solabs_rutten-rob

file: solabs_rutten-rob.html = solar physics author: rutten-rob
ADS abstracts papers/articles/publications/books by: rutten-rob
last: May 05 2012
explanation parallel bibtex collection for author: rutten-rob
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Title: Chromospheric backradiation in ultraviolet continua
and Halpha
Authors: Rutten, R. J.; Uitenbroek, H.
Bibliographic Code: 2012A&A...540A..86R ArXiv preprint
Paper (if ADS pdf and access) ADS page A recent paper states that ultraviolet backradiation from the solar
transition region and upper chromosphere strongly affects the degree of
ionization of minority stages at the top of the photosphere, i.e., in
the temperature minimum of the one-dimensional static model atmospheres
presented in that paper. We show that this claim is incompatible with
observations and we demonstrate that the pertinent ionization balances
are instead dominated by outward photospheric radiation, as in older
static models. We then analyze the formation of Halpha in the above
model and show that it has significant backradiation across the opacity
gap by which Halpha differs from other strong scatttering lines.

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Title: LEMUR: Large European module for solar Ultraviolet
Research
Authors: Teriaca, Luca; Andretta, Vincenzo; Auchère, Frédéric;
Brown, Charles M.; Buchlin, Eric; Cauzzi, Gianna;
Culhane, J. Len; Curdt, Werner; Davila, Joseph M.;
Del Zanna, Giulio; Doschek, George A.;
Fineschi, Silvano; Fludra, Andrzej;
Gallagher, Peter T.; Green, Lucie; Harra, Louise K.;
Imada, Shinsuke; Innes, Davina; Kliem, Bernhard;
Korendyke, Clarence; Mariska, John T.;
Martínez-Pillet, Valentin; Parenti, Susanna;
Patsourakos, Spiros; Peter, Hardi; Poletto, Luca;
Rutten, Robert J.; Schühle, Udo; Siemer, Martin;
Shimizu, Toshifumi; Socas-Navarro, Hector;
Solanki, Sami K.; Spadaro, Daniele;
Trujillo-Bueno, Javier; Tsuneta, Saku;
Dominguez, Santiago Vargas; Vial, Jean-Claude;
Walsh, Robert; Warren, Harry P.; Wiegelmann, Thomas;
Winter, Berend; Young, Peter
Bibliographic Code: 2011ExA...tmp..135T
Paper (if ADS pdf and access) ADS page
The solar outer atmosphere is an extremely dynamic environment
characterized by the continuous interplay between the plasma and the
magnetic field that generates and permeates it. Such interactions play a
fundamental role in hugely diverse astrophysical systems, but occur at
scales that cannot be studied outside the solar system. Understanding
this complex system requires concerted, simultaneous solar observations
from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at
high spatial resolution (between 0.1'' and 0.3''), at high temporal
resolution (on the order of 10 s, i.e., the time scale of chromospheric
dynamics), with a wide temperature coverage (0.01 MK to 20 MK, from the
chromosphere to the flaring corona), and the capability of measuring
magnetic fields through spectropolarimetry at visible and near-infrared
wavelengths. Simultaneous spectroscopic measurements sampling the entire
temperature range are particularly important. These requirements are
fulfilled by the Japanese Solar-C mission (Plan B), composed of a
spacecraft in a geosynchronous orbit with a payload providing a
significant improvement of imaging and spectropolarimetric capabilities
in the UV, visible, and near-infrared with respect to what is available
today and foreseen in the near future. The Large European Module for
solar Ultraviolet Research (LEMUR), described in this paper, is a large
VUV telescope feeding a scientific payload of high-resolution imaging
spectrographs and cameras. LEMUR consists of two major components: a VUV
solar telescope with a 30 cm diameter mirror and a focal length of 3.6
m, and a focal-plane package composed of VUV spectrometers covering six
carefully chosen wavelength ranges between 170 Å and 1270 Å.
The LEMUR slit covers 280'' on the Sun with 0.14'' per pixel sampling.
In addition, LEMUR is capable of measuring mass flows velocities (line
shifts) down to 2 km s - 1 or better. LEMUR has been proposed
to ESA as the European contribution to the Solar C mission.

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Title: The Quiet-Sun Photosphere and Chromosphere
Authors: Rutten, Robert J.
Bibliographic Code: 2011arXiv1110.6606R ArXiv preprint
Paper (if ADS pdf and access) ADS page The overall structure and the fine structure of the solar photosphere
outside active regions are largely understood, except possibly important
roles of a turbulent near-surface dynamo at its bottom, internal gravity
waves at its top, and small-scale vorticity. Classical 1D static
radiation-escape modelling has been replaced by 3D time-dependent MHD
simulations that come closer to reality. The solar chromosphere, in
contrast, remains ill-understood although its pivotal role in coronal
mass and energy loading makes it a principal research area. Its fine
structure defines its overall structure, so that hard-to-observe and
hard-to-model small-scale dynamical processes are the key to
understanding. However, both chromospheric observation and chromospheric
simulation presently mature towards the required sophistication. The
open-field features seem of greater interest than the easier-to-see
closed-field features.

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Title: LEMUR: Large European Module for solar Ultraviolet
Research. European contribution to JAXA's Solar-C
mission
Authors: Teriaca, Luca; Andretta, Vincenzo; Auchère, Frédéric;
Brown, Charles M.; Buchlin, Eric; Cauzzi, Gianna;
Culhane, J. Len; Curdt, Werner; Davila, Joseph M.;
Del Zanna, Giulio; Doschek, George A.;
Fineschi, Silvano; Fludra, Andrzej;
Gallagher, Peter T.; Green, Lucie; Harra, Louise K.;
Imada, Shinsuke; Innes, Davina; Kliem, Bernhard;
Korendyke, Clarence; Mariska, John T.;
Martínez-Pillet, Valentin; Parenti, Susanna;
Patsourakos, Spiros; Peter, Hardi; Poletto, Luca;
Rutten, Rob; Schühle, Udo; Siemer, Martin;
Shimizu, Toshifumi; Socas-Navarro, Hector;
Solanki, Sami K.; Spadaro, Daniele;
Trujillo-Bueno, Javier; Tsuneta, Saku;
Vargas Dominguez, Santiago; Vial, Jean-Claude;
Walsh, Robert; Warren, Harry P.; Wiegelmann, Thomas;
Winter, Berend; Young, Peter
Bibliographic Code: 2011arXiv1109.4301T
Paper (if ADS pdf and access) ADS page
Understanding the solar outer atmosphere requires concerted,
simultaneous solar observations from the visible to the vacuum
ultraviolet (VUV) and soft X-rays, at high spatial resolution (between
0.1" and 0.3"), at high temporal resolution (on the order of 10 s, i.e.,
the time scale of chromospheric dynamics), with a wide temperature
coverage (0.01 MK to 20 MK, from the chromosphere to the flaring
corona), and the capability of measuring magnetic fields through
spectropolarimetry at visible and near-infrared wavelengths.
Simultaneous spectroscopic measurements sampling the entire temperature
range are particularly important. These requirements are fulfilled by
the Japanese Solar-C mission (Plan B), composed of a spacecraft in a
geosynchronous orbit with a payload providing a significant improvement
of imaging and spectropolarimetric capabilities in the UV, visible, and
near-infrared with respect to what is available today and foreseen in
the near future. The Large European Module for solar Ultraviolet
Research (LEMUR), described in this paper, is a large VUV telescope
feeding a scientific payload of high-resolution imaging spectrographs
and cameras. LEMUR consists of two major components: a VUV solar
telescope with a 30 cm diameter mirror and a focal length of 3.6 m, and
a focal-plane package composed of VUV spectrometers covering six
carefully chosen wavelength ranges between 17 and 127 nm. The LEMUR slit
covers 280" on the Sun with 0.14" per pixel sampling. In addition, LEMUR
is capable of measuring mass flows velocities (line shifts) down to 2
km/s or better. LEMUR has been proposed to ESA as the European
contribution to the Solar C mission.

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Title: Ellerman Bombs at High Resolution. I. Morphological
Evidence for Photospheric Reconnection
Authors: Watanabe, Hiroko; Vissers, Gregal; Kitai, Reizaburo;
Rouppe van der Voort, Luc; Rutten, Robert J.
Bibliographic Code: 2011ApJ...736...71W ArXiv preprint
Paper (if ADS pdf and access) ADS page High-resolution imaging-spectroscopy movies of solar active region NOAA
10998 obtained with the Crisp Imaging Spectropolarimeter at the Swedish
1-m Solar Telescope show very bright, rapidly flickering, flame-like
features that appear intermittently in the wings of the Balmer Halpha
line in a region with moat flows and likely some flux emergence. They
show up at regular Halpha blue-wing bright points that outline the
magnetic network, but flare upward with much larger brightness and
distinct "jet" morphology seen from aside in the limbward view of these
movies. We classify these features as Ellerman bombs and present a
morphological study of their appearance at the unprecedented spatial,
temporal, and spectral resolution of these observations. The bombs
appear along the magnetic network with footpoint extents up to 900 km.
They show apparent travel away from the spot along the pre-existing
network at speeds of about 1 km s-1. The bombs flare
repetitively with much rapid variation at timescales of seconds only, in
the form of upward jet-shaped brightness features. These reach heights
of 600-1200 km and tend to show blueshifts; some show bi-directional
Doppler signature and some seem accompanied with an Halpha surge. They
are not seen in the core of Halpha due to shielding by overlying
chromospheric fibrils. The network where they originate has normal
properties. The morphology of these jets strongly supports deep-seated
photospheric reconnection of emergent or moat-driven magnetic flux with
pre-existing strong vertical network fields as the mechanism underlying
the Ellerman bomb phenomenon.

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Title: Quiet-Sun imaging asymmetries in Na I D1 compared
with other strong Fraunhofer lines
Authors: Rutten, R. J.; Leenaarts, J.;
Rouppe van der Voort, L. H. M.; de Wijn, A. G.;
Carlsson, M.; Hansteen, V.
Bibliographic Code: 2011A&A...531A..17R ArXiv preprint
Paper (if ADS pdf and access) ADS page Imaging spectroscopy of the solar atmosphere using the Na I
D1 line yields marked asymmetry between the blue and red line
wings: sampling a quiet-Sun area in the blue wing displays reversed
granulation, whereas sampling in the red wing displays normal
granulation. The Mg I b2 line of comparable strength does not
show this asymmetry, nor does the stronger Ca II 8542 Å line. We
demonstrate the phenomenon with near-simultaneous spectral images in Na
I D1, Mg I b2, and Ca II 8542 Å from the
Swedish 1-m Solar Telescope. We then explain it with line-formation
insights from classical 1D modeling and with a 3D magnetohydrodynamical
simulation combined with NLTE spectral line synthesis that permits
detailed comparison with the observations in a common format. The cause
of the imaging asymmetry is the combination of correlations between
intensity and Dopplershift modulation in granular overshoot and the
sensitivity to these of the steep profile flanks of the Na I
D1 line. The Mg I b2 line has similar core
formation but much wider wings due to larger opacity buildup and damping
in the photosphere. Both lines obtain marked core asymmetry from
photospheric shocks in or near strong magnetic concentrations, less from
higher-up internetwork shocks that produce similar asymmetry in the
spatially averaged Ca II 8542 Å profile.

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Title: The quiet chromosphere. Old wisdom, new insights,
future needs
Authors: Rutten, Robert J.
Bibliographic Code: 2010MmSAI..81..565R ArXiv preprint
Paper (if ADS pdf and access) ADS page The introduction to this review summarizes chromosphere observation with
two figures. The first part showcases the historical emphasis on the
eclipse chromosphere in the development of NLTE line formation theory
and criticizes 1D modeling. The second part advertises recent
breakthroughs after many decades of standstill. The third part discusses
what may or should come next.

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Title: Waves in the chromosphere: observations
Authors: Rutten, R. J.
Bibliographic Code: 2010arXiv1012.1196R ArXiv preprint
Paper (if ADS pdf and access) ADS page I review the literature on observational aspects of waves in the solar
chromosphere in the first part of this contribution. High-frequency
waves are invoked to build elaborate cool-star chromosphere heating
theories but have not been detected decisively so far, neither as
magnetic modes in network elements nor as acoustic modes in
below-the-canopy internetwork regions. Three-minute upward-propagating
acoustic shocks are thoroughly established through numerical simulation
as the cause of intermittent bright internetwork grains, but their
pistoning and their role in the low-chromosphere energy budget remain in
debate. Three-minute wave interaction with magnetic canopies is a newer
interest, presently progressing through numerical simulation.
Three-minute umbral flashes and running penumbral waves seem a similar
acoustic-shock phenomenon awaiting numerical simulation. The
low-frequency network Doppler modulation remains enigmatic. In the
second part, I address low-frequency ultraviolet brightness variations
of the internetwork chromosphere in more detail. They contribute about
half of the internetwork brightness modulation and presumably figure in
cool-star basal flux. They appear to be a mixture of inverse-contrast
granular overshoot at small scales and gravity-wave interference at
mesogranular scales. I present TRACE evidence for the latter
interpretation, and speculate that the low-frequency brightness minima
map canopy heights.

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Title: The Irkutsk Barium filter for narrow-band wide-field
high-resolution solar images at the Dutch Open
Telescope
Authors: Hammerschlag, Robert H.; Skomorovsky, Valery I.;
Bettonvil, Felix C. M.; Kushtal, Galina I.;
Olshevsky, Vyacheslav L.; Rutten, Robert J.;
Jägers, Aswin P. L.; Sliepen, Guus; Snik, Frans
Bibliographic Code: 2010SPIE.7735E.265H
Paper (if ADS pdf and access) ADS page
A wide-field birefringent filter for the barium II line at 455.4nm is
developed in Irkutsk. The Barium line is excellent for Doppler-shift
measurements because of low thermal line-broadening and steep flanks of
the line profile. The filter width is 0.008nm and the filter is tunable
over 0.4nm through the whole line and far enough in the neighboring
regions. A fast tuning system with servomotor is developed at the Dutch
Open Telescope (DOT). Observations are done in speckle mode with 10
images per second and Keller-VonDerLühe reconstruction using
synchronous images of a nearby bluecontinuum channel at 450.5nm.
Simultaneous observation of several line positions, typically 3 or 5,
are made with this combination of fast tuning and speckle. All
polarizers are birefringent prisms which largely reduced the light loss
compared to polarizing sheets. The advantage of this filter over
Fabry-Perot filters is its wide field due to a large permitted entrance
angle and no need of polishing extremely precise surfaces. The BaII
observations at the DOT occur simultaneously with those of a
fast-tunable birefringent H-alpha filter. This gives the unique
possibility of simultaneous speckle-reconstructed observations of
velocities in photosphere (BaII) and chromosphere (H-alpha).

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Title: Solar Spectroscopy and (Pseudo-)Diagnostics of the
Solar Chromosphere
Authors: Rutten, Robert J.
Bibliographic Code: 2010rast.conf..163R
Paper (if ADS pdf and access) ADS page
I first review trends in current solar spectrometry and then concentrate
on comparing various spectroscopic diagnostics of the solar
chromosphere. Some are actually not at all chromospheric but just
photospheric or clapotispheric and do not convey information on
chromospheric heating, even though this is often assumed. Balmer
Halpha is the principal displayer of the closed-field chromosphere,
but it is unclear how chromospheric fibrils gain their large Halpha
opacity. The open-field chromosphere seems to harbor most if not all
coronal heating and solar wind driving, but is hardly seen in optical
diagnostics.

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Title: The Quiet Solar Atmosphere Observed and Simulated in
Na I D1
Authors: Leenaarts, J.; Rutten, R. J.; Reardon, K.;
Carlsson, M.; Hansteen, V.
Bibliographic Code: 2010ApJ...709.1362L ArXiv preprint
Paper (if ADS pdf and access) ADS page The Na I D1 line in the solar spectrum is sometimes
attributed to the solar chromosphere. We study its formation in
quiet-Sun network and internetwork. We first present high-resolution
profile-resolved images taken in this line with the imaging spectrometer
Interferometric Bidimensional Spectrometer at the Dunn Solar Telescope
and compare these to simultaneous chromospheric images taken in Ca II
8542 Å and Halpha. We then model Na I D1 formation by
performing three-dimensional (3D) non-local thermodynamic equilibrium
profile synthesis for a snapshot from a 3D
radiation-magnetohydrodynamics simulation. We find that most Na I
D1 brightness is not chromospheric but samples the magnetic
concentrations that make up the quiet-Sun network in the photosphere,
well below the height where they merge into chromospheric canopies, with
aureoles from 3D resonance scattering. The line core is sensitive to
magneto-acoustic shocks in and near magnetic concentrations, where
shocks occur deeper than elsewhere, and may provide evidence of heating
deep within magnetic concentrations.

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Title: Solar Spectroscopy and (Pseudo-)Diagnostics of the
Solar Chromosphere
Authors: Rutten, Robert J.
Bibliographic Code: 2010rast.book..163R
Paper (if ADS pdf and access) ADS page
I first review trends in current solar spectrometry and then concentrate
on comparing various spectroscopic diagnostics of the solar
chromosphere. Some are actually not at all chromospheric but just
photospheric or clapotispheric and do not convey information on
chromospheric heating, even though this is often assumed. Balmer
Halpha is the principal displayer of the closed-field chromosphere,
but it is unclear how chromospheric fibrils gain their large Halpha
opacity. The open-field chromosphere seems to harbor most if not all
coronal heating and solar wind driving, but is hardly seen in optical
diagnostics.

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Title: Dual-Line Spectral Imaging of the Chromosphere
Authors: Cauzzi, G.; Reardon, K.; Rutten, R. J.;
Tritschler, A.; Uitenbroek, H.
Bibliographic Code: 2010mcia.conf..513C
Paper (if ADS pdf and access) ADS page
Halpha filtergrams are notoriously difficult to interpret, "beautiful
to view but not fit for analysis." We try to remedy this by using the
IBIS bi-dimensional spectrometer at the Dunn Solar Telescope at
NSO/Sacramento Peak to compare the quiet-sun chromosphere observed in
Halpha to what is observed simultaneously in Ca II 854.2 nm, sampling
both lines with high angular and spectral resolution and extended
coverage of space, time, and wavelength. Per (x, y, t) pixel we measured
the intensity and Dopplershift of the minimum of each line's
profile at that pixel, as well as the width of their inner chromospheric
cores. A paper submitted to A&A (December 2008) compares these
measurements in detail.

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Title: Magnetic Coupling between the Interior and
Atmosphere of the Sun
Authors: Hasan, S. S.; Rutten, R. J.
Bibliographic Code: 2010mcia.conf.....H
Paper (if ADS pdf and access) ADS page

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Title: The solar chromosphere at high resolution with IBIS.
IV. Dual-line evidence of heating in chromospheric
network
Authors: Cauzzi, G.; Reardon, K.; Rutten, R. J.;
Tritschler, A.; Uitenbroek, H.
Bibliographic Code: 2009A&A...503..577C ArXiv preprint
Paper (if ADS pdf and access) ADS page The structure and energy balance of the solar chromosphere remain poorly
known. We used the imaging spectrometer IBIS at the Dunn Solar Telescope
to obtain fast-cadence, multi-wavelength profile sampling of Halpha
and Ca ii 854.2 nm over a sizable two-dimensional field of view
encompassing quiet-Sun network. We provide a first inventory of how the
quiet chromosphere appears in these two lines by comparing basic profile
measurements in the form of image displays, temporal-average displays,
time slices, and pixel-by-pixel correlations. We find that the two lines
can be markedly dissimilar in their rendering of the chromosphere, but
that, nevertheless, both show evidence of chromospheric heating,
particularly in and around network: Halpha in its core width and Ca ii
854.2 nm in its brightness. We discuss venues for improved modeling.

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Title: Dynamic Lyalpha jets
Authors: Koza, J.; Rutten, R. J.; Vourlidas, A.
Bibliographic Code: 2009A&A...499..917K ArXiv preprint
Paper (if ADS pdf and access) ADS page Context: The solar chromosphere and transition region are highly
structured and complex regimes. A recent breakthrough has been the
identification of dynamic fibrils observed in Halpha as caused by
field-aligned magnetoacoustic shocks. Aims: We seek to find
whether such dynamic fibrils are also observed in Lyalpha. Methods: We used a brief sequence of four high-resolution Lyalpha
images of the solar limb taken by the Very high Angular resolution
ULtraviolet Telescope (VAULT), which displays many extending and
retracting Lyalpha jets. We measured their top trajectories and fitted
parabolas to the 30 best-defined ones. Results: Most jet tops
move supersonically. Half of them decelerate, sometimes
superballistically, the others accelerate. This bifurcation may arise
from incomplete sampling of recurrent jets. Conclusions: The
similarities between dynamic Lyalpha jets and Halpha fibrils suggest
that the magnetoacoustic shocks causing dynamic Halpha fibrils also
affect dynamic Lyalpha jets.

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Title: Explanation of the activity sensitivity of Mn I
5394.7 Å
Authors: Vitas, N.; Viticchiè, B.; Rutten, R. J.; Vögler, A.
Bibliographic Code: 2009A&A...499..301V ArXiv preprint
Paper (if ADS pdf and access) ADS page There is a long-standing debate why the Mn i 5394.7 Å line in the
solar irradiance spectrum brightens more at higher activity than other
photospheric lines. The claim that this is caused by spectral
interlocking to chromospheric emission in the Mg ii h & k lines is
disputed. In this paper we settle this issue, using classical
one-dimensional modeling for demonstration and modern three-dimensional
MHD simulation for verification and analysis. The unusual sensitivity of
the Mn i 5394.7 Å line to solar activity is due to its excessive
hyperfine structure. This overrides the thermal and granular Doppler
smearing through which the other, narrower, photospheric lines lose such
sensitivity. We take the nearby Fe i 5395.2 Å line as example of
the latter, and analyze the formation of both lines in detail to
demonstrate and explain the granular Doppler brightening which affects
all narrow photospheric lines. Neither the chromosphere nor Mg ii h
& k emission play a role, nor is it correct to describe the activity
sensitivity of Mn i 5394.7 Å in terms of plage models with outward
increasing temperature contrast. The Mn i 5394.7 Å line represents
a proxy diagnostic of strong-field magnetic concentrations in the deep
solar photosphere comparable to the G band and the blue wing of
Halpha, but not a better one than these. The Mn i lines are more
promising as diagnostics of weak fields in high-resolution Stokes
polarimetry.

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Title: DOT Tomography of the Solar Atmosphere VII.
Chromospheric Response to Acoustic Events
Authors: Rutten, R. J.; van Veelen, B.; Sütterlin, P.
Bibliographic Code: 2008SoPh..251..533R ArXiv preprint
Paper (if ADS pdf and access) ADS page We use synchronous movies from the Dutch Open Telescope sampling the G
band, Ca ii H, and Halpha with five-wavelength profile sampling to
study the response of the chromosphere to acoustic events in the
underlying photosphere. We first compare the visibility of the
chromosphere in Ca ii H and Halpha, demonstrate that studying the
chromosphere requires Halpha data, and summarize recent developments
in understanding why this is so. We construct divergence and vorticity
maps of the photospheric flow field from the G-band images and locate
specific events through the appearance of bright Ca ii H grains. The
reaction of the Halpha chromosphere is diagnosed in terms of
brightness and Doppler shift. We show and discuss three particular cases
in detail: a regular acoustic grain marking shock excitation by granular
dynamics, a persistent flasher, which probably marks magnetic-field
concentration, and an exploding granule. All three appear to buffet
overlying fibrils, most clearly in Dopplergrams. Although our diagnostic
displays to dissect these phenomena are unprecedentedly comprehensive,
adding even more information (photospheric Doppler tomography and
magnetograms along with chromospheric imaging and Doppler mapping in the
ultraviolet) is warranted.

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Title: Dynamic Fibrils in Ly-alpha
Authors: Koza, J.; Rutten, R. J.; Vourlidas, A.;
Suetterlin, P.
Bibliographic Code: 2008ESPM...12.2.16K
Paper (if ADS pdf and access) ADS page
We have detected dynamic fibrils (DFs) in Ly-alpha filtergrams taken
with the rocket-borne Very high Angular resolution ULtraviolet Telescope
(VAULT). Although the data consist of only a 1-min sequence of 4 images
taken near the solar limb during the second VAULT flight, they enable us
to identify and study the time evolution of over 50 DFs. Most show
parabolic trajectories in their angular extent, with supersonic maximum
velocities. The measured decelerations vary from sub-ballistic to
super-ballistic. The similarities with DFs seen in Halpha suggest a
common cause, possibly the presence of hot transition-region interfaces
around cool oscillation-fed jets.

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Title: Concluding remarks
Authors: Rutten, R. J.
Bibliographic Code: 2008ESPM...12..7.1R
Paper (if ADS pdf and access) ADS page

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Title: Halpha as a Chromospheric Diagnostic
Authors: Rutten, R. J.
Bibliographic Code: 2008ASPC..397...54R
Paper (if ADS pdf and access) ADS page
I first illustrate with images from the Dutch Open Telescope (DOT) that
Halpha is the principal diagnostic of the solar chromosphere. The DOT
movies at http://dot.astro.uu.nl demonstrate this fact even more
vividly.
I then summarize, on the basis of the recent numerical simulations by
Leenaarts et al. (2007),
why Halpha; is such an omnipresent diagnostic of the chromosphere. The
ubiquity of Halpha fibrils in both hot and cool gas is due to (i)- the
presence of shocks everywhere, guided by the magnetic field into dynamic
fibrils near the network and pushing the canopy and transition region
upward in weaker-field internetwork regions, (ii)- the large rate
difference between the fast hydrogen ionization/recombination balancing
in hot shocks and the slow balancing in cool post-shock gas, and (iii)-
the large excitation energy of Halpha's nis2 lower level, causing
strong coupling to the ion population. These three facts combine to
cause appreciable Halpha opacity throughout the chromosphere,
enormously in excess of instantaneous Saha-Boltzmann partitioning in
cool post-shock gas. Thus, sluggish post-shock recombination causes
Halpha to be visible everywhere.
Finally, I address Halpha observing. Since Hinode's Halpha imaging
is affected by bubbles and limited in cadence, the DOT may serve as a
complementary facility furnishing profile-sampling Halpha image
sequences at the same 0.3 arcsec angular resolution as Hinode whenever
the La Palma seeing is good. However, imminent loss of DOT funding
requires outside financing of an on-site observer for DOT utilization in
co-pointed joint observing.

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Title: On the solar abundance of indium
Authors: Vitas, N.; Vince, I.; Lugaro, M.; Andriyenko, O.;
Gosic, M.; Rutten, R. J.
Bibliographic Code: 2008MNRAS.384..370V ArXiv preprint
Paper (if ADS pdf and access) ADS page The generally adopted value for the solar abundance of indium is over
six times higher than the meteoritic value. We address this discrepancy
through numerical synthesis of the 451.13-nm line on which all indium
abundance studies are based, both for the quiet Sun and the sunspot
umbra spectrum, employing standard atmosphere models and accounting for
hyperfine structure and Zeeman splitting in detail. The results, as well
as a re-appraisal of indium nucleosynthesis, suggest that the solar
indium abundance is close to the meteoritic value, and that some
unidentified ion line causes the 451.13-nm feature in the quiet-Sun
spectrum.

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Title: Search for photospheric footpoints of quiet Sun
transition region loops
Authors: Sánchez Almeida, J.; Teriaca, L.; Sütterlin, P.;
Spadaro, D.; Schühle, U.; Rutten, R. J.
Bibliographic Code: 2007A&A...475.1101S ArXiv preprint
Paper (if ADS pdf and access) ADS page Context: The footpoints of quiet Sun Transition Region (TR) loops do not
seem to coincide with the photospheric magnetic structures appearing in
traditional low-sensitivity magnetograms. Aims: We look for the
so-far unidentified photospheric footpoints of TR loops using G-band
bright points (BPs) as proxies for photospheric magnetic field
concentrations. Methods: We compare TR measurements with
SoHO/SUMER and photospheric magnetic field observations obtained with
the Dutch Open Telescope. Results: Photospheric BPs are associated
with bright TR structures, but they seem to avoid the brightest parts of
the structure. BPs appear in regions that are globally redshifted, but
they avoid extreme velocities. TR explosive events are not clearly
associated with BPs. Conclusions: The observations are not
inconsistent with the BPs being footpoints of TR loops, although we have
not succeeded to uniquely identify particular BPs with specific TR
loops.

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Title: Non-equilibrium hydrogen ionization in 2D
simulations of the solar atmosphere
Authors: Leenaarts, J.; Carlsson, M.; Hansteen, V.;
Rutten, R. J.
Bibliographic Code: 2007A&A...473..625L ArXiv preprint
Paper (if ADS pdf and access) ADS page Context: The ionization of hydrogen in the solar chromosphere and
transition region does not obey LTE or instantaneous statistical
equilibrium because the timescale is long compared with important
hydrodynamical timescales, especially of magneto-acoustic shocks. Since
the pressure, temperature, and electron density depend sensitively on
hydrogen ionization, numerical simulation of the solar atmosphere
requires non-equilibrium treatment of all pertinent hydrogen
transitions. The same holds for any diagnostic application employing
hydrogen lines. Aims: To demonstrate the importance and to
quantify the effects of non-equilibrium hydrogen ionization, both on the
dynamical structure of the solar atmosphere and on hydrogen line
formation, in particular Halpha. Methods: We implement an
algorithm to compute non-equilibrium hydrogen ionization and its
coupling into the MHD equations within an existing radiation MHD code,
and perform a two-dimensional simulation of the solar atmosphere from
the convection zone to the corona. Results: Analysis of the
simulation results and comparison to a companion simulation assuming LTE
shows that: a) non-equilibrium computation delivers much smaller
variations of the chromospheric hydrogen ionization than for LTE. The
ionization is smaller within shocks but subsequently remains high in the
cool intershock phases. As a result, the chromospheric temperature
variations are much larger than for LTE because in non-equilibrium,
hydrogen ionization is a less effective internal energy buffer. The
actual shock temperatures are therefore higher and the intershock
temperatures lower. b) The chromospheric populations of the hydrogen n =
2 level, which governs the opacity of Halpha, are coupled to the ion
populations. They are set by the high temperature in shocks and
subsequently remain high in the cool intershock phases. c) The
temperature structure and the hydrogen level populations differ much
between the chromosphere above photospheric magnetic elements and above
quiet internetwork. d) The hydrogen n = 2 population and column density
are persistently high in dynamic fibrils, suggesting that these obtain
their visibility from being optically thick in Halpha also at low
temperature.
Movie and Appendix A are only available in electronic form at
http://www.aanda.org

@--------------------------------------------------------------------
Title: Aperture Increase Options for the Dutch Open
Telescope
Authors: Hammerschlag, R. H.; Bettonvil, F. C. M.;
Jägers, A. P. L.; Rutten, R. J.
Bibliographic Code: 2007ASPC..368..573H ArXiv preprint
Paper (if ADS pdf and access) ADS page This paper is an invitation to the international community to
participate in the usage and a substantial upgrade of the Dutch Open
Telescope on La Palma (DOT, http://dot.astro.uu.nl).
We first give a brief overview of the approach, design, and current
science capabilities of the DOT. It became a successful
0.2-arcsec-resolution solar movie producer through its combination of
(i) an excellent site, (ii) effective wind flushing through the fully
open design and construction of both the 45-cm telescope and the 15-m
support tower, (iii) special designs which produce extraordinary
pointing stability of the tower, equatorial mount, and telescope, (iv)
simple and excellent optics with minimum wavefront distortion, and (v)
large-volume speckle reconstruction including narrow-band processing.
The DOT's multi-camera multi-wavelength speckle imaging system samples
the solar photosphere and chromosphere simultaneously in various optical
continua, the G band, Ca II H (tunable throughout the blue wing), and
Halpha (tunable throughout the line). The resulting DOT data sets are
all public. The DOT database (http://dotdb.phys.uu.nl/DOT) now contains
many tomographic image sequences with 0.2-0.3 arcsec resolution and up
to multi-hour duration. You are welcome to pull them over for analysis.
The main part of this contribution outlines DOT upgrade designs
implementing larger aperture. The motivation for aperture increase is
the recognition that optical solar physics needs the substantially
larger telescope apertures that became useful with the advent of
adaptive optics and viable through the DOT's open principle, both for
photospheric polarimetry at high resolution and high sensitivity and for
chromospheric fine-structure diagnosis at high cadence and full spectral
sampling.
Our upgrade designs for the DOT are presented in an incremental sequence
of five options of which the simplest (Option I) achieves 1.4 m aperture
using the present tower, mount, fold-away canopy, and multi-wavelength
speckle imaging and processing systems. The most advanced (Option V)
offers unblocked 2.5 m aperture in an off-axis design with a large
canopy, a wide 30-m high support tower, and image transfer to a
groundbased optics lab for advanced instrumentation. All five designs
employ adaptive optics. The important advantages of fully open,
wind-transparent and wind-flushed structure, polarimetric constancy, and
absence of primary-image rotation remain. All designs are relatively
cheap through re-using as much of the existing DOT hardware as possible.
Realization of an upgrade requires external partnership(s). This report
about DOT upgrade options therefore serves also as initial documentation
for potential partners.

@--------------------------------------------------------------------
Title: Chromospheric and Transition-Region Dynamics in
Plage
Authors: de Wijn, A. G.; de Pontieu, B.; Rutten, R. J.
Bibliographic Code: 2007ASPC..368..137D
Paper (if ADS pdf and access) ADS page
We study the dynamical interaction of the solar chromosphere with the
transition region in mossy and non-mossy active-region plage. We
carefully align image sequences taken with the Transition Region And
Coronal Explorer (TRACE) in the ultraviolet passbands around 1550, 1600,
and 1700 Å and the extreme ultraviolet passbands at 171 and 195
Å. We compute Fourier phase-difference spectra that are spatially
averaged separately over mossy and non-mossy plage to study temporal
modulations as a function of temporal frequency. The 1550 versus 171
Å comparison shows zero phase difference in non-mossy plage. In
mossy plage, the phase differences between all UV and EUV passbands show
pronounced upward trends with increasing frequency, which abruptly
changes into zero phase difference beyond 4 -- 6 mHz. The phase
difference between the 171 and 195 Å sequences exhibits a shallow
dip below 3 mHz and then also turns to zero phase difference beyond this
value. We attribute the various similarities between the UV and EUV
diagnostics that are evident in the phase-difference diagrams to the
contribution of the C IV resonance lines in the 1550 and 1600 Å
passbands. The strong upward trend at the lower frequencies indicates
the presence of upward-traveling disturbances. It points to
correspondence between the lower chromosphere and the upper transition
region, perhaps by slow-mode magnetosonic disturbances, or by a
connection between chromospheric and coronal heating mechanisms. The
transition from this upward trend to zero phase difference at higher
frequencies is due to the intermittent obscuration by fibrils that
occult the foot points of hot loops, which are bright in the EUV and C
IV lines, in oscillatory manner.

@--------------------------------------------------------------------
Title: Observing the Solar Chromosphere
Authors: Rutten, R. J.
Bibliographic Code: 2007ASPC..368...27R ArXiv preprint
Paper (if ADS pdf and access) ADS page This review is split into two parts: one on chromospheric line formation
in answer to the frequent question ``where is my line formed'', and one
presenting state-of-the-art imagery of the chromosphere. In the first
part I specifically treat the formation of the Na D lines, Ca II
H&K, and Halpha. In the second I show DOT, IBIS, VAULT, and TRACE
images as evidence that the chromosphere consists of fibrils of
intrinsically different types. The straight-up ones are hottest. The
slanted ones are filled by shocks and likely possess thin transition
sheaths to coronal plasma. The ones hovering horizontally over
``clapotispheric'' cell interiors outline magnetic canopies and are
buffeted by shocks, most violently in the quietest regions.
In the absence of integral-field ultraviolet spectrometry, Halpha
remains the principal chromosphere diagnostic. The required
fast-cadence profile-sampling imaging is an important quest for new
telescope technology.

@--------------------------------------------------------------------
Title: ESMN in Memoriam (1998 -- 2006)
Authors: Rutten, R. J.
Bibliographic Code: 2007ASPC..368...21R
Paper (if ADS pdf and access) ADS page
The EC-FP5 European Solar Magnetism Network (ESMN) was terminated during
this conference. Together with its FP4 predecessor, the European Solar
Magnetometry Network (ESMN), it funded 22 postdoc and 9 graduate-student
appointments at nine solar physics groups in Western Europe, it enhanced
Europe-wide collaboration in solar physics, and it contributed to the
integration of East-European groups in West-European enterprises. Its
unfortunate demise results from lack of further fortune in the FP6
lottery. The FP6-funded Utrecht-Stockholm-Oslo graduate school in solar
physics represents offspring, the FP6 Solaire network is a partial
replacement, and the EAST undertaking and pledge to build an EST is a
most worthy FP7 stake. The EC's policy shifts from postdoc to predoc
funding and from requiring (too) small to requiring (too) large
consortia are criticized.

@--------------------------------------------------------------------
Title: The Physics of Chromospheric Plasmas
Authors: Heinzel, P.; Dorotovic, I.; Rutten, R. J.
Bibliographic Code: 2007ASPC..368.....H
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Fourier Analysis of Active-Region Plage
Authors: de Wijn, A. G.; De Pontieu, B.; Rutten, R. J.
Bibliographic Code: 2007ApJ...654.1128D ArXiv preprint
Paper (if ADS pdf and access) ADS page We study the dynamical interaction of the solar chromosphere with the
transition region in mossy and nonmossy active-region plage. We
carefully align image sequences taken with the Transition Region And
Coronal Explorer (TRACE) in the ultraviolet passbands around 1550, 1600,
and 1700 Å and the extreme ultraviolet passbands at 171 and 195
Å. We compute Fourier phase-difference spectra that are spatially
averaged separately over mossy and nonmossy plage to study temporal
modulations as a function of temporal frequency. The 1550 versus 171
Å comparison shows zero phase difference in nonmossy plage. In
mossy plage, the phase differences between all UV and EUV passbands show
pronounced upward trends with increasing frequency, which abruptly
changes into zero phase difference beyond 4-6 mHz. The phase difference
between the 171 and 195 Å sequences exhibits a shallow dip below 3
mHz and then also turns to zero phase difference beyond this value. We
attribute the various similarities between the UV and EUV diagnostics
that are evident in the phase-difference diagrams to the contribution of
the C IV resonance lines in the 1550 and 1600 Å passbands. The
strong upward trend at the lower frequencies indicates the presence of
upward-traveling disturbances. It points to correspondence between the
lower chromosphere and the upper transition region, perhaps by slow-mode
magnetosonic disturbances, or by a connection between chromospheric and
coronal heating mechanisms. The transition from this upward trend to
zero phase difference at higher frequencies is due to the intermittent
obscuration by fibrils that occult the footpoints of hot loops, which
are bright in the EUV and C IV lines, in an oscillatory manner.

@--------------------------------------------------------------------
Title: The Ba II 4554 / Hbeta Imaging Polarimeter for the
Dutch Open Telescope
Authors: Snik, F.; Bettonvil, F. C. M.; Jägers, A. P. L.;
Hammerschlag, R. H.; Rutten, R. J.; Keller, C. U.
Bibliographic Code: 2006ASPC..358..205S
Paper (if ADS pdf and access) ADS page
In order to expand the high-resolution, multi-wavelength imaging
capabilities of the Dutch Open Telescope (DOT), an additional
polarimetric channel based on a 80 mÅ tunable Lyot filter for Ba
II 4554 and Hbeta has been designed and constructed. The large atomic
mass and the resulting steep line wings, make Ba II 4554 particularly
suitable for the creation of photospheric Dopplergrams and Stokes-V
magnetograms. The line also yields a significant degree of linear
(scattering) polarization for observations near the limb of the Sun,
which is modified by both horizontal and vertical weak-field topologies
through the Hanle effect and hyperfine-structure level crossing. The
polarimeter is based on liquid crystal variable retarders (LCVRs) as
polarization modulators in combination with the Lyot filter's entrance
polarizer. The tunability of the LCVRs is exploited to enable specific
wavelength calibration, selection of the reference frame of linear
polarization, and optimization of instrumental polarization cross-talk,
which for the DOT is constant in time. With the future Ba II 4554
photospheric magnetograms, we expect to be able to discern magnetic
structures of about 150 km with field strengths down to 100 G, and that
Hanle-type observations can be performed at a resolution of about 1
arcsec. The range of applicability of Hbeta imaging polarimetry has to
be explored after installation.

@--------------------------------------------------------------------
Title: On the Nature of the Solar Chromosphere
Authors: Rutten, R. J.
Bibliographic Code: 2006ASPC..354..276R ArXiv preprint
Paper (if ADS pdf and access) ADS page DOT high-resolution imagery suggests that only internetwork-spanning
Halpha ``mottles'' constitute the quiet-Sun chromosphere, whereas more
upright network ``straws'' in ``hedge rows'' reflect transition-region
conditions.

@--------------------------------------------------------------------
Title: Magnetic Patches in Internetwork Areas
Authors: de Wijn, A. G.; Rutten, R. J.;
Haverkamp, E. M. W. P.; Sütterlin, P.
Bibliographic Code: 2006ASPC..354...20D
Paper (if ADS pdf and access) ADS page
We present a study of internetwork magnetic elements that appear as
bright points in G-band (photosphere) and Ca II H (low chromosphere)
image sequences from the Dutch Open Telescope. Many bright points
appear intermittently in groups of long-lived structures that we call
``magnetic patches''. We develop an algorithm for the identification of
bright points and magnetic patches. The average internetwork bright
point lifetimes is measured to be 3.5 minutes in the G band, and 4.3
minutes in the Ca II H. We find an internetwork bright point number
density of 0.02 Mm^{-2} in the G-band sequence and 0.05 Mm^{-2} in the
Ca II H sequence. The bright points show a bimodal distribution of the
frame-to-frame horizontal velocities, with a peak at 0 km s^{-1} and a
wide hump centered around 1.2 km s^{-1}. The patches last much longer
than granular time scales (about nine hours) and outline cell-like
structures on mesogranular scale. We conclude that transient
internetwork bright points trace the locations of strong magnetic fields
that exist before the bright point appears and remain after it
disappears.

@--------------------------------------------------------------------
Title: Fourier analysis of chromospheric and transition
region emission above active region plage
Authors: de Wijn, A. G.; de Pontieu, B.; Rutten, R. J.
Bibliographic Code: 2006AGUFMSH23B0364D
Paper (if ADS pdf and access) ADS page
We study the dynamical interaction of the solar chromosphere with the
transition region (TR) in mossy and non-mossy active region plage, and
find evidence for correlated brightness changes or upward travelling
disturbances between the low chromosphere and the upper transition
region. We carefully align image sequences taken with the Transition
Region and Coronal Explorer (TRACE) in the ultraviolet passbands around
1550, 1600 and 1700 Å\ (indicative of low chromosphere and low TR)
and the extreme ultraviolet passbands at 171 and 195 Å\
(indicative of upper transition region). We compute Fourier
phase-difference spectra that are spatially averaged separately over
mossy and non-mossy plage to study temporal modulations as a function of
temporal frequency. We find that in non-mossy plage there is zero phase
difference between 1550 Å\ and 171 Å. In mossy plage, the
phase differences between all UV and EUV passbands show pronounced
upward trends with increasing frequency, which abruptly changes into
zero phase differences for frequencies beyond 4-6 mHz. The phase
difference between the 171 and 195 Å\ sequences exhibits a shallow
dip below 3 mHz and then also turns to zero phase difference beyond this
value. We attribute some of the various similarities between the UV and
EUV diagnostics that are evident in the phase-difference diagrams to the
contribution of the C IV resonance lines in the 1550 and 1600 Å\
passbands. The strong upward trend at lower frequencies in the phase
difference between all UV passbands (including 1700 Å) and 171
Å\ indicates the presence of upward travelling disturbances. Since
1700 Å\ does not contain C IV emission (low TR), this points to a
correlation between brightness changes in the lower chromosphere and the
upper TR, perhaps by slow-mode disturbances, or by a connection between
chromospheric and coronal heating mechanisms. We find that such
correlated brightness changes first occur in the low chromosphere, and
are followed about 400 s later in the upper TR. The transition from the
upward trend in phase difference at low frequencies to zero phase
difference at higher frequencies is due to the intermittent obscuration
by fibrils. These chromospheric jets occult the footpoints of hot loops,
which are bright in the EUV and C IV lines, in oscillatory manner.

@--------------------------------------------------------------------
Title: Tunable H-alpha Lyot filter with advanced servo
system and image processing: instrument design and
new scientific results with the Dutch Open Telescope
Authors: Bettonvil, Felix C. M.; Hammerschlag, Robert H.;
Sütterlin, Peter; Rutten, Robert J.;
Jägers, Aswin P. L.; Sliepen, Guus
Bibliographic Code: 2006SPIE.6269E..12B
Paper (if ADS pdf and access) ADS page
The Dutch Open Telescope (DOT; http://dot.astro.uu.nl) on La Palma is a
revolutionary open solar telescope, on an excellent site, on top of a
transparent tower of steel framework, and uses natural air flow to
minimize local seeing. The DOT is a high-resolution multi-wavelength
imager capable of long-duration time series aiming at magnetic fine
structure, topology and dynamics in the photosphere and low- and high
chromosphere. In this paper we describe the latest addition to the
multi-wavelength imaging system: a Lyot H-alpha camera channel operating
at a wavelength of 656.3 nm, being of major interest for
high-chromospheric phenomena. The channel is operated strictly
synchronous with the other channels and all data are speckle
reconstructed. The channel permits profile sampling and delivers
Dopplergrams in a 15 second time cadence, up to several hours long and
adding up to a total data amount of 1.6 Terabyte/day. A dedicated
computer (DSP, DOT Speckle Processor) has been built for processing the
data overnight.

@--------------------------------------------------------------------
Title: A comparison of solar proxy-magnetometry diagnostics
Authors: Leenaarts, J.; Rutten, R. J.; Carlsson, M.;
Uitenbroek, H.
Bibliographic Code: 2006A&A...452L..15L
Paper (if ADS pdf and access) ADS page
Aims.We test various proxy-magnetometry diagnostics, i.e., brightness
signatures of small-scale magnetic elements, for studying magnetic field
structures in the solar photosphere. Methods: .Images are
numerically synthesized from a 3D solar magneto-convection simulation
for, respectively, the G band at 430.5 nm, the CN band at 388.3 nm, and
the blue wings of the H alpha, H beta, Ca ii H, and Ca ii 854.2 nm
lines. Results: .Both visual comparison and scatter diagrams of
the computed intensity versus the magnetic field strength show that, in
particular for somewhat spatially extended magnetic elements, the blue H
alpha wing presents the best proxy-magnetometry diagnostic, followed
by the blue wing of H beta. The latter yields higher diffraction-limit
resolution. Conclusions: .We recommend using the blue H alpha
wing to locate and track small-scale photospheric magnetic elements
through their brightness appearance.

@--------------------------------------------------------------------
Title: DOT tomography of the solar atmosphere. VI. Magnetic
elements as bright points in the blue wing of Halpha
Authors: Leenaarts, J.; Rutten, R. J.; Sütterlin, P.;
Carlsson, M.; Uitenbroek, H.
Bibliographic Code: 2006A&A...449.1209L
Paper (if ADS pdf and access) ADS page
High-resolution solar images taken in the blue wing of the Balmer H
alpha line with the Dutch Open Telescope show intergranular magnetic
elements as strikingly bright features, similar to, but with appreciably
larger contrast over the surrounding granulation than their more
familiar manifestation as G-band bright points. Part of this prominent
appearance is due to low granular contrast, without granule/lane
brightness reversal as, e.g., in the wings of Ca II H & K. We use 1D
and 2D radiative transfer modeling and 3D solar convection and
magnetoconvection simulations to reproduce and explain the H alpha
wing images. We find that the blue H alpha wing obeys near-LTE line
formation. It appears particularly bright in magnetic elements through
low temperature gradients. The granulation observed in the blue wing of
H alpha has low contrast because of the lack of H alpha opacity in
the upper photosphere, Doppler cancellation, and large opacity
sensitivity to temperature working against source function sensitivity.
We conclude that the blue H alpha wing represents a promising proxy
magnetometer to locate and track isolated intermittent magnetic
elements, a better one than the G band and the wings of Ca II H & K
although less sharp at given aperture.

@--------------------------------------------------------------------
Title: Small Scale Magnetic Elements as Bright Points in
the Blue Halpha Wing
Authors: Leenaarts, J.; Sütterlin, P.; Rutten, R. J.;
Carlsson, M.; Uitenbroek, H.
Bibliographic Code: 2005ESASP.596E..15L
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: DOT tomography of the solar atmosphere. IV.
Magnetic patches in internetwork areas
Authors: de Wijn, A. G.; Rutten, R. J.;
Haverkamp, E. M. W. P.; Sütterlin, P.
Bibliographic Code: 2005A&A...441.1183D ArXiv preprint
Paper (if ADS pdf and access) ADS page We use G-band and Ca ii H image sequences from the Dutch Open Telescope
(DOT) to study magnetic elements that appear as bright points in
internetwork parts of the quiet solar photosphere and chromosphere. We
find that many of these bright points appear recurrently with varying
intensity and horizontal motion within longer-lived magnetic patches. We
develop an algorithm for detection of the patches and find that all
patches identified last much longer than the granulation. The patches
outline cell patterns on mesogranular scales, indicating that magnetic
flux tubes are advected by granular flows to mesogranular boundaries.
Statistical analysis of the emergence and disappearance of the patches
points to an average patch lifetime as long as 530±50~min (about
nine hours), which suggests that the magnetic elements constituting
strong internetwork fields are not generated by a local turbulent
dynamo.

@--------------------------------------------------------------------
Title: The wings of Ca II H and K as solar fluxtube
diagnostics
Authors: Sheminova, V. A.; Rutten, R. J.;
Rouppe van der Voort, L. H. M.
Bibliographic Code: 2005A&A...437.1069S
Paper (if ADS pdf and access) ADS page
We combine high-resolution Ca II H and K spectrograms from the
Swedish Vacuum Solar Telescope with standard fluxtube modeling to derive
photospheric temperature and velocity stratifications within individual
magnetic elements in plage near a sunspot. We find that 1D on-axis
modeling gives better consistency than spatial averaging over
flaring-fluxtube geometry. Our best-fit temperature stratifications
suggest that magnetic elements are close to radiative equilibrium
throughout their photospheres. Their brightness excess throughout the H
and K wings compared with the quiet photosphere is primarily due to low
density, not to mechanical heating. We conclude that the extended H and
K wings provide excellent fine-structure diagnostics for both
high-resolution observations and simulations of the solar photosphere.

@--------------------------------------------------------------------
Title: The temperature gradient in and around solar
magnetic fluxtubes
Authors: Sheminova, V. A.; Rutten, R. J.;
Rouppe van der Voort, L. H. M.
Bibliographic Code: 2005KFNTS...5..110S
Paper (if ADS pdf and access) ADS page
We use spectra covering the outer part of the extended wing of the solar
Ca II K line observed at high angular resolution with the Swedish Vacuum
Solar Telescope to test standard solar fluxtube models. The wings of the
Ca II resonance lines are formed in LTE both with regard to excitation
(source function) and to ionization (opacity) and, therefore, sample
temperature stratifications in relatively straightforward fashion. We
obtain best fits by combining steeper temperature gradients than those
in the standard models for both the tube inside and the tube
environment. Similarly steep gradients are also determined from a
numerical magnetoconvection simulation by the late A. S. Gadun. It is
found that the energy balance in the individual magnetic elements
appears to be close to radiative equilibrium throughout the photosphere.

@--------------------------------------------------------------------
Title: MAO-SIU solar physics collaborations
Authors: Rutten, R. J.
Bibliographic Code: 2005KFNTS...5...11R
Paper (if ADS pdf and access) ADS page
The Kyiv-Utrecht collaboration in solar physics has a long history and a
bright future. In this report I highlight some of our joint analyses in
the past, discuss the general solar physics context as I see it at
present, and describe exciting research challenges which fit the
Kyiv-Utrecht expertise and interests.

@--------------------------------------------------------------------
Title: Dynamics of the solar chromosphere. V.
High-frequency modulation in ultraviolet image
sequences from TRACE
Authors: de Wijn, A. G.; Rutten, R. J.; Tarbell, T. D.
Bibliographic Code: 2005A&A...430.1119D ArXiv preprint
Paper (if ADS pdf and access) ADS page We search for signatures of high-frequency oscillations in the upper
solar photosphere and low chromosphere in the context of acoustic
heating of outer stellar atmospheres. We use ultraviolet image sequences
of a quiet center-disk area from the Transition Region and Coronal
Explorer (TRACE) mission which were taken with strict cadence
regularity. The latter permits more reliable high-frequency diagnosis
than in earlier work. Spatial Fourier power maps, spatially averaged
coherence and phase-difference spectra, and spatio-temporal
(kh,f) decompositions all contain high-frequency features
that at first sight seem of considerable intrinsic interest but actually
are more likely to represent artifacts of different nature. Spatially
averaged phase difference measurement provides the most sensitive
diagnostic and indicates the presence of acoustic modulation up to
f&ap;20 mHz (periods down to 50 s) in internetwork areas.

@--------------------------------------------------------------------
Title: DOT++: the Dutch Open Telescope with 1.4-m aperture
Authors: Bettonvil, Felix C.; Hammerschlag, Robert H.;
Sütterlin, Peter; Rutten, Robert J.;
Jägers, Aswin P.; Snik, Frans
Bibliographic Code: 2004SPIE.5489..362B
Paper (if ADS pdf and access) ADS page
The Dutch Open Telescope (DOT; http://dot.astro.uu.nl) on La Palma is a
revolutionary open solar telescope, on an excellent site, on top of a
transparent steel tower, and uses natural air flow to minimize local
seeing. The aim is long-duration high-resolution imaging with a
multi-wavelength camera system. In order to achieve this, the DOT is
equipped with a diffraction limited imaging system and uses the speckle
reconstruction technique for removing the remaining atmospheric
turbulence. The DOT optical system is simple and consists currently of a
0.45m/F4.44 parabolic mirror and a 10x enlargement lens system. We
present our plans to increase the aperture of the DOT from 0.45m to
1.4m. The mirror support and telescope top shall be redesigned, but
telescope, tower, multi-wavelength camera system and speckle system
remain intact. The new optical design permits user selectable choice
between angular resolution and field size, as well as transversal pupil
shift introducing the possibility to use obstruction free apertures up
to 65cm. The design will include a low order AO system, which improves
the speckle S/N substantially during moderate seeing conditions.

@--------------------------------------------------------------------
Title: DOT tomography of the solar atmosphere. II. Reversed
granulation in Ca II H
Authors: Rutten, R. J.; de Wijn, A. G.; Sütterlin, P.
Bibliographic Code: 2004A&A...416..333R
Paper (if ADS pdf and access) ADS page
High-quality simultaneous image sequences from the Dutch Open Telescope
(DOT) in the G band and the Ca II H line are used to quantify the
occurrence of reversed granulation as a constituent of the subsonic
brightness pattern observed as a background to acoustic oscillations in
the quiet-Sun internetwork atmosphere. In the middle photosphere
reversed granulation constitutes a much larger part of this background
than at the larger heights sampled by ultraviolet radiation. The
anticorrelation with the underlying granulation reaches about 50% at a
temporal delay of 2-3 min, and increases with spatial image smoothing to
mesogranular resolution. We discuss the nature of reversed granulation
in terms of convection reversal, gravity waves, acoustic waves, and
intergranular magnetism, suggest that the internetwork background
pattern is primarily a mixture of the first two ingredients, and
speculate that it is also an inverse canopy mapper.

@--------------------------------------------------------------------
Title: DOT tomography of the solar atmosphere. I. Telescope
summary and program definition
Authors: Rutten, R. J.; Hammerschlag, R. H.;
Bettonvil, F. C. M.; Sütterlin, P.; de Wijn, A. G.
Bibliographic Code: 2004A&A...413.1183R
Paper (if ADS pdf and access) ADS page
The Dutch Open Telescope (DOT) on La Palma is an innovative optical
solar telescope capable of reaching 0.2 arcsec angular resolution over
extended durations. The DOT presently progresses from technology testbed
to a stable science configuration providing multi-wavelength imaging and
multi-camera speckle data acquisition for tomographic mapping of the
solar atmosphere. Large-volume speckle processing will soon enable
frequent usage and community-wide time allocation, in particular for
tandem operation with other solar telescopes pursuing spectropolarimetry
and EUV imaging. We summarize the DOT hardware and software in the
context of this increasing availability and outline the corresponding
``open-DOT'' program.

@--------------------------------------------------------------------
Title: The Dutch Open Telescope on La Palma
Authors: Rutten, R. J.; Bettonvil, F. C. M.;
Hammerschlag, R. H.; Jägers, A. P. L.; Leenaarts, J.;
Snik, F.; Sütterlin, P.; Tziotziou, K.;
de Wijn, A. G.
Bibliographic Code: 2004IAUS..223..597R
Paper (if ADS pdf and access) ADS page
The Dutch Open Telescope (DOT) on La Palma is an innovative solar
telescope combining open telescope structure and an open support tower
with a multi-wavelength imaging assembly and with synchronous speckle
cameras to generate high-resolution movies which sample different layers
of the solar atmosphere simultaneously and co-spatially at high
resolution over long durations. The DOT test and development phase is
nearly concluded. The installation of an advanced speckle processor
enables full science utilization including "Open-DOT" time allocation to
the international community. Co-pointing with spectropolarimeters at
other Canary Island telescopes and with TRACE furnishes valuable Solar-B
precursor capabilities.

@--------------------------------------------------------------------
Title: Dynamics of the solar chromosphere IV. Evidence for
atmospheric gravity waves from TRACE
Authors: Rutten, R. J.; Krijger, J. M.
Bibliographic Code: 2003A&A...407..735R
Paper (if ADS pdf and access) ADS page
We study the low-frequency brightness modulation of internetwork regions
in the low solar chromosphere using simultaneous ultraviolet and
white-light image sequences from the Transition Region and Coronal
Explorer (TRACE). The ultraviolet sequences exhibit a slowly varying
brightness pattern in internetwork regions on which the more familiar
acoustic three-minute oscillation is superimposed, with about half of
the peak brightness reached in internetwork grains contributed by the
low-frequency background. We address the nature of the latter, applying
two-dimensional Fourier filtering to isolate it from the acoustic
modulation. Spatio-temporal comparisons and selective time-delay scatter
correlations between the ultraviolet and white-light low-frequency
sequences establish that reversed granulation constitutes at most a
minor part of the ultraviolet background. Fourier analysis shows that
the meso-scale contribution dominates and consists of atmospheric
gravity waves.

@--------------------------------------------------------------------
Title: The Dutch Open Telescope
Authors: Rutten, Robert J.
Bibliographic Code: 2003ASSL..288..111R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Radiative Transfer in Stellar Atmospheres
Authors: Rutten, Robert J.
Bibliographic Code: 2003rtsa.book.....R
Paper (if ADS pdf and access) ADS page
The main topic treated in these graduate course notes is the classical
theory of radiative transfer for explaining stellar spectra. It needs
relatively much attention to be mastered. Radiative transfer in gaseous
media that are neither optically thin nor fully opaque and scatter to
boot is a key part of astrophysics but not a transparent subject. These
course notes represent a middle road between Mihalas' "Stellar
Atmospheres" (graduate level and up) and the books by Novotny and
Boehm-Vitense (undergraduate level). They are at about the level of
Gray's "The observation and analysis of stellar photospheres" but
emphasize NLTE radiative transfer rather than observational techniques
and data interpretation.

@--------------------------------------------------------------------
Title: La Palma observations of umbral flashes
Authors: Rouppe van der Voort, L. H. M.; Rutten, R. J.;
Sütterlin, P.; Sloover, P. J.; Krijger, J. M.
Bibliographic Code: 2003A&A...403..277R
Paper (if ADS pdf and access) ADS page
We present high-quality Ca II H & K data showing chromospheric
flashes in sunspot umbrae collected with the Swedish Vacuum Solar
Telescope, the Dutch Open Telescope, and the Swedish 1-m Solar Telescope
at the Roque de los Muchachos Observatory on La Palma. Differential
movies, time slices, spectrograms, and Fourier power maps demonstrate
that umbral flashes and running penumbral waves are closely related
oscillatory phenomena, combining upward shock propagation with coherent
wave spreading over the entire spot. We attribute the flash brightening
to large redshift by post-shock material higher up. We find no obvious
relation between umbral dots and umbral flashes.

@--------------------------------------------------------------------
Title: Multi-wavelength imaging system for the Dutch Open
Telescope
Authors: Bettonvil, Felix C.; Suetterlin, Peter;
Hammerschlag, Robert H.; Jagers, Aswin P.;
Rutten, Robert J.
Bibliographic Code: 2003SPIE.4853..306B
Paper (if ADS pdf and access) ADS page
The Dutch Open Telescope (DOT) is an innovative solar telescope,
completely open, on an open steel tower, without a vacuum system. The
aim is long-duration high resolution imaging and in order to achieve
this the DOT is equipped with a diffraction limited imaging system in
combination with a data acquisition system designed for use with the
speckle masking reconstruction technique for removing atmospheric
aberrations. Currently the DOT is being equipped with a multi-wavelength
system forming a high-resolution tomographic imager of magnetic fine
structure, topology and dynamics in the photosphere and low- and high
chromosphere. Finally the system will contain 6 channels: G-band (430.5
nm), Ca II H (K) (396.8 nm), H-alpha (656.3 nm), Ba II (455.4 nm), and
two continuum channels (432 and 651 nm). Two channels are in full
operation now and observations show that the DOT produces real
diffraction limited movies (with 0.2" resolution) over hours in G-band
(430.5 nm) and continuum (432 nm).

@--------------------------------------------------------------------
Title: NLTE in a Hot Hydrogen Star: Auer & Mihalas
Revisited
Authors: Wiersma, J.; Rutten, R. J.; Lanz, T.
Bibliographic Code: 2003ASPC..288..130W
Paper (if ADS pdf and access) ADS page
We pay tribute to two landmark papers published by Auer & Mihalas in
1969. They modeled hot-star NLTE-RE hydrogen-only atmospheres, using
two simplified hydrogen atoms: ApJ 156, 157: H I levels 1, 2 and c,
Lyman alpha the only line ApJ 156, 681: H I levels 1, 2, 3 and c,
Balmer alpha the only line and computed LTE and NLTE models with the
single line turned on and off. The results were extensively analyzed in
the two papers.
Any student of stellar line formation should take these beautiful papers
to heart. The final exercise in Rutten's lecture notes ``Radiative
Transfer in Stellar Atmospheres'' asks the student to work through five
pages of questions concerning diagrams from the first paper alone! That
exercise led to the present work in which we recompute the Auer-Mihalas
hot-hydrogen-star models with TLUSTY, adding results from a complete
hydrogen atom for comparison.
Our motivation for this Auer-Mihalas re-visitation is twofold:
1. to add diagnostic diagrams to the ones published by Auer &
Mihalas, in particular Bnu, Jnu,
Snu graphs to illustrate the role of the radiation field,
and radiative heating & cooling graphs to illustrate the radiative
energy budget,
2. to see the effect of adding the rest of the hydrogen atom.

@--------------------------------------------------------------------
Title: Utrecht Radiative Transfer Courses
Authors: Rutten, R. J.
Bibliographic Code: 2003ASPC..288...99R
Paper (if ADS pdf and access) ADS page
The Utrecht course ``The Generation and Transport of Radiation'' teaches
basic radiative transfer to second-year students. It is a much-expanded
version of the first chapter of Rybicki & Lightman's ``Radiative
Processes in Astrophysics''. After this course, students understand why
intensity is measured per steradian, have an Eddington-Barbier feel for
optically thick line formation, and know that scattering upsets LTE. The
text is a computer-aided translation by Ruth Peterson of my 1992
Dutch-language course. My aim is to rewrite this course in non-computer
English and make it web-available at some time. In the meantime, copies
of the Peterson translation are made yearly at Uppsala -- ask them, not
me. Eventually it should become a textbook.
The Utrecht course ``Radiative Transfer in Stellar Atmospheres'' is a
30-hour course for third-year students. It treats NLTE line formation
in plane-parallel stellar atmospheres at a level intermediate between
the books by Novotny and Boehm-Vitense, and Mihalas' ``Stellar
Atmospheres''. After this course, students appreciate that epsilon is
small, that radiation can heat or cool, and that computers have changed
the field. This course is web-available since 1995 and is regularly
improved -- but remains incomplete. Eventually it should become a
textbook.
The three Utrecht exercise sets ``Stellar Spectra A: Basic Line
Formation'', ``Stellar Spectra B: LTE Line Formation'', and ``Stellar
Spectra C: NLTE Line Formation'' are IDL-based computer exercises for
first-year, second-year, and third-year students, respectively. They
treat spectral classification, Saha-Boltzmann population statistics, the
curve of growth, the FAL-C solar atmosphere model, the role of H-minus
in the solar continuum, LTE formation of Fraunhofer lines, inversion
tactics, the Feautrier method, classical lambda iteration, and ALI
computation. The first two sets are web-available since 1998; the third
will follow.
Acknowledgement. Both courses owe much to previous Utrecht courses
taught by the late Kees Zwaan. The third exercise set was developed by
Phil Judge, Mandy Hagenaar, and Thijs Krijger.
Reverse acknowledgement. If you are a user of this free material you
might refer to this summary and so boost my citation standing.
Corrections are also welcome.

@--------------------------------------------------------------------
Title: Dynamical Behavior of the Upper Solar Photosphere
Authors: Rutten, R. J.
Bibliographic Code: 2003IAUS..210..221R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Solar Atmosphere Models
Authors: Rutten, R. J.
Bibliographic Code: 2002JAD.....8....8R
Paper (if ADS pdf and access) ADS page
This contribution honoring Kees de Jager's 80th birthday is a review of
"one-dimensional" solar atmosphere modeling that followed on the initial
"Utrecht Reference Photosphere" of Heintze, Hubenet & de Jager
(1964). My starting point is the Bilderberg conference, convened by de
Jager in 1967 at the time when NLTE radiative transfer theory became
mature. The resulting Bilderberg model was quickly superseded by the
HSRA and later by the VAL-FAL sequence of increasingly sophisticated
NLTE continuum-fitting models from Harvard. They became the "standard
models" of solar atmosphere physics, but Holweger's relatively simple
LTE line-fitting model still persists as a favorite of solar abundance
determiners. After a brief model inventory I discuss subsequent work on
the major modeling issues (coherency, NLTE, dynamics) listed as to-do
items by de Jager in 1968. The present conclusion is that
one-dimensional modeling recovers Schwarzschild's (1906) finding that
the lower solar atmosphere is grosso modo in radiative equilibrium. This
is a boon for applications regarding the solar atmosphere as
one-dimensional stellar example - but the real sun, including all the
intricate phenomena that now constitute the mainstay of solar physics,
is vastly more interesting.

@--------------------------------------------------------------------
Title: Dutch Open Telescope: status, results, prospects
Authors: Rutten, Robert J.; Sütterlin, Peter;
de Wijn, Alfred G.; Hammerschlag, Robert H.;
Bettonvil, Felix C. M.; Hoogendoorn, Piet W.;
Jägers, Aswin P. L.
Bibliographic Code: 2002ESASP.506..903R
Paper (if ADS pdf and access) ADS page
The Dutch Open Telescope (DOT) on La Palma is a revolutionary telescope
achieving high-resolution imaging of the solar surface. The DOT combines
a pioneering open design at an excellent wind-swept site with image
restoration through speckle interferometry. Its open principle is now
followed in major solar-telescope projects elsewhere. In the past three
years the DOT became the first solar telescope to regularly obtain 0.2"
resolution in extended image sequences, i.e., reaching the diffraction
limit of its 45-cm primary mirror. Our aim for 2003-2005 is to turn the
DOT into a 0.2" tomographic mapper of the solar atmosphere with frequent
partnership in international multi-telescope campaigns through
student-serviced time allocation. After 2005 we aim to triple the DOT
resolution to 0.07" by increasing the aperture to 140 cm and to renew
the speckle cameras and the speckle pipeline in order to increase the
field size and sequence duration appreciably. These upgrades will
maintain the DOT's niche as a tomographic high-resolution mapper in the
era when GREGOR, Solar-B and SDO set the stage.

@--------------------------------------------------------------------
Title: European Solar Magnetism Network
Authors: Rutten, Robert J.
Bibliographic Code: 2002ESASP.505..569R
Paper (if ADS pdf and access) ADS page
The future European Solar Magnetism Network (ESMN) will continue and
expand collaborations of the past European Solar Magnetometry Network
(ESMN). Both ESMN incarnations are funded by the European Commission, in
the Fourth and Fifth Framework programmes respectively. The major past
and future ESMN activity is the employment/deployment of European
postdocs.

@--------------------------------------------------------------------
Title: Opening the Dutch Open Telescope
Authors: Rutten, R. J.; de Wijn, A. G.; Sütterlin, P.;
Bettonvil, F. C. M.; Hammerschlag, R. H.
Bibliographic Code: 2002ESASP.505..565R
Paper (if ADS pdf and access) ADS page
We hope to "open the DOT" to the international solar physics community
as a facility for high-resolution tomography of the solar atmosphere.
Our aim is to do so combining peer-review time allocation with
service-mode operation in a "hands-on-telescope" education program
bringing students to La Palma to assist in the observing and processing.
The largest step needed is considerable speedup of the DOT speckle
processing.

@--------------------------------------------------------------------
Title: Small-scale topology of solar atmospheric dynamics.
V. Acoustic events and internetwork grains
Authors: Hoekzema, N. M.; Rimmele, T. R.; Rutten, R. J.
Bibliographic Code: 2002A&A...390..681H
Paper (if ADS pdf and access) ADS page
We use high-quality observations from the Dunn Solar Telescope at
NSO/Sacramento Peak to study spatio-temporal co-location of acoustic
flux events in the photosphere and internetwork grains in the
chromosphere. The events are diagnosed as sites with excess
upward-propagating five-minute waves measured from Dopplergrams. The
grains are repetitive bright internetwork features in simultaneous \CaII
\KtwoV filtergrams. We find that the largest-flux sites in the
granulation have appreciably larger than random probability to co-locate
with exceptionally bright chromospheric internetwork grains, at an
average delay of about two minutes which is likely to represent sound
travel time to the chromosphere. This finding strengthens the case for
acoustic grain excitation.

@--------------------------------------------------------------------
Title: The European Solar Magnetometry Network in 2000 -
2001
Authors: Rutten, R. J.
Bibliographic Code: 2002joso.book....7R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Dynamics of the solar chromosphere. III. Ultraviolet
brightness oscillations from TRACE
Authors: Krijger, J. M.; Rutten, R. J.; Lites, B. W.;
Straus, Th.; Shine, R. A.; Tarbell, T. D.
Bibliographic Code: 2001A&A...379.1052K
Paper (if ADS pdf and access) ADS page
We analyze oscillations in the solar atmosphere using image sequences
from the Transition Region and Coronal Explorer (TRACE) in three
ultraviolet passbands which sample the upper solar photosphere and low
chromosphere. We exploit the absence of atmospheric seeing in TRACE data
to furnish comprehensive Fourier diagnostics (amplitude maps,
phase-difference spectra, spatio-temporal decomposition) for quiet-Sun
network and internetwork areas with excellent sampling statistics.
Comparison displays from the ground-based Ca Ii H spectrometry that was
numerically reproduced by Carlsson & Stein are added to link our
results to the acoustic shock dynamics in this simulation. The TRACE
image sequences confirm the dichotomy in oscillatory behaviour between
network and internetwork and show upward propagation above the cutoff
frequency, the onset of acoustic shock formation in the upper
photosphere, phase-difference contrast between pseudo-mode ridges and
the interridge background, enhanced three-minute modulation aureoles
around network patches, a persistent low-intensity background pattern
largely made up of internal gravity waves, ubiquitous magnetic flashers,
and low-lying magnetic canopies with much low-frequency modulation. The
spatio-temporal occurrence pattern of internetwork grains is found to be
dominated by acoustic and gravity wave interference. We find no sign of
the high-frequency sound waves that have been proposed to heat the quiet
chromosphere, but such measurement is hampered by non-simultaneous
imaging in different passbands. We also find no signature of particular
low-frequency fluxtube waves that have been proposed to heat the
network. However, internal gravity waves may play a role in their
excitation.

@--------------------------------------------------------------------
Title: Ba II 4554 Å speckle imaging as solar Doppler
diagnostic
Authors: Sütterlin, P.; Rutten, R. J.; Skomorovsky, V. I.
Bibliographic Code: 2001A&A...378..251S
Paper (if ADS pdf and access) ADS page
We present observations testing the Dopplergram capability of a
narrow-band (80 mÅ) Lyot filter imaging the solar surface in the
wings of the Ba II 4554 Å resonance line in combination with
speckle reconstruction to obtain high angular resolution. The Ba II 4554
Å line is found to be an excellent tool for high-resolution
Doppler mapping thanks to opacity insensitivity to temperature
variations and line-width insensitivity to thermal broadening. The
resulting Dopplergrams show concentrated downflows of 1.2-2.2
km;s-1 in intergranular lanes that probably mark magnetic
fluxtubes. Two-wavelength profile sampling is found to suffice for
high-resolution Dopplergram construction. The filter will be installed
as part of a multi-wavelength speckle imaging system on the new Dutch
Open Telescope.

@--------------------------------------------------------------------
Title: DOT strategies versus Orbiter strategies
Authors: Rutten, Robert J.
Bibliographic Code: 2001ESASP.493..357R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: ESMN / European solar physics research area
Authors: Rutten, Robert J.
Bibliographic Code: 2001ESASP.493..353R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Proxy Magnetometry of the Photosphere: Why are
G-Band Bright Points so Bright?
Authors: Rutten, R. J.; Kiselman, D.;
Rouppe van der Voort, L.; Plez, B.
Bibliographic Code: 2001ASPC..236..445R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: A Multi-Channel Speckle Imaging System for the DOT
Authors: Sütterlin, P.; Hammerschlag, R. H.;
Bettonvil, F. C. M.; Rutten, R. J.;
Skomorovsky, V. I.; Domyshev, G. N.
Bibliographic Code: 2001ASPC..236..431S
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Proxy Magnetometry with the Dutch Open Telescope
Authors: Rutten, R. J.; Hammerschlag, R. H.; Sütterlin, P.;
Bettonvil, F. C. M.
Bibliographic Code: 2001ASPC..236...25R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The formation of G-band bright points I: Standard
LTE modelling
Authors: Kiselman, D.; Rutten, R. J.; Plez, B.
Bibliographic Code: 2001IAUS..203..287K
Paper (if ADS pdf and access) ADS page
Assuming LTE, we investigate the formation of the G band in models of
quiet solar photosphere and a semiempirical flux-tube model (Briand
& Solanki 1995). Preliminary results agree with observations of of
G-band bright-point contrast, though this a sensitive function of the
amount of scattered light in the observations. Thus LTE line modelling
in models constructed under the LTE assumptions seems to fit
observations. This does not, however, necessarily imply that LTE is
valid here. We also present LTE synthetic spectra of the same models for
the full wavelength range from UV to IR. This serves to point out other
promising pass bands for the observations of flux-tube structures.

@--------------------------------------------------------------------
Title: Solar Atmospheric Dynamics (CD-ROM Directory:
contribs/rutten)
Authors: Rutten, R. J.
Bibliographic Code: 2001ASPC..223..117R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Dutch Open Telescope: Status and Prospects
Authors: Rutten, R. J.; Hammerschlag, R. H.; Bettonvil, F. M.;
Suetterlin, P.
Bibliographic Code: 2000SPD....3102107R
Paper (if ADS pdf and access) ADS page
The Dutch Open Telescope (DOT) on La Palma in the Canary Islands is a
small but revolutionary solar telescope of which the image quality
matches the superb imaging of the Swedish Vacuum Solar Telescope (from
whose building the DOT is operated). The DOT is an open parabolic 45cm
reflector on an open 15m high tower, relying on mirror flushing by the
trade winds that bring the best seeing at La Palma to avoid internal
turbulence. A water-cooled field stop in the primary image reflects most
sunlight and heat out of the telescope. The first data from the DOT
combined with speckle reconstruction have yielded sunspot movies of
outstanding quality. At present, a multi-channel imaging system is in
construction for simultaneous registration of speckle sequences in the G
band, in Ca II K and in Halpha. The data pipeline permits continuous
speckle data acquisition up to 0.5 Tb per day. The advantage of speckle
reconstruction over adaptive optics is the much larger field of the
restored scene, with the DOT camera's 100x130 arcsec at 0.2 arcsec
resolution. The DOT science program is to study magnetic topology and
dynamics throughout the photosphere and chromosphere.

@--------------------------------------------------------------------
Title: The formation of G-band bright points. I: Standard
LTE modelling
Authors: Kiselman, D.; Rutten, R. J.; Plez, B.
Bibliographic Code: 2000astro.ph.10390K ArXiv preprint
Paper (if ADS pdf and access) ADS page Assuming LTE, we synthesise solar G band spectra from the semiempirical
flux-tube model of Briand Solanki (1995). The results agree with
observed G-band bright-point contrasts within the uncertainty set by the
amount of scattered light. We find that it is the weakening of spectral
lines within the flux tube that makes the bright-point contrast in the G
band exceed the continuum contrast. We also synthesise flux-tube spectra
assuming LTE for the full wavelength range from UV to IR, and identify
other promising passbands for flux-tube observations.

@--------------------------------------------------------------------
Title: C. Fröhlich, M. C. E. Huber, S. K. Solanki and R.
von Steiger (eds.), Solar Composition and its
Evolution from Core to Corona
Authors: Rutten, R. J.
Bibliographic Code: 1999SSRv...90..526R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: (Inter-),Network Structure and DynamicS
Authors: Rutten, R. J.
Bibliographic Code: 1999ASPC..184..181R
Paper (if ADS pdf and access) ADS page
The dynamical nature of the low solar atmosphere outside active regions
is emphasized by recent observations and simulations alike. La Palma
images, MDI maps, SUMER spectra, TRACE movies, hydrodynamic shock
simulations and magnetohydrodynamic sheet simulations all impart
non-quiet behavior to the "quiet Sun". This review begins with a brief
summary of current insights and then focuses on various quiet-Sun
questions that seem pertinent and solvable.

@--------------------------------------------------------------------
Title: C. Zwaan (1928 - 16 June 1999).
Authors: Rutten, R. J.; Schrijver, C. J.
Bibliographic Code: 1999SoPh..188....0R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Dynamics of the Solar Chromosphere. II. Ca II H_2V
and K_2V Grains versus Internetwork Fields
Authors: Lites, B. W.; Rutten, R. J.; Berger, T. E.
Bibliographic Code: 1999ApJ...517.1013L
Paper (if ADS pdf and access) ADS page
We use the Advanced Stokes Polarimeter at the NSO/Sacramento Peak Vacuum
Tower Telescope to search for spatio-temporal correlations between
enhanced magnetic fields in the quiet solar internetwork photosphere and
the occurrence of Ca II H_2V grains in the overlying chromosphere. We
address the question of whether the shocks that produce the latter are
caused by magnetism-related processes, or whether they are of purely
hydrodynamic nature. The observations presented here are the first in
which sensitive Stokes polarimetry is combined synchronously with
high-resolution Ca II H spectrometry. We pay particular attention to the
nature and significance of weak polarization signals from the
internetwork domain, obtaining a robust estimate of our magnetographic
noise level at an apparent flux density of only 3 Mx cm^-2. For the
quiet Sun internetwork area analyzed here, we find no direct correlation
between the presence of magnetic features with apparent flux density
above this limit and the occurrence of H_2V brightenings. This result
contradicts the one-to-one correspondence claimed by Sivaraman &
Livingston. We also find no correspondence between H_2V grains and the
horizontal-field internetwork features discovered by Lites et al.

@--------------------------------------------------------------------
Title: F.-L. Deubner, J. Christensen-Dalsgaard, and D.
Kurtz (eds.), New Eyes to See Inside the Sun and
Stars, Proceedings of the 185th Symposium of the
International Astronomical Union held in Kyoto,
Japan, August 18 22, 1997
Authors: Rutten, R. J.
Book Authors: Deubner, F. L.; Christensen-Dalsgaard, J.; Kurtz, D.
Review Author: Rutten, R. J.
Bibliographic Code: 1999SSRv...88..605R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Magnetic Fields and Oscillations
Authors: Rutten, Robert J.
Bibliographic Code: 1999PASP..111..380R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Obituary: Cornelis Zwaan, 1928-1999
Authors: Rutten, Rob; Schrijver, Karel
Bibliographic Code: 1999BAAS...31.1612R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Internetwork Grains with TRACE
Authors: Rutten, R. J.; de Pontieu, B.; Lites, B.
Bibliographic Code: 1999ASPC..183..383R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Radiative Transfer for Grabs
Authors: Rutten, R. J.
Bibliographic Code: 1999ASPC..158..306R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Dynamics of the Quiet Solar Chromosphere
Authors: Rutten, R. J.; Lites, B. W.; Berger, T. E.;
Shine, R. A.
Bibliographic Code: 1999ASPC..158..249R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The Dutch Open Telescope
Authors: Rutten, R. J.; Hammerschlag, R. H.;
Bettonvil, F. C. M.
Bibliographic Code: 1999ASPC..158...57R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Site tests for CLEAR by solar scintillometry
Authors: Beckers, J. M.; Rutten, R. J.
Bibliographic Code: 1998NewAR..42..489B
Paper (if ADS pdf and access) ADS page
We briefly describe the ongoing site survey for the NSO CLEAR project
which aims to put a large-aperture solar telescope at a superior
location. The initial results indicate that lake sites are far better
than mountain sites, at least in the US.

@--------------------------------------------------------------------
Title: The Lower Solar Atmosphere Rapporteur Paper II
Authors: Rutten, Robert J.
Bibliographic Code: 1998SSRv...85..269R
Paper (if ADS pdf and access) ADS page
This ``rapporteur'' report discusses the solar photosphere and
low chromosphere in the context of chemical composition studies. The
highly dynamical nature of the photosphere does not seem to jeopardize
precise determination of solar abundances in classical fashion. It is
still an open question how the highly dynamical nature of the low
chromosphere contributes to first ionization potential (FIP)
fractionation.

@--------------------------------------------------------------------
Title: Small-scale topology of solar atmosphere dynamics.
III. Granular persistence and photospheric wave
amplitudes
Authors: Hoekzema, N. M.; Brandt, P. N.; Rutten, R. J.
Bibliographic Code: 1998A&A...333..322H
Paper (if ADS pdf and access) ADS page
We use a superb five-hour sequence of 900 solar images taken at La Palma
to study long-duration persistence in the solar granulation, in the
context of the long-lived ``intergranular holes'' discovered by
\cite*{Roudier+others1997} %T AA: intergranular plumes + BP formation
and the contention that these mark sites of convective downflow plumes.
We develop a procedure to locate ``persistency regions'' that contain
granular brightness maxima or minima over extended periods (up to 45
min), while allowing for lateral drifts due to horizontal flows.
Statistical evaluation of the co-location probability for different
pixel classes is first used to quantify the likelihood of long-term
stationarity for different granular brightness classes and for the
persistency regions, and then to evaluate the amount of preferential
alignment, at different frequencies and time delays, between excessive
Fourier modulation and granular brightness and persistence. The results
support the existence of long-lived intergranular holes. There is large
persistency difference between the brightest and the darkest features;
some of the latter have location memories as long as two hours. In
addition, the darkest intergranular features are found to be sites of
enhanced Fourier modulation in the 3-min acoustic regime, improving
earlier results through much higher statistical significance. However,
the persistency regions containing intergranular holes do not seem to
produce the excess acoustic emission that would be expected above
downflow plumes.

@--------------------------------------------------------------------
Title: Small-scale topology of solar atmosphere dynamics.
II. Granulation, K2v grains and waves
Authors: Hoekzema, N. M.; Rutten, R. J.
Bibliographic Code: 1998A&A...329..725H
Paper (if ADS pdf and access) ADS page
We continue studying the small-scale topology of dynamical phenomena in
the quiet-sun internetwork atmosphere through statistical estimation of
the co-location probability of different fine-structure elements and
wave modes. In this paper we chart spatial alignments between the
granular brightness structuring of the photosphere, Ca ii K2V
brightness patterns in the chromosphere, and wave amplitude patterns in
both regimes as a function of time delay between the occurrences of the
various features. These charts confirm the presence of excess 2--4 min
waves above dark intergranular lanes, the absence of excess 5 min waves
above bright granules, the absence of expected alignments between
photospheric and chromospheric wave patterning, and the broad-band
nature of Ca ii K2V grain formation. In addition, they show
significant alignments at large time delays that seem to be regulated by
mesoscale patterning and pattern = migration.

@--------------------------------------------------------------------
Title: Small-scale topology of solar atmosphere dynamics.
I. Wave sources and wave diffraction
Authors: Hoekzema, N. M.; Rutten, R. J.; Brandt, P. N.;
Shine, R. A.
Bibliographic Code: 1998A&A...329..276H
Paper (if ADS pdf and access) ADS page
We study the small-scale topology of dynamical phenomena in the
quiet-sun internetwork atmosphere, using short-duration Fourier analysis
of high-resolution filtergram sequences to obtain statistical estimates
for the co-location probability of different fine-structure elements and
wave modes. In this initial paper we concentrate on the topology of
short-duration Fourier amplitude maps for the photosphere and the
simultaneously observed overlying chromosphere. We find that these maps
portray a complex mix of global modes and locally excited waves which
necessitates a statistical approach. Various aspects including mesoscale
patterning indicate the presence of subsurface wave sources and of
subsurface wave diffraction by convective inhomogeneities.

@--------------------------------------------------------------------
Title: The Lower Solar Atmosphere
Authors: Rutten, R. J.
Bibliographic Code: 1998sce..conf..269R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Problem of iron abundance in the solar photosphere.
Authors: Kostyk, R. I.; Shchukina, N. G.; Rutten, R. J.
Bibliographic Code: 1998BCrAO..94..118K
Paper (if ADS pdf and access) ADS page
The authors analyze the causes of the discrepancies.

@--------------------------------------------------------------------
Title: The Dutch Open Telescope
Authors: Rutten, R. J.; Hammerschlag, R. H.; Bettonvil, F. M.
Bibliographic Code: 1997ASSL..225..289R
Paper (if ADS pdf and access) ADS page
The Dutch Open Telescope is now being installed at La Palma. It is
intended for optical solar observations with high spatial resolution.
Its open design aims to minimize disturbances of the local air flow and
so reduce the locally-generated component of the atmospheric seeing.
This paper briefly describes the design, construction, short-term plans,
and longer-term prospects.

@--------------------------------------------------------------------
Title: E. Kontizas, M. Kontizas, D.H. Morgan, and G.P.
Vettolani (eds.). Wide-Faceted Field Spectroscopy,
Proceedings of the 2nd Conference of the Working
Group of IAU Commission 9 on "Wide-Field Imaging".
Authors: Rutten, R. J.
Bibliographic Code: 1997SSRv...82..467R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Modeling LiI and KI sensitivity to Pleiades
activity.
Authors: Stuik, R.; Bruls, J. H. M. J.; Rutten, R. J.
Bibliographic Code: 1997A&A...322..911S
Paper (if ADS pdf and access) ADS page
We compare schematic modeling of spots and plage on the surface of cool
dwarfs with Pleiades data to assess effects of magnetic activity on the
strengths of the LiI and KI resonance lines in Pleiades spectra.
Comprehensive LiI and KI NLTE line formation computation is combined
with comparatively well-established empirical solar spot and plage
stratifications for solar-like stars. For other stars, we use
theoretical constructs to model spots and plage that portray recipes
commonly applied in stellar activity analyses. We find that - up to
B-V=~1.1 - neither the LiI 670.8nm nor the KI 769.9nm line is sensitive
to the presence of a chromosphere, in contrast to what is often
supposed. Instead, both lines respond to the effects of activity on the
stratification in the deep photosphere. They do so in similar fashion,
making the KI line a valid proxy to study LiI line formation without
spread from abundance variations. The computed effects of activity on
line strength are opposite between plage and spots, differ noticeably
between the empirical and theoretical solar-like stratifications, and
considerably affect stellar broad-band colors. Our results indicate that
one can neither easily establish, nor easily exclude, magnetic activity
as major provider of KI line strength variation in the Pleiades. Since
LiI line formation follows KI line formation closely, the same holds for
LiI and the apparent lithium abundance.

@--------------------------------------------------------------------
Title: Ultraviolet Jets and Bright Points in the Solar
Chromosphere. II. Statistical Correlations
Authors: Hoekzema, N. M.; Rutten, R. J.; Cook, J. W.
Bibliographic Code: 1997ApJ...474..518H
Paper (if ADS pdf and access) ADS page
We use HRTS--VI rocket observations of the solar chromosphere to search
for relationships between high-Dopplershift "jets" observed in the C I
lines near lambda = 156 nm and internetwork "bright points" observed in
the lambda = 160 nm continuum, in sequel to the analysis by Cook et al.
which failed to find a direct connection between these phenomena. We now
use the same data to establish statistical correlations between C I
Dopplershift and 160 nm brightness modulation in internetwork areas.
These mean relations emerge only after extensive spatial averaging and
have small amplitude, but are definitely significant. They show that
both C I Dopplershift and 160 nm brightness participate in oscillatory
behavior with 3 minute periodicity and mesoscale (8 Mm wavelength) as
well as small-scale (1.4 Mm wavelength) spatial patterning. We find
spatial and temporal phase relations between Dopplershift and brightness
that confirm that jets and bright points should not be interpreted as
isolated entities. Rather, they are chromospheric manifestations, with
much pattern interference, of the oscillatory acoustic shock dynamics in
the internetwork which also cause Ca II K2V grains. Additional
small-scale modulation is present which we attribute to waves with
f-mode character.

@--------------------------------------------------------------------
Title: Chromospheric Dynamics and the FIP Flip
Authors: Rutten, R. J.
Bibliographic Code: 1997ASPC..118..298R
Paper (if ADS pdf and access) ADS page
This paper consists of two parts. The first, resembling many other SOHO
contributions in this volume, reports on a recent campaign in which
SUMER was employed simultaneously with groundbased telescopes. The
campaign is described but results are not yet in hand. The second part
differs by proposing SUMER measurements and analysis to be contributed
by you. It calls attention to the FIP effect, a puzzling
outer-atmosphere element segregation that may have to do with quiet-sun
chromospheric dynamics. SUMER data, including yours, may provide
pertinent diagnostics.

@--------------------------------------------------------------------
Title: First Results from SOHO on Waves Near the Solar
Transition Region
Authors: Steffens, S.; Deubner, F.-L.; Fleck, B.; Wilhelm, K.;
Schuhle, U.; Curdt, W.; Harrison, R.; Gurman, J.;
Thompson, B. J.; Brekke, P.; Delaboudiniere, J.-P.;
Lemaire, P.; Hessel, B.; Rutten, R. J.
Bibliographic Code: 1997ASPC..118..284S
Paper (if ADS pdf and access) ADS page
We present first results from simultaneous observations with the CDS,
EIT and SUMER instruments {please see Solar Physics 162 (1995) for a
description of the instruments} onboard SOHO and the VTT at Tenerife.
Our aim is to study the wave propagation, shock formation, and
transmission properties of the upper chromosphere and transition region.
The preliminary results presented here include the variation of velocity
power spectra with height, difference in power between internetwork and
network regions, and variations in mean flows displayed by different
spectral lines.

@--------------------------------------------------------------------
Title: Ultraviolet Jets and Bright Points in the Solar
Chromosphere. I. Search for One-to-One Relationships
Authors: Cook, J. W.; Rutten, R. J.; Hoekzema, N. M.
Bibliographic Code: 1996ApJ...470..647C
Paper (if ADS pdf and access) ADS page
Ultraviolet spectrograms and spectroheliograms of the solar chromosphere
are used to test the suggestion of Dere, Bartoe, & Brueckner and
Rutten & Uitenbroek that bright points in quiet Sun cell interiors
observed at = 1600 A, chromospheric jets observed in C I lines near
lambda = 1560 Å, and Ca II K2v bright points are
associated with each other and that they are all manifestations of the
same wave interaction in the nonmagnetic chromosphere. We search for
spatio-temporal connections between 1600 Å bright points and C I
blue jets using data from the High Resolution Telescope and Spectrograph
VI rocket flight, comparing 1600 A spectrohellograms and a cospatial C I
Doppler shift map on a pixel-by-pixel basis. We find no direct evidence
for spatial colocation of bright points and jets, not for instantaneous
correspondence and also not when allowing for phase delays as long as 3
minutes. Also, the average brightness evolution and its rms fluctuation
are not obviously different between sites of large C I blueshift and the
remaining surface.

@--------------------------------------------------------------------
Title: Book Review: Solar surface magnetism / Kluwer, 1994
Book Authors: Rutten, R. J.; Schrijver, C. J.
Bibliographic Code: 1996SSRv...76..370R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The solar iron abundance: not the last word.
Authors: Kostik, R. I.; Shchukina, N. G.; Rutten, R. J.
Bibliographic Code: 1996A&A...305..325K
Paper (if ADS pdf and access) ADS page
Determinations of the solar iron abundance have converged to the
meteoritic value with the FeII studies of Holweger et al. (1990),
Biemont et al. (1991) and Hannaford et al. (1992) and the FeI results of
Holweger et al. (1991). However, the latter authors pointed out that
Blackwell et al. (1984) obtained a discordant result from similar
oscillator strengths. A recent debate on this lingering discrepancy by
the Oxford and Kiel contenders themselves has not clarified the issue.
We do so here by showing that it stems from systematic differences
between equivalent widths and oscillator strengths which masquerade as
difference in fitted damping enhancement factors. We first discuss the
various error sources in classical abundance determination and then
emulate both sides of the debate with abundance fits of our own. Our
emulation of the Oxford side shows that the abundance anomaly claimed by
Blackwell et al. (1984) for solar FeI 2.2eV lines vanishes when
equivalent width measurements from other authors are combined with
better evaluation of the collisional damping parameter. On the Kiel
side, we find that the oscillator strengths of Bard et al. (1991) used
by Holweger et al. (1991) produce a suspicious trend when used to fit
solar FeI lines, whereas comparable application of oscillator strengths
from Oxford does not. The trend is mainly set by categories of FeI lines
not measured at Oxford; for lines of overlap the two sets agree and
deliver the iron abundance value A_Fe_=7.62+/-0.04 which exceeds the
meteorite value. The dissimilar lines may suffer from solar
line-formation effects. We conclude that the issue of the solar iron
abundance remains open. Definitive oscillator strengths are still
needed, as well as verification of classical abundance determination by
more realistic representations of the solar photosphere and of
photospheric line formation.

@--------------------------------------------------------------------
Title: Book Review: Solar surface magnetism / Kluwer, 1994
Book Authors: Rutten, R. J.; Schrijver, C. J.
Review Author: Somov, B. V.
Bibliographic Code: 1995SoPh..160...61S
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Book Review: Solar surface magnetism / Kluwer, 1994
Book Authors: Rutten, R. J.; Schrijver, C. J.
Review Author: Priest, E.
Bibliographic Code: 1995Obs...115..103P
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Infrared lines as probes of solar magnetic features.
VIII. MgI 12mum diagnostics of sunspots.
Authors: Bruls, J. H. M. J.; Solanki, S. K.; Rutten, R. J.;
Carlsson, M.
Bibliographic Code: 1995A&A...293..225B
Paper (if ADS pdf and access) ADS page
Due to their large Zeeman sensitivity, the MgI lines at 12mum are
important diagnostics of solar magnetism. The formation of their central
emission features is now understood, enabling quantitative modeling and
diagnostic application of these lines. We supply the first systematic
analysis of solar MgI 12mum Stokes profiles employing detailed
line-profile synthesis. We compute Stokes profiles of MgI 12.32mum for
the quiet Sun, for sunspot penumbrae and for the extended
("superpenumbral") magnetic canopies surrounding sunspots. We use these
computations to analyze recent MgI 12mum observations by Hewagama et
al. (1993). Our results are the following: (1) -Saha-Boltzmann
temperature sensitivity explains that the emission peaks are stronger in
penumbrae than in the quiet Sun, and that they disappear in umbrae. (2)
-The formation heights of the emission features are approximately the
same in penumbrae and in the quiet Sun, namely tau_500_=~10^-3^. (3)
-The simple Seares formula allows relatively accurate determinations of
field strength and magnetic inclination. (4) -The observed excess
broadening of the sigma-component peaks compared with the pi
component in penumbrae is well explained by primarily horizontal, smooth
radial variation of the magnetic field strength. Additional small-scale
variations are less than {DELTA}B =~200G. (5) -The vertical field
gradients dB/dz in penumbrae range from 0.7G/km to 3G/km; the larger
gradients occur near the umbra, the smaller ones near the outer edge of
the penumbra. (6) -The MgI 12mum lines are well-suited to measure the
base heights of superpenumbral magnetic canopies. These heights range
between 300km and 500km above tau_500_=1 out to twice the sunspot
radius, in excellent agreement with determinations from other infrared
lines.

@--------------------------------------------------------------------
Title: Chromospheric Oscillations
Authors: Rutten, R. J.
Bibliographic Code: 1995ESASP.376a.151R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The Determination of the Solar Iron Abundance from
Fe I Lines
Authors: Kostik, R. I.; Shchukina, N. G.; Rutten, R. J.
Bibliographic Code: 1995ASPC...78..399K
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The non-LTE formation of Li I lines in cool stars
Authors: Carlsson, M.; Rutten, R. J.; Bruls, J. H. M. J.;
Shchukina, N. G.
Bibliographic Code: 1994A&A...288..860C
Paper (if ADS pdf and access) ADS page
We study the non-LTE (non local thermodynamic equilibrium) formation of
Li I lines in the spectra of cool stars for a grid of
radiative-equilibrium model atmospheres with variation in effective
temperature, gravity, metallicity and lithium abundance. We analyze the
mechanisms by which departures from LTE (local thermodynamic
equilibrium) arise for Li I lines, first for the young sun (prior to its
lithium depletion) and then across the cool-star grid. There are various
mechanisms which compete in their effects on emergent Li I line
strengths. Their neglect produces errors in lithium abundance
determinations that vary in sign as well as size, both across the
stellar grid and between different Li I lines (Figs). The errors are
appreciable for all cooler stars and largest for cool lithium-rich
metal-poor giants. They reverse sign between lithium-rich stars and
lithium-poor stars for the lambda=670.8nm resonance line, but not for
the lambda=610.4nm subordinate line. The non-LTE corrections are large
enough that they should be taken into account in ongoing debates on
lithium synthesis and depletion. We provide convenient numerical
approximations of our results (Table 1) to this purpose. We end the
paper with some examples in which non-LTE corrections change the slope
of published relationships.

@--------------------------------------------------------------------
Title: The SIMURIS interferometric mission: Solar physics
objectives and model payload
Authors: Dame, L.; Rutten, R. J.; Thorne, A. P.; Vial, J. C.
Bibliographic Code: 1994AdSpR..14..167D
Paper (if ADS pdf and access) ADS page
We describe the Solar, Solar System, and Stellar Interferometric Mission
for Ultrahigh Resolution Imaging and Spectroscopy (SIMURIS) Mission with
emphasis on the scientific goals and related capabilities of the major
instruments of the model payload.

@--------------------------------------------------------------------
Title: Book Review: Sunspots: theory and observations /
Kluwer, 1992
Book Authors: Thomas, J. H.; Weiss, N. O.
Review Author: Rutten, R. J.
Bibliographic Code: 1994SSRv...67..227R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: On photospheric flows and chromospheric corks
Authors: Brandt, P. N.; Rutten, R. J.; Shine, R. A.;
Trujillo Bueno, J.
Bibliographic Code: 1994ssm..work..251B
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Chromospheric oscillations
Authors: Lites, B. W.; Rutten, R. J.; Thomas, J. H.
Bibliographic Code: 1994ssm..work..159L
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Solar Surface Magnetism
Authors: Rutten, Robert J.; Schrijver, Carolus J.
Bibliographic Code: 1994ssm..work.....R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: MgI 12 mum diagnostics of sunspot penumbrae
Authors: Bruls, J. H. M. J.; Solanki, S. K.; Rutten, R. J.;
Carlsson, M.
Bibliographic Code: 1994smf..conf..191B
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Computation of Infrared Hydrogen Lines
Authors: Carlsson, M.; Rutten, R. J.
Bibliographic Code: 1994IAUS..154..341C
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The Formation of Infrared Rydberg Lines
Authors: Rutten, R. J.; Carlsson, M.
Bibliographic Code: 1994IAUS..154..309R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The Non-LTE Formation of Li I Lines from Cool Stars
Authors: Carlsson, M.; Rutten, R. J.; Bruls, J. H. M. J.;
Shchukina, N. G.
Bibliographic Code: 1994ASPC...64..270C
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Dynamics of the solar chromosphere. I - Long-period
network oscillations
Authors: Lites, B. W.; Rutten, R. J.; Kalkofen, W.
Bibliographic Code: 1993ApJ...414..345L
Paper (if ADS pdf and access) ADS page
We analyze differences in solar oscillations between the chromospheric
network and internetwork regions from a 1 hr sequence of spectrograms of
a quiet region near disk center. The spectrograms contain Ca II H, Ca I
422.7 nm, and various Fe I blends in the Ca II H wing. They permit
vertical tracing of oscillations throughout the photosphere and into the
low chromosphere. We find that the rms amplitude of Ca II H line center
Doppler fluctuations is about 1.5 km/s for both network and
internetwork, but that the character of the oscillations differs
markedly in these two regions. Within internetwork areas the
chromospheric velocity power spectrum is dominated by oscillations with
frequencies at and above the acoustic cutoff frequency. They are well
correlated with the oscillations in the underlying photosphere, but they
are much reduced in the network. In contrast, the network Ca II H line
center velocity and intensity power spectra are dominated by
low-frequency oscillations with periods of 5-20 min. Their signature is
much clearer in our Ca II H line center measurements than in previously
used diagnostics which are contaminated by signals from deeper layers.
We find that these long-period oscillations are not correlated with
underlying photospheric disturbances, and we discuss their nature.

@--------------------------------------------------------------------
Title: Prospects for very-high-resolution solar physics
with the SIMURIS inteferometric mission
Authors: Dame, L.; Martic, M.; Rutten, R. J.
Bibliographic Code: 1993ESASP1157..119D
Paper (if ADS pdf and access) ADS page
The Simuris (Solar, Solar System, and Stellar Interferometric Mission
for Ultrahigh Resolution Imaging and Spectroscopy) mission, its
scientific objectives, instrument concepts and system design, are
addressed. Simuris employs advanced interferometric techniques. Its
payload includes two major instruments, which are the Solar Ultraviolet
Network (SUN), an interferometric array of four 20 cm telescopes on a 2
m baseline, and the Imaging Fourier Transform Spectrometer (IFTS), which
uses light from a 40 cm Gregory telescope. Both instruments have active
pointing capabilities of 3 mas stability, and in addition SUN has an
active cophasing control to 1/50th of a wavelength. EUV multilayer
telescopes complete the payload for diagnostics of the very high
temperature plasma.

@--------------------------------------------------------------------
Title: Oscillations of the Magnetic Network
Authors: Lites, B. W.; Rutten, R. J.; Kalkofen, W.
Bibliographic Code: 1993ASPC...46..530L
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: SIMURIS: High-Resolution Solar Physics
Authors: Rutten, R. J.; Dame, L.
Bibliographic Code: 1993ASPC...46..184R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Book-Review - the Sun - a Laboratory for
Astrophysics
Authors: Schmelz, J. T.; Brown, J. C.; Rutten, R. J.
Bibliographic Code: 1993SSRv...65..370S
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Book Review: The observation and analysis of stellar
photospheres / Cambridge U Press, 1992
Book Authors: Gray, D. F.
Review Author: Rutten, R. J.
Bibliographic Code: 1993SSRv...65..183R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Stellar objectives of SIMURIS
Authors: Damé, L.; Coradini, M.; Foing, B.; Rutten, R. J.;
Thorne, A.; Vial, J. C.
Bibliographic Code: 1993MmSAI..64..345D
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The SIMURIS interferometric mission: solar physics
objectives and model payload (invited paper)
Authors: Damé, L.; Coradini, M.; Foing, B.; Rutten, R. J.;
Thorne, A.; Vial, J. C.
Bibliographic Code: 1993MmSAI..64..333D
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: High resolution solar physics
Authors: Rutten, Robert J.
Bibliographic Code: 1992ESASP.354..163R
Paper (if ADS pdf and access) ADS page
The importance of high spatial resolution in the future of astrophysics,
and in the revolutionization of solar physics, is addressed. The
proximity of the Sun brings the enormous advantage that modest baselines
suffice to fulfill an important goal: to resolve basic plasma processes
at their characteristic scales. At such resolution, the solar atmosphere
represents a plasma physics laboratory of broad interest. Concerted
observations combining high spatial and temporal resolution with narrow
band diagnostics in the ultraviolet and the visible will deliver
detailed insights in plasma processes that are ubiquitous in the cosmos,
but resolvable only for the Sun. Space interferometry is the obvious way
to fulfill this promise and reasons for this are given. The space time
resolution characteristics of solar phenomena and solar inspired
paradigms of magnetohydrodynamics are considered together with the
ground based resolution limit.

@--------------------------------------------------------------------
Title: The formation of helioseismology lines. II -
Modeling of alkali resonance lines with granulation
Authors: Bruls, J. H. M. J.; Rutten, R. J.
Bibliographic Code: 1992A&A...265..257B
Paper (if ADS pdf and access) ADS page
We model the NLTE formation of the solar Na I and K I resonance lines
for an array of one-dimensional atmospheric models taken from a
numerical simulation of the solar granulation by Nordlund and Stein
(1990, 1991). We discuss the nature of alkali-line sensitivity to
granulation using hot and cool extremes from the simulation and we study
the granular modulation of diagnostics such as line bisectors and
helioseismological resonance-cell response. We also show that granular
structuring produces apparent spatially-averaged line broadening of
similar magnitude as the ad-hoc microturbulent and damping broadening
invoked in traditional plane-parallel modeling.

@--------------------------------------------------------------------
Title: The formation of helioseismology lines. I - NLTE
effects in alkali spectra
Authors: Bruls, J. H. M. J.; Rutten, R. J.; Shchukina, N. G.
Bibliographic Code: 1992A&A...265..237B
Paper (if ADS pdf and access) ADS page
We study the NLTE formation of the solar K I and Na I resonance lines
employed in helioseismology. We combine standard modeling of the solar
atmosphere with comprehensive alkali model atoms, complete up to the
Rydberg regime near the continuum, to study various NLTE mechanisms
which interact to make the alkali population balances more complex than
is the case for other minority species. In particular, we discuss a
'photon suction' process which produces overpopulation of the neutral
stage by driving a population flow from the reservoir in the singly
ionized stage. We isolate this and other mechanisms with specifically
tailored model atoms, and we provide a choice of simplified model atoms,
trading precision against size, which are appropriate for future use in
numerical simulations of the solar atmosphere.

@--------------------------------------------------------------------
Title: Model payload and system design of the SIMURIS
interferometric mission
Authors: Dame, L.; Rutten, R. J.; Thorne, A. P.; Vial, J. C.
Bibliographic Code: 1992wadc.iafcZ....D
Paper (if ADS pdf and access) ADS page
SIMURIS (Solar, Solar System, and Stellar Interferometric Mission for
Ultrahigh Resolution Imaging and Spectroscopy) has been proposed to ESA
as a Mission in the context of the Space Station in November 1989 in
answer to the Call for the Next Medium Size Mission (M2). It has
completed, since, an Assessment Study, and is now proceeding for a Phase
A. SIMURIS employs advanced interferometric techniques. The payload
includes two major instruments which are the Solar Ultraviolet Network
(SUN), an interferometric array of four 20-cm telescopes on a 2-m
baseline, and the Imaging Fourier Transform Spectrometer (IFTS) which
uses light from a 40-cm Gregory telescope. Both instruments have active
pointing capabilities of 3 milliarcsec stability, and SUN has, in
addition, an active cophasing control to 1/50th of a wavelength. EUV
multilayer telescopes complete the payload for diagnostics of the very
high temperature plasma. The SIMURIS model payload will be described
with emphasis on the system design of the interferometric aspects of the
instruments.

@--------------------------------------------------------------------
Title: Solar hydrogen lines in the infrared
Authors: Carlsson, M.; Rutten, R. J.
Bibliographic Code: 1992A&A...259L..53C
Paper (if ADS pdf and access) ADS page
We study recently observed H I lines in the infrared solar spectrum,
employing detailed NLTE modeling to explain their formation and to
evaluate their diagnostic merits. The solar infrared H I lines vary much
in character, depending on opacity and wavelength; our computations
reproduce the observations closely. The line wings are primarily set by
Stark broadening due to metal ions and protons; the line cores are
sensitive to NLTE population departure divergence which is driven by
Balmer-continuum photoionization. The formation heights of the H I lines
range from the deep photosphere for near-infrared line wings to the
chromosphere for line cores with wavelengths greater than 10 microns;
these features provide valuable diagnostics of the thermal structure of
the solar atmosphere.

@--------------------------------------------------------------------
Title: Prospects with SIMURIS
Authors: Dame, L.; Rutten, R. J.
Bibliographic Code: 1992ESASP.344...21D
Paper (if ADS pdf and access) ADS page
The SIMURIS (Solar, solar system and stellar Interferometric Mission for
Ultrahigh Resolution Imaging and Spectroscopy) payload is introduced and
its goals and concepts outlined. The major goal of SIMURIS is to achieve
solar physics at unprecedented image resolution, sufficiently high
enough to resolve the fine structuring governed by basic
magnetohydrodynamical and plasma physics processes. Requirements of
SIMURIS are outlined; these include very high spatial resolution,
multiband observation, narrowband imaging, broadband line selection, two
dimensional spectrometry, and photon usage versatility. The main
instruments on SIMURIS are the Solar Ultraviolet Network (SUN), and the
Imaging Fourier Transform Spectrometer (IFTS). The concepts from which
these were designed are discussed.

@--------------------------------------------------------------------
Title: Design Rationale of the Solar Ultraviolet Network /
Sun
Authors: Dame, L.; Acton, L.; Bruner, M. E.; Connes, P.;
Cornwell, T. J.; Curdt, W.; Foing, B. H.; Hammer, R.;
Harrison, R.; Heyvaerts, J.; Karabin, M.; Marsch, E.;
Martic, M.; Mattic, W.; Muller, R.; Patchett, B.;
Roca-Cortes, T.; Rutten, R. J.; Schmidt, W.;
Title, A. M.; Tondello, G.; Vial, J. C.; Visser, H.
Bibliographic Code: 1992ESOC...39..995D
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The formation of the MG I emission features near 12
microns
Authors: Carlsson, M.; Rutten, R. J.; Shchukina, N. G.
Bibliographic Code: 1992A&A...253..567C
Paper (if ADS pdf and access) ADS page
The formation of two Mg I 12-micron emission features in the solar
spectrum, the existence of which was reported by Murcray et al. (1981),
is explained using plane-parallel nonlocal thermodynamic equilibrium
modeling with a radiative-equilibrium model atmosphere without
chromosphere. It is shown that these emissions are a natural consequence
of population depletion by line photon losses followed by population
replenishment from the ionic reservoir in the highly excited levels. The
results confirm the suggestion by Lemke and Holweger (1987) that the
12-micron lines are formed in the photosphere and disprove the claim by
Zirin and Popp (1989) that the temperature minimum occurs much deeper
than in standard models of the solar atmosphere.

@--------------------------------------------------------------------
Title: Formation of the MG 112 TTM Lines
Authors: Carlsson, M.; Rutten, R. J.; Shchukina, N. G.
Bibliographic Code: 1992ASPC...26..518C
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Dynamics of the Quiet Solar Atmosphere: K2v Cell
Grains Versus Magnetic Elements
Authors: Brandt, P. N.; Rutten, R. J.; Shine, R. A.;
Trujillo Bueno, J.
Bibliographic Code: 1992ASPC...26..161B
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: CA II H(2v) and K(2v) cell grains
Authors: Rutten, Robert J.; Uitenbroek, Han
Bibliographic Code: 1991SoPh..134...15R
Paper (if ADS pdf and access) ADS page
The bright Ca II H(2v) and K(2v) grains, which are intermittently
present in the interiors of network cells in quiet-sun areas, should
provide important diagnostics of the dynamical interaction between the
quiet photosphere and the chromosphere above it, but their nature has so
far eluded identification. The extensive observational literature on
these grains and on related phenomena is here reviewed, and various
contradictions are resolved. It is concluded that the grains are a
hydrodynamical phenomenon in which magnetic fields do not play a major
role. The grains are due to interference between a pervasive standing
oscillation and an 8 Mm horizontal wavelength in the chromosphere, and
the wave trains of the evanescent p-mode interference pattern in the
upper photosphere.

@--------------------------------------------------------------------
Title: Photospheric dynamics and the NLTE formation of the
solar K I 769.9 NM line
Authors: Gomez, M. T.; Severino, G.; Rutten, R. J.
Bibliographic Code: 1991A&A...244..501G
Paper (if ADS pdf and access) ADS page
Earlier analyses of the K I 769.9 nm resonance line are extended as a
diagnostic of dynamical phenomena in the solar photosphere by evaluating
the effects of dynamical variations on departures from LTE in the K I
spectrum. Representative models for the solar granulation and the solar
five-minute oscillation are used to estimate dynamical NLTE departures
in the K I populations and to compare these to standarad plane-parallel
NLTE modeling. Various NLTE mechanisms operate together in K I
simultaneously with fortuitous cancellations; the resulting population
departures vary less than 30 percent between dynamical perturbations.
These results validate the assumption of departure invariance, i.e.,
adopting NLTE population departure coefficients from a standard static
model for use in dynamical perturbations, as a good first-order
approximation in K I 769.9 nm formation studies.

@--------------------------------------------------------------------
Title: Long-Period Oscillations of the Chromospheric
Network
Authors: Lites, B. W.; Kalkofen, W.; Rutten, R. J.
Bibliographic Code: 1991BAAS...23.1050L
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Book-Review - Solar and Stellar Granulation
Authors: Rutten, R. J.; Severino, G.; Rudiger, G.
Bibliographic Code: 1991AN....312..147R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: K2V Cell Grains and Chromospheric Heating (With 1
Figure)
Authors: Rutten, R. J.; Uitenbroek, H.
Bibliographic Code: 1991mcch.conf...48R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The solar photosphere: video movies and computer
simulations.
Authors: Rutten, R. J.
Bibliographic Code: 1990ComAp..14..297R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The formation of the Mg I 12-micron emission lines.
Authors: Carlsson, M.; Rutten, R. J.; Shchukina, N. G.
Bibliographic Code: 1990PDHO....7..260C
Paper (if ADS pdf and access) ADS page
Contents: The Mg I 12 mum line, LTE or NLTE, chromospheric formation,
photospheric formation, collisional NLTE; departure diffusion.

@--------------------------------------------------------------------
Title: Summary Lecture
Authors: Rutten, R. J.
Bibliographic Code: 1990IAUS..138..501R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Solar Oscillator Strengths as a Diagnostic Tool
Authors: Gurtovenko, E. A.; Kostik, R. I.; Rutten, R. J.
Bibliographic Code: 1990IAUS..138...35G
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Temperature Diagnostics of the Upper Photosphere
Authors: Shchukina, N. G.; Shcherbina, T. G.; Rutten, R. J.
Bibliographic Code: 1990IAUS..138...29S
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The Formation of the Mg I 12-Micron Emission Lines
Authors: Carlsson, M.; Rutten, R. J.; Shchukina, N. G.
Bibliographic Code: 1990dysu.conf..260C
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Sun-as-a-star line formation
Authors: Rutten, Robert J.
Bibliographic Code: 1990ASPC....9...91R
Paper (if ADS pdf and access) ADS page
Spectral line formation in the upper solar photosphere and
temperature-minimum region is discussed to examine the effectiveness of
spatially averaged '1D' modeling in solar and stellar applications.
Problems associated with NLTE radiative transfer are described for the
two-level atom, one bound level with a continuum, three bound levels,
and for multiple levels. Successful applications of 1D modeling are
reviewed where solar photospheric optical lines are used to calibrate
stellar abundance determinations. The homogeneity or 1D LTE-RE formation
of the sun is doubted, and the atmosphere is described as being highly
dynamic. The LTE-RE assumption can be applied to the spatially averaged
upper photosphere, but the problems associated with the NLTE effects
must be considered to investigate the fine elements of solar structure.

@--------------------------------------------------------------------
Title: New solar oscillator strengths from Kiev
Authors: Gurtovenko, E. A.; Kostik, R. I.; Rutten, R. J.
Bibliographic Code: 1990asos.conf...92G
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Book-Review - Solar and Stallar Granulation
Authors: Rutten, R. J.; Severino, G.
Bibliographic Code: 1989Sci...246..137R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Book Review: Physics of formation of Fe II lines
outside LTE (IAU Coll. 94) / Reidel, 1988
Authors: Viotti, R.; Vittone, A.; Friedjung, M.;
Rutten, R. J.
Book Authors: Viotti, R.; et al.
Bibliographic Code: 1989SSRv...50..618V
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Book-Review - Physics of Formation of Feii Lines
Outside LTE
Authors: Viotti, R.; Vittone, A.; Friedjung, M.;
Rutten, R. J.
Bibliographic Code: 1989SSRv...50..617V
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Book-Review - Space - the Next Twenty-Five Years
Authors: Manno, V.; Kresák, L.; de Jong, T.;
Trimble, Virginia; Marov, Mikhail Ya.;
Rutten, Robert J.; Vreeburg, J. P. B.; Kaufmann, P.
Bibliographic Code: 1989SSRv...50..615M
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Granulation and the NLTE Formation of K I 769. 9
Authors: Gomez, M. T.; Severino, G.; Rutten, R. J.
Bibliographic Code: 1989ssg..conf..565G
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The Granulation Sensitivity of Neutral Metal Lines
Authors: Bruls, J. H. M. J.; Uitenbroek, H.; Rutten, R. J.
Bibliographic Code: 1989ssg..conf..311B
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Workshop Introduction
Authors: Rutten, R. J.
Bibliographic Code: 1989ssg..conf....1R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Solar and stellar granulation
Authors: Rutten, Robert J.; Severino, Giuseppe
Bibliographic Code: 1989ssg..conf.....R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The Solar Photosphere: Video Movies and Computer
Simulations
Authors: Rutten, Robert J.
Bibliographic Code: 1989ComAp..14..297R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The granulation sensitivity of helioseismology lines
Authors: Rutten, R. J.; Bruls, J. H. M. J.; Gomez, M. T.;
Severino, G.
Bibliographic Code: 1988ESASP.286..251R
Paper (if ADS pdf and access) ADS page
The sensitivity of the Ni I 676.78 nm Global Oscillation Network Group
line and the K I 769.9 nm resonance line to the temperature fluctuations
present in the solar granulation are discussed. The temperature
contrasts due to granulation are probably small in the upper photosphere
where the cores of these two helioseismology lines are formed. However,
the cores are sensitive also to the granulation temperature contrasts in
the deep photosphere, through nonlocal NLTE effects in their formation.
The largest effects are due to the ultraviolet radiation field, which is
strongly modulated by the granulation in the deep layers where it
escapes and carries these contrasts upwards to the line formation
height. The resulting NLTE mechanisms and their influence on the two
lines are considered.

@--------------------------------------------------------------------
Title: Oscillator Strengths from the High S/n Solar
Spectrum
Authors: Rutten, R. J.
Bibliographic Code: 1988IAUS..132..367R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Feii Prospects in Solar Physics
Authors: Rutten, R. J.
Bibliographic Code: 1988ASSL..138..317R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The NLTE formation of iron lines in the solar
photosphere
Authors: Rutten, Robert J.
Bibliographic Code: 1988ASSL..138..185R
Paper (if ADS pdf and access) ADS page
The use of solar iron lines as diagnostics of the solar photosphere is
discussed. NLTE in photospheric iron lines is discussed, including NLTE
mechanisms, the description of NLTE, and published NLTE modeling of Fe I
and Fe II. Iron NLTE and the mean atmosphere is addressed, including
empirical plane-parallel modeling from lines and from continua and
radiative-equilibrium modeling. The use of NLTE to study granulation,
flux tubes, and flux bifurcations in the sun is considered.

@--------------------------------------------------------------------
Title: Empirical gf-determination from the solar spectrum
Authors: Rutten, Robert J.; Kostik, Roman I.
Bibliographic Code: 1988ASSL..138...83R
Paper (if ADS pdf and access) ADS page
The reliability of Fe I and Fe II oscillator strengths determined
empirically from optical solar lines is tested. A comparison is made
between gfW fits to the equivalent widths and gfD fits to the depths of
354 Fe I lines and 22 Fe II lines for various combinations of input
parameters. The resulting scatter diagrams provide a measure of the
attainable precision.

@--------------------------------------------------------------------
Title: Book-Review - Progress in Stellar Spectral Line
Formation Theory
Authors: Beckman, J. E.; Crivellari, L.; Rutten, R. J.
Bibliographic Code: 1986SSRv...43Q.384B
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Book-Review - the A-Stars - Problems and
Perspectives
Authors: Wolff, S. C.; Rutten, R. J.
Bibliographic Code: 1985SSRv...41..396W
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Book-Review - Stellar Atmospheric Structural
Patterns
Authors: Thoma, R. N.; Rutten, R. J.
Bibliographic Code: 1985SSRv...41..394T
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Velocity Field in the Region of the Temperature
Minimum of the Solar Atmosphere - Preliminary
Results of a Determination of the Amplitude of the
General Velocity Field
Authors: Gurtovenko, E. A.; Sheminova, V. A.; Rutten, R. J.
Bibliographic Code: 1985SvA....29...72G
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Velocity field in the region of the temperature
minimum of the solar atmosphere - Preliminary
results of a determination of the amplitude of the
general velocity field
Authors: Gurtovenko, E. A.; Sheminova, V. A.; Rutten, R. J.
Bibliographic Code: 1985AZh....62..124G
Paper (if ADS pdf and access) ADS page
The weak Fraunhofer lines in the near wings of H, K Ca II lines have
been analysed to study the velocity amplitude of the general velocity
field in the middle and outer photospheric layers. The results confirm
the basic well-known data on the velocity amplitude in the middle
photospheric layers. Besides, it is shown that the radial and tangential
components of the velocity amplitude continue to decrease with height
also in the outer photosphere.

@--------------------------------------------------------------------
Title: Clean lines in the solar flux spectrum
Authors: Rutten, R. J.; van der Zalm, E. B. J.
Bibliographic Code: 1984A&AS...55..171R
Paper (if ADS pdf and access) ADS page
Profile parameters of 602 unblended lines in the Sacramento Peak Atlas
of the visual solar irradiance spectrum are profiled and compared to
earlier measurements of the same lines in the Jungfraujoch Atlas of the
solar disk-center intensity spectrum. The expected effects of solar
rotation and of center-to-limb variations in the intensity profiles are
discussed and compared to the actual trends. Finally, the spread is
discussed.

@--------------------------------------------------------------------
Title: Revision of solar equivalent widths, Fe I oscillator
strengths and the solar iron abundance
Authors: Rutten, R. J.; van der Zalm, E. B. J.
Bibliographic Code: 1984A&AS...55..143R
Paper (if ADS pdf and access) ADS page
The authors employ detailed modelling of solar Fe I and Fe II lines to
calibrate the correction of equivalent widths for contamination by
unresolved blends. They then determine the equivalent widths of 750
clean lines in the Jungfraujoch Atlas of the optical solar spectrum, and
they compare these to the values given for the Utrecht Atlas by Moore et
al. (1966). The authors also select clean Fe I lines, discuss their NLTE
formation, construct a NLTE Fe I curve of growth, provide new oscillator
strengths for weak Fe I lines, and revise the solar iron abundance to
NFe/NH = (4.3±0.5)10-5. The
authors use the results to appraise the basis and methods of classical
stellar abundance determination.

@--------------------------------------------------------------------
Title: One Eye Closed - Two Eyes Closed
Authors: Rutten, R. J.
Bibliographic Code: 1984ssdp.conf..446R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Spectral Lines: Diagnostics
Authors: Rutten, R. J.
Bibliographic Code: 1984ssdp.conf..379R
Paper (if ADS pdf and access) ADS page
The author discusses three aspects of employing spatially-averaged solar
lines as diagnostics of small-scale photospheric structure: (1) partial
redistribution vs. turbulence, (2) advertising the extreme limb, (3)
quality of mean models.

@--------------------------------------------------------------------
Title: Book-Review - Automated Data Retrieval in Astronomy
Authors: Jaschek, G.; Heintz, W.; Rutten, R. J.
Bibliographic Code: 1983SSRv...36..417J
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Empirical NLTE analyses of solar spectral lines. IV
- The Fe I curve of growth
Authors: Rutten, R. J.; Zwaan, C.
Bibliographic Code: 1983A&A...117...21R
Paper (if ADS pdf and access) ADS page
The effects of departures from local thermodynamic equilibrium on the
equivalent widths of solar Fe I lines are studied as an example for the
analysis of the stellar curve of growth. The solar curve of growth
obtained is based on the nonlocal thermodynamic equilibrium (NLTE)
modeling of the solar spectrum of Lites (1972, 1973) and the best
available oscillator strengths for 991 Fe I lines. The empirical curve
obtained relating the equivalent width-wavelength ratio to the
oscillator strength under NLTE is shown to differ appreciably from
curves neglecting the NLTE ionization departures, although these effects
may be corrected by assuming a NLTE-masking model. Theoretical NLTE
curves of growth are also presented, and splittings due to wavelength
dependency, differences in NLTE excitation, and variation in collisional
damping, which are largely hidden by noise in observed values, are
discussed. A new value for the solar iron abundance of 0.000047 times
the hydrogen abundance is also derived.

@--------------------------------------------------------------------
Title: NLTE masking and the Kiev Fe I oscillator strengths.
Authors: Rutten, R. J.
Bibliographic Code: 1983HiA.....6..801R
Paper (if ADS pdf and access) ADS page
This paper describes the empirical solar-spectrum determinations of the
oscillator strengths of 860 Fe I lines by Gurtovenko and Kostik (1981),
and attempts to show their particular value for abundance analyses of
cool stars.

@--------------------------------------------------------------------
Title: Empirical NLTE analyses of solar spectral lines. III
- Iron lines versus LTE models of the photosphere
Authors: Rutten, R. J.; Kostik, R. I.
Bibliographic Code: 1982A&A...115..104R
Paper (if ADS pdf and access) ADS page
We compare observational indications of departures from LTE in solar
Fe I lines with published NLTE computations in the context of
discrepancies between empirical LTE and NLTE models of the solar
atmosphere. We find that the importance of departures from LTE in Fe I
and similar spectra is often underestimated through neglect of opacity
departures. We demonstrate with numerical experiments that the
peculiarities of the LTE models are artifacts due to the neglect of
NLTE departures; in particular, we so explain the Holweger-Müller
LTE model quantitatively. However, we show also that the NLTE
formation of most optical metal lines is fortuitously well-mimicked by
LTE computation when using LTE models. Thus, LTE-derived metal
abundances and empirical oscillator strengths happen to be fairly
precise. The same may hold for the use of theoretical radiative-
equilibrium models in stellar abundance determinations.

@--------------------------------------------------------------------
Title: The Sun as a star
Authors: Rutten, R. J.; Cram, L. E.
Bibliographic Code: 1981NASSP.450..473R
Paper (if ADS pdf and access) ADS page
The ways in which solar astrophysics serves to improve the methodology
for the interpretation of stellar observations and the construction of
stellar atmospheric models are summarized. The astrophysical processes
highlighted are: stellar mass; stellar rotation; stellar magnetism;
stellar composition; stellar companions; and evolutionary history.

@--------------------------------------------------------------------
Title: On the formation of Fe II lines in stellar spectra.
I - Solar spatial intensity variation of lambda
3969.4
Authors: Cram, L. E.; Lites, B. W.; Rutten, R. J.
Bibliographic Code: 1980ApJ...241..374C
Paper (if ADS pdf and access) ADS page
High-spatial-resolution solar observations of the weak Fe II lambda
3969.4 line are employed to study non-local thermodynamic equilibrium
effects in Fe II line formation. This line is superposed on the wing of
the Ca II H line, which raises its height of formation. The line shows
extraordinary spatial intensity variations, including emission features
whose contrast increases toward the limb. Observed profiles of the Fe II
resonance lines in the UV are used to define formation parameters in a
15-level atomic model computation, which shows that Fe II subordinate
lines are generally formed out of local thermodynamic equilibrium as a
result of pumping by UV line-wing photons from the deep photosphere. For
the lambda 3969.4 line, this pumping results in large sensitivity to the
atmospheric structure in layers deeper than the layer of formation of
the H-wing background intensity. The absence of intense emission cores
in the Fe II resonance lines, the effects of partially coherent
scattering, and the effects of chromospheric and photospheric
inhomogeneities are discussed. It is found that emission of lambda
3969.4 provides a diagnostic of the inhomogeneous structure of the deep
photosphere, for the sun and for late-type stars.

@--------------------------------------------------------------------
Title: Solar limb emission lines near CA II H & K and their
spatial intensity variations
Authors: Rutten, R. J.; Stencel, R. E.
Bibliographic Code: 1980A&AS...39..415R
Paper (if ADS pdf and access) ADS page
The paper employs solar observations of high spatial and spectral
resolution to identify emission lines seen in the extended wings of Ca
II H & K near the solar limb. Emission lines in the wings of H &
K represent valuable diagnostics of the atmospheres of cool stars, with
a varying information content which depends on their particular
formation mechanism. In solar spectrograms different emission line
formation mechanisms can be distinguished by the character of the
spatial intensity variation (SIV) apparent in the lines. Various classes
of H & K emission features, their spatial intensity variations and
their formation mechanisms (of which some pose further problems) are
discussed. A new extended list of line identifications is compiled based
on their formation class and compared with other line lists. Evidence is
found that stellar luminosity-sensitive lines tend to show large spatial
intensity variation on the sun.

@--------------------------------------------------------------------
Title: Afbuiging van straling door de zon. 2. Nieuwe
metingen.
Authors: Rutten, R. J.
Bibliographic Code: 1980Zenit...7..372R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Afbuiging van straling door de zon. 1. De
zonsverduistering van 1919.
Authors: Rutten, R. J.
Bibliographic Code: 1980Zenit...7..276R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Diagnostic Use of Feii H and K Wing Emission Lines
Authors: Cram, L. E.; Rutten, R. J.; Lites, B. W.
Bibliographic Code: 1980LNP...114..102C
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Report from the discussion group on two dimensional
spectroscopy
Authors: Righini, A.; Rutten, R. J.
Bibliographic Code: 1980fsoo.conf..308R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Solar observations with high spectral purity: needs
and constraints (This paper was actually presented
at the end of session 4.)
Authors: Rutten, R. J.
Bibliographic Code: 1980fsoo.conf..221R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: An open LEST?
Authors: Hammerschlag, R. H.; Rutten, R. J.
Bibliographic Code: 1980fsoo.conf..115H
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Partial redistribution in the solar photospheric BA
II spectrum
Authors: Rutten, R. J.; Milkey, R. W.
Bibliographic Code: 1979ApJ...231..277R
Paper (if ADS pdf and access) ADS page
Recent studies of the effects of partial frequency redistribution (PRD)
on the formation of strong chromospheric resonance lines are extended to
weaker lines formed in the photosphere. Methods that have been derived
to compute the PRD formation of the Ca II spectrum are applied to the
solar Ba II spectrum. It is found that PRD is important in the formation
of the 4554-A resonance line, and the results confirm that its effects
on the line source function explain the emission wings of this line
observed near the limb. Source function structure and line profiles for
Ba II 4554 A and Ba II 5854 A are discussed; they may serve as an
example for estimating effects of PRD in other photospheric lines in
stellar atmospheres.

@--------------------------------------------------------------------
Title: Report from the discussion on two-dimensional
spectroscopy requirements for Lest (Large European
Solar Telescope).
Authors: Righini, A.; Rutten, R. J.
Bibliographic Code: 1979MmArc.106..308R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Solar observations with high spectral purity: needs
and constraints.
Authors: Rutten, R. J.
Bibliographic Code: 1979MmArc.106..221R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: An open LEST (Large European Solar Telescope)?
Authors: Hammerschlag, R. H.; Rutten, R. J.
Bibliographic Code: 1979MmArc.106..115H
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Empirical NLTE analyses of solar spectral lines. II
- The formation of the BA II lambda 4554 resonance
line
Authors: Rutten, R. J.
Bibliographic Code: 1978SoPh...56..237R
Paper (if ADS pdf and access) ADS page
The center-to-limb behavior of the Ba II lambda 4554 resonance line is
analyzed with attention to data from the extreme limb, flash
intensities, and profiles of the other Ba II lines. By means of an
empirical NLTE method, observed profiles are compared with synthesized
profiles based on a standard one-dimensional model atmosphere; the free
parameters of this model are the line source function, the barium
abundance, the collisional damping, and the atmospheric turbulence. Wing
characteristics and the form of the empirically derived
frequency-dependent line source function are discussed, and results for
gf-values, solar barium abundance and isotope ratios, collisional
damping, microturbulence, and macroturbulence are provided.

@--------------------------------------------------------------------
Title: Report from the discussion group on two dimensional
spectroscopy
Authors: Righini, A.; Rutten, R. J.
Bibliographic Code: 1978fsoo.conf..308R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Solar observations with high spectral purity: needs
and constraints
Authors: Rutten, R. J.
Bibliographic Code: 1978fsoo.conf..221R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: An open LEST?
Authors: Hammerschlag, R. H.; Rutten, R. J.
Bibliographic Code: 1978fsoo.conf..115H
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Extreme limb observations of BA II lambda 4554 and
MG I lambda 4571
Authors: Rutten, R. J.
Bibliographic Code: 1977SoPh...51....3R
Paper (if ADS pdf and access) ADS page
Eclipse observations, observed near the solar limb, of the Ba II lambda
4554.0 resonance line and the Mg I lambda 4571.1 intercombination line
are presented. Attention is given to the geometry of the observations,
microphotometry, and restoration. Detailed profiles are given for a
range of viewing angles (1/cos theta = 4-22).

@--------------------------------------------------------------------
Title: The formation of Ba lambda 4554 in the solar
atmosphere. Ch. 3.
Authors: Rutten, R. J.
Bibliographic Code: 1976seob.conf...47R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Extreme limb observations of Ba lambda 4554 and Mg I
lambda 4571. Ch. 2.
Authors: Rutten, R. J.
Bibliographic Code: 1976seob.conf...21R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Report of the Dutch expedition to the 1970 March 7
solar eclipse. Ch. 1.
Authors: Houtgast, J.; Namba, O.; Rutten, R. J.
Bibliographic Code: 1976seob.conf....3H
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Report of the Dutch expedition to the 1970 March 7
solar eclipse.
Authors: Houtgast, J.; Namba, O.; Rutten, R. J.
Bibliographic Code: 1976RNAAS..79..221H
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Non-thermal broadening of weak lines
Authors: Gurtovenko, E. A.; de Jager, C.; Lindenbergh, A.;
Rutten, R. J.
Bibliographic Code: 1976pmas.conf..331G
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Report of the Dutch expedition to the 1970 March 7
solar eclipse.
Authors: Houtgast, J.; Namba, C.; Rutten, R. J.
Bibliographic Code: 1976PKNAW..79..221H
Paper (if ADS pdf and access) ADS page
Authors: Rutten, R. J.
Bibliographic Code: 1976PhDT.......169R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The Design of Vamp Software for the Measurement and
Reduction of Stellar Spectrograms
Authors: Rutten, R. J.; van Gelder, G. P.
Bibliographic Code: 1975ASSL...54..311R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: a Very Simple Digital Microdensitometer-Comparator
Authors: Rutten, R. J.; van Amerongen, H. J.
Bibliographic Code: 1975ASSL...54..261R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: On the determination of the photospheric velocity
distribution from profiles of weak Fraunhofer lines
Authors: Rutten, R. J.; Hoyng, P.; de Jager, C.
Bibliographic Code: 1974SoPh...38..321R
Paper (if ADS pdf and access) ADS page
Abstract image available at:
http://esoads.eso.org/abs/1974SoPh...38..321R

@--------------------------------------------------------------------
Title: Afplatting van de zon: toets voor theorieën over de
zwaartekracht.
Authors: Rutten, R. J.
Bibliographic Code: 1974Zenit...1....7R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: The Solar Temperature Distribution with Latitude
Authors: Rutten, R. J.
Bibliographic Code: 1973SoPh...28..347R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Spectral lines from photosphere to chromosphere,
observed during the March 1970 eclipse; A first
comparison with theory.
Authors: Houtgast, J.; Namba, O.; Rutten, R. J.;
Wijbenga, J. W.
Bibliographic Code: 1972SoPh...21..281H
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Spectral Lines from Photosphere to Chromosphere,
Observed During the March 1970 Eclipse; A First
Comparison with Theory (Papers presented at the
Proceedings of the International Symposium on the
1970 Solar Eclipse, held in Seattle, U. S. A. ,
18-21 June, 1971.)
Authors: Houtgast, J.; Namba, O.; Rutten, R. J.;
Wijbenga, J. W.
Bibliographic Code: 1971SoPh...21..281H
Paper (if ADS pdf and access) ADS page
Abstract image available at:
http://esoads.eso.org/abs/1971SoPh...21..281H

@--------------------------------------------------------------------
Title: Variations in Line Profiles from Photosphere to
Chromosphere
Authors: Houtgast, J.; Namba, O.; Rutten, R. J.;
de Graauw, Th.
Bibliographic Code: 1970Natur.226.1144H
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Neutrino's van de zon.
Authors: Rutten, R. J.
Bibliographic Code: 1969HemD...67..322R
Paper (if ADS pdf and access) ADS page

@--------------------------------------------------------------------
Title: Coronal scattering of radiation from an
anisotropically radiating solar radio source.
Authors: Fokker, A. D.; Rutten, R. J.
Bibliographic Code: 1967BAN....19..254F
Paper (if ADS pdf and access) ADS page

Rob Rutten
2012-05-05