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Author name code: schadee
ADS astronomy entries on 2022-09-14
author:"Schadee, Aert"
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Title: Book reviews
Authors: Hermsen, W.; Stamm, W.; Nieuwenhuijzen, H.; Plez, B.;
Koch-Miramond, L.; Schadee, A.; De Greve, J. P.; Icke, Vincent;
Kresák, Ľ.; Dekker, E.; Bonnet-Bidaud, J. -M.; Foing, B. H.
1994SSRv...67..421H Altcode:
No abstract at ADS
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Title: Book Review: The Cambridge guide to astronomical discovery /
Cambridge U Press, 1992
Authors: Schadee, A.
1994SSRv...67..426S Altcode: 1994SSRv...67..426L
No abstract at ADS
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Title: Book-Review - the Astronomy and Astrophysics Encyclopedia
Authors: Maran, S. P.; Schadee, A.
1993SSRv...64..367M Altcode:
No abstract at ADS
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Title: Book reviews
Authors: Heintze, J. R. W.; van Genderen, A. M.; van Oss, R.; van
der Klis, M.; Fárník, F.; Schadee, A.; Sylwester, J.; Torii, S.;
Iwaniszewska, C.; Nieuwenhuijzen, H.; Kleczek, J.; Schwartz, S. J.
1993SSRv...64..363H Altcode:
No abstract at ADS
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Title: Book Review: Space science dictionary I / Academia Praha ;
Elsevier, 1990
Authors: Schadee, A.
1992SSRv...61R.425S Altcode:
No abstract at ADS
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Title: Book Review: Molecular astrophysics / CUP, 1990
Authors: Schadee, A.
1991SSRv...58..191S Altcode:
No abstract at ADS
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Title: Book reviews
Authors: Hovenier, J. W.; Cornet, Gerard; De Greve, J. P.; Schadee,
A.; Kresák, L.; Néeman, Y.
1991SSRv...58..189H Altcode:
No abstract at ADS
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Title: Book reviews
Authors: Iwanowska, W.; Sehnal, L.; van der Kruit, P. C.; Schadee,
A.; Smoliński, J.; Longair, M. S.; Thé, P. S.; McLean, I. S.
1991SSRv...56..241I Altcode:
No abstract at ADS
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Title: Book Review: Introduction to stellar astrophysics. Vol. 2:
Stellar atmospheres / CUP, 1989
Authors: Schadee, A.
1991SSRv...56..245S Altcode:
No abstract at ADS
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Title: Book Review: Introduction to stellar astrophysics Volume 1:
Basic stellar observations and data / CUP, 1989
Authors: Schadee, A.
1990SSRv...54..452S Altcode: 1990SSRv...54..452B
No abstract at ADS
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Title: De zon, een overzicht.
Authors: Schadee, A.
1990Zenit..17..306S Altcode:
No abstract at ADS
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Title: Book reviews
Authors: Marov, M. Ya; Garmany, C. D.; Heck, André; Schadee, A.;
McNally, D.; van der Kruit, P. C.; Pecker, J. -C.; de Jager, Cornelis;
Somov, B. V.
1989SSRv...50..385M Altcode:
No abstract at ADS
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Title: Preflare activity.
Authors: Priest, E. R.; Gaizauskas, V.; Hagyard, M. J.; Schmahl, E. J.;
Webb, D. F.; Cargill, P.; Forbes, T. G.; Hood, A. W.; Steinolfson,
R. S.; Chapman, G. A.; Deloach, A. C.; Gary, G. A.; Jones, H. P.;
Karpen, J. T.; Martres, M. -J.; Porter, J. G.; Schmieder, B.; Smith,
J. B., Jr.; Toomre, J.; Woodgate, B.; Waggett, P.; Bentley, R.;
Hurford, G.; Schadee, A.; Schrijver, J.; Harrison, R.; Martens, P.
1989epos.conf....1P Altcode:
Contents: 1. Introduction. 2. Magnetohydrodynamic
instability. 3. Preflare magnetic and velocity fields. 4. Coronal
manifestations of preflare activity.
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Title: High resolution microwave and X-ray observations of solar
flares
Authors: Alissandrakis, C. E.; Schadee, A.; Kundu, M. R.
1988A&A...195..290A Altcode:
This paper presents an analysis of high spatial resolution observations
of 18 weak flares, carried out during the Solar Maximum Year in the
microwave range, H-alpha, and soft X-rays, together with observations
of the associated hard X-ray emission and the photospheric magnetic
field. This combination of observations made it possible to obtain a
picture of the flare geometry and the relative position of the various
emissions, to study the change of the geometry during the flare, to
estimate the electron temperature and emission measure of the thermal
plasma, and to compute the contribution of the free-free process in
the microwave emission. Results are interpreted as evidence for the
presence of energetic electrons even in the post-burst phase of some
flares. There was also found a clear case of homologous radio and X-ray
bursts, one case of foot-point expansion with a relative velocity of
20 km/s at 6.16 cm, as well as some evidence of triggering of flares
by disturbances moving with a velocity of 5000-13,000 km/s.
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Title: Coronal manifestations of preflare activity
Authors: Schmahl, E. J.; Webb, D. F.; Woodgate, B.; Waggett, P.;
Bentley, R.; Hurford, G.; Schadee, A.; Schrijver, J.; Harrison, R.;
Martens, P.
1986epos.conf.1.48S Altcode: 1986epos.confA..48S
A variety of coronal manifestations of precursors or preheating for
flares are discussed. Researchers found that almost everyone with a
telescope sees something before flares. Whether an all-encompassing
scenario will ever be developed is not at all clear at present. The
clearest example of preflare activity appears to be activated filaments
and their manifestations, which presumably are signatures of a changing
magnetic field. But researchers have seen two similar eruptions, one
without any evidence of emerging flux (Kundu et al., 1985) and the
other with colliding poles (Simon et al., 1984). While the reconnection
of flux is generally agreed to be required to energize a flare, the
emergence of flux from below (at least on short timescales and in
compact regions) does not appear to be a necessary condition. In some
cases the cancelling of magnetic flux (Martin, 1984) by horizontal
motions instead may provide the trigger (Priest, 1985) Researchers
found similarities and some differences between these and previous
observations. The similarities, besides the frequent involvement of
filaments, include compact, multiple precursors which can occur both at
and near (not at) the flare site, and the association between coronal
sources and activity lower in the atmosphere (i.e., transition zone
and chromosphere).
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Title: Book-Review - Molecular Astrophysics
Authors: Diercksen, G. H. F.; Huebner, W. F.; Langhoff, P. W.;
Schadee, A.
1986SSRv...44..178D Altcode:
No abstract at ADS
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Title: Book reviews
Authors: Gurtovenko, E. A.; Kostik, R. I.; Tlamicha, A.; Zerull, R.;
Schadee, Aert; Mészáros, A.; Néeman, Y.; Giese, R. H.; Sinclair,
A. T.; Kleczek, J.; Trendelenburg, E. A.; Hillebrandt, Wolfgang;
Sehnal, L.; de Graaff, W.; Slottje, C.; Courvisier, T.; van Beek,
H. F.; Baud, B.; de Jager, C.; Danby, J. M. A.; Somov, B. V.;
Cassinelli, J.; Verbunt, F.
1986SSRv...44..177G Altcode:
No abstract at ADS
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Title: Preflare activity.
Authors: Priest, E. R.; Gaizauskas, V.; Hagyard, M. J.; Schmahl, E. J.;
Webb, D. F.; Cargill, P.; Forbes, T. G.; Hood, A. W.; Steinolfson,
R. S.; Chapman, G. A.; Deloach, A. C.; Gary, G. A.; Jones, H. P.;
Karpen, J. T.; Martres, M. -J.; Porter, J. G.; Schmieder, B.; Smith,
J. B., Jr.; Toomre, J.; Woodgate, B.; Waggett, P.; Bentley, R.;
Hurford, G.; Schadee, A.; Schrijver, J.; Harrison, R.; Martens, P.
1986NASCP2439....1P Altcode:
Contents: 1. Introduction: the preflare state - a review of previous
results. 2. Magnetohydrodynamic instability: magnetic reconnection,
nonlinear tearing, nonlinear reconnection experiments, emerging flux and
moving satellite sunspots, main phase reconnection in two-ribbon flares,
magnetic instability responsible for filament eruption in two-ribbon
flares. 3. Preflare magnetic and velocity fields: general morphology of
the preflare magnetic field, magnetic field shear, electric currents in
the preflare active region, characterization of the preflare velocity
field, emerging flux. 4. Coronal manifestations of preflare activity:
defining the preflare regime, specific illustrative events, comparison
of preflare X-rays and ultraviolet, preflare microwave intensity and
polarization changes, non-thermal precursors, precursors of coronal
mass ejections, short-lived and long-lived HXIS sources as possible
precursors.
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Title: Survey of an active region in H<SUB>&</SUB>alpha;
and X-rays.
Authors: Schadee, Aert; Martin, Sara F.
1986lasf.conf..360S Altcode: 1986lasf.symp..360S
The authors studied Hale Active Region No. 16918 during almost
15 hours of simultaneous observation by Big Bear Solar Observatory
(H<SUB>&</SUB>alpha;) and HXIS (3.5 - 5.5 keV) aboard SMM on 18 -
22 June 1980.
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Title: On the nature of small X-ray flux over active regions
Authors: Schadee, Aert
1986AdSpR...6f..41S Altcode: 1986AdSpR...6...41S
Long-lived weak X-ray flux is often observed in active regions. The
speculation that this flux is the collective result of a manifold of
“nanoflares” is investigated. Modelling nanoflares as instantaneously
energized loops, it is shown that these loops cannot be shorter than
10 000 km. A modest number of loops with lengths ranging from 10 000
to 30 000 km and electron densities of (1 - 3) × 10<SUP>11</SUP>
cm<SUP>-3</SUP> could produce the observed X-ray flux.
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Title: Can nanoflares produce weak X-ray sources?
Authors: Schadee, Aert
1986lasf.conf..356S Altcode: 1986lasf.symp..356S
Long-lived weak X-ray flux is often observed in active
regions. The speculation that this flux is the collective result
of a manifold of nanoflares is investigated. Modelling nanoflares
as instantaneously energized loops, it is shown that these loops
cannot be shorter than 10,000 km. A modest number of loops with
lengths ranging from 10,000 to 30,000 km and electron densities of
(1 - 3)×10<SUP>11</SUP>cm<SUP>-3</SUP> could produce the observed
X-ray flux.
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Title: Identification of two X-ray miniflares with
H<SUB>α</SUB>-subflares
Authors: Schadee, A.; Gaizauskas, V.
1984AdSpR...4g.117S Altcode: 1984AdSpR...4..117S
Active regions show many short-lived emissions in the 3.5 - 5.5
keV range that are 100 to 1000 times weaker than “normal” X-ray
flares. The hypothesis that they may well be miniflares is supported
by the simultaneous occurrence of 2 H<SUB>α</SUB>-subflares at the
site of weak X-ray sources.
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Title: Relationships of a growing magnetic flux region to flares
Authors: Martin, S. F.; Bentley, R. D.; Schadee, A.; Antalova, A.;
Kucera, A.; Dezső, L.; Gesztelyi, L.; Harvey, K. L.; Jones, H.;
Livi, S. H. B.; Wang, J.
1984AdSpR...4g..61M Altcode: 1984AdSpR...4...61M
Some sites for solar flares are known to develop where new magnetic
flux emerges and becomes abutted against opposite polarity pre-existing
magnetic flux (review by Galzauskas/1/). We have identified and analyzed
the evolution of such flare sites at the boundaries of a major new and
growing magnetic flux region within a complex of active regions, Hale
No. 16918. This analysis was done as a part of a continuing study of the
circumstances associated with flares in Hale Region 16918, which was
designated as an FBS target during the interval 18 - 23 June 1980. We
studied the initiation and development of both major and minor flares in
Hα images in relation to the identified potential flare sites at the
boundaries of the growing flux region and to the general development
of the new flux. This study lead to our recognition of a spectrum of
possible relationships of growing flux regions to flares as follows:
(1) intimate interaction with adjacent old flux - flare sites centered
at new/old flux boundary, (2) forced or “intimidated” interaction
in which new flux pushes old field having lower flux density towards a
neighboring old polarity inversion line where a flare then takes place,
(3) “influential” interaction - magnetic lines of force over an old
polarity inversion line, typically containing a filament, reconnect to
the new emerging flux; a flare occurs with erupting filament when the
magnetic field overlying the filament becomes too weak to prevent its
eruption, (4) inconsequential interaction - new flux region is too small
or has wrong orientation for creating flare conditions, (5) incidental -
flare occurs without any significant relationship to new flux regions.
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Title: Enhanced X-Ray Emission above 3.5-KEV in Active Regions in
the Absence of Flares
Authors: Schadee, A.; de Jager, C.; Svestka, Z.
1983SoPh...89..287S Altcode:
We demonstrate that even in the absence of flares there are very
often volumes of hot plasma in the corona above active regions with
temperatures in excess of 10 million degrees. Characteristics of
this hot plasma and its time variations seem to be different in
active regions of different phase of development. These hot plasma
regions are sources of very weak, but clearly recognizable, X-ray
emission above 3.5 keV. Long-lived X-ray brightenings, 10<SUP>4</SUP>
times weaker than a flare, but lasting up to 10 hr occur predominantly
along the H<SUB>∥</SUB> = 0 line, apparently low in the corona. After
major flares, long-lived X-ray emission is also radiated from tops of
arches extending high into the corona. Some other long-lived sources,
far from the H<SUB>∥</SUB> = 0 line, may be associated with newly
emerging flux. Short-lived X-ray sources, with fluxes ranging from
subflare levels to 10<SUP>−3</SUP> times the flare flux, last for
2 to more than 30 min and are probably microflares. They seem to be
most frequent in growing young active regions and appear often in
areas with newly emerging flux.
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Title: Radio, X-ray, and optical observations of the flare of June
13, 1980, at 6<SUP>h</SUP>22<SUP>m</SUP> UT
Authors: Kattenberg, A.; Allaart, M.; de Jager, C.; Schadee, A.;
Schrijver, J.; Shibasaki, K.; Švestka, Z.; van Tend, W.
1983SoPh...88..315K Altcode:
A subflare of importance Sf was observed on June 13, 1980 simultaneously
by instruments aboard the Solar Maximum Mission (SMM) and various
ground based observatories. We describe and compare different kinds
of observations, with emphasis on the Hard X-Ray Imaging Spectrometer
(HXIS) images and spectra, and on the one-dimensional microwave images
with high time and spatial resolution, obtained with the Westerbork
Synthesis Radio Telescope (WSRT). The fast electrons causing the X-ray
and microwave impulsive bursts had a common acceleration source, but the
burst were produced at the opposite footpoints of the loops involved,
with microwaves emitted near to a sunspot penumbra. The flare (of a
`compact' type) was probably triggered by an emerging flux, and two
possible interpretations of this process are briefly discussed.
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Title: Pre-Flare and Post-Flare X-Ray Variations in Active Regions
Authors: Svestka, Z.; Schadee, A.
1983SoPh...86..267S Altcode:
Extremely low background noise of the HXIS experiment aboard the SMM
made it possible to detect > 3.5 keV X-ray emissions from non-flaring
active regions which are 10<SUP>3</SUP>-10<SUP>4</SUP> times weaker than
the X-ray flux from flares. Short-lived X-ray bursts and long-lived
X-ray enhancements of various intensities seem to characterize active
regions in different phases of their development. After major two-ribbon
flares, giant X-ray arches are seen in the corona, slowly decaying for
many hours after the flare end. Associated with these arches appear
to be quasi-periodic flare-like variations of purely coronal nature.
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Title: The Queen's Flare - its Structure and Development - Precursors
Pre-Flare Brightenings and Aftermaths
Authors: de Jager, Cornelis; Machado, Marcos E.; Schadee, Aert;
Strong, Keith T.; Švestka, Zdeněk; Woodgate, Bruce E.; van Tend, W.
1983SoPh...84..205D Altcode:
We continue previous research on the limb flare of 30 April, 1980, 20:20
UT, observed in X-rays by several instruments aboard the Solar Maximum
Mission (SMM). It is shown quantitatively that the flare originated in
an emerging magnetically confined kernel (diameter ∼ 20″) which
existed for about ten to fifteen minutes, and from which energetic
electrons streamed, in at least two injections, into a previously
existing complicated magnetic loop system thus forming a less bright but
extended and long-lived tongue. The tongue had a length of ∼ 35 000 km
and lasted ∼ 90 min in X-rays (∼ 10 keV); at lower energies (∼ 0.7
keV) it was larger (∼ 80 000 km) and lasted longer. The total number
of energetic electrons (≈ 10<SUP>37</SUP>) initially present in the
kernel is of the same order as the number present in the tongue after
the kernel's decline. This gives evidence that the energetic electrons
in the tongue originated mainly in the kernel. The electron number
densities in the kernel and tongue at maximum brightness were ∼ 4.5
× 10<SUP>11</SUP> and ∼ 1 × 10<SUP>11</SUP> cm<SUP>#X2212;3</SUP>,
respectively. During the first eight minutes of its existence the tongue
was hotter than the kernel, but it cooled off gradually. Its decline in
intensity and temperature was exponential; energy was lost by radiation
and by conduction through the footpoints of the loop system. These
footpoints have a cross-section of only ∼ 3 × 10<SUP>6</SUP>
km<SUP>2</SUP>. This small value, as well as photographs in a CIV UV
emission line, suggests a highly filamentary structure of the system;
this is further supported by the finding that the tongue had a `filling
factor' of ∼ 10<SUP>#X2212;2</SUP>. Several faint X-ray brightenings
(≲ 0.005 of the flare's maximum intensity) were observed at various
locations along the solar limb for several hours before and after the
flare. At ∼ 30 min before the flare's onset a faint (≲ 0.02) flare
precursor occurred, coinciding in place and shape with the flare. First
the kernel precursor was brightest but the tongue precursor increased
continuously in brightness and was the brightest part of the precursor
some 10-15 min after the first visibility of the kernel precursor,
until the start of the main flare. This suggests (weak) continuous
electron acceleration in the tongue during a period of at least 30
min. The main flare was caused by strong emergence of magnetic field
followed by two consecutive field line reconnections and accelerations
in a small loop system, causing footpoint heating. Subsequently plasma
streamed (convectively) into a pre-existing system of larger loops,
forming the tongue.
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Title: 3.5 keV X-ray Emission in Absence of Flares
Authors: Schadee, A.; de Jager, C.; Svestka, Z.
1983BAAS...15R.704S Altcode:
No abstract at ADS
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Title: The limb flare of 1980 April 30 as seen by the hard X-ray
imaging spectrometer
Authors: van Beek, H. F.; de Jager, C.; Schadee, A.; Svestka, Z.;
Boelee, A.; Duijveman, A.; Galama, M.; Hoekstra, R.; Hoyng, P.; Fryer,
R.; Simnett, G. M.; Imhof, J. P.; LaFleur, H.; Maseland, H. V. A. M.;
Mels, W. M.; Schrijver, J.; van der Laan, J. J. M.; van Rens, P.; van
Tend, W.; Werkhoven, F.; Willmore, A. P.; Wilson, J. W. G.; Machado,
M. E.; Zandee, W.
1981ApJ...244L.157V Altcode:
X-ray imaging of the limb event of 1980 April 30 shows that the flaring
involved two distinct components: a pointlike component, which was the
source of the initial hard X-ray burst and an extensive tongue reaching
some 30,000 km above the limb. The tongue had a higher temperature
than the other parts of the structure and seemed to be enhanced by
energetic electrons that derived their energy from the initial source.
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Title: Structural development of the X-ray limb flare of 30 April 1980
Authors: de Jager, C.; Hoyng, P.; Lafleur, H.; Schadee, A.; Svestka,
Z.; van Beek, H. F.; van Tend, W.; Fryer, R.; Simnett, G. M.
1981AdSpR...1m.251D Altcode: 1981AdSpR...1..251D
We describe the development of the limb flare of 30 April 1980, 20:20
UT, as observed by the Hard X-ray Imaging Spectrometer (HXIS) aboard
the Solar Maximum Mission (SMM). It consisted of a short-lived bright
nucleus (FWHM < 10,000 km), just inside the Sun's limb; a longer
lasting tongue, extending to a height of ~ 30,000 km, and a more
complicated feature, approximately situated at the Sun's limb. The
tongue was a pre-existing magnetic structure that started emitting
X-rays only a few seconds after the bright nucleus, and which had a
slightly higher temperature than the nucleus; its X-ray emission may
be caused by electrons escaped from the nucleus.
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Title: Solar maximum mission experiment: Early results of the hard
X-ray imaging experiment
Authors: Boelee, A.; de Jager, C.; Duijveman, A.; Galama, M.; Hoekstra,
R.; Hoyng, P.; Imhof, J. P.; Lafleur, H.; Maseland, H. V. A. M.; Mels,
W. A.; Schadee, A.; Schrijver, J.; Svestka, Z.; van Beek, H. F.;
van Rens, P.; van der Laan, J. J. M.; van Tend, W.; Werkhoven, F.;
Wiersma, G.; Zandee, W.; Simnett, G. M.; Charlton, C. P.; Fryer, R.;
Willmore, A. P.; Wilson, J. W. G.; Machado, M. E.
1981AdSpR...1m.255B Altcode: 1981AdSpR...1R.255B
We have selected four widely different flares from the early
period of operations of the Hard X-Ray Imaging Spectrometer (HXIS)
on SMM to illustrate the characteristic imaging properties of this
experiment. For the small flare of April 4, 1980, we demonstrate the
instrument's capability for locating a compact source. In the weak,
but extensive, flare of April 6 we show how well the instrument can
display spatial structure, and also the low level of the instrument
background. In the 1B flare of April 7 we are able to locate positions
of the X-ray emission in the soft and hard channels, and estimate
the positional variations of the emission patches. Finally, in the IN
flare of April 10, which produced the strongest hard X-ray burst we
have seen so far, we repeat some of the studies made for the April 7
event, and also demonstrate the capability of the HXIS instrument to
study the development, with high time resolution, of individual 8”
× 8” elements of the flare.
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Title: Structural development of the X-ray limb flare of 30 April
1980.
Authors: de Jager, C.; Fryer, R.; Hoyng, P.; Lafleur, H.; Schadee,
A.; Simnett, G. M.; Svestka, Z.; van Beek, H. F.; van Tend, W.
1981hea..conf..251D Altcode:
No abstract at ADS
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Title: Solar Maximum Mission experiment: early results of the hard
X-ray imaging experiment.
Authors: Simnett, G. M.; Boelee, A.; Charlton, C. P.; de Jager, C.;
Duijveman, A.; Fryer, R.; Galama, M.; Hoekstra, R.; Hoyng, P.; Imhof,
J. P.; Lafleur, H.; Machado, M. E.; Maseland, H. V. A. M.; Mels,
W. A.; Schadee, A.; Schrijver, J.; Svestka, Z.; van Beek, H. F.;
van Rens, P.; van der Laan, J. J. M.; van Tend, W.; Werkhoven, F.;
Wiersma, G.; Willmore, A. P.; Wilson, J. W. G.; Zandee, W.
1981hea..conf..255S Altcode:
No abstract at ADS
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Title: Errata: "On the Zeeman effect in electronic transitions of
diatomic molecules" [J. Quant. Spectrosc. Radiat. Transfer, Vol. 23,
p. 517 - 531 (1978)].
Authors: Schadee, A.
1980JQSRT..23..533S Altcode:
No abstract at ADS
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Title: Unique definitions for the band strength and the
electronic-vibrational dipole moment of diatomic molecular radiative
transitions.
Authors: Schadee, A.
1978JQSRT..19..451S Altcode:
No abstract at ADS
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Title: On the Zeeman effect in electronic transitions of diatomic
molecules.
Authors: Schadee, A.
1978JQSRT..19..517S Altcode:
No abstract at ADS
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Title: Theory of First Rotational Lines in Transitions of Diatomic
Molecules
Authors: Schadee, A.
1975A&A....41..203S Altcode:
Summary. Correct expressions for the energies of the first rotational
levels (those with J < A + S) and the H6nl-London factors for
transitions involving these levels are derived for doublet and triplet
states and transitions in diatomic molecular spectra. Key words: first
rotational lines H6nl-London factors - interstellar lines spectroscopy
---------------------------------------------------------
Title: Honl-London Factors for 3H-32 and 3L'-~J1 Transitions with
Intermediate Coupling
Authors: Schadee, A.
1975A&A....41..213S Altcode:
Summary. H6nl-London factors of rotational lines for 3H - and -
3H transitions of diatomic molecules are calculated, allowing for
non-zero values of both the splitting constant of the state and the
coupling constant Y of the H state. Key words: H6nl-London factors
molecular spectro sco py
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Title: Book reviews
Authors: van de Stadt, Herman; Rawer, Karl; Schadee, A.; Noyes, R. W.;
Bleeker, J. A. M.; Wittenberg, H.; de Graaff, W.; Akasofu, S. -I.;
Hooykaas, R.; Bappu, M. K. V.; Atanasijević, I.; Icke, Vincent;
van der Valk, F.; Kresàk, L.; Müller, Edith A.
1975SSRv...17..159V Altcode:
No abstract at ADS
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Title: On the Normalization of H6nl-London Factors
Authors: Schadee, A.
1971A&A....14..401S Altcode:
A new normalization of -London factors, which govern the intensity
distribution within a molecular band, is presented. Problems posed
by previous normalizations are solved. Key worde: -London factors -
molecular spectroscopy
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Title: An Upper Limit of the Swan Band Intensity in a Sunspot Spectrum
Authors: Schadee, Aert
1970SoPh...15..345S Altcode:
There is no evidence for the C<SUB>2</SUB>(0,1) band in an investigated
sunspot spectrum. Upper limits are given for the band intensity.
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Title: On the oscillator strengths of MgO and F<SUB>2</SUB>.
Authors: Main, R. P.; Schadee, A.
1969JQSRT...9..713M Altcode:
No abstract at ADS
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Title: Zirconium Isotope Ratios in the S-Type Star HR 1105
Authors: Schadee, Aert; Davis, Dorothy N.
1968ApJ...152..169S Altcode:
The spectrum of the bright non-variable star HR 1105 was studied at
3 A/mm; it is S type with some features of type M. The wavelengths
of isotopes of ZrO were computed and used to improve the molecular
constants by comparison with laboratory measurements. Direct use of
isotope shifts is not possible. The isotope ratios of zirconium in HR
1105 were estimated by fitting elaborately computed ZrO profiles to the
observed spectrum in a limited, supposedly uncon- taminated, region. Two
sets of isotope ratios which best match the stellar spectrum were found:
(a) a terrestrial mixture, but with a high abundance of unstable Zr93,
i.e., Zr93/Zr9° ~ ~, and (b) the ratios Zr91/Zr90, Zr92/Zr90, and
Zr94/Zr9° larger by a factor of 2 or 3 than the terrestrial ratios,
with Zr93 at low abundance. The present observations do not permit a
choice between these two possible isotopic mixtures. An upper limit
to Zr96 is probably less than 10 per cent of the Zr content. No trace
of strong lines of ZrO'7 or ZrO'8 was found. Thus Zr isotopes produced
by the s-process apparently differ, in this star, from the terrestrial
values, and the supposed production of 018 has probably not occurred
---------------------------------------------------------
Title: Molecular Band Intensities in G and K Stars
Authors: Schadee, Aert
1968ApJ...151..239S Altcode:
Intensities of CO, CH, C2, and CN bands are studied for G and K stars
with various surface gravities and metal content, assuming different
C, N, and 0 compositions. Atmospheric models are based on a scaled,
solar T(r) relation A simple method predicts the molecular intensities
accurately, and it is therefore not necessary to work out the equilibria
of all possible C, N, and 0 compounds in detail. The dependences of
the computed band intensities on the metal content, Teff, and g are
discussed and found to be in agreement with the observations. The
possibilities of determining CNO abundances from ob- served band
intensities are also discussed. The molecular equilibria are dominated
by the association of CO, which is complete for stars later than KO. Two
independent spectral features are required to deter- mine the C and 0
abundances, like the G-band and an [Oi] line in oxygen-rich giants. In
oxygen-rich dwarfs, there is oniy one easily observable feature, the
G-band, which yields a relation between 0 and C. In carbon-rich stars
the C2 and CH intensities are not independent since each is a function
of the abun- dance difference between carbon and oxygen. For oxygen-rich
dwarfs and carbon-rich stars the second datum required to derive 0 and
C can only be obtained from infrared CO observations. The nitrogen
abundance may be determined from CN bands for carbon-rich stars, if
the C - 0 abundance difference is known, and for oxygen-rich stars, if
both the carbon and the oxygen abundances are known. The division of
late-type stars into oxygen-rich and carbon-rich is extremely sharp;
differences of more than 1 per cent from the mathematical equality
0 = C places a star in either class. All bands of C and N compounds
are formed near r 0.1 in carbon-rich stars and, except for CO, near
r 1 or 2 in oxygen-rich stars. Especially in the latter stars, the
optical depth of formation (r) is a function of the CNO composition,
and since the carbon depletion is a critical function of both r and
the CNO composi- tion, an a priori assumption of (r) in determining
abundances may lead to erroneous results
---------------------------------------------------------
Title: Zr isotope ratios in HR 1105.
Authors: Schadee, A.; Davis, D. N.
1967PASP...79..437S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Zirconium Isotope Ratios in HR 1105
Authors: Schadee, A.; Davis, D. N.
1967PASP...79Q.437S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Solar Line at λ8668 Å Interpreted as CN
Authors: Schadee, Aert
1967ApJ...147..363S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the Rotational Temperature of a Sunspot
Authors: Schadee, Aert
1966ApJ...145..348S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Reduction of Molecular Line Intensities
Authors: Schadee, A.
1966IAUS...26...92S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The formation of molecular lines in the solar spectrum (Errata:
17 537)
Authors: Schadee, A.
1964BAN....17..311S Altcode:
No abstract at ADS