer, N. J.; Deetjen, J. L.; Dreizler, S.; Werner, K.;
Kruk, J. W.
2003ASIB..105..103H Altcode: 2003whdw.conf..103H; 2003whsw.conf..103H
No abstract at ADS
---------------------------------------------------------
Title: Towards asteroseismology of the non-radial pulsating sdB star
PG 1605+072
Authors: Falter, S.; Heber, U.; Dreizler, S.; Schuh, S. L.; Cordes, O.
2003ASIB..105...73F Altcode: 2003whdw.conf...73F; 2002astro.ph.12489F; 2003whsw.conf...73F
The recently discovered new class of sdB pulsators (sdBV) offers a
powerful possibility for the investigation of their interior and
thus their evolutionary history. The first step towards applying
asteroseismologic tools is the identification of pulsation modes. We
reoport on simultaneous spectroscopic and multi-band photometric time
series observations of PG 1605+072 and analyse its radial velocity
and light curve.
---------------------------------------------------------
Title: Vertical Structures and Spectra of Accretion Disks in
Symbiotic Stars
Authors: Nagel, T.; Dreizler, S.; Werner, K.
2003ASPC..303..482N Altcode: 2003ssps.conf..482N
No abstract at ADS
---------------------------------------------------------
Title: Stellar Atmosphere and Accretion Disk Models for the Hot
Component in Symbiotic Stars
Authors: Werner, K.; Deetjen, J. L.; Dreizler, S.; Nagel, T.; Rauch, T.
2003ASPC..303..303W Altcode: 2003ssps.conf..303W; 2002astro.ph..8199W
We describe our NLTE codes which allow the computation of synthetic
spectra of hot stars and accretion disks. They can be combined to
compute ionizing fluxes from the hot component in symbiotic stars.
---------------------------------------------------------
Title: Calculating Vertical Structures and Spectra of Accretion
Disks with the New Code AcDc
Authors: Nagel, T.; Dreizler, S.; Werner, K.
2003ASPC..288..641N Altcode: 2003sam..conf..641N
We present a new code to calculate the vertical structure of accretion
disks in cataclysmic variables. The disk is divided into concentric
rings, each ring is treated like an independent plane-parallel
radiating slab. We first calculate a gray LTE model and then a NLTE
model of the ring. Finally we integrate over all ring spectra to get the
spectrum of the full disk for a specific inclination angle. The system
of hydrostatic and radiative equilibrium, atomic level populations
and particle conservation is solved consistently with the radiative
transfer. <P />This allows to calculate detailed theoretical spectra
of accretion disks. Comparison with observations will allow to derive
radial temperature distribution, mass accretion rate, viscosity and
chemical composition. We also plan to compare our vertical structures
to those of hydrodynamic simulations in order to estimate the influence
of a detailed radiation transport on the stratification.
---------------------------------------------------------
Title: Transfer of Polarized Radiation - Practical Experience with
the Accelerated Lambda Iteration Method
Authors: Deetjen, J. L.; Dreizler, S.; Jordan, S.; Werner, K.
2003ASPC..288..617D Altcode: 2003sam..conf..617D
Neutron stars and some of the white dwarfs have magnetic fields. The
light emitted by these stars is polarized and can be characterized
by the four Stokes components I, Q, U, and V. Therefore the polarized
radiation transport equation differs significantly from the non-magnetic
case. It is a system of linear differential equations coupled in
I, Q, U, and V with depth dependent opacities and magneto-optical
parameters. The most potential method, the accelerated lambda iteration,
is presented in detail and practical experiences calculating neutron
star atmospheres are reported.
---------------------------------------------------------
Title: Modeling C/O/Ne Dominated Accretion in Ultracompact X-ray
Binaries
Authors: Werner, K.; Nagel, T.; Dreizler, S.; Rauch, T.
2003gcfe.confE..35W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Calculating spectra of accretion disks in AM CVn systems
Authors: Nagel, T.; Dreizler, S.; Werner, K.
2003ASIB..105..357N Altcode: 2003whdw.conf..357N; 2003whsw.conf..357N
No abstract at ADS
---------------------------------------------------------
Title: Discovery of A New Class of Pulsating Stars: Gravity-Mode
Pulsators among Subdwarf B Stars
Authors: Green, E. M.; Fontaine, G.; Reed, M. D.; Callerame, K.;
Seitenzahl, I. R.; White, B. A.; Hyde, E. A.; Østensen, R.; Cordes,
O.; Brassard, P.; Falter, S.; Jeffery, E. J.; Dreizler, S.; Schuh,
S. L.; Giovanni, M.; Edelmann, H.; Rigby, J.; Bronowska, A.
2003ApJ...583L..31G Altcode:
During the course of an ongoing CCD monitoring program to investigate
low-level light variations in subdwarf B (sdB) stars, we have
serendipitously discovered a new class of low-amplitude, multimode sdB
pulsators with periods of the order of an hour. These periods are more
than a factor of 10 longer than those of previously known multimode
sdB pulsators (EC 14026 stars), implying that they are due to gravity
modes rather than pressure modes. The longer period pulsators are found
only among cooler sdB stars, where they are surprisingly common. The
iron opacity instability that drives the short-period EC 14026 stars
is effective only in hot sdB stars, leaving the driving mechanism
for the deeper gravity modes in cool sdB stars currently unknown. We
present the first observational results for our newly identified sdB
variables and discuss possible implications.
---------------------------------------------------------
Title: FUSE Spectra of DO White Dwarfs
Authors: Dreizler, S.; Werner, K.; Kruk, J. W.
2003ASIB..105..135D Altcode: 2003whsw.conf..135D; 2003whdw.conf..135D
FUSE observations of DO white dwarfs allow to determine their
photospheric abundances of trace elements (e.g. C, N, O, H, Fe,
Ni,...). FUSE spectroscopy is ideal for this purpose since the FUV
allows to explore a large variety of line transitions of various
elements which are not detectable in existing optical or UV spectra of
the targets. We present our analysis with non-LTE metal line blanketed
model atmospheres. The results will be compared to our newly developed,
self-consistent diffusion/radiative levitation calculations under
non-LTE conditions. The observed metal abundances will serve as
bench-marks for such kind of new calculations.
---------------------------------------------------------
Title: Metal abundances in PG1159 stars from Chandra and FUSE
spectroscopy
Authors: Werner, K.; Deetjen, J. L.; Dreizler, S.; Rauch, T.; Barstow,
M. A.; Kruk, J. W.
2003ASIB..105..117W Altcode: 2002astro.ph..8505W; 2003whsw.conf..117W; 2003whdw.conf..117W
We investigate FUSE spectra of three PG1159 stars and do not find any
evidence for iron lines. From a comparison with NLTE models we conclude
a deficiency of 1--1.5 dex. We speculate that iron was transformed
into heavier elements. A soft X-ray Chandra spectrum of the unique H-
and He-deficient star H1504+65 is analyzed. We find high neon and
magnesium abundances and confirm that H1504+65 is the bare core of
either a C-O or a O-Ne-Mg white dwarf.
---------------------------------------------------------
Title: Improved results for equilibrium abundances from diffusion
calculations
Authors: Schuh, S. L.; Dreizler, S.; Deetjen, J. L.
2003ASIB..105..147S Altcode: 2003whsw.conf..147S; 2003whdw.conf..147S
No abstract at ADS
---------------------------------------------------------
Title: Computation of Element Diffusion in Non-LTE Stellar Atmosphere
Models
Authors: Schuh, S. L.; Dreizler, S.
2003ASPC..288..633S Altcode: 2003sam..conf..633S
No abstract at ADS
---------------------------------------------------------
Title: Temperature Scale and Iron Abundances of Very Hot Central
Stars of Planetary Nebulae (invited review)
Authors: Werner, K.; Deetjen, J. L.; Dreizler, S.; Rauch, T.; Kruk,
J. W.
2003IAUS..209..169W Altcode: 2002astro.ph..2012W
The determination of effective temperatures of very hot central stars
(Teff>70000K) by model atmosphere analyses of optical H and He
line profiles is afflicted with considerable uncertainty, primarily
due to the lack of neutral helium lines. Ionization balances of
metals, accessible only with UV lines, allow more precise temperature
estimates. The potential of iron lines is pointed out. At the same time
iron and other metal abundances, hardly investigated until today, may be
derived from UV spectra. We describe recent HST spectroscopy performed
for this purpose. A search for iron lines in FUV spectra of the hottest
H-deficient central stars (PG1159-type, Teff>100000K) taken with FUSE
was unsuccessful. The derived deficiency is interpreted in terms of
iron depletion due to n-capture nucleosynthesis in intershell matter,
which is now exposed at the stellar surface as a consequence of a late
He shell flash.
---------------------------------------------------------
Title: Modeling He-rich Disks in Am CVn Binaries
Authors: Nagel, T.; Dreizler, S.; Rauch, T.; Werner, K.
2003gcfe.confE..34N Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Preliminary results of the WET Xcov22 campaign at Calar
Alto Observatory
Authors: Schuh, S. L.; Nagel, T.; Deetjen, J. L.; Dreizler, S.;
Handler, G.; O'Brien, M. S.; Riddle, R.; Hürkal, Ö.; Pakstiene, E.;
Klumpe, E.; Lawrence, T.; Vuckovic, M.; Zola, S.; Kawaler, S.; Kanaan,
A.; Giovannini, O.; Kepler, S. O.; Mukadam, A.; Provencal, J.; Nitta,
A.; Shipman, H.; Mullally, F.; Grauer, A.; Wood, M. A.; Bradley, P. A.;
Kilic, M.; Sekiguchi, K.; Crowe, R.; Sullivan, D.; Rosen, R.; Clemens,
C.; Jiang, Xiaojun; Janulis, R.; O'Donoghue, D.; Ogloza, W.; Baran, A.;
Silvotti, R.; Marinoni, S.; Vauclair, G.; Dolez, N.; Chevreton, M.;
Gonzalez, J. M.; Solheim, J. -E.; Ulla, A.; Burleigh, M.; Good, S.;
Metcalfe, T.; da Costa, A. F. M.; Costa, J. E. S.; Kim, S. -L.; Lee,
H.; Sergeev, A.; Akan, C.; Cakirli, Ö.; Paparo, M.; Viraghalmy, G.
2003ASIB..105..263S Altcode: 2003whdw.conf..263S; 2003whsw.conf..263S
No abstract at ADS
---------------------------------------------------------
Title: WET Observations of GD 358 in 2000
Authors: Kepler, S. O.; Nather, E. R.; Winget, D. E.; Nitta, A.;
Kleinman, S. J.; Metcalfe, T.; Sekiguchi, K.; Jiang, Xiaojun;
Sullivan, D.; Sullivan, T.; Janulis, R.; Meištas, E. G.; Kalytis,
R.; Krzesiński, J.; Ogłoza, W.; Zola, S.; O'Donoghue, D.;
Romero-Colmenero, E.; Martinez, P.; Dreizler, S.; Deetjen, J.;
Nagel, T.; Schuh, S. L.; Vauclair, G.; Fu, J. N.; Chevreton, M.;
Solheim, J. -E.; Gonzalez Perez, J. M.; Johannessen, F.; Kanaan,
A.; Costa, J. E.; Murillo Costa, A. F.; Wood, M. A.; Silvestri, N.;
Ahrens, T. J.; Jones, A. Kyle; Collins, A. E.; Boyer, M.; Shaw, J. S.;
Mukadam, A. S.; Klumpe, E. W.; Larrison, J.; Kawaler, S. D.; Riddle,
R. L.; Ulla, A.; Bradley, P.
2003BaltA..12...45K Altcode: 2003OAst...12...45K
We report on the 323 hours of nearly uninterrupted time series
photometric observations of the DBV star GD 358 acquired with the Whole
Earth Telescope (WET) during May 23 to June 8, 2000. We acquired more
than 232000 independent measurements and detected the non-radial g-modes
consistent with degree l=1 and radial order 8 to 20 and their linear
combinations up to 6th order. We also detect, for the first time,
a high amplitude l=2 mode, with a period of 796 s. In the 2000 WET
data, the largest amplitude modes are similar to those detected with
the WET observations of 1990 and 1994, but the highest combination
order previously detected was 4th order.
---------------------------------------------------------
Title: Stratified NLTE Model Atmospheres for Hot Stars
Authors: Dreizler, S.; Schuh, S. L.
2003IAUS..210...33D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Photometric and Spectroscopic Monitoring of the sdBV star PG
1605+072: The Multi-Site Spectroscopic Telescope (MSST) Project
Authors: Heber, U.; Dreizler, S.; Schuh, S. L.; O'Toole, S.; Jeffery,
C. S.; Falter, S.; Woolf, V.; Ahmad, A.; Billeres, M.; Charpinet,
S.; Cordes, O. -M.; For, B. -Q.; Green, E.; Hyde, E. A.; Jacob, A.;
Kjeldsen, H.; Kleinman, S.; Krzesinski, J.; Lopes, I.; Marinoni, S.;
Mauch, T.; Nitta, A.; O'Donoghue, D.; Østensen, R.; Pollacco, D.;
Pereira, R.; Pereira, T.; Reed, M. D.; Silvotti, R.; Townsend, R.;
Vuckovic, M.; White, B. A.; Jiang, Xiaojun
2003ASIB..105..105H Altcode: 2003whdw.conf..105H; 2002astro.ph.12447H; 2003whsw.conf..105H
A small fraction of subluminous B stars show short-period, multiperiodic
light variations and form the new class of pulsating star known as EC
14026 variables, after the prototype. The Multi-Site Spectroscopic
Telescope (MSST) is a virtual instrument and is also the name of
a collaboration that aims to open up a new observational window to
provide access to a mode identification for and an asteroseismological
analysis of the pulsating sdB star PG 1605+072. Although the primary
aim is to obtain time resolved spectroscopy it also includes the most
extended photometric monitoring campaign for PG 1605+072.
---------------------------------------------------------
Title: PG 1605+072 in WET XCov22: Support for the Multi Site
Spectroscopic Telescope
Authors: Schuh, S. L.; Heber, U.; Dreizler, S.; O'Toole, S.; Jeffery,
C. S.; Falter, S.; Woolf, V. M.; Riddle, R. L.; Handler, G.; Hürkal,
Ö.; Pakštiene, E.; Klumpe, E. W.; Laurance, T.; Vuckovic, M.;
Zoa, S.; Kawaler, S. D.; Kanaan, A.; Monteiro, H.; Giovannini, O.;
Kepler, S. O.; Mukadam, A.; Provencal, J. L.; Nitta, A.; Shipman, H.;
Mullally, F.; Grauer, A.; Wood, M. A.; Bradley, P. A.; Kilic, M.;
Sekiguchi, K.; Crowe, R.; Sullivan, D. J.; Rosen, R.; Clemens, C.;
Jiang, Xiaojun; Janulis, R.; O'Donoghue, D.; Ogloza, W.; Baran, A.;
Silvotti, R.; Marinoni, S.; Vauclair, G.; Dolez, N.; Chevreton, M.;
Deetjen, J. L.; Nagel, T.; González Pérez, J. M.; Solheim, J. -E.;
Østensen, R.; Ulla, A.; Burleigh, M.; Good, S.; Metcalfe, T. S.; da
Costa, A. F. M.; Costa, J. E. S.; O'Brien, M. S.; Kim, S. -L.; Lee,
H.; Sergeev, A.; Akan, C.; Cakirli, Ö.; Paparo, M.; Viraghalmy, G.
2003BaltA..12...55S Altcode: 2003OAst...12...55S
The Multi-site Spectroscopic Telescope is a virtual instrument and
the name of a collaboration that opens up a new observational window
by combining continuous observations of spectroscopic variations and
simultaneous photometric monitoring. This constitutes an enormous
observational effort, but in return promises to finally provide access
to a mode identification for and an asteroseismological analysis
of the pulsating sdB star PG 1605+072. Multi-Site Spectroscopic
Telescope observations for this object have been secured during a
large coordinated campaign in May and June of the year 2002. The
frequency resolution and coverage of the photometric time series has
been noticeably enhanced by a significant contribution from the Whole
Earth Telescope, which was used to observe PG 1605+072 as an alternate
target during the WET XCov22 campaign, also conducted in May 2002. This
paper briefly outlines the motivation for the MSST project and tries
to give a first assessment of the overall quality of the data obtained,
with a focus on the Whole Earth Telescope observations.
---------------------------------------------------------
Title: WET Observations of PG 1159--035
Authors: Costa, J. E. S.; Kepler, S. O.; Winget, D. E.; O'Brien,
M. S.; Bond, H. E.; Kawaler, S. D.; Dreizler, S.
2003BaltA..12...23C Altcode: 2003OAst...12...23C
PG 1159-035 has been observed with the Whole Earth Telescope on XCov3,
9, 19 and 22. In this work we present a brief summary of the campaigns.
---------------------------------------------------------
Title: Model Photospheres with Accelerated Lambda Iteration
Authors: Werner, K.; Deetjen, J. L.; Dreizler, S.; Nagel, T.; Rauch,
T.; Schuh, S. L.
2003ASPC..288...31W Altcode: 2002astro.ph..9535W; 2003sam..conf...31W
We review the computational procedure to construct classical
line-blanketed NLTE model atmospheres with the ALI method. In detail
we discuss: Approximate Lambda Operators, fast solution techniques
for non-linear rate equations, pre-conditioning of rate equations,
super-level approach for heavy metal line-blanketing. Most recent
successes and failures in applications are shortly presented.
---------------------------------------------------------
Title: The Rotational Velocity of Helium-rich Pre-White Dwarfs
Authors: Rauch, T.; Koeper, S.; Dreizler, S.; Werner, K.; Heber, U.;
Reid, I. N.
2002astro.ph.12163R Altcode:
Previous investigations on hydrogen-rich white dwarfs generally
yield only very small rotational velocities (v_rot sin i). We have
analyzed line profiles in high-resolution optical spectra of eight
hydrogen-deficient (pre-) white dwarfs and find deviations from the
dominant Stark line broadening in five cases which, interpreted as an
effect of stellar rotation, indicate projected rotational velocities of
40 - 70 km/sec. For the three least luminous stars upper limits of v_rot
sin i = 15 - 25 km/sec could be derived only. The resulting velocities
correlate with luminosity and mass. However, since the mass-loss rate is
correlated to the luminosity of a star, the observed line profiles may
be affected by a stellar wind as well. In the case of RX J2117.1+3412,
this would solve discrepancies to results of pulsational modeling
(v_rot sin i ~ 0).
---------------------------------------------------------
Title: Spectroscopic analyses of the “blue hook” stars in omega
Centauri: A test of the late hot flasher scenario
Authors: Moehler, S.; Sweigart, A. V.; Landsman, W. B.; Dreizler, S.
2002A&A...395...37M Altcode: 2002astro.ph..9028M
omega Cen contains the largest population of very hot horizontal
branch (HB) stars known in a globular cluster. Recent UV observations
(Whitney et al. \cite{whro98}; D'Cruz et al. \cite{dcoc00}) show a
significant population of hot stars below the zero-age horizontal branch
(“blue hook” stars), which cannot be explained by canonical stellar
evolution. Stars which suffer unusually large mass loss on the red giant
branch and thus experience the helium core flash while descending the
white dwarf cooling curve could populate this region. Theory predicts
that these “late hot flashers” should show higher temperatures than
the hottest canonical HB stars and should have helium- and carbon-rich
atmospheres. We obtained and analysed medium resolution spectra of a
sample of blue hook stars to derive their atmospheric parameters. The
blue hook stars are indeed both hotter (T<SUB>eff</SUB> >=35 000
K) and more helium-rich than classical extreme HB stars. In addition
we find indications for a large enhancement of the carbon abundance
relative to the cluster abundance.
---------------------------------------------------------
Title: Spectral types of planetary host star candidates: Two new
transiting planets?
Authors: Dreizler, S.; Rauch, T.; Hauschildt, P.; Schuh, S. L.; Kley,
W.; Werner, K.
2002A&A...391L..17D Altcode: 2002astro.ph..7192D
Recently, 46 low-luminosity object transits were reported from
the Optical Gravitational Lensing Experiment. Our follow-up
spectroscopy of the 16 most promising candidates provides a spectral
classification of the primary. Together with the radius ratio from
the transit measurements, we derived the radii of the low-luminosity
companions. This allows to examine the possible sub-stellar nature
of these objects. Fourteen of them can be clearly identified as
low-mass stars. Two objects, <ASTROBJ>OGLE-TR-03</ASTROBJ> and
<ASTROBJ>OGLE-TR-10</ASTROBJ> have companions with radii of 0.15
R_sun which is very similar to the radius of the transiting planet HD
209458 B. The planetary nature of these two objects should therefore
be confirmed by dynamical mass determinations.
---------------------------------------------------------
Title: The temporal spectrum of the sdB pulsating star HS 2201+2610
at 2 ms resolution
Authors: Silvotti, R.; Janulis, R.; Schuh, S. L.; Charpinet, S.;
Oswalt, T.; Silvestri, N.; Gonzalez Perez, J. M.; Kalytis, R.;
Meištas, E.; Ališauskas, D.; Marinoni, S.; Jiang, X. J.; Reed, M. D.;
Riddle, R. L.; Bernabei, S.; Heber, U.; Bärnbantner, O.; Cordes, O.;
Dreizler, S.; Goehler, E.; Østensen, R.; Bochanski, J.; Carlson, G.
2002A&A...389..180S Altcode:
In this article we present the results of more than 180 hours of
time-series photometry on the low gravity (log g=5.4, T<SUB>eff</SUB>=29
300 K, log He/H=-3.0 by number) sdB pulsating star HS 2201+2610,
obtained between September 2000 and August 2001. The temporal
spectrum is resolved and shows 5 close frequencies: three main
signals at 2860.94, 2824.10 and 2880.69 mu Hz, with amplitudes of
about 1%, 0.5% and 0.1% respectively, are detected from single run
observations; two further peaks with very low amplitude (<0.07%) at
2738.01 and 2921.82 mu Hz are confirmed by phase analysis on several
independent runs. Due to the small number of detected frequencies,
it is not possible to obtain a univocal identification of the excited
modes and perform a detailed seismological analysis of the star. No
clear signatures of rotational splitting are seen. Nevertheless,
the observed period spectrum is well inside the excited period window
obtained from pulsation calculations with nonadiabatic models having
effective temperature and surface gravity close to the spectroscopic
estimates. Due to its relatively simple temporal spectrum, HS 2201+2610
is a very good candidate for trying to measure the secular variation of
the pulsation periods in time. With this purpose a long-term monitoring
of the star was started. The results of the first 11 months show
amplitude variations up to ~ 20% on time-scales of months, which are
probably real, and allow us to measure the pulsation frequencies with
an unprecedented 0.02 mu Hz resolution. Based on observations obtained
at the following telescopes: Loiano 1.5 m (Bologna Astronomical
Observatory), Moletai 1.65 m (Institute of Theoretical Physics
and Astronomy, Vilnius), Calar Alto 2.2 and 1.2 m (German-Spanish
Astronomical Center operated by the Max-Plank-Institute für Astronomie
Heidelberg jointly with the Spanish National Commission for Astronomy),
SARA 0.9 m (Southeastern Association for Research in Astronomy, at Kitt
Peak, Arizona), Tenerife 0.8 m (Instituto de Astrofisica de Canarias),
NOT 2.6 m (operated on the island of La Palma jointly by Denmark,
Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del
Roque de los Muchachos of the Instituto de Astrofisica de Canarias),
Beijing 0.85 m (Beijing Astronomical Observatory), Fick 0.6 m (Iowa
State University), Wendelstein 0.8 m (University of Munich).
---------------------------------------------------------
Title: Iron abundance in hot hydrogen-deficient central stars and
white dwarfs from FUSE, HST, and IUE spectroscopy
Authors: Miksa, S.; Deetjen, J. L.; Dreizler, S.; Kruk, J. W.; Rauch,
T.; Werner, K.
2002A&A...389..953M Altcode: 2002astro.ph..5058M
We present a first systematic investigation of the iron abundance
in very hot (T<SUB>eff</SUB> >= 50 000 K) hydrogen-deficient
post-AGB stars. Our sample comprises 16 PG 1159 stars and four DO white
dwarfs. We use recent FUSE observations as well as HST and IUE archival
data to perform spectral analyses with line blanketed NLTE model
atmospheres. Iron is not detected in any PG 1159 star. In most cases
this is compatible with a solar iron abundance due to limited quality of
HST and IUE data, although the tendency to an iron underabundance may be
recognized. However, the absence of iron lines in excellent FUSE spectra
suggests an underabundance by at least 1 dex in two objects (K 1-16,
NGC 7094). A similar result has been reported recently in the [WC]-PG
1159 transition object Abell 78 (Werner et al. \cite{Werner2002}). We
discuss dust fractionation and s-process neutron-captures as possible
origins. We also announce the first identification of sulfur in PG
1159 stars. Based on observations obtained with the Far Ultraviolet
Spectroscopic Explorer (FUSE), the Hubble Space Telescope (HST),
and the International Ultraviolet Explorer (IUE).
---------------------------------------------------------
Title: Is RX J1856.5-3754 a Quark Star?
Authors: Drake, Jeremy J.; Marshall, Herman L.; Dreizler, Stefan;
Freeman, Peter E.; Fruscione, Antonella; Juda, Michael; Kashyap,
Vinay; Nicastro, Fabrizio; Pease, Deron O.; Wargelin, Bradford J.;
Werner, Klaus
2002ApJ...572..996D Altcode: 2002astro.ph..4159D
Deep Chandra Low Energy Transmission Grating and High Resolution Camera
spectroscopic observations of the isolated neutron star candidate RX
J1856.5-3754 have been analyzed to search for metallic and resonance
cyclotron spectral features and for pulsation behavior. As found
from earlier observations, the X-ray spectrum is well represented
by an ~60 eV (7×10<SUP>5</SUP> K) blackbody. No unequivocal
evidence of spectral line or edge features has been found, arguing
against metal-dominated models. The data contain no evidence for
pulsation, and we place a 99% confidence upper limit of 2.7% on
the unaccelerated pulse fraction over a wide frequency range from
10<SUP>-4</SUP> to 100 Hz. We argue that the derived interstellar
medium neutral hydrogen column density of 8×10<SUP>19</SUP>cm<SUP>-
2</SUP><=N<SUB>H</SUB><=1.1×10<SUP>20</SUP> cm<SUP>-2</SUP>
favors the larger distance from two recent Hubble Space Telescope
parallax analyses, placing RX J1856.5-3754 at ~140 pc instead of ~60
pc and in the outskirts of the R CrA dark molecular cloud. That such
a comparatively rare region of high interstellar matter (ISM) density
is precisely where an isolated neutron star reheated by accretion
of ISM would be expected is either entirely coincidental or current
theoretical arguments excluding this scenario for RX J1856.5-3754
are premature. Taken at face value, the combined observational
evidence-a lack of spectral and temporal features and an implied
radius of R<SUB>∞</SUB>=3.8-8.2 km that is too small for current
neutron star models-points to a more compact object, such as allowed
for quark matter equations of state.
---------------------------------------------------------
Title: HS0702+6043 - A new large amplitude sdB variable at the cool
end of the instability region
Authors: Dreizler, S.; Schuh, S. L.; Deetjen, J. L.; Edelmann, H.;
Heber, U.
2002A&A...386..249D Altcode:
We report on time series photometry of hot sdB stars from the
Hamburg Schmidt survey carried out at the Calar Alto 1.23 m and
2.2 m telescopes. Among 14 spectroscopically selected candidates we
detected oscillations in the sdB star <ASTROBJ>HS0702+6043</ASTROBJ>
with a period of 363 s and an amplitude of 29 mmag which is among
the largest amplitude observed in sdBV stars. A second period of
382 s with a significantly smaller amplitude (3.8 mmag) might be
present. Our NLTE model atmosphere analysis of the time-averaged
optical spectra, obtained at the Calar Alto 3.5 m telescope, indicates
that <ASTROBJ>HS0702+6043</ASTROBJ> has T<SUB>eff</SUB>=28 400 K and
log g=5.35. This places the star at the cool end of the theoretical
sdBV instability strip (EC 14026 stars). Among the other thirteen
sdB stars we confirmed the variablity of the previously discovered
sdBV <ASTROBJ>HS0815+4243</ASTROBJ> and identified twelve stars to be
stable, for which we give upper limits for light variations. Based on
observations collected at the German-Spanish Astronomical Center, Calar
Alto, operated by the Max-Planck-Institut für Astronomie Heidelberg
jointly with the Spanish National Commission for Astronomy.
---------------------------------------------------------
Title: Analysis of the FUSE spectrum of the sdOB EC 11481-2303.
Authors: Hammer, N.; Deetjen, J. L.; Dreizler, S.; Werner, K.; Kruk,
J. W.
2002AGAb...19R..96H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: PG 1325+101 and PG 2303+019: Two new large amplitude subdwarf
B pulsators
Authors: Silvotti, R.; Østensen, R.; Heber, U.; Solheim, J. -E.;
Dreizler, S.; Altmann, M.
2002A&A...383..239S Altcode:
We report the detection of short period oscillations in the sdB stars
PG 1325+101 (B=13.8) and PG 2303+019 (alias HS 2303+0152, B=16.0) from
time-series photometry made at the Nordic Optical Telescope of a sample
of 21 candidates. Both stars are multi-mode pulsators with at least
three distinct periods in the range 100-140 s, and relatively large
amplitudes up to 2.6 and 1.6% respectively. Moreover PG 1325+101 shows
the shortest pulsation period ever registered among sdBV stars, 68.9 s,
which corresponds to the first harmonic of the main signal. Following
previous temperature and gravity determinations for PG 1325+101
(T<SUB>eff</SUB> = 34 500 K, log g=6.1) and our NLTE model atmosphere
analysis for PG 2303+019 (T<SUB>eff</SUB> = 35 200 K, log g=5.7), both
stars are well inside the theoretical sdBV instability strip. Based
on observations obtained at the Nordic Optical Telescope, operated on
the island of La Palma jointly by Denmark, Finland, Iceland, Norway,
and Sweden, in the Spanish Observatorio del Roque de los Muchachos of
the Instituto de Astrofisica de Canarias; and at the German-Spanish
Astronomical Center, Calar Alto, operated by the Max-Plank-Institute
für Astronomie Heidelberg jointly with the Spanish National Commission
for Astronomy.
---------------------------------------------------------
Title: Extremely Faint Blue-tail Stars in ω Centauri
Authors: Moehler, S.; Napiwotzki, R.; Sweigart, A. V.; Landsman,
W. B.; Dreizler, S.
2002ASPC..265..247M Altcode: 2002ocuw.conf..247M
No abstract at ADS
---------------------------------------------------------
Title: AcDc -- A new code to calculate vertical structures and
spectra of accretion disks
Authors: Nagel, T.; Dreizler, S.; Werner, K.
2002ASPC..261..509N Altcode: 2002pcvr.conf..509N
We are developing a new program which computes vertical structures
and emergent spectra of accretion disks in CVs and AGN. It solves the
radiation transfer equation together with the NLTE rate equations for
atomic level populations using an ALI (Accelerated Lambda Iteration)
scheme. First results are presented.
---------------------------------------------------------
Title: Spectral types of planetary host star candidates: new
transiting planets ?
Authors: Dreizler, S.; Rauch, T.; Hauschildt, P.; Schuh, S. L.; Kley,
W.; Werner, K.
2002AGAb...19R...6D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: To be or not to be a late hot flasher.
Authors: Moehler, S.; Sweigart, A. V.; Landsman, W. B.; Dreizler, S.
2002AGAb...19Q.104M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Equilibrium abundances in hot DA white dwarfs as derived
from self-consistent diffusion models. I. Analysis of spectroscopic
EUVE data
Authors: Schuh, S. L.; Dreizler, S.; Wolff, B.
2002A&A...382..164S Altcode: 2001astro.ph.11245S
We present the first analysis of an EUV selected sample of hot DA
white dwarfs using a new type of atmospheric models. These models
take into account the interplay between gravitational settling and
radiative acceleration to predict the chemical stratification from
an equilibrium between the two forces while self-consistently solving
for the atmospheric structure. In contrast to atmospheric models with
the assumption of chemical homogeneity, the number of free parameters
in the new models is reduced to the effective temperature and surface
gravity alone. The overall good reproduction of observed EUV spectra
reveals that these models are able to describe the physical conditions
in hot DA white dwarf atmospheres correctly. A comparison with previous
analyses highlights the improvements as well as the limits of our new
models. Based on observations made with the EUVE Satellite.
---------------------------------------------------------
Title: The Origin of Hot Subluminous Horizontal-Branch Stars in ω
Cen and NGC 2808
Authors: Sweigart, A. V.; Brown, T. M.; Moehler, S.; Lanz, T.;
Landsman, W. B.; Hubeny, I.; Dreizler, S.; Napiwotzki, R.
2001AAS...19913704S Altcode: 2001BAAS...33.1512S
Ultraviolet (UV) observations of the globular clusters ω Cen and NGC
2808 have revealed an unexpected population of hot subluminous stars
lying up to 0.7 mag below the extreme horizontal branch (EHB) in the
UV, which are not explained by canonical stellar models. In order to
explore the evolutionary status of these stars, we have evolved a set
of low-mass stars from the main sequence through the helium flash to
the horizontal branch (HB) for a wide range in the mass loss along the
red-giant branch (RGB). Stars with the largest mass loss evolve off
the RGB to high effective temperatures before igniting helium in their
cores. Our results indicate that the subluminous stars can be explained
if these stars undergo a late helium flash while descending the white
dwarf cooling curve. Under these conditions the convection zone produced
by the helium flash will penetrate into the stellar envelope, thereby
mixing the envelope hydrogen into the hot helium-burning interior, where
it is rapidly consumed. Such “flash-mixed” stars will have helium-
and carbon-rich envelopes and will lie at higher effective temperatures
than the hottest canonical (i.e., unmixed) EHB stars. Using new stellar
atmospheres, we show that these changes in the envelope abundances
will suppress the UV flux in the spectra of the flash-mixed stars by
the amount needed to explain the hot subluminous stars in ω Cen and
NGC 2808. To test this evolutionary scenario, we have obtained medium
resolution spectra of a sample of the hottest HB stars in ω Cen. We
find that these stars are indeed helium-rich compared to classical
EHB stars and also considerably hotter than the hottest EHB models
without flash mixing.
---------------------------------------------------------
Title: Introduction to Volume 322 (5/6) Proceedings of the
Joint-Discussion #1 and the Mini-Symposia #9 and #10 at the Joint
European and National Astronomical Meeting (JENAM) for 2001
Authors: Strassmeier, K. G.; Staude, J.; Dreizler, S.
2001AN....322..271S Altcode:
This volume of AN contains the proceedings of the Joint Discussion
#1 (JD-1) “Astronomy with Robotic Telescopes: Present and Future
Projects” and of the Mini Symposia #9 (MS-9) “Hot subdwarfs,
white dwarfs, and low-mass star evolution”, and #10 (MS-10) “Large
Telescopes for Solar Physics”. The meetings were held as part of the
JENAM 2001 conference “Five Days of Creation. Astronomy with Large
Telescopes from Ground and Space” in Munich, Germany, from September
10 through 15, 2001.
---------------------------------------------------------
Title: Four new subdwarf B pulsators
Authors: Østensen, R.; Heber, U.; Silvotti, R.; Solheim, J. -E.;
Dreizler, S.; Edelmann, H.
2001A&A...378..466O Altcode:
We report the detection of short period oscillations in the sdB stars HS
0039+4302, HS 0444+0408, HS 1824+5745 and HS 2151+0857 from time-series
photometry made at the Nordic Optical Telescope (NOT) of a sample of
55 candidates. Hence these four hot subdwarfs are new members of the
EC 14026 class of pulsating sdB stars. HS 0039+4302 is a multi-mode
pulsator with at least four distinct periods in the range between 182
and 234 s, and amplitudes up to 8 mma. HS 0444+0408 shows one dominant
pulsation at 137 s (A ~ 12 mma) and a second weaker pulsation at 170 s
(A ~ 3 mma). For HS 1824+5745 we find a single period of 139 s with
an amplitude of about 5 mma. HS 2151+0857 shows four periods in the
range 129-151 s with amplitudes between 2 and 5 mma. Our NLTE model
atmosphere analysis of the time-averaged optical spectra place all
stars well within the theoretical sdBV instability strip. Based on
observations obtained at the Nordic Optical Telescope, operated on
the island of La Palma jointly by Denmark, Finland, Iceland, Norway,
and Sweden, in the Spanish Observatorio del Roque de los Muchachos of
the Instituto de Astrofisica de Canarias. }\fnmsep\thanks{ Based on
observations collected at the German-Spanish Astronomical Center, Calar
Alto, operated by the Max-Plank-Institute für Astronomie Heidelberg
jointly with the Spanish National Commission for Astronomy. Based on
observations collected at the European Southern Observatory, Chile
(ESO No. 66.D-0031).
---------------------------------------------------------
Title: The extraordinarily bright optical afterglow of GRB 991208
and its host galaxy
Authors: Castro-Tirado, A. J.; Sokolov, V. V.; Gorosabel, J.;
Castro Cerón, J. M.; Greiner, J.; Wijers, R. A. M. J.; Jensen,
B. L.; Hjorth, J.; Toft, S.; Pedersen, H.; Palazzi, E.; Pian, E.;
Masetti, N.; Sagar, R.; Mohan, V.; Pandey, A. K.; Pandey, S. B.;
Dodonov, S. N.; Fatkhullin, T. A.; Afanasiev, V. L.; Komarova, V. N.;
Moiseev, A. V.; Hudec, R.; Simon, V.; Vreeswijk, P.; Rol, E.; Klose,
S.; Stecklum, B.; Zapatero-Osorio, M. R.; Caon, N.; Blake, C.; Wall,
J.; Heinlein, D.; Henden, A.; Benetti, S.; Magazzù, A.; Ghinassi,
F.; Tommasi, L.; Bremer, M.; Kouveliotou, C.; Guziy, S.; Shlyapnikov,
A.; Hopp, U.; Feulner, G.; Dreizler, S.; Hartmann, D.; Boehnhardt,
H.; Paredes, J. M.; Martí, J.; Xanthopoulos, E.; Kristen, H. E.;
Smoker, J.; Hurley, K.
2001A&A...370..398C Altcode: 2001astro.ph..2177C
Broad-band optical observations of the extraordinarily bright optical
afterglow of the intense gamma-ray burst GRB 991208 started ~2.1 days
after the event and continued until 4 Apr. 2000. The flux decay constant
of the optical afterglow in the R-band is -2.30 +/- 0.07 up to ~5 days,
which is very likely due to the jet effect, and it is followed by a
much steeper decay with constant -3.2 +/- 0.2, the fastest one ever
seen in a GRB optical afterglow. A negative detection in several
all-sky films taken simultaneously with the event, that otherwise
would have reached naked eye brightness, implies either a previous
additional break prior to ~2 days after the occurrence of the GRB
(as expected from the jet effect) or a maximum, as observed in GRB
970508. The existence of a second break might indicate a steepening in
the electron spectrum or the superposition of two events, resembling
GRB 000301C. Once the afterglow emission vanished, contribution of a
bright underlying supernova was found on the basis of the late-time
R-band measurements, but the light curve is not sufficiently well
sampled to rule out a dust echo explanation. Our redshift determination
of z = 0.706 indicates that GRB 991208 is at 3.7 Gpc (for Ho = 60 km
s<SUP>-1</SUP> Mpc<SUP>-1</SUP>, OMEGAo = 1 and LAMDAo = 0), implying
an isotropic energy release of 1.15 x 10<SUP>53</SUP> erg which may be
relaxed by beaming by a factor >10<SUP>2</SUP>. Precise astrometry
indicates that the GRB coincides within 0.2" with the host galaxy,
thus supporting a massive star origin. The absolute magnitude of the
galaxy is MB = -18.2, well below the knee of the galaxy luminosity
function and we derive a star-forming rate of (11.5 +/- 7.1) Msun
yr<SUP>-1</SUP>, which is much larger than the present-day rate in our
Galaxy. The quasi-simultaneous broad-band photometric spectral energy
distribution of the afterglow was determined ~3.5 day after the burst
(Dec. 12.0) implying a cooling frequency nuc below the optical band,
i.e. supporting a jet model with p = -2.30 as the index of the power-law
electron distribution.
---------------------------------------------------------
Title: Detection of pulsations in three subdwarf B stars
Authors: Østensen, R.; Solheim, J. -E.; Heber, U.; Silvotti, R.;
Dreizler, S.; Edelmann, H.
2001A&A...368..175O Altcode:
We report the detection of short period oscillations in the sdB stars
<ASTROBJ>HS 0815+4243</ASTROBJ>, <ASTROBJ>HS 2149+0847</ASTROBJ> and
<ASTROBJ>HS 2201+2610</ASTROBJ> from time-series photometry made at the
Nordic Optical Telescope (NOT) from a sample of 31 candidates. Hence
these three hot subdwarfs are new members of the EC 14026 class of
pulsating sdB stars. One short period is detected for <ASTROBJ>HS
0815+4243</ASTROBJ> (P ~ 126 s; A ~ 7 mma) and two short periods
are seen for <ASTROBJ>HS 2149+0847</ASTROBJ> (P ~ 142, 159 s; A ~
11, 7 mma), whereas the single oscillation detected for <ASTROBJ>HS
2201+2610</ASTROBJ> has a considerably longer period (P ~ 350 s; A ~
11 mma). Our NLTE model atmosphere analysis of the time-averaged
optical spectra indicate that <ASTROBJ>HS 0815+4243</ASTROBJ>
has T<SUB>eff</SUB> = 33 700 K and log g=5.95, <ASTROBJ>HS
2149+0847</ASTROBJ> has T<SUB>eff</SUB> = 35 600 K and log g = 5.9,
and <ASTROBJ>HS 2201+2610</ASTROBJ> has T<SUB>eff</SUB> = 29 300 K and
log g= 5.4. This places the former two at the hot end and the latter
at the cool end of the theoretical sdBV instability strip. Based on
observations obtained at the Nordic Optical Telescope, operated on the
island of La Palma jointly by Denmark, Finland, Iceland, Norway, and
Sweden, in the Spanish Observatorio del Roque de los Muchachos of the
Instituto de Astrofisica de Canarias. Based on observations collected
at the German-Spanish Astronomical Center, Calar Alto, operated by
the Max-Plank-Institute für Astronomie Heidelberg jointly with the
Spanish National Commission for Astronomy.
---------------------------------------------------------
Title: Photometric and Spectroscopic Modelling of Non-radial
Oscillations in the sdB Star PG1605+072
Authors: Falter, S.; Heber, U.; Dreizler, S.; Cordes, O.
2001AGM....18.P101F Altcode: 2001AGAb...18R.185F
We present the results of photometric and spectroscopic modelling of
nonradial oscillations in subluminous B stars. Time-resolved synthetic
spectra for a rotating star showing multi-mode non-radial pulsation are
calculated. We use the program package BRUCE developed by R. Townsend
(UCL, London) to compute the structure of the rotating and pulsating
envelope. A code to construct the rotationally distorted synthetic
spectra from these models has been developed by us. The equilibrium grid
is distorted by one or more pulsation modes including temperature,
velocity and geometric perturbations. We are able to model line
profile variations in these stars as well as the photometric changes
in different photometric filters. To test our modelling we have chosen
the pulsating sdB stars: PG1605+072. which shows a great variety of
pulsation modes (> 50). Furthermore it has the longest periods (main
mode at P = 480 s) and the largest radial velocity amplitudes (up to 14
km/s). Simultaneous photometric and spectroscopic observations of this
object recently obtained at Calar Alto Observatory are also presented.
---------------------------------------------------------
Title: PG 1605+072: First Application of BUSCA
Authors: Cordes, O.; Reif, K.; Dreizler, S.; Heber, U.; Schuh, S.
2001AGM....18..P53C Altcode: 2001AGAb...18R.161C
BUSCA (“Bonn University Simultaneous CAmera”) has now reached its
final state. The instrument is now fully equipped with four 4 k×4 k 15
μm CCDs, one backside thinned device for the UV channel and 3 frontside
devices for the other channels. After four successful observing runs
at Calar Alto Observatory in 2000 and 2001 BUSCA will be a standard
instrument at the 2.2m telescope beginning with the first semester
2002. During the commissioning procedures we were able to demonstrate
the good optical quality of the system as well as the colour index
stability during non photometric conditions. We found out that BUSCA
reaches a stability of a factor of 100 better than the brightness
fluctuations caused by clouds. As one of the first applications of BUSCA
we observed the rapid variable star PG1605 +072. Belonging to the class
of pulsating sdB (EC 14026) stars PG1605+072 has a dominant period
of 480s which we are able to measure in the four primary BUSCA bands
(UV, blue, green-yellow, near-infrared). Our relativ photometric data
from this first simultaneous four colour observation are of excellent
quality although the atmospheric conditions were highly variable. We
expect to get new hints about the origin of the pulsating mechanisms
from analysing the colour index light curves.
---------------------------------------------------------
Title: Stratified Non-LTE Model Atmospheres for Hot Hydrogen Rich
White Dwarfs
Authors: Schuh, Sonja L.; Dreizler, Stefan; Wolff, Burkhard
2001AGM....18S0916S Altcode:
We present our recent work towards stratified non-LTE model atmospheres
and applications thereof. The chemical stratification in our stellar
atmosphere models is determined from the equilibrium between gravity
and radiative levitation. The chemical composition is therefore
no longer a free parameter but is determined from the fundamental
atmospheric parameters, effective temperature and surface gravity,
alone. Spectroscopic EUV data of hot DA white dwarfs are used as
an observational basis to test the predictions of these chemically
stratified, self-consistently constructed models. New values for the
fundamental parameters are being derived for the sample stars and
successfully interpreted within the framework of diffusion theory. For
the first time, equilibrium abundance calculations are found to be in
good agreement with observations for a large sample.
---------------------------------------------------------
Title: AcDc - A new Code to Calculate the Vertical Structure of
Accretion Disks
Authors: Nagel, T.; Werner, K.; Dreizler, S.
2001AGM....18..P47N Altcode:
We present a new code to calculate the vertical structure of accretion
disks in cataclysmic variables. The disk is divided into concentric
rings, each ring is treated like an independent plane-parallel
radiating slab. We first calculate a gray LTE model and then a NLTE
model of the ring. Finally we integrate over all ring spectra to get
the spectrum of the full disk. The system of hydrostatic and radiative
equilibrium, atomic level populations and particle conservation
is solved consistently with the radiative transfer. This allows to
calculate detailed theoretical spectra of accretion disks. Comparison
with observations will allow to derive radial temperature distribution,
mass accretion rate, viscosity and chemical composition. We also plan
to compare our vertical structures to those of hydrodynamic simulations
in order to estimate the influence of a detailed radiation transport
on the stratification.
---------------------------------------------------------
Title: High resolution Keck and NTT spectra of PG 1159 stars
Authors: Köper, S.; Rauch, T.; Dreizler, S.; Heber, U.; Reid, I. N.;
Werner, K.
2001ASPC..226...65K Altcode: 2001ewwd.work...65K
No abstract at ADS
---------------------------------------------------------
Title: FUSE observations of the PG 1159-type Central Star K 1-16
Authors: Miksa, S.; Deetjen, J. L.; Dreizler, S.; Herwig, F.; Kruk,
J. W.; Rauch, T.; Werner, K.
2001ASPC..226...60M Altcode: 2001ewwd.work...60M
No abstract at ADS
---------------------------------------------------------
Title: Sphericity Effects in Metal-Line Blanketed NLTE Model
Atmospheres
Authors: Nagel, T.; Dreizler, S.; Werner, K.
2001ASPC..226...86N Altcode: 2001ewwd.work...86N
No abstract at ADS
---------------------------------------------------------
Title: Rotation Velocities of White Dwarfs
Authors: Karl, C.; Napiwotzki, R.; Heber, U.; Dreizler, S.; Koester,
D.; Reid, I. N.
2001AGM....18S0918K Altcode: 2001AGAb...18...98K
White dwarfs are the compact remnants of low and intermediate
mass stars (M < 8M<SUB>solar</SUB>). Due to the conservation of
angular momentum white dwarfs should be very fast rotators, if a
significant fraction of the angular momentum of the progenitor stars
were preserved. The existence of sharp NLTE cores of the hydrogen Hα
line in high resolution spectra (obtained at the Keck observatory)
of DA white dwarfs allowed us to determine (projected) rotational
velocities v sin i for white dwarfs. Among those of our targets
lying close to the ZZ Ceti instability many show evidence for extra
broadening similar to rotation, whereas stars at higher temperatures
(and therefore younger ones) rotate more slowly or not at all. Our
result based on a large sample is in accordance with previous results
presented by Koester et al. (1998). We discuss possible explanations
for this astonishing result.
---------------------------------------------------------
Title: Polarized Thermal Radiation from Neutron Star Atmospheres
Authors: Deetjen, Jochen L.; Dreizler, Stefan; Werner, Klaus
2001AGM....18.P121D Altcode:
We present model atmospheres appropriate for the spectroscopic analysis
of the thermal spectra of old isolated neutron stars. The models
consider the correct opacities from hydrogen exposed to magnetic fields
in the range of 10<SUP>7</SUP> Gauss from Ruder et al. (1994). For the
first time, these models account for deviations from LTE as well. Our
synthetic spectra are calculated in two successive steps. At first a
model atmosphere is calculated by the simultaneous solution of many
thousands of radiation transfer equations under the constraints
of hydrostatic and radiative equilibrium as well as statistical
equilibrium for atomic level populations. The solution method is an
Accelerated Lambda Iteration (ALI) technique (Werner & Dreizler,
1999). Thereby we neglect the magnetic field. In the second step the
atmospheric structure is kept fix and and a synthetic spectrum is
calculated by solving the full polarized radiation transfer equation
(PRT). We are using the Stokes vector to describe the radiation
field and apply the PRT version of Accelerated Lambda Iteration (ALI)
technique (Takeda, 1991). References: Ruder H., Wunner G., Herold H.,
Geyer F., 1994, Atoms in Strong Magnetic Fields, A&A Library,
1st edition Takeda Y, 1991, PASJ 43, 719 Werner K., Dreizler S., 1999,
Journal of Computational and Applied Math. 109, 65
---------------------------------------------------------
Title: New Pulsating sdB Stars from the HS Survey
Authors: Silvotti, R.; Solheim, J. -E.; Heber, U.; Østensen, R.;
Dreizler, S.; Edelmann, H.
2001ASPC..226..177S Altcode: 2001ewwd.work..177S
No abstract at ADS
---------------------------------------------------------
Title: Application of Stratified Non-LTE Model Atmospheres to Hot
DA White Dwarfs
Authors: Schuh, S.; Dreizler, S.; Wolff, B.
2001ASPC..226...79S Altcode: 2001ewwd.work...79S
No abstract at ADS
---------------------------------------------------------
Title: Stratified Non-LTE Model Atmospheres for hot White Dwarfs
Authors: Dreizler, S.; Schuh, S.
2001ASPC..226...69D Altcode: 2001ewwd.work...69D
No abstract at ADS
---------------------------------------------------------
Title: sdO Stars
Authors: Dreizler, S.
2000eaa..bookE5412D Altcode:
Subdwarfs of spectral type O (sdO stars) are hot evolved stars with a
lower luminosity than main sequence O stars. The sdO stars cover a wide
range in the HERTZSPRUNG-RUSSELL DIAGRAM (HRD, see figure 1). At lower
luminosities and temperatures they form the extension of the subdwarfs
of spectral type B (sdB), bounded by the extreme blue extension of
the Horizontal Branch (EHB) and the helium mai...
---------------------------------------------------------
Title: PG 1618+563B: A new bright pulsating sdB star
Authors: Silvotti, R.; Solheim, J. -E.; Gonzalez Perez, J. M.; Heber,
U.; Dreizler, S.; Edelmann, H.; Østensen, R.; Kotak, R.
2000A&A...359.1068S Altcode:
The results of two runs of time-series photometry made at the Nordic
Optical Telescope clearly show that the sdB star PG 1618+563B is a
new member of the EC 14026 class of sdB pulsators. Its power spectrum
shows a doublet of frequencies at about 6.95 and 7.18 mHz (P ~ 144 and
139 s respectively), which produce a modulation effect in the light
curve with a beat period of about 1.2 hours. The amplitudes of the two
signals are very low, not more than 2 mma. Thanks to its brightness
(B=13.4), which makes PG 1618+563B one of the brightest objects of its
class, we were able to observe the star also in different colours and
measure its UBV pulsation amplitudes and phases. The comparison of these
“nonadiabatic observables” with models may help the identification
of the oscillation modes. The spectral analysis of the sdB star and the
spectral classification of PG 1618+563A suggest that both stars form a
wide visual binary ( ~ 2500 A.U. separation), at a distance of about 680
pc from the sun. Based on observations obtained at the Nordic Optical
Telescope, operated on the island of La Palma jointly by Denmark,
Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del
Roque de los Muchachos of the Instituto de Astrofisica de Canarias. And
on observations obtained at the German-Spanish Astronomical Center,
Calar Alto, operated by the Max-Planck-Institut für Astronomie
Heidelberg jointly with the Spanish National Commission for Astronomy
---------------------------------------------------------
Title: NLTE Model Atmospheres for Extremely Hot Compact Stars
Authors: Rauch, T.; Deetjen, J. L.; Dreizler, S.; Werner, K.
2000IAUS..195..423R Altcode:
Present observational techniques provide stellar spectra with
high resolution at a high signal-to-noise ratio over the complete
wavelength range---from the far infrared to X-rays. The effects of
Non-“Local Thermal Equilibrium” (NLTE) are particularly important
for hot stars, hence the use of reliable NLTE stellar model atmosphere
fluxes is required for an adequate spectral analysis. State-of-the-art
NLTE model atmospheres include metal-line blanketing of millions of
lines of all elements from hydrogen up to the iron-group elements,
and thus permit precise analyses of extremely hot compact stars, e.g.,
central stars of planetary nebulae, PG 1159 stars, white dwarfs, and
neutron stars. Their careful spectroscopic study is of great interest
in several branches of modern astrophysics, e.g., stellar and galactic
evolution, and interstellar matter.
---------------------------------------------------------
Title: The discovery of photospheric nickel in the hot DO white
dwarf REJ 0503-289
Authors: Barstow, M. A.; Dreizler, S.; Holberg, J. B.; Finley, D. S.;
Werner, K.; Hubeny, I.; Sion, E. M.
2000MNRAS.314..109B Altcode:
We present the first evidence for the direct detection of nickel
in the photosphere of the hot DO white dwarf REJ 0503-289. While
this element has been seen previously in the atmospheres of hot
H-rich white dwarfs, this is one of the first similar discoveries
in a He-rich object. Intriguingly, iron, which is observed to
be more abundant than Ni in the hot DA stars, is not detected,
the upper limit to its abundance (Fe/He=10<SUP>-6</SUP>) implying
an Fe/Ni ratio a factor of 10 lower than seen in the H-rich objects
(Ni/He=10<SUP>-5</SUP> for REJ 0503-289). The abundances of nickel and
various other elements heavier than He were determined from Goddard High
Resolution Spectrograph spectra. We used two completely independent
sets of non-local thermodynamic equilibrium model atmospheres, which
both provide the same results. This not only reduces the possibility of
systematic errors in our analysis, but is also an important consistency
check for both model atmosphere codes. We have also developed a more
objective method of determining T<SUB>eff</SUB> and logg, from the He
lines in the optical spectrum, in the form of a formal fitting of the
line profiles to a grid of model spectra, an analogue of the standard
procedure utilizing the Balmer lines in DA white dwarfs. This gives the
assigned uncertainties in T<SUB>eff</SUB> and logg a firm statistical
basis and allows us to demonstrate that inclusion of elements heavier
than H, He and C in the spectral calculations, exclusively considered
in most published optical analyses, yields a systematic downward shift
in the measured value of T<SUB>eff</SUB>.
---------------------------------------------------------
Title: NLTE Model Atmospheres for Central Stars of Planetary Nebulae
Authors: Rauch, Thomas; Deetjen, Jochen L.; Dreizler, Stefan;
Werner, Klaus
2000ASPC..199..337R Altcode: 2000apn..conf..337R; 1999astro.ph..9507R
Present observational techniques provide stellar spectra with
high resolution at a high signal-to-noise ratio over the complete
wavelength range - from the far infrared to the X-ray. NLTE effects are
particularly important for hot stars, hence the use of reliable NLTE
stellar model atmosphere fluxes is required for an adequate spectral
analysis. State-of-the-art NLTE model atmospheres include the metal-line
blanketing of millions of lines of all elements from hydrogen up to
the iron-group elements and thus permit precise analyses of extremely
hot compact stars, e.g. central stars of planetary nebulae, PG 1159
stars, white dwarfs, and neutron stars. Their careful spectroscopic
study is of great interest in several branches of modern astrophysics,
e.g. stellar and galactic evolution, and interstellar matter.
---------------------------------------------------------
Title: CCD Photometry of Variable Subdwarfs and White Dwarfs at
Calar Alto Observatory
Authors: Schuh, Sonja; Dreizler, Stefan; Deetjen, Jochen L.; Heber,
Uli; Geckeler, Ralf D.
2000BaltA...9..395S Altcode: 2000OAst....9..395S
We report on our time-resolved photometry of subdwarfs and white
dwarfs at the Calar Alto Observatory. Candidates are taken from a
spectroscopically pre-selected sample obtained from the Hamburg Schmidt
Survey. We also report on our experience during the WET run in April
1999 and introduce our revised CCD photometry reduction package TRIPP,
as well as preliminary results.
---------------------------------------------------------
Title: PG 1618+563: A New Bright Pulsating sdB Star
Authors: Silvotti, R.; Gonzalez Perez, J. M.; Solheim, J. -E.; Heber,
U.; Dreizler, S.; Edelmann, H.
2000BaltA...9..205S Altcode: 2000OAst....9..205S
Recent observations at the NOT telescope clearly show that PG 1618+563
is a new member of the EC14026 class of sdB pulsating stars (Kilkenny
et al. 1997, O'Donoghue et al. 1999). The very good quality of the
non-filtered data allows to detect an amplitude modulation effect
with a beat period of about 1.2 hours, which is consistent with the
presence in the temporal spectrum of two close frequencies at 6.95
and 7.14 mHz ( ~ 144 and 140 s). The amplitudes are very low: between
1 and 2 mma. Moreover, from UBV data we find amplitude (and phase)
differences, that could be useful for mode identification.
---------------------------------------------------------
Title: Preliminary Results from XCOV 17: PG 1336-018
Authors: Reed, M. D.; Kilkenny, D.; Kawaler, S. D.; Mukadam, A.;
Kleinman, S. J.; Nitta-Kleinman, A.; Provencal, J. L.; Watson, T.;
Sullivan, D.; Sullivan, T.; Shobbrook, B.; Jiang, X. J.; Ashoka, B. N.;
Seetha, S.; Leibowitz, E.; Ibbetson, P.; Mendelson, H.; Meistas, E. G.;
Kalytis, R.; Alisauskas, D.; O'Donoghue, D.; Martinez, P.; van Wyk,
F.; Stobie, R.; Marang, F.; Zola, S.; Krzesinski, J.; Ogloza, W.;
Moskalik, P.; Silvotti, R.; Piccioni, A.; Vauclair, G.; Dolez, N.;
Rene-Fremy, J.; Chevreton, M.; Ulla, A.; Dreizler, S.; Schuh, S.;
Deetjen, J.; Solheim, J. E.; Perez, J.; Suarez, O.; Manteiga, M.;
Burleigh, M.; Barstow, M.; Kepler, S. O.; Kanaan, A.; Giovannini,
O.; Metcalfe, T.; Ostensen, R.
2000BaltA...9..183R Altcode: 2000OAst....9..183R
We present a preliminary analysis of the data collected during the
1999/1 (XCOV17) Whole Earth Telescope (WET) campaign to observe the
pulsating subdwarf B star PG 1336-018. Since PG 1336-018 is an HW Vir
type eclipsing binary, our hope is to use the known orbital period,
assume a tidally locked system, and search for rotationally split
modes. To this end, we can already report some success.
---------------------------------------------------------
Title: The Amplitude Differences Between CCD and PMT Measurements
Authors: Kanaan, A.; O'Donoghue, D.; Kleinman, S. J.; Krzesinski,
J.; Koester, D.; Dreizler, S.
2000BaltA...9..387K Altcode: 2000OAst....9..387K
Using model atmospheres, quantum efficiency and transmission curves,
we compute expected values for amplitudes of DAV, DBV and DOV
stellar models as measured through different detectors and/or filter
combinations. We conclude that choosing the wrong detector may lead to
amplitudes lower by 20 % than those measured by phototubes. The correct
choice of CCD + filter may reduce this problem down to a difference
of 6 %.
---------------------------------------------------------
Title: Trace elements and radiative levitation in hot helium-rich
white dwarfs
Authors: Dreizler, Stefan
2000fuse.prop.A013D Altcode:
We propose to observe three helium-rich (DO) white dwarfs in order to
determine their photospheric abundances of trace elements (e.g. C, N, O,
H, Fe, Ni,...). FUSE spectroscopy is ideal for this purpose since the
FUV allows to explore a large variety of line transitions of various
elements which are not detectable in existing optical or UV spectra
of the targets. The data will be analyzed with non-LTE metal line
blanketed model atmospheres. The results will be compared to predictions
from newly developed, self-consistent diffusion/radiative levitation
calculations under non-LTE conditions. The observed metal abundances
will serve as bench-marks for such kind of new calculations. <P />As a
basis for this work we have obtained high-S/N optical spectra of almost
all known DO white dwarfs within the last five years as well as HST
GHRS spectra of selected DO white dwarfs. A comprehensive analysis of
the atmospheric parameters is now available. For the present proposal
we have selected three targets which -- together with calibration and
PI targets-- represent the non-DA white dwarf cooling sequence from
the hot end down to the DB gap.
---------------------------------------------------------
Title: Time-Resolved Spectroscopy of BPM 37093 and PG 1336-018
Authors: Dreizler, Stefan; Koester, Detlev; Heber, Uli
2000BaltA...9..113D Altcode: 2000OAst....9..113D
We present time-resolved spectroscopy of two pulsating stars using VLT
UT1. Primary aim is an identification of the pulsation modes from the
wavelength dependency of the amplitudes. A mode identification is the
prerequisite to make full use of the photometric data obtained for
asteroseismologic studies.
---------------------------------------------------------
Title: Hubble Space Telescope spectroscopy of hot helium-rich white
dwarfs: metal abundances along the cooling sequence
Authors: Dreizler, S.
1999A&A...352..632D Altcode:
Metal abundances are the indicators of the chemical evolution in white
dwarfs, which is dominated by the element separation due to the strong
gravitational field. A reliable analysis and interpretation requires
high resolution and high signal-to-noise UV spectroscopy. For hot
helium rich DO white dwarfs this is currently only feasible with the
Hubble Space Telescope. In this paper I report on our HST spectroscopy
of DO white dwarfs and describe our model atmospheres employed for the
analysis. This includes an introduction to our new self-consistent,
chemically stratified non-LTE model atmospheres, which take into
account gravitational sedimentation and radiative levitation. The
results of the analysis shows that DO white dwarfs can best be fitted
with chemically homogeneous models, whereas stratified models show
significant deviations. Several possible reasons for this unexpected
result are discussed. At the current stage, weak mass loss is the
most plausible explanation. Based on observations obtained with the
NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science
Institute, which is operated by the Association of Universities for
Research in Astronomy, Inc., under NASA contract NAS 5-26555
---------------------------------------------------------
Title: HST/STIS ultraviolet spectroscopy of the supersoft X-ray
source RX J0439.8-6809
Authors: van Teeseling, A.; Gänsicke, B. T.; Beuermann, K.; Dreizler,
S.; Rauch, T.; Reinsch, K.
1999A&A...351L..27V Altcode: 1999astro.ph.10330V
We present ultraviolet observations of the supersoft X-ray source
RX J0439.8-6809 obtained with the Hubble Space Telescope Imaging
Spectrograph. The ultraviolet spectrum is a very blue continuum
overlayed with interstellar absorption lines. The observed broad Lyalpha
absorption line is consistent with an interstellar column density of
neutral hydrogen N_HI=(4.0+/-1.0)*E<SUP>20};cm<SUP>{-2</SUP></SUP>. The
light curve obtained from the time-tagged dataset puts a 3sigma upper
limit of 0.04 mag on the ultraviolet variability of RX J0439.8-6809 on
time scales between 10 s and 35 min. The long-term X-ray light curve
obtained from our three-year ROSAT HRI monitoring of RX J0439.8-6809
shows the source with a constant count rate, and implies that the
temperature did not change more than a few 1000 K. If RX J0439.8-6809 is
a massive extremely hot pre-white dwarf on the horizontal shell-burning
track, opposed to the alternative possibility of a very compact
double-degenerate supersoft X-ray binary, its constant temperature and
luminosity are a challenge to stellar evolution theory. Interestingly,
RX J0439-6809 is found close to the theoretical carbon-burning
main-sequence. Based on observations made with the NASA/ESA Hubble
Space Telescope, obtained at the Space Telescope Science Institute,
which is operated by the Association of Universities for Research in
Astronomy, Inc., under NASA contract NAS 5-26555.
---------------------------------------------------------
Title: The classical stellar atmosphere problem.
Authors: Werner, K.; Dreizler, S.
1999JCoAM.109...65W Altcode: 1999astro.ph..6130W
The authors introduce the classical stellar atmosphere problem and
describe in detail its numerical solution. The problem consists of the
solution of the radiation transfer equations under the constraints of
hydrostatic, radiative and statistical equilibrium (non-LTE). They
outline the basic idea of the accelerated lambda iteration (ALI)
technique and statistical methods which finally allow the construction
of non-LTE model atmospheres considering the influence of millions
of metal absorption lines. Some applications of the new models are
presented.
---------------------------------------------------------
Title: Analysis of ultraviolet and extreme-ultraviolet spectra of
the DA white dwarf G 191-B2B using self-consistent diffusion models
Authors: Dreizler, S.; Wolff, B.
1999A&A...348..189D Altcode:
We present a multi-wavelength spectral analysis of the DA white dwarf
G 191-B2B. The employed atmospheric models account for gravitational
settling and radiative levitation, which are, for the first time,
calculated self-consistently with the atmospheric structure. The
resulting spectra can reproduce the complete EUVE spectrum and
the ultraviolet lines of iron. Some restrictions regarding the UV
lines of other elements (C, N, O, Ni), however, still remain. In
contrast to homogeneous models, it is not necessary to introduce
additional photospheric or interstellar absorbers to account for
the high opacity at lambda <~ 230 Ä. Abundance profile changing
mechanisms, like mass-loss or accretion, are also not needed. Based on
observations made with the EUVE Sattelite and with the NASA/ESA Hubble
Space Telescope, obtained from the data archive at the Space Telescope
Science Institute. STScI is operated by the Association of Universities
for Research in Astronomy, Inc. under NASA contract NAS 5-26555.
---------------------------------------------------------
Title: The iron abundance in hot central stars of planetary nebulae
derived from IUE spectra
Authors: Deetjen, J. L.; Dreizler, S.; Rauch, T.; Werner, K.
1999A&A...348..940D Altcode: 2000astro.ph..6338D
We present the first attempt to determine the iron abundance in
hot central stars of planetary nebulae. We perform an analysis with
fully metal-line blanketed NLTE model atmospheres for a sample of ten
stars (T_eff >~ 70 000 K) for which high-resolution UV spectra
are available from the IUE archive. In all cases lines of Fe Vi or
Fe Vii can be identified. As a general trend, the iron abundance
appears to be subsolar by 0.5-1 dex, however, the S/N of the IUE
spectra is not sufficient to exclude a solar abundance in any specific
case. Improved spectroscopy by either FUSE or HST is necessary to verify
the possibility of a general iron deficiency in central stars. The
suspected deficiency may be the result of gravitational settling in
the case of three high-gravity objects. For the other stars with low
gravity and high luminosity dust fractionation during the previous
AGB phase is a conceivable origin. Based on observations with the
International Ultraviolet Explorer (IUE) satellite.
---------------------------------------------------------
Title: The photometric behaviour of the peculiar PG 1159 star HS
2324+3944 at high frequency resolution
Authors: Silvotti, R.; Dreizler, S.; Handler, G.; Jiang, X. J.
1999A&A...342..745S Altcode: 1998astro.ph.11178S
We present the results from 135 hours of nearly continuous time
series photometry on the “hybrid” (H-rich) PG 1159 variable star HS
2324+3944, obtained in August-September 1997. The power spectrum of
the data shows several frequencies (about 20 or more), concentrated
in three narrow and very crowded regions near 475, 390 and 950 mu Hz
in decreasing amplitude order. Most (if not all) of the peaks in the
latter region are linear combinations of the high-amplitude frequencies
between 455 and 500 mu Hz. If we divide the data set into two equal
parts, the power spectra are different. This is probably due to a not
sufficiently long (and therefore not completely resolved) light curve;
nevertheless an alternative hypothesis of a single damped oscillator
may not be completely ruled out. If we adopt the first hypothesis,
the high concentration of peaks between 455 and 500 mu Hz suggests
the presence of both l=1 and l=2 high-overtone nonradial g-modes. The
insufficient frequency resolution of our data does not allow to obtain
definite precision asteroseismology results. Nevertheless a spacing
of the signals is observed, probably due to stellar rotation with a
period of 2.3 days. If the signal spacing was due to the successive
overtones, the period spacings would be equal to 18.8 (l=1) and 10.4
(l=2) s. Based on observations obtained at the McDonald, Loiano and
Beijing Observatories and at the German-Spanish Astronomical Center,
Calar Alto, operated by the Max-Planck-Institut für Astronomie
Heidelberg jointly with the Spanish National Commission for Astronomy.
---------------------------------------------------------
Title: Iron abundance in hot central stars of planetary nebulae
Authors: Deetjen, J. L.; Dreizler, S.; Rauch, T.; Werner, K.
1999AGAb...15..119D Altcode: 1999AGM....15..P64D
We present the first attempt to determine the iron abundance in
hot central stars of planetary nebulae. We perform an analysis with
fully metal-line blanketed NLTE model atmospheres for a sample of ten
stars (T_eff >~ 70 000 K) for which high-resolution UV spectra
are available from the IUE archive. In all cases lines of Fe vi or
Fe vii can be identified. As a general trend, the iron abundance
appears to be subsolar by 0.5-1 dex, however, the S/N of the IUE
spectra is not sufficient to exclude a solar abundance in any specific
case. Improved spectroscopy by either FUSE or HST is necessary to verify
the possibility of a general iron deficiency in central stars. The
suspected deficiency may be the result of gravitational settling in
the case of three high-gravity objects. For the other stars with low
gravity and high luminosity dust fractionation during the previous
AGB phase is a conceivable origin.
---------------------------------------------------------
Title: HST spectroscopy of hot hydrogen deficient white dwarfs
Authors: Dreizler, S.
1999ASPC..169..499D Altcode: 1999ewwd.conf..499D
No abstract at ADS
---------------------------------------------------------
Title: Iron and nickel abundances in hot hydrogen-rich central stars
of planetary nebulae
Authors: Deetjen, J. L.; Dreizler, S.; Rauch, T.; Werner, K.
1999ASPC..169..475D Altcode: 1999ewwd.conf..475D
No abstract at ADS
---------------------------------------------------------
Title: Born-again AGB stars: Starting point of the H-deficient
post-AGB evolutionary sequence?
Authors: Werner, K.; Dreizler, S.; Rauch, T.; Koesterke, L.; Heber, U.
1999IAUS..191..493W Altcode:
We discuss the origin of hot hydrogen-deficient post-AGB stars. Evidence
is growing that the “born-again AGB star scenario” as a consequence of
a late He shell flash cannot explain the diverse observations. Analyses
of the stars and their associated planetary nebulae suggest that
the H-deficiency is not formed during the second post-AGB phase but
already while the star is still on the AGB. There are even hints that
the H-deficiency can occur before the first departure from the AGB.
---------------------------------------------------------
Title: Sphericity effects in non-LTE model atmospheres for hot stars
Authors: Nagel, T.; Dreizler, S.; Werner, K.
1999AGAb...15..104N Altcode: 1999AGM....15..P35N
Spectral analyses of hot compact stars (white dwarfs, sdO stars,
central stars of planetary nebulae) are usually performed with model
atmospheres assuming plane-parallel geometry. This approximation
becomes questionable in case of observational data with very high
signal-to-noise where even tiny effects become visible or, because of
their extended atmospheres, for objects close to the Eddington limit. As
long as wind effects are negligible, static and spherically symmetric
models can be used. We describe how our non-LTE model atmosphere code
has been generalized to spherical geometry and present results from
our first model calculations. This new implementation is used to study
sphericity effects on atmospheric structure and line profiles which
are compared to effects arising from non-LTE metal line blanketing.
---------------------------------------------------------
Title: EUVE observations of DA white dwarfs
Authors: Wolff, B.; Koester, D.; Dreizler, S.
1999ASPC..169..524W Altcode: 1999ewwd.conf..524W
No abstract at ADS
---------------------------------------------------------
Title: NLTE Model Atmospheres for Extremely Hot Compact Stars
Authors: Rauch, Thomas; Deetjen, Jochen L.; Dreizler, Stefan;
Werner, Klaus
1999AGAb...15..105R Altcode: 1999AGM....15..P36R
Present observational techniques provide stellar spectra with
high resolution at a high signal-to-noise ratio over the complete
wavelength range - from the far infrared to the X-ray. NLTE effects are
particularly important for hot stars, hence the use of relia ble NLTE
stellar model atmosphere fluxes is required for an adequate spectral
analysis. State-of-the-art NLTE model atmospheres include the metal-line
blanketing of millions of lines of all elements from hydrogen up to
the iron-group elements and thus permit precise analyses of extremely
hot compact stars, e.g. central stars of planetary nebulae, PG 1159
stars, white dwarfs, and neutron stars. Their careful spectroscopic
study is of great interest in several branches of modern astrophysics,
e.g. stellar and galactic evolution, and interstellar mat ter.
---------------------------------------------------------
Title: Spectroscopy of Hot Hydrogen Deficient White Dwarfs
Authors: Dreizler, Stefan
1999RvMA...12..255D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Equilibrium Abundances in Hot White Dwarfs
Authors: Schuh, Sonja; Dreizler, Stefan; Wolff, Burkhard
1999AGAb...15..105S Altcode:
Metal abundances are the indicators of the chemical evolution in
white dwarfs, which is dominated by the sedimentation of the heavier
elements due to the strong gravitational field. A reliable analysis
and interpretation requires high resolution and high signal-to-noise
UV and EUV spectroscopy. It can only be performed in these wavelength
ranges as the weak metal lines needed for the analysis do not show up
in the optical regime. During previous work by Wolff et al. (A&A
329, 1045), the spectra of hot, hydrogen rich white dwarfs as detected
by EUVE were analysed and effective temperatures, surface gravity
and metallicities were determined using chemically homogeneous
model atmospheres. We now present calculations of self-consistent,
chemically stratified non-LTE model atmospheres which take into
account gravitational sedimentation and radiative levitation. In the
case of G191-B2B, these new, refined models are able to reproduce the
EUVE observations to an unprecedented degree of accuracy (Dreizler et
al., A&A 348, 189). This result is now to be checked for a larger
sample of objects using UV spectra from IUE and HST as well as future
FUSE spectra.
---------------------------------------------------------
Title: The stellar content of the Hamburg Quasar Survey
Authors: Homeier, D.; Koester, D.; Jordan, S.; Hagen, H. -J.; Engels,
S.; Heber, U.; Dreizler, S.
1999ASPC..169...37H Altcode: 1999ewwd.conf...37H
No abstract at ADS
---------------------------------------------------------
Title: Results of the multi-site photometric campaign on HS 2324+3944
Authors: Silvotti, R.; Dreizler, S.; Handler, G.; Jiang, X.
1999ASPC..169..100S Altcode: 1999ewwd.conf..100S
No abstract at ADS
---------------------------------------------------------
Title: Observations of Variable [pre-] White Dwarfs
Authors: Dreizler, S.; Schuh, S.; Deetjen, J.; Heber, U.; Edelmann,
H.; Koester, D.
1999AGAb...15..106D Altcode:
Stellar seismology is an extremely valuable tool for a direct
investigation of stellar structure and evolution. The usual
observational approach is photometric monitoring of stars, yielding
pulsation frequencies and amplitudes. The comparison of the observed
modes with predicted ones are then used to probe the stellar
structure. The typical separation of consecutive overtones in these
stars are of the same order as the side bands in the Fourier spectrum
produced by the periodic day interruption. Thus, in order to obtain
light curves suitable for a detailed seismologic analysis, world wide
coordinated observing campaigns are required (Whole Earth Telescope,
WET). Using the Calar Alto 1.23m telescope, we participated in the
last WET campaign, where the close binary PG 1336-018, a pulsating
sdB and a very cool main sequence star, was observed. Using the same
instrumentation, we also searched for new candidates of variable
[pre-] white dwarfs. A seismologic analysis requires a reliable mode
identification, namely the degree l denoting the number of node lines of
the non-radial pulsation. In the case of many observed eigenmodes these
can be identified by a comparison with theoretical predictions. When
only very few modes are present this comparison is ambiguous and an
alternative approach is required, i.e. an evaluation of wavelength
dependent pulsation amplitudes as seen in time-resolved spectroscopy
of two variable [pre-] white dwarfs performed with the VLT.
---------------------------------------------------------
Title: Search for rotation in white dwarfs
Authors: Koester, D.; Dreizler, S.; Weidemann, V.; Allard, N. F.
1999ASPC..169..415K Altcode: 1999ewwd.conf..415K
No abstract at ADS
---------------------------------------------------------
Title: FUV spectroscopy of DO and PG 1159 stars with ORFEUS
Authors: Werner, K.; Dreizler, S.; Rauch, T.; Barnstedt, J.; Gölz,
M.; Gringel, W.; Kappelmann, N.; Krämer, G.; Widmann, H.; Koesterke,
L.; Haas, S.; Heber, U.; Appenzeller, I.; Grewing, M.
1999ASPC..169..511W Altcode: 1999ewwd.conf..511W
No abstract at ADS
---------------------------------------------------------
Title: An analysis of DA white dwarfs from the Hamburg Quasar Survey
Authors: Homeier, D.; Koester, D.; Hagen, H. -J.; Jordan, S.; Heber,
U.; Engels, D.; Reimers, D.; Dreizler, S.
1998A&A...338..563H Altcode:
Follow-up spectroscopy of several hundred hot stars detected by
the Hamburg Quasar Survey (HQS) has been carried out between 1989
and 1996. We present the analysis of 80 DA white dwarfs using model
atmospheres and theoretical cooling tracks to derive the atmospheric
parameters T_eff and log g, masses and absolute magnitudes. The HQS
turned out to be sensitive to the detection of hydrogen-rich white
dwarfs in a wide temperature range, from 10 000 K upwards. Star counts
within four HQS fields for magnitudes B<= 16fm 4 exceed those from
the Palomar Green survey by about 50%. The more recent observation
campaigns emphasized the detection of very hot degenerates, yielding
a large fraction of DA stars with T_eff > 50 000 K compared to
other surveys. The mean mass of our DA sample is M=0.61{M}_{\odot},
with three massive DA stars exceeding 1{M}_{\odot} and three DA
stars with masses significantly below the assummed lower mass limit
for single white dwarf evolution of 0.45{M}_{\odot}. Among the cool
DA stars, thirteen are potential ZZ Ceti candidates because their
effective temperatures lie close to the instability strip. Based
on observations collected at the German-Spanish Astronomical Center
(DSAZ), Calar Alto, operated by the Max-Plank-Institut für Astronomie
Heidelberg jointly with the Spanish National Commission for Astronomy;
with the International Ultraviolet Explorer satellite (IUE) collected
at Villafranca, Spain, and with the ROSAT X-ray telescope.
---------------------------------------------------------
Title: Search for rotation in white dwarfs
Authors: Koester, D.; Dreizler, S.; Weidemann, V.; Allard, N. F.
1998A&A...338..612K Altcode:
We report high-resolution spectroscopic observations of the
NLTE Hα core in 28 DA white dwarfs. From a comparison with
theoretically broadened NLTE models projected rotation velocities can
be determined. The majority of objects are found to be compatible with
zero or very small rotation with typical upper limits for v sin i of 15
km/s, corresponding to periods of hours or longer. The implications for
the loss of angular momentum during the evolution of the progenitors
is discussed. Three new magnetic white dwarfs are detected with very
small tangential fields in the range of 30 to 50 kG. In two more
magnetic objects known before we found field strengths significantly
larger than the mean longitudinal fields determined from the circular
polarization. Very puzzling is the result for three ZZ Ceti stars in the
sample, which all seem to have projected rotational velocities between
30 and 45 km/s, in conflict with asteroseismological results. Based on
observations collected at the European Southern Observatory, La Silla,
Chile (55.D-0459, 57.D-0631)
---------------------------------------------------------
Title: Spectral analysis of O(He)-type post-AGB stars
Authors: Rauch, T.; Dreizler, S.; Wolff, B.
1998A&A...338..651R Altcode:
We present an analysis of two recently discovered, very hot
hydrogen-deficient post-AGB stars of spectral type O(He), namely HS
1522+6615 and HS 2209+8229, by means of state-of-the-art NLTE model
atmospheres based on new optical, UV, and X-ray observations. In
the spectra of HS 1522+6615 we discovered a variability of the
\Ionw{O}{6}{5290} line complex on a time scale of few days. We also
report on the discovery of a ring structure in the planetary nebula K
1-27 which has an O(He)-type central star. We discuss how the group
of O(He) stars fits in our picture of hydrogen-deficient post-AGB
stellar evolution. Based on observations obtained at the German-Spanish
Astronomical Center, Calar Alto, operated by the Max-Planck-Institut
für Astronomie Heidelberg jointly with the Spanish National Commission
for Astronomy; collected at the European Southern Observatory, La Silla,
Chile; on observations made with ROSAT, retrieved from the archive;
and on observations made with the International Ultraviolet Explorer
(IUE) and retrieved from the IUE Final Archive; this research has made
use of the SIMBAD database, operated at CDS, Strasbourg, France
---------------------------------------------------------
Title: Spectral analyses of PG 1159 star: constraints on the GW
Virginis pulsations from HST observations
Authors: Dreizler, S.; Heber, U.
1998A&A...334..618D Altcode:
We present the results of a quantitative analysis of UV and optical
spectra of nine PG 0122+200ls, very hot hydrogen-deficient [pre-]
white dwarfs, by means of line blanketed NLTE model atmospheres. Four
programme stars constitute the GW Vir variables, a class of non-radial
g-mode pulsators. Precise effective temperatures, carbon, nitrogen and
oxygen abundances and spectroscopic masses are used to constrain the
GW Vir pulsations. The blue edge of the instability strip is at 140
000 K (PG 1159-035). PG 0122+200 sets the red edge at 80 000 K, but
is also one of the coolest PG 0122+200ls\ known, suggesting that the
pulsations are stopped when the transformation of a PG 1159 star into
a hot white dwarf occurs by gravitational settling of the metals. Four
non-variables are found to lie inside the GW Vir instability strip
indicating that an additional parameter determines whether a PG 1159
star pulsates. Abundances of C and O in the pulsating stars appear to
be higher than in the non-variables in agreement with the theoretical
prediction that the pulsations are driven by cyclic ionization of C
and O. The outstanding discovery of our investigation, however, is a
strong correlation between the nitrogen abundance and pulsations. All GW
Vir stars are nitrogen rich, whereas no nitrogen can be detected in the
non-variables except in PG 1144+005. We conjecture that this correlation
provides a key for the understanding of the driving mechanism. Comparing
their position in the T_eff-log g diagram to new evolutionary models
we conclude that most programme stars are post-AGB stars of rather low
mass (0.5 ... 0.65 M_sun) which have lost their entire hydrogen-rich
envelope and part of their helium-rich envelope whereas we confirm
HS 0704+6153 to be an AGB manquestar. The high nitrogen abundance in
four stars is a tracer of mixing processes which have led to ingestion
and burning of hydrogen during the final helium shell flash. Based
on observations obtained a) with the NASA/ESA Hubble Space Telescope,
obtained at the Space Telescope Science Institute, which is operated
by the Association of Universities for Research in Astronomy, Inc.,
under NASA contract NAS 5-26555; b) at the German-Spanish Astronomical
Center, Calar Alto, operated by the Max-Planck-Institut für Astronomie
Heidelberg jointly with the Spanish National Commission for Astronomy;
c) at the European Southern Observatory, La Silla, Chile; d) with the
International Ultraviolet Explorer (IUE).
---------------------------------------------------------
Title: The Pulsating “HYBRID” PG 1159 Star HS 2324+3944: Past,
Present and Future
Authors: Handler, G.; Dreizler, S.; Silvotti, R.; Xiao-Jun, Jiang
1998BaltA...7..105H Altcode: 1998OAst....7..105H
We review past efforts to unravel the nature of the light variations
of the “hybrid” PG 1159 star HS 2324+3944 and present preliminary
results of a recent multisite campaign devoted to this interesting
object. From the on-line frequency analysis of our measurements, we can
safely conclude that this star is a multimode pulsating variable. Some
suggestions for further investigations are given.
---------------------------------------------------------
Title: On the inclination and binarity of the pulsating pre-white
dwarf PG 2131+066
Authors: Paunzen, Ernst; Konig, Michael; Dreizler, Stefan
1998A&A...331..162P Altcode:
We report on new spectroscopic data as well as recent results from
a temporal analysis of PG 2131+066 WET time series, yielding a new
interpretation of the binarity nature for PG 2131+066. The newly
discovered Hα emission features, the estimated low inclination and
the found 3.9h period, support the picture of a close binary system,
composed of the nonradial oscillating white dwarf with a cool red
dwarf companion. Since the spin and the orbital period are not
yet synchronized and because PG 2131+066 has no X-ray counterpart,
we classify it as a progenitor of a cataclysmic variable. Based on
observations obtained at the German-Spanish Astronomical Center, Calar
Alto, operated by the Max Planck Institut für Astronomie Heidelberg
jointly with the Spanish National Commission for Astronomy.
---------------------------------------------------------
Title: HST Spectroscopy of PG 1159 Stars: the Boundary of the GW
VIR Instability Strip
Authors: Dreizler, S.
1998BaltA...7...71D Altcode: 1998OAst....7...71D
Our recent analysis of PG 1159 stars, mainly based on the HST
spectroscopy, is presented. The results allow several conclusions
regarding the boundary of the GW Vir instability strip and the driving
mechanism for these pulsations.
---------------------------------------------------------
Title: On the mass-loss of PG1159 stars
Authors: Koesterke, L.; Dreizler, S.; Rauch, T.
1998A&A...330.1041K Altcode:
The winds of the four PG1159 stars NGC7094, NGC246, K1-16 and
RXJ2117.1+3412 are investigated by means of non-LTE models for
spherically expanding atmospheres. Based on the results of recent
plane-parallel non-LTE analyses, several individual models with various
mass-loss rates are calculated. Synthetic profiles of the C Iv resonance
line are compared to high resolution, high quality HST and IUE UV
spectra in order to determine mass-loss rates of the stars and terminal
velocities of their winds. Complex model atoms of hydrogen, helium,
carbon and oxygen are taken into account. In contrast to previous
studies we find from the C Iv line at 1550 Angstroms exceedingly high
mass-loss rates of -7.6<=log(dot {M}/[M_sunyr(-1) ])<=-6.9 which
are, in case of K1-16, only two times smaller than the mass-loss rates
of [WC]-PG1159 stars. From the comparison with theoretical predictions
of line strength and terminal wind velocity it is most likely that
the theory of radiation driven winds is appropriate for the PG1159
stars. The results are discussed in the light of the evolutionary
sequence [WCL]->[WCE]->[WC]-PG1159->PG1159\= rightarrowWD,
which is suggested for hydrogen deficient post-AGB stars. Similarities
between the winds of PG1159 stars and the exceptional strong winds of
[WC]-type stars lead to the assumption that the theory of radiation
driven winds might also apply for [WCE] stars. Changes of ionization
degrees, which might enhance the mass-loss by multi-scattering
processes, are found in the atmospheres of [WCE] stars but not in the
atmospheres of PG1159 stars. Partly based on observations made with
NASA/ESA Hubble Space Telescope, obtained from the data archive at the
Space Telescope Science Institute, which is operated by the Association
of Universities for Research in Astronomy, Inc., under NASA contract NAS
5-26555; Partly based on observations obtained with the IUE satellite
from VILSPA, Spain, jointly operated by the NASA, ESA, and PPARC.
---------------------------------------------------------
Title: HS0507+0434: a double DA degenerate with a ZZCeti component
Authors: Jordan, S.; Koester, D.; Vauclair, G.; Dolez, N.; Heber,
U.; Hagen, H. -J.; Reimers, D.; Chevreton, M.; Dreizler, S.
1998A&A...330..277J Altcode:
HS0507+0434 and HS2240+1234 are two new common proper motion pairs of
DA white dwarfs, discovered by the Hamburg Quasar Survey. Our model
atmosphere analysis shows that HS0507+0434A has an effective temperature
of 20000K and is remarkably young (tau_cool < 1Gyr) compared to the
average cooling time of all known wide double degenerates (~ 3Gyr). The
cooler B component of HS0507+0434 is particularly interesting; the
determination of the atmospheric parameters is complicated by the
strong dependence of the solution on the details of the treatment of
convection. Only those parameterizations of mixing length theory are
consistent with all observations (especially the magnitude difference
between the components), which lead to an intermediate efficiency of the
convective flux. In the standard version of the mixing length theory
this corresponds to a mixing length parameter of l/H_p = 1.75 - 2.0,
where H_p is the pressure scale height. This result does not depend on
the model atmosphere code and is in agreement with previous studies of
convection in DA white dwarfs; there are, however, slightly different
formulations of the MLT in use, which achieve the same efficiency at
different values of l/H. These versions are discussed and compared
in the paper. The result of our analysis (T_eff=11900K, log g=8)
places the B component into the ZZCeti instability strip, where DA
white dwarfs are pulsating non-radially. Photometric observations
have now confirmed that HS0507+0434 is variable and identified 3 or
4 fundamental g-modes in the Fourier spectrum. Based on observations
collected at the German-Spanish Astronomical Center (DSAZ) at Calar
Alto, Spain, at the European Southern Observatory, La Silla, Chile,
with the International Ultraviolet Explorer Satellite, and at the
Observatoire de Haute Provence (CNRS), France.
---------------------------------------------------------
Title: Iron and Nickel Abundances in DA White Dwarfs and SDO Stars
Authors: Werner, K.; Dreizler, S.; Haas, S.; Heber, U.
1998ESASP.413..301W Altcode: 1998uabi.conf..301W
No abstract at ADS
---------------------------------------------------------
Title: White Dwarfs in the Hamburg Quasar Survey
Authors: Homeier, D.; Koester, D.; Hagen, H. -J.; Jordan, S.; Heber,
U.; Engels, D.; Reimers, D.; Dreizler, S.
1998AGAb...14..148H Altcode: 1998AGM....14..P98H
The spatial distribution and the luminosity function of white dwarfs
provide important information on stellar evolution and the structure
and age of the Galactic disk. A total of about 2 200 white dwarfs is
known to date. The Hamburg Quasar Survey (HQS) has the capability to
substantially enlarge this number and to provide an optically selected
sample of white dwarfs not relying on EUV/X-ray emission. The HQS,
covering 14 000 deg^2 of the northern sky, has produced objective prism
spectra of several thousand stellar UV-excess sources. We expect to be
able to identify 2 000-3 000 white dwarfs down to a limiting magnitude
of B=17_{\cdot}<SUP>m</SUP>5 from this database. The spectra also
allow a rough estimate of T<SUB>eff</SUB> by the Balmer line strengh
of DA white dwarfs. Follow-up observations of hot star candidates
in selected fields of the survey and comparisons with the catalogue
of known white dwarfs have shown that DAs with temperatures down to,
and below, the ZZ-Ceti instability strip (~ 11 000 K) are found. The
number density of DA per deg^2 found within the magnitude range of the
Palomar-Green survey (B <= 16_{\cdot}<SUP>m</SUP>4) was higher than
estimated from that survey. The 80 DA white dwarfs discovered by the
follow-up spectroscopy have been analyzed using LTE model atmospheres to
determine T<SUB>eff</SUB> and \log g, from which the mass distribution,
luminosities and photometric distances can be derived.
---------------------------------------------------------
Title: Photospheric metals in hot DA white dwarfs
Authors: Wolff, B.; Koester, D.; Dreizler, S.; Haas, S.
1998A&A...329.1045W Altcode:
Previous observations of the soft X-ray and EUV region with the
Einstein, EXOSAT, and ROSAT satellites have indicated the presence
of photospheric absorbers in most DA white dwarfs with {T_eff}
ga 40000K. Several of these objects have now been observed with the
Extreme Ultraviolet Explorer (EUVE). Since the detection of individual
metal lines is rather difficult with EUVE spectra we chose the well
studied DA G191-B2B as reference object for the analysis of other white
dwarfs. In spectra obtained with the GHRS of the Hubble Space Telescope
photospheric lines of nitrogen, silicon, iron, and nickel could be
detected. With the abundances determined from these observations we were
able to reproduce the EUVE spectrum of G191-B2B. The main source of EUV
opacity turned out to be iron, followed by nickel. The analysis of both
the EUV continuum and the hydrogen Balmer lines led to {T_eff} = 56000
+/- 2000K. For the analysis of other DA white dwarfs we used the same
relative abundances as for G191-B2B but introduced a free scaling factor
(“metallicity”) for the total amount of metals. From EUVE spectra
we determined relative metallicities for 20 objects with {T_eff} ga
40000K. The main result is that all DAs with {T_eff} ga 50000K contain
additional photospheric absorbers, whereas at lower temperatures all
observations, with the exception of GD394, are compatible with pure
hydrogen atmospheres. As in the case of G191-B2B, iron determines
also the EUV opacity in the objects at {T_eff} ga 50000K. This is in
agreement with radiative levitation theory which predicts the support
of iron above this temperature. Based on observations with the HST and
EUVE satellites, and on optical spectra obtained at the DSAZ Calar Alto
---------------------------------------------------------
Title: On the Red Edge of the GW Virginis Instability Strip
Authors: Werner, K.; Dreizler, S.; Heber, U.; Rauch, T.
1998ASPC..135..130W Altcode: 1998hcsp.conf..130W
GW Vir (alias PG1159-035) is the prototype of a spectroscopic class of
extremely hot hydrogen-deficient (pre-) White Dwarfs. The prototype
as well as a number of other PG1159 stars define the GW Vir (or DOV)
instability strip in the HR diagram. Considerable effort has been made
to confine the limits of this instability strip by both, pulsational
theory (Kawaler and collaborators) as well as by spectroscopic analysis
(Werner and collaborators). Our first analysis of the prototype (Werner,
Heber, Hunger 1991 A&A 244, 437) revealed the peculiar surface
abundances which entered as an essential ingredient into the pulsational
analysis of Whole Earth Telescope (WET) observations (Kawaler &
Bradley 1994, ApJ 427, 415). We succeeded in constraining the blue edge
of the instability strip (Werner et al. 1996, IAU Coll. 155, p. 96). We
now present non-LTE model atmosphere analyses of RcoolS (Teff <
100,000K) PG1159 stars based on latest UV spectra obtained with the
Hubble Space Telescope, aiming at the red edge of the instability
strip. Preliminary results indicate that the red edge is much less
well defined and seems to depend rather sensitively on photospheric
and stellar parameters. The analysis comprises one pulsator which was a
target of a WET observation run and it will support the interpretation
of asteroseismologic analyses.
---------------------------------------------------------
Title: Photospheric metals in hot DA white dwarfs.
Authors: Wolff, B.; Koester, D.; Dreizler, S.; Haas, S.
1997AGAb...13..218W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: (Erratum) On the hot ends of the white dwarf spectral
sequences: white dwarfs containing helium from the Hamburg-Schmidt
survey.
Authors: Heber, U.; Dreizler, S.; Hagen, H. -J.
1997A&A...319..363H Altcode:
Erratum to Astron. Astrophys. 311, L17 (1996).
---------------------------------------------------------
Title: Spectral Analyses of PG 1159 Stars with Line-Blanketed Non-Lte
Model Atmospheres
Authors: Werner, K.; Dreizler, S.; Rauch, T.; Heber, U.
1997fbs..conf..227W Altcode: 1997LDP....22..227W
No abstract at ADS
---------------------------------------------------------
Title: Analysis of hydrogen rich PG 1159 central stars of Planetary
Nebulae
Authors: Dreizler, S.; Werner, K.; Heber, U.
1997IAUS..180..103D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: NLTE analyses of PG 1159 stars: constraints for the structure
and evolution of post-AGB stars.
Authors: Dreizler, S.; Werner, K.; Rauch, T.; Heber, U.; Reid, I. N.;
Koesterke, L.
1997IAUS..189..369D Altcode: 1998IAUS..189..369D
The majority of all stars (M<SUB>i</SUB> < 8M<SUB>sun</SUB>)
end their lives as white dwarfs (WD). On the tip of the Asymptotic
Giant Branch (AGB) the star ejects its outer layers which become a
planetary nebula and the stellar core evolves rapidly towards very high
effective temperatures (T<SUB>eff</SUB> > 100 kK). When the nuclear
burning in the H or He shell ceases the star enters the WD cooling
sequence. The evolution starting from the AGB is separated in a H-rich
and a H-deficient sequence where the latter contributes with a number
fraction of ≍20%. In this paper the authors describe their recent
effort in the analysis of one group of these stars, the PG 1159 stars.
---------------------------------------------------------
Title: Abundance Patterns of Iron and Nickel in SDO Stellar
Atmospheres
Authors: Haas, Stefan; Heber, Ulrich; Dreizler, Stefan; Werner, Klaus
1997fbs..conf..177H Altcode: 1997LDP....22..177H
No abstract at ADS
---------------------------------------------------------
Title: Ultraviolet Spectroscopy of Hot Compact Stars.
Authors: Werner, K.; Dreizler, S.; Heber, U.; Kappelmann, N.; Kruk,
J.; Rauch, T.; Wolff, B.
1997RvMA...10..219W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the fate of born-again red giants.
Authors: Werner, K.; Dreizler, S.; Heber, U.; Rauch, T.
1997seas.conf..163W Altcode: 1997ase..work..163W
Post-AGB stars which are burning hydrogen in a shell and hot white
dwarfs may suffer a final helium shell flash. Subsequently the stellar
envelope re-expands and the star becomes a "born-again" red giant. What
is the consequence for the chemistry in the envelope? In particular,
what surface abundances can be expected and how are they affected by
mass loss during the second descent from the AGB? Iben and MacDonald
(1995) provided the only appropriate theoretical calculation available
up to now for this scenario. The authors present here the results of
spectroscopic analyses from hot H-deficient stars, which they believe
to have undergone a late helium flash. The surface abundance pattern
strongly varies from star to star. An explanation of this variety
demands extensive parameter studies in evolutionary calculations.
---------------------------------------------------------
Title: Trace Elements in White Dwarfs
Authors: Koester, Detlev; Wolff, Burkhard; Jordan, Stefan; Dreizler,
Stefan
1997fbs..conf..313K Altcode: 1997LDP....22..313K
No abstract at ADS
---------------------------------------------------------
Title: New Spectral analyses of pre-white dwarfs
Authors: Rauch, T.; Dreizler, S.; Werner, K.
1997ASSL..214..221R Altcode: 1997whdw.work..221R
No abstract at ADS
---------------------------------------------------------
Title: Apparently Normal o- and B-Type Stars at High Galactic
Latitudes?
Authors: Heber, U.; Moehler, S.; Schmidt, J. H. K.; Dreizler, S.;
Geffert, M.; Reid, I. N.
1997fbs..conf...87H Altcode: 1997LDP....22...87H
No abstract at ADS
---------------------------------------------------------
Title: Non-LTE analyses of DO white dwarfs
Authors: Dreizler, S.; Werner, K.
1997ASSL..214..213D Altcode: 1997whdw.work..213D
No abstract at ADS
---------------------------------------------------------
Title: New results on PG 1159 stars and ultrahigh-excitation DO
white dwarfs
Authors: Werner, K.; Dreizler, S.; Heber, U.; Rauch, T.
1997ASSL..214..207W Altcode: 1997whdw.work..207W
No abstract at ADS
---------------------------------------------------------
Title: Do White Dwarfs
Authors: Dreizler, S.; Werner, K.; Heber, U.; Reid, N.; Hagen, Hans
1997fbs..conf..303D Altcode: 1997LDP....22..303D
No abstract at ADS
---------------------------------------------------------
Title: New Results from the Stellar Component of the Hamburg Schmidt
Survey: a Sample of SDO Stars
Authors: Lemke, M.; Heber, U.; Napiwotzki, R.; Dreizler, S.; Engels, D.
1997fbs..conf..375L Altcode: 1997LDP....22..375L
No abstract at ADS
---------------------------------------------------------
Title: The extreme-ultraviolet spectrum of the central star of the
planetary nebula NGC 1360
Authors: Hoare, Melvin G.; Drake, Jeremy J.; Werner, Klaus; Dreizler,
Stefan
1996MNRAS.283..830H Altcode:
We have used the Extreme Ultraviolet Explorer (EUVE) to obtain the
first EUV spectrum of the central star of a planetary nebula, that of
NGC 1360. The photospheric spectrum shows continuum absorption edges
due to O^4+ as well as absorption-line features. NLTE model atmospheres
including line blanketing by iron-group elements can match the general
level and shape of the spectrum, but are not capable of explaining all
the observed features, precluding a detailed fit. Our solar abundance
models require T_eff=110000K, logg=6.0 and N_H=8.5x10^19cm^-2. A new
optical spectrum is presented and analysed with NLTE models. Stellar
parameters in reasonable agreement with the EUV results are derived. It
is found that many optical lines need to be considered, otherwise the
best fits are not necessarily unique. This data set will provide a
stern test for future NLTE models, which will need to include still
more line blanketing before a totally satisfactory fit is obtained.
---------------------------------------------------------
Title: Spectral analysis of hot helium-rich white dwarfs.
Authors: Dreizler, S.; Werner, K.
1996A&A...314..217D Altcode:
We present a model atmosphere analysis of most known hot helium-rich
white dwarfs of spectral type DO. The stars represent the non-DA white
dwarf cooling sequence from the hot end (T_eff_=~120000K) down to
the DB gap (T_eff_=~45000K). From medium resolution optical spectra,
effective temperatures, surface gravities, and element abundances
are determined by means of non-LTE model atmospheres. Compared to
previous LTE analyses available for some of the program stars, higher
effective temperatures are derived. The existence of the DB gap is
confirmed. For the first time reliable surface gravities for a large
sample of DO white dwarfs are determined. With the help of theoretical
evolutionary tracks the DO masses are determined. We find a mean value
of 0.59+/-0.08M<SUB>sun</SUB>_ which virtually coincides with the mean
masses of the DA and DB white dwarfs. Hydrogen cannot be identified
in any optical DO spectrum, which includes the former DOA prototype
HZ21. Hence HD149499B remains the only DO white dwarf with a positive
(FUV) detection of trace hydrogen in the photosphere. The number ratio
of DA/non-DA white dwarfs significantly increases along the cooling
sequence and thus corroborates the hydrogen float-up hypothesis as an
explanation for the DB gap. From optical, IUE, and HST spectra metal
abundances or upper limits could be derived for most DOs, allowing
a comprehensive comparison with predictions from diffusion/radiative
levitation calculations. A large scatter in metallicities is found,
even among objects with similar parameters and no clear trend along
the cooling sequence is detectable. This is severely at odds with
theoretical predictions. The evolutionary link between DO white dwarfs,
the PG1159 stars and DB white dwarfs is discussed, in particular
considering the overlapping positions of DO and PG1159 stars in the
HR diagram.
---------------------------------------------------------
Title: Confining the edges of the GW Vir instability strip.
Authors: Werner, K.; Dreizler, S.; Heber, U.; Rauch, T.
1996AGAb...12..198W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the hot ends of the white dwarf spectral sequences: Hot
white dwarfs containing helium from the Hamburg-Schmidt survey.
Authors: Heber, U.; Dreizler, S.; Hagen, H. -J.
1996A&A...311L..17H Altcode:
We report on the discovery of twelve very hot white dwarf stars
containing helium by follow-up spectroscopy of candidates selected
by the Hamburg-Schmidt survey. These stars belong to the sparsely
populated spectral subclasses DAO, DO and PG1159 tracing the hottest
ends of the white dwarf spectral sequences. Eight stars show helium
dominated spectra (four DOs, two PG1159 stars and two very hot DO/sdO
transition objects). Four stars have hydrogen dominated spectra (DAO),
out of which one is a spectroscopic binary. Metal absorption lines
are detected in one DO and one DAO star. The latter is unique and has
to be classified as the first known DAOZ star. Spectral comparison
indicates that all stars lie beyond the DB gap with T_eff_ exceeding
45000K. Evidence is given for T_eff_ as high as 100000K or more in
some stars. With these new discoveries the Hamburg-Schmidt survey has
increased the number of known DO and DAO white dwarfs and PG1159 stars
by 55%, 30% and 40%, respectively, an important step towards deriving
statistically meaningful samples of the hottest white dwarfs.
---------------------------------------------------------
Title: Iron and nickel abundances of subluminous
O-stars. I. NLTE-model atmospheres with line blanketing by iron
group elements.
Authors: Haas, S.; Dreizler, S.; Heber, U.; Jeffery, S.; Werner, K.
1996A&A...311..669H Altcode:
NLTE model atmospheres for hot evolved stars including line blanketing
of all iron group elements were first constructed by Dreizler &
Werner (1993). In this paper we improve computational details and check
the adopted simplifications. We also present a systematic investigation
of the consequences of iron group line blanketing on the atmospheric
structure (temperature stratification and ionization equilibria of
iron and nickel) and for various observational quantities in the case
of hot sdO model atmospheres. The inclusion of a vast number of iron
group lines yields a substantial flux blocking in the vicinity of the
He{2} 228A edge. The resulting effects on the optical line profiles
of hydrogen and helium lines are none the less marginal. The most
pronounced differences occur in the cores of these lines, in particular
of the He{2} 4686A line. The new models are applied to an abundance
analysis of Fe{5}, Fe{6} and Ni{6} lines in the high resolution IUE
spectrum of the hot sdO star BD+28 4211. An underabundance of iron by
1dex with respect to the sun is found, while nickel displays a solar
abundance. The reduced n_Fe_/n_Ni_ ratio (~1dex compared to the solar
value) is an important hint that radiative levitation may hinder the
gravitational settling of these species. It is demonstrated that the
Fe{5}/Fe{6} ionization equilibrium is a reliable indicator for T_eff_
consistent with results from the optical He{1}/He{2} ionization
equilibrium routinely used for spectroscopic analyses.
---------------------------------------------------------
Title: The Origin of the Peculiar Hybrid PG 1159 Stars
Authors: Dreizler, S.
1996hst..prop.6463D Altcode: 1996hst..prop.2874D
The PG 1159 stars form a new class of hydrogen deficient prewhite dwarfs
(PWD) representing the hottest stage of PWDevolution. Quantitative
spectral analyses of most knownPG 1159 stars have been carried out by
the proposers fromoptical, UV (IUE, HST) and EUV (EUVE) observations. It
hasbeen shown that these stars have atmospheres dominated by Cand
He. In the hottest stars also a significant amount of O ispresent. The
proposed targets, HS2324+3944, NGC7094, and Abell43define a small
group of peculiar PG 1159 stars. Unlikeall other PG 1159 stars
hydrogen is detected in their spectra.Stellar parameters derived by the
investigators from opticalspectra suggest that, as a consequence of a
lower mass, theywent through a less drastic mass-loss phase than the
ordinaryPG 1159 stars. In order to verify that hypothesis a moreprecise
determination of the effective temperature isrequired. This is not
possible from optical analyses alone. Wedemonstrate that a great
improvement on the determination ofthe effective temperatures can
be achieved by HST-GHRSspectra. The spectra will be analyzed with new
highlysophisticated NLTE line blanketed model atmospheres, whichallow to
include many elements up to the iron group self-consistently. A precise
placement of HS2324+3944, NGC7094, and Abell43in the HR-diagram holds
the key for understanding theevolutionary history of the PG 1159 class.
---------------------------------------------------------
Title: Discovery and analysis of a hydrogen-rich PG1159 star.
Authors: Dreizler, S.; Werner, K.; Heber, U.; Engels, D.
1996A&A...309..820D Altcode:
The discovery of a new peculiar PG1159 star by follow-up spectroscopy of
candidates selected from objective-prism plates of the Hamburg Schmidt
Survey is presented. From a NLTE model atmosphere analysis an effective
temperature of 130000+/-10000K and a surface gravity of logg=6.2+/-0.2
are determined, which together with the high carbon abundance place
HS2324+3944 in the region of low gravity PG1159 stars. The detection
of hydrogen, however, makes HS2324+3944 unique amongst the PG1159
stars. While three central stars of Planetary Nebulae have spectra
similar to HS2324+3944, hydrogen could not be detected up to now in
any PG1159 star not associated with a nebula. The abundances of helium,
carbon and nitrogen (C/He=0.3, N/He<2x10^-3^) are similar to that of
"normal" PG1159 stars while the O abundance is found to be somewhat
lower than "normal" (O/He=2-10x10^-3^).
---------------------------------------------------------
Title: High resolution UV spectroscopy of two hot (pre-) white dwarfs
with the Hubble Space Telescope. KPD0005+5106 and RXJ2117+3412.
Authors: Werner, K.; Dreizler, S.; Heber, U.; Rauch, T.; Fleming,
T. A.; Sion, E. M.; Vauclair, G.
1996A&A...307..860W Altcode:
High resolution UV spectra of KPD0005+5106 and RXJ2117+3412 have
been obtained with the Goddard High Resolution Spectrograph aboard
the Hubble Space Telescope. The data were subject to a non-LTE model
atmosphere analysis. For KPD0005+5106, the hottest known helium-rich
white dwarf, the C and N abundances as well as an upper limit for O
have been determined (log(C/He)=-3, log(N/He)=-6, log(O/He)<-5.5,
by number), improving results from previous studies. These abundances
are severely at odds with diffusion/radiative forces theory. They
are possible primordial relics of their ancestral progenitor in the
post-AGB phase. Besides the photospheric lines with a velocity shift
of +35km/s we find a distinct interstellar/circumstellar absorption
line system shifted by -15km/s. Difficulties are encountered with
line profile fits to the spectrum of RXJ2117+3412, an extremely hot
hydrogen-deficient (PG1159-type) central star. Some of the strong C
IV and O VI lines are too narrow to match the observations. Either
the neglect of wind-effects in our models or the lack of reliable line
broadening data may be responsible for this. A weak O V 1371A line is
detected which suggests, that the effective temperature is higher than
thought before (T_eff_=170000K). This means that RXJ2117+3412 is the
hottest known PG1159 star together with H1504+65. Interstellar and
photospheric line spectra are clearly separated, with shifts of -19
and +23km/s, respectively. Both stars exhibit a strong O VIII emission
line near 2977A, which cannot be of photospheric origin but probably
arises from shock fronts along a stellar wind. The line widths are
of the order of 150km/s. In addition, KPD0005+5106 shows another,
equally strong emission feature near 2982A which either stems from
photospheric N V or from non-photospheric C V.
---------------------------------------------------------
Title: Spectral analysis of hot helium-rich white dwarfs
Authors: Dreizler, S.; Werner, K.
1996ASPC...96..281D Altcode: 1996hds..conf..281D
No abstract at ADS
---------------------------------------------------------
Title: Confining the Edges of the GW VIR Instability Strip
Authors: Werner, Klaus; Dreizler, Stefan; Heber, Ulrich; Rauch, Thomas
1996aeu..conf..229W Altcode: 1996IAUCo.152..229W
No abstract at ADS
---------------------------------------------------------
Title: Helium-rich stars from the HS, PG and KPD surveys
Authors: Heber, U.; Dreizler, S.; Werner, K.; Engels, D.; Hagen, H. -J.
1996ASPC...96..241H Altcode: 1996hds..conf..241H
No abstract at ADS
---------------------------------------------------------
Title: NLTE spectral analysis of helium-rich sdO stars from the
southern HK survey
Authors: Drilling, J. S.; Napiwotzki, R.; Dreizler, S.; Heber, U.;
Beers, T. C.
1996ASPC...96..317D Altcode: 1996hds..conf..317D
No abstract at ADS
---------------------------------------------------------
Title: A catalogue of hydrogen-deficient stars
Authors: Jeffery, C. S.; Heber, U.; Hill, P. W.; Dreizler, S.;
Drilling, J. S.; Lawson, W. A.; Leuenhagen, U.; Werner, K.
1996ASPC...96..471J Altcode: 1996hds..conf..471J
No abstract at ADS
---------------------------------------------------------
Title: PG 1159 stars
Authors: Werner, K.; Dreizler, S.; Heber, U.; Rauch, T.
1996ASPC...96..267W Altcode: 1996hds..conf..267W
No abstract at ADS
---------------------------------------------------------
Title: Ultra-high excitation features in hot white dwarfs: A DAO
and three DO stars discovered by the Hamburg-Schmidt survey.
Authors: Dreizler, S.; Heber, U.; Napiwotzki, R.; Hagen, H. J.
1995A&A...303L..53D Altcode:
We report on the discovery of four hot white dwarfs, one DAO
(HS2115+1148) and three DO (HS0158+2335, HS 0727+6003 and HS
2027+0651). The spectra of these stars exhibit shallow metal
absorption lines from ultrahighly excited ionization stages (C V, C
VI/N VI, N VII/O VII, O VIII, Ne IX, Ne X) with ionization energies
ranging from 392eV to 1362eV. We propose that they are formed in a
stellar wind, explaining their asymmetric shape. However, the He II
line spectra of the three DOs as well as the Balmer-line spectrum
of the DAO are peculiar and cannot be fitted by static NLTE model
atmospheres. These stars increase the number of hot degenerate stars
showing this phenomenon to six, this is the first time it is observed
in a hydrogen-rich star. Thus, these six stars might constitute a new
spectral subclass of hot white dwarfs suffering mass-loss from a hot
and fast wind.
---------------------------------------------------------
Title: Spectral analysis of the hot DO white dwarf PG1034+001.
Authors: Werner, K.; Dreizler, S.; Wolff, B.
1995A&A...298..567W Altcode:
We present a non-LTE model atmosphere analysis of the hot DO white dwarf
PG1034+001. It is based on archival HST GHRS spectra, on new optical
medium resolution spectra and pointed ROSAT PSPC observations. The
effective temperature is higher than previously thought (T_eff_=100000K,
Logg=7.5). We determined abundances of carbon, nitrogen, and oxygen
which are roughly in agreement with earlier LTE results. We also
determined the silicon abundance and, for the first time in a DO white
dwarf, the abundance of iron on hand of newly identified Fe VI lines in
the HST spectra. An upper abundance limit for nickel is derived. The
results are discussed in the framework of diffusion theory. We derive
a stellar mass of 0.59M<SUB>sun</SUB>_ and propose that PG1034+001 is
a descendant from the hydrogen-deficient PG1159 stars.
---------------------------------------------------------
Title: Detection of QSO Ton S 180 by the EUVE satellite.
Authors: Wisotzki, L.; Dreizler, S.; Engels, D.; Fink, H. -H.;
Heber, U.
1995A&A...297L..55W Altcode:
We report the detection of the bright QSO Ton S 180 by the Extreme
Ultraviolet Explorer satellite during its all-sky survey. The measured
count rate is 58cts/ksec, more than any other QSO or Sy-1 listed by
the First EUVE Source Catalog. We have compiled previously unpublished
optical, ultraviolet, and X-ray observations of this source, and
construct the continuum spectral energy distribution. The soft X-ray
range is well described by a single power law with spectral energy
index α=-2.0. Although different ROSAT pointings show that the total
X-ray counts have varied by a factor of 3, the shape of the spectrum
has remained unchanged. The EUVE flux is fully compatible with the
ROSAT survey measurement, confirming that the power law shape reaches
well into the EUV regime. No additional soft X-ray or EUV excess could
be found. The optical-UV continuum displays a strongly convex shape,
with a turnover in νxf<SUB>nu</SUB>_ already below 10eV. The overall
shape of the continuum suggests that more than a single emission
component contributes to the big blue bump.
---------------------------------------------------------
Title: Analysis of the DO White Dwarf PG 1034+001: Solution of the
He II 4686 Å Line Problem
Authors: Werner, Klaus; Dreizler, Stefan; Wolff, Burkhard
1995LNP...443..204W Altcode: 1995whdw.conf..204W
No abstract at ADS
---------------------------------------------------------
Title: Iron- and Nickel Abundances of sdO Stars
Authors: Haas, Stefan; Dreizler, Stefan; Heber, Ulrich; Meier, Thomas;
Werner, Klaus
1995LNP...443..243H Altcode: 1995whdw.conf..243H
No abstract at ADS
---------------------------------------------------------
Title: Confining the Edges of the GW VIR Instability Strip
Authors: Werner, K.; Rauch, T.; Dreizler, S.; Heber, U.
1995ASPC...83...96W Altcode: 1995aasp.conf...96W; 1995IAUCo.155...96W
No abstract at ADS
---------------------------------------------------------
Title: Discovery of two hot DO white dwarfs exhibiting
ultrahigh-excitation absorption lines.
Authors: Werner, K.; Dreizler, S.; Heber, U.; Rauch, T.; Wisotzki,
L.; Hagen, H. -J.
1995A&A...293L..75W Altcode:
We report on the detection of two faint blue stars (HE0504-2408 and
HS0713+3958) discovered by the Hamburg Schmidt surveys whose spectra are
dominated by broad and shallow metal absorption lines from ultrahighly
excited ionization stages (CV, CVI/NVI, NVII/OVII, OVIII, NeIX, NeX)
with ionization energies ranging from 392eV to 1362eV. Detailed non-LTE
modeling excludes a photospheric origin of these lines. Instead we
propose that they are formed in a stellar wind, explaining their
asymmetric shape. The underlying stellar source is probably a hot
helium-rich white dwarf (Teff about 70000K) causing the observed HeII
line spectrum with symmetric profiles. However, the HeII absorptions are
relatively strong and cannot simply be reproduced by a model atmosphere
for a DO white dwarf. Thus, these two stars might constitute a new
spectral subclass of hot helium-rich white dwarfs exhibiting spectral
signatures never observed before in any astrophysical object.
---------------------------------------------------------
Title: Triple-Alpha Burning Products on the Surface of Peculiar
Post-AGB Stars
Authors: Werner, K.; Dreizler, S.; Heber, U.; Rauch, T.
1995AIPC..327...45W Altcode: 1995nct3.conf...45W
The so-called PG 1159 stars form a new spectroscopic class of extremely
hot hydrogen-deficient post-AGB stars. Our spectral analyses with model
atmospheres show that their chemical surface composition is dominated
by carbon, helium, and oxygen. We suggest that these peculiar stars
have suffered a late helium-shell flash which has caused the removal of
the hydrogen-rich envelope and even most of the helium-rich intershell
matter. The idea that the former helium-burning region is now exposed at
the surface of the PG 1159 stars is supported by the recent detection
of a very high amount of neon in some objects. The most extreme object
is H1504+65 which is one of the brightest X-ray sources in the sky
and the hottest star ever analyzed with model atmosphere techniques
(T<SUB>eff</SUB>=170 000 K). The photosphere is devoid of hydrogen and
helium and composed of oxygen and carbon by equal amounts! This means
that we look at the naked core of the former Red Giant. This gives us
the unique possibility to confine empirically the still uncertainty
known <SUP>12</SUP>C(α,γ)<SUP>16</SUP>O nuclear reaction rate.
---------------------------------------------------------
Title: Detection of Ultra-Hot Pre-White Dwarfs?
Authors: Werner, Klaus; Rauch, Thomas; Dreizler, Stefan; Heber, Ulrich
1995LNP...443..171W Altcode: 1995whdw.conf..171W
No abstract at ADS
---------------------------------------------------------
Title: The EUVE spectrum of the hot DA white dwarf PG 1234+482
Authors: Jordan, Stefan; Koester, Detlev; Finley, David; Werner,
Klaus; Dreizler, Stefan
1995LNP...443..332J Altcode: 1995whdw.conf..332J
We have analyzed the EUVE spectrum of PG 1234+482 with fully blanketed
model atmospheres taking into account several million lines of heavy
elements. Most of the spectral features in the short (SW) and medium
(MW) wavelength spectrum can be identified with lines of iron, nickel
and calcium ions.
---------------------------------------------------------
Title: PG 1159 Stars and Their Evolutionary Link to DO White Dwarfs
Authors: Dreizler, Stefan; Werner, Klaus; Heber, Ulrich
1995LNP...443..160D Altcode: 1995whdw.conf..160D
No abstract at ADS
---------------------------------------------------------
Title: Stratification of helium in the photospheres of the helium-weak
stars HD 28843 and HD 49333.
Authors: Farthmann, M.; Dreizler, S.; Heber, U.; Hunger, K.
1994A&A...291..919F Altcode:
For four helium-weak and variable B stars phase-dependent
high-resolution spectrograms have been obtained with the
Echelec-spectrograph attached to the 1.5 m ESO telescope, with the
aim of testing whether HeI 4471A will give evidence of chemical
stratification within their photospheres. Of the four candidates, HR
3448=HD 74196 is a fast rotator (vsini=300km/s), however, no variability
is detectable, while HR 1100=HD 22470 does not exhibit any helium line
(posibly due to incomplete phase coverage). Only HR 1441=HD 28843 and
HR 2509=HD 49333 are genuine helium variables. Profile analyses of
HeI 4471, based on fully line blanketed model atmospheres which are
adapted to the relevant helium-content show that HD 28843 can fully be
explained by a cap model with two asymmetrically located helium caps
of equal radii. For HD 49333 vertical stratification in addition has
to be assumed in order to explain the excessively broad wings. This
confirms earlier (preliminary) results by Groote et al. (see Hunger
1986). Vertical stratification is infered for both inside and outside
the helium-caps of HD 49333.
---------------------------------------------------------
Title: On the nickel abundance in hot hydrogen-rich white dwarfs.
Authors: Werner, K.; Dreizler, S.
1994A&A...286L..31W Altcode:
We present a non-LTE iron and nickel abundance analysis of four
hot hydrogen rich white dwarfs from high resolution IUE spectra. The
investigation aims at the determination of the Ni/Fe ratio in order to
investigate if radiative acceleration prevents gravitational settling of
both elements. We succeeded in the first identification of nickel lines
in white dwarfs. In fact we find enhanced Ni/Fe ratios (compared to the
solar value) in the two extremely iron rich (for white dwarf standards)
stars RE0623--377 and RE2214--2 The effect is slightly smaller in the
other two objects considered (G191-B2B and Feige24). This is regarded
as evidence that radiation pressure acting through the huge number
of spectral lines is responsible for radiative levitation of iron
and nickel.
---------------------------------------------------------
Title: A "cool" PG 1159 star discovered by the Hamburg Schmidt Survey:
NLTE analysis of HS 0704+6153.
Authors: Dreizler, S.; Werner, K.; Jordan, S.; Hagen, H.
1994A&A...286..463D Altcode:
The discovery of a new PG 1159 star by follow-up spectroscopy of
candidates selected from objective-prism plates of the Hamburg Schmidt
Survey is presented. From a NLTE model atmosphere analysis an effective
temperature of 65 000 K and a surface gravity of logg=7.0 is determined,
which together with the extreme helium abundance (H/He<1 by number)
place HS 0704+6153 in the region of hot DO white dwarfs. The high carbon
and oxygen abundances (C/He=0.2, O/He~0.05 by number), however, are
typical for PG 1159 stars. Its effective temperature is by far lower
than that of any other PG 1159 star. HS 0704+6153 therefore is in the
transition stage between the PG 1159 stars and the DO white dwarfs,
it hence is an ideal object to study the gravitational settling of
metals in helium-rich atmospheres.
---------------------------------------------------------
Title: PG 2120+062 : an apparently normal O-star at high galactic
latitude.
Authors: Moehler, S.; Heber, U.; Dreizler, S.
1994A&A...282L..29M Altcode:
We report the spectroscopic identification of the faint blue star PG
2120+062 (V = 14.4 m) as an apparently normal O9 star. If massive, PG
2120+062 would be at a distance of 50 kpc and 25 kpc below the galactic
plane. T<SUB>eff</SUB> = 38000 K, log g = 4.25 results from a nonlocal
thermodynamic equilibrium (NLTE) model atmosphere analysis. PG 2120+062
could, however, also be a low mass post-AGB star at a distance of 5 kpc
that mimics a normal O star spectroscopically. Variable H-alpha emission
is interpreted as due to a circumstellar disk (Be star phenomenon) or
a close companion star. In the latter case, the primary to secondary
mass ratio would be very large M<SUB>p</SUB>/M<SUB>s</SUB> greater
than 7) and PG 2120+062 could be the progenitor of a symbiotic star
or a cataclysmic variable.
---------------------------------------------------------
Title: PG 1159 stars and their evolutionary link to DO white dwarfs.
Authors: Dreizler, S.; Werner, K.; Heber, U.
1994AGAb...10...62D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: PG 2120+062: an apparently normal O-star at high galactic
latitude.
Authors: Moehler, S.; Heber, U.; Dreizler, S.
1994AGAb...10...34M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Faint Blue Stars from the Hamburg Schmidt Survey
Authors: Dreizler, Stefan; Heber, Uli; Jordan, S.; Engels, D.
1994hsgh.conf..228D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the Evolutionary Link Between the PG 1159 Stars and the
DO White Dwarfs
Authors: Dreizler, S.
1994iue..prop.4896D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Quantitative Spectroscopy of the Very Hot Subluminous O-Stars:
K648 PG1159-035, and KPD0005+5106
Authors: Heber, Ulrich; Dreizler, Stefan; Werner, Klaus
1994hsgh.conf..187H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Detection of a possible new ultra-hot pre-white dwarf.
Authors: Werner, K.; Dreizler, S.; Heber, U.; Rauch, T.; Wisotzki, L.
1994AGAb...10...58W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Line blanketing by iron group elements in non-LTE model
atmospheres of hot stars.
Authors: Dreizler, S.; Werner, K.
1994ems..conf..147D Altcode:
The authors report on their recent progress in modeling non-LTE
atmospheres of O-stars including blanketing by lines from the iron
group elements. The numerical method to account for the huge number of
atomic levels and line transitions is presented. Results of exploratory
model calculations examining the effects on the temperature structure,
the hydrogen and helium line profiles and UV/EUV fluxes are discussed.
---------------------------------------------------------
Title: Quantitative Spectroscopy of K 648 --the PNN of Ps1 in the
Globular Cluster M15
Authors: Heber, Ulrich; Dreizler, Stefan; Werner, Klaus
1993AcA....43..337H Altcode:
We report preliminary results of a quantitative study of high resolution
UV and optical spectra of K648 obtained with the Hubble Space Telescope
and the Calar Alto 3.5 m telescope, respectively. Using state of the
art NLTE model- atmospheres we determine atmospheric parameters and the
abundances of hydrogen, helium and carbon. K648 is found to be helium-
and carbon-rich when compared to solar composition.
---------------------------------------------------------
Title: Two New Extremely Iron-rich Hot DA White Dwarfs and the Nature
of the EUV Opacity
Authors: Holberg, J. B.; Barstow, M. A.; Buckley, D. A. H.; Chen,
A.; Dreizler, S.; Marsh, M. C.; O'Donoghue, D.; Sion, E. M.; Tweedy,
R. W.; Vauclair, G.; Werner, K.
1993ApJ...416..806H Altcode:
We have obtained IUE echelle spectra of two bright extreme ultraviolet
(EUV) sources discovered by the ROSAT wide field camera all-sky
survey. These stars, RE 2214-492 and RE 0623-377, are previously
uncataloged hot DA white dwarfs with respective apparent visual
magnitudes of 11.71 and 12.09 and exhibit short-wavelength EUV cutoffs
steeper than most other DAs. The IUE echelle spectra are rich in
absorption lines due to a large number of Fe V and Fe VI features, in
addition to the highly ionized C, N, O ions frequently seen in other
hot DA white dwarfs. No He is observed in either star. Comparison
of RE 2214-492 and RE 0623-377 with two well-studied hot DA white
dwarfs, G191 B2B and Feige 24, indicates that these new stars are
both significantly hotter and more metal-rich than G191 B2B and Feige
24. From optical and UV line profiles we find T<SUB>eff</SUB> = 63,500
K and 60,300 K for RE 2214-492 and RE 0623-377, respectively. From
modeling of Fe V features in the echelle spectra we find corresponding
Fe abundances of log [N(Fe)/ n(H)] = -4.25±0.25. The association
of steep EUV cutoffs in these stars, and in G191 B2B and Feige 24,
with the observed presence of Fe suggests that iron-group elements
along with other heavy elements are responsible for much of the EUV
opacity observed by ROSA T in the hottest DA stars.
---------------------------------------------------------
Title: Line blanketing by iron group elements in non-LTE model
atmospheres for hot stars.
Authors: Dreizler, S.; Werner, K.
1993A&A...278..199D Altcode:
We present the first metal line blanketed non-Local Thermodynamic
Equilibrium (LTE) model atmospheres for O stars which include 130,000
lines of the iron group elements scandium through nickel, a subset
from Kurucz' (1991) line list, fully self-consistently. It is shown
that even the treatment of the complete line list (greater than
10<SUP>6</SUP> lines) in NLTE models poses no longer any fundamental
problem. The numerical solution of the metal line blanketing problem
consists of an opacity sampling technique within the framework of
the Accelerated Lambda Iteration method. Exploratory models with
different parameters were successfully constructed, e.g. for hot
subdwarfs and central stars of planetary nebulae as well as for white
dwarfs. We discuss the blanketing effects of metal lines (1) onto the
atmospheric stratification, (2) onto UV and EUV fluxes, (3) onto the
emergent H and He line profiles, and (4) the potential of iron lines
as sensitive temperature indicators. The models are used to interprete
EUV observations of the white dwarf G191-B2B and UV spectra of the
hot sdO star BD+28 deg 4211.
---------------------------------------------------------
Title: Metal Line Blanketed Non-LTE Model Atmospheres for Planetary
Nebula Nuclei
Authors: Werner, K.; Dreizler, S.
1993AcA....43..321W Altcode:
We report on our recent progress in modeling non-LTE central
star atmospheres including blanketing by lines from the iron group
elements. It is found that the spectroscopic analysis of the hottest
stars (T<SUB>eff</SUB> approx 90,000 K) based on hydrogen Balmer and
HeII lines is hardly affected by metal opacities in the models. As a
consequence, results from earlier analyses based on models composed
of hydrogen and helium only remain essentially unchanged.
---------------------------------------------------------
Title: Spectral analysis of extremely helium rich subdwarfs O-stars.
Authors: Dreizler, S.
1993A&A...273..212D Altcode:
The NLTE analyses of four extremely helium rich sdO stars based on
high resolution, high S/N CASPEC spectra are presented. Effective
temperatures, gravities and the abundances of H, He, C, N, O, Ne, Mg,
and Si have been deter- mined. It is found that LS<SUB>IV</SUB>+1O°9,
LSS 1274, and UV 0832-01 have very similar parameters: T<SUB>eff</SUB>
= 44500±1000 K, log g = 5.55±0.15. H is undetected in all programme
stars resulting in a upper limit of n<SUB>H</SUB>/n<SUB>He</SUB> ≤
0.1. C, N, and Ne are enriched, while Mg and Si are solar and O is
slightly depleted. Microturbulent velocity is found to be lower than to
km/s. The positions of these stars in the (log T<SUB>eff</SUB>,log g)
diagram indicate, that they are post-EHB (Extended Horizontal Branch)
stars. Their atmospheric composition can be understood as a mixture
of CNO and 3 - α processed material. UV 0904-02 is slightly hotter,
T<SUB>eff</SUB> = 46500±1000 K, log g = 5.55±0.15, and is as well
a post-EHB star. The atmosphere also displays a mixture of CNO and
3-α processed material, the primordial metallicity however, was
possibly lower.
---------------------------------------------------------
Title: Line blanketing by iron group elements in non-LTE model
atmospheres of hot stars
Authors: Dreizler, Stefan; Werner, Klaus
1993SSRv...66..147D Altcode:
We report on our recent progress in modeling non-LTE atmospheres of
O-stars including blanketing by lines from the iron group elements. The
numerical method to account for the huge number of atomic levels and
line transitions is presented. Results of exploratory model calculations
examining the effects on the temperature structure, the hydrogen and
helium line profiles and UV/EUV fluxes are discussed.
---------------------------------------------------------
Title: Faint blue stars from the Hamburg Schmidt Survey.
Authors: Dreizler, S.; Heber, U.; Jordan, S.
1993AGAb....9..152D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Metal Line Blanketed Non-LTE Model Atmospheres for Central
Stars of Planetary Nebulae
Authors: Werner, K.; Dreizler, S.
1993IAUS..155...83W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Line blanketing by iron group elements in non-LTE model
atmospheres for hot stars.
Authors: Haas, S.; Dreizler, S.; Werner, K.
1993AGAb....9..153H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: High resolution optical and UV spectroscopy of the central
star of K648.
Authors: Heber, U.; Dreizler, S.; Werner, K.
1993AGAb....9...70H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Metal line blanketing in non-LTE model atmospheres
Authors: Dreizler, S.; Werner, K.
1993ASIC..403..205D Altcode: 1993wdao.conf..205D
No abstract at ADS
---------------------------------------------------------
Title: NLTE analysis of extremely helium rich subdwarf O stars
Authors: Dreizler, S.
1993ASIC..403..287D Altcode: 1993wdao.conf..287D
No abstract at ADS
---------------------------------------------------------
Title: High Resolution UV Spectroscopy of 3 Metal Weak LIned SdO Stars
Authors: Dreizler, S.
1993iue..prop.4737D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: NLTE analysis of helium rich subdwarf O stars
Authors: Dreizler, S.
1992LNP...401..270D Altcode: 1992aets.conf..270D
No abstract at ADS
---------------------------------------------------------
Title: Iron line blanketing in NLTE model atmospheres for O stars:
First results
Authors: Dreizler, S.; Werner, K.
1992LNP...401..436D Altcode: 1992aets.conf..436D
No abstract at ADS
---------------------------------------------------------
Title: Non-Lte Model Atmosphere Calculations with Approximate Lambda
Operators
Authors: Dreizler, S.; Werner, K.
1991ASIC..341..155D Altcode: 1991sabc.conf..155D
No abstract at ADS
---------------------------------------------------------
Title: Non-LTE Sternatmosphärenmodelle für heliumreiche Sterne
des Spektraltyps sd0
---------------------------------------------------------
Title: Non-LTE Sternatmosphärenmodelle für
heliumreiche Sterne des Spektraltyps sd0
---------------------------------------------------------
Title: Non-LTE stellar
atmosphere models for helium-rich stars of spectral type sd0;
Authors: Dreizler, Stefan
1991PhDT.......156D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Hot subluminous stars at high galactic latitudes. III. Non-LTE
analysis of extremely helium rich sdO-stars.
Authors: Dreizler, S.; Heber, U.; Werner, K.; Moehler, S.; de Boer,
K. S.
1990A&A...235..234D Altcode:
The visual spectra of 15 extremely helium rich subdwarf O-stars are
analyzed. Effective temperatures and gravities are determined by means
of a new grid of helium and hydrogen line-blanketed non-LTE model
atmospheres calculated with the accelerated lambda iteration. Effective
temperatures cluster around 45,000 K and 65,000 K. Gravities range
from log g = 4.8 to log g = 6.0. Hydrogen is detected in 5 stars. Upper
limits to the hydrogen content are derived for the others. From these
spectroscopic results first conclusions about the evolutionary status
of these stars can be drawn. The program stars probably evolve from
the extended or blue horizontal branch. Mixing induced by thermal
pulses might account for the helium enrichment.
---------------------------------------------------------
Title: NLTE model atmospheres for He-rich sdO-stars.
Authors: Dreizler, S.; Heber, U.; Werner, K.
1990AGAb....5...16D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Non-LTE model atmospheres for hot evolved stars.
Authors: Werner, K.; Dreizler, S.; Heber, U.; Hunger, K.; Rauch, T.
1990nba..meet..379W Altcode: 1990taco.conf..379W
During the last years the authors have developed a computer code
to construct non-LTE model atmospheres for hot stars including
line blanketing effects. The particular methods gave way to the
computation of non-LTE model atmospheres which account for many more
opacity sources than could be treated within the classical complete
linearisation approach by Auer and Mihalas. With this code it became
possible for the first time to calculate grids of realistic non-LTE
line blanketed model atmospheres for subdwarf O-stars in a critical
temperature range as well as for the extremely hot (100,000K to
150,000K) so-called PG1159 stars. Both groups of stars consist of
objects being in advanced evolutionary stages representing immediate
White Dwarf progenitors. The atmospheres of these stars are enriched or
even dominated by nuclear processed material, namely either by helium
(sdO stars) or also by carbon and oxygen (PG1159 stars).
---------------------------------------------------------
Title: NLTE-analysis of extremely helium-rich sd0 stars
Authors: Dreizler, S.; Heber, U.; Werner, K.; de Boer, K. S.;
Moehler, S.
1989AGAb....3...45D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: NLTE-analysis of extremely helium-rich sdO-stars.
Authors: Dreizler, S.; Heber, U.; Werner, K.; de Boer, K. S.;
Moehler, S.
1989AGAb....3...44D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Spectroscopy of helium-rich subluminous O and B stars.
Authors: Heber, U.; Dreizler, S.; de Boer, K. S.; Moehler, S.;
Richtler, T.
1988AGAb....1...16H Altcode:
No abstract at ADS