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Author name code: elste
ADS astronomy entries on 2022-09-14
author:"Elste, Guenther"
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Title: Limb Darkening Measurements Free of Instrumental Stray Light
Authors: Elste, G.; Gilliam, L.
2007SoPh..240....9E Altcode:
We have used the 40 cm coronagraph with an inverse occulting disk
to observe the limb darkening free of instrumental stray light. Our
results agree remarkably well with those of Petro et al. (1984,
Astrophys. J.283, 426) who used the McMath - Pierce tower telescope
but employed a different correction procedure for instrumental stray
light than Neckel and Labs (1994, Solar Phys.153, 91), whose results for
λ=445.1 nm deviate systematically, apparently overcorrecting for stray
light. Future continuation of such highly reproducible measurements
offers an interesting independent diagnostic of possible slow trends in
effective temperature (T<SUB>eff</SUB>) and in total solar irradiance.
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Title: Coffee breaks in Ann Arbor
Authors: Elste, Guenther H.
1998ASSL..222...43E Altcode: 1998ream.conf...43E
No abstract at ADS
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Title: Fine-Resolution Imaging of Solar Features using Phase-Diverse
Speckle
Authors: Paxman, R. G.; Seldin, J. H.; Elste, G. H.
1995SPD....26..201P Altcode: 1995BAAS...27..950P
No abstract at ADS
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Title: Solar Granulation Restoration using Phase-Diverse Speckle
Imaging: Verification via Simulations and Measurements
Authors: Seldin, J. H.; Paxman, R. G.; Elste, G. H.
1995SPD....26..502S Altcode: 1995BAAS...27..956S
No abstract at ADS
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Title: Line Shapes of Rotating Stars with Application to Alpha Lyrae
Authors: Elste, G. H.
1992ApJ...384..284E Altcode:
Profiles of weak and medium strong lines in the high-resolution
spectrum of Vega can in principle be understood by the center-to-limb
variation of their equivalent widths, predicted by a standard model
atmosphere. Finer details may require a different model structure
depending on the latitude of the rotating star, and perhaps differential
rotation.
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Title: Asymmetries in Limb Darkening Reanalyzed
Authors: Elste, G. H.
1990SoPh..126...37E Altcode:
The cause of the asymmetries in limb darkening reported by Neckel
and Labs (1987) is discussed on the basis of new, stray-light-free
observations, and found to be of instrumental origin.
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Title: Limb Darkening Variations
Authors: Elste, G.
1988srov.proc..204E Altcode:
No abstract at ADS
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Title: Manganese and carbon lines as temperature indicators.
Authors: Elste, G.
1986SoPh..107...47E Altcode: 1987SoPh..107...47E
Selected hyperfine structure broadened lines of various excitations and
the carbon line at 5380 Å are tested as temperature diagnostics for
photospheric heterogeneities. This is done by comparing the observed
center-to-limb variation of the equivalent widths of these lines with
predictions by several proposed models of homogeneous type. Model 10
(Elste, 1968), which also explains the limb-darkening of the continuum
in the same spectral range, provides a better basis for the analysis
of heterogeneities at different photospheric levels than other recent
reference models.
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Title: Temperature Gradients in Regions with and Without Magnetic
Fields
Authors: Elste, G.
1985tphr.conf..185E Altcode:
No abstract at ADS
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Title: Temperature Gradients in the Solar Granulation
Authors: Elste, G.
1985LNP...233..169E Altcode: 1985hrsp.proc..169E
Profiles of the C 5380 and the Mn 5395 recorded using two CCDs in the
focal plane of the Echelle grating spectrograph of the Vacuum Tower at
Sacramento Peak Observatory are analyzed. The behavior of the C 5380
and the Mn 5395 with increasing resolution is studied and compared to
the photographic spectra of Edmonds et al. (1965); the relation between
continuum and line strength is investigated. It is observed that: the
continuum intensity and carbon line equivalent width are positively
correlated with the Edmonds et al. data for C 5052 and continuum;
the carbon lines originate in the same deep layer as the continuum and
become stronger with increasing temperatures; and the manganese line
weakens with increasing temperatures and displays a positive correlation
with the continuum intensity. The data reveal that temperature gradients
are steeper in regions with higher temperatures in deep layers and
flatter in regions with lower temperatures in deep layers. The spatial
distribution of the varying temperature gradients is examined.
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Title: Temperature gradients in regions with and without magnetic
fields.
Authors: Elste, G.
1985MPARp.212..185E Altcode:
Observational evidence for the flattening of the temperature gradients
in the deep photosphere by magnetic flux tubes is derived from the
equivalent widths of the high excitation carbon line at 5380 Å and
a ground level manganese line at 5395 Å, which also serves as an
indicator for the presence of longitudinal magnetic fields.
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Title: On the Sun's Limb Brightening in the Visible
Authors: Elste, G. H.
1984SoPh...93...15E Altcode:
It is shown that in practice the method by Julius (1906) is incapable
to determine the limb intensity drop. The brief intensity reversal
near the extreme limb as derived from cinematography of flash spectra
can be explained by diffraction.
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Title: Book-Review - Stellar Turbulence
Authors: Gray, D. F.; Linsky, J. L.; Elste, G. H.
1983ApL....23..174G Altcode:
No abstract at ADS
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Title: Characterististics of plage fragments with photospheric
network properties
Authors: Nauer, D. J.; Teske, R. G.; Elste, G. E.
1980SoPh...67...23N Altcode:
Using data taken with the multi-channel magnetograph at KPNO, we
demonstrate that plage regions surrounding a sunspot have thermal
properties found in the photospheric network. These network-like regions
existed up to the edge of the penumbra of the sunspot. Temperature
gradients inferred from equivalent width fluctuations in our data
do not conflict with the requirements of the theory (Parker, 1978)
for flux tubes to exist at subphotospheric levels.
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Title: Dependence of the correlation of small scale photospheric
structures upon resolution.
Authors: Teske, R. G.; Elste, G. H.
1979SoPh...62..241T Altcode:
Correlations between continuum intensity, velocity, and equivalent
widths of two Mn I lines as observed with two different entrance
apertures tend to deteriorate with improvement in spatial
resolution. The KPNO multichannel magnetograph was used to make area
scans at the center of the disk with entrance apertures 3.5″×2.5″
arc and 1″×1″ arc. A coherence analysis shows that this effect
is caused by marked differences of fluctuations in temperature
and temperature gradients as well as in the velocity structure of
photospheric elements of various sizes.
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Title: Photospheric network from study of manganese lines.
Authors: Elste, G.; Teske, R. G.
1978SoPh...59..275E Altcode:
Area scans with the multi-channel magnetograph at the Kitt
Peak McMath Telescope provided simultaneous measures of
equivalent widths in two Mn lines, continuum intensity and
longitudinal magnetic field component. Observations were
carried out with apertures of 2.5″ × 3.5″ arc and 1″
× 1″ arc. For the network elements, which were identified
using the magnetic field as tracer, we developed relationships
betweenI<SUB>Continuum</SUB>,W<SUB>λ</SUB>V<SUB>Doppler</SUB>
and longitudinal field strength. With a minimum of assumptions it
is possible to write from these observed relations an expression
connecting true temperature perturbation in the line forming layers of
the network to true longitudinal field strength. The results provide
some constraints upon possible network models.
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Title: Vanadium abundances in early A stars.
Authors: Cowley, C. R.; Elste, G. H.; Urbanski, J. L.
1978PASP...90..536C Altcode:
Vanadium-to-hydrogen ratios have been determined for Omicron Peg,
HR 6127, HR 465 (rare-earth minimum), and HR 8216. With respect to
the solar system, vanadium is overabundant in the first two stars,
possibly normal in the third, and underabundant in the fourth. The
range in the V/H ratio in these four stars is between one and two
orders of magnitude. An intercomparison of the four spectra shows
that the strong V II lines occur in the stars with weaker Cr and Fe
spectra. The vanadium anomaly is thus suggestive of the well-known
calcium anomaly in peculiar A stars, but the vanadium and calcium
abundances are not believed to be closely correlated.
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Title: Reliable of Equivalent Width Determinations or how much can
we Trust Published Data?
Authors: Elste, G.
1978hrs..conf..692E Altcode:
No abstract at ADS
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Title: Hydrogen Lines in the Solar Atmosphere
Authors: Elste, G.
1975BAAS....7..366E Altcode:
No abstract at ADS
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Title: Balmer Lines and the Harvard - Smithsonian Reference
Atmosphere.
Authors: Elste, G.; Hartoog, M.
1973BAAS....5...20E Altcode:
No abstract at ADS
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Title: Inhomogeneous photospheres.
Authors: Elste, G.
1972BAAS....4..424E Altcode:
No abstract at ADS
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Title: Microturbulence in Main Sequence A and F Stars.
Authors: Elste, G.; Ionson, J.
1971BAAS....3..380E Altcode:
No abstract at ADS
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Title: Line broadening in gamma Equulei.
Authors: Evans, J. C.; Elste, G.
1971A&A....12..428E Altcode:
Weak and medium strong iron lines in y Equ have been used to show that
velocities of 3 km/s exist in the photosphere. The proffles of the
sharpest lines, which are more triangniar than bell-shaped, and the
curve-of- growth indicate ouly small effects from microturbulence, the
major influences on the proffle are macroturbulence and rotation. As can
be expected for a magnetic star most lines are broadened by unresolved
Zeeman patterns. This is concluded from a comparison of observed with
theoretical line proffles formed in an LTE model atmosphere (0vff =
0.654, log g = 3.5, solar abundances) under the presence of a transverse
Zeeman effect for field strengths in excess of 2000 Gauss. Although
it is possible to recognize Zeeman broadening as distinct from other
broadening mechanisms it may be physically unrealistic to expect
a unique field strength for all sorts of lines in the spectrum. Key
words: line broadening - stellar magnetic fields - Ap star
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Title: Effects of Penumbral Radiation on Physical Conditions in the
Umbra of Sun Spots.
Authors: Fullerton, W.; Elste, G.
1971BAAS....3..247F Altcode:
No abstract at ADS
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Title: The Ionization of Atoms in the Umbra by the Radiation Field
of the Penumbra
Authors: Fullerton, Wayne; Elste, Günther
1970BAAS....2R.193F Altcode:
No abstract at ADS
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Title: Astrophysical Damping Constants for Neutral Iron
Authors: Cowley, Charles R.; Elste, Guenther H.; Allen, Robert H.
1969ApJ...158.1177C Altcode:
Empirical damping constants are derived for twenty-six lines of
neutral iron by using the solar spec- trum. Eight of these lines
have also been measured by Kusch, and the agreement between the two
sets of measurements is satisfactory. We suggest that these damping
constants may be used to obtain abundances and to strengthen spec-
troscopic determinations of surface gravity
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Title: Excitation Temperatures of Fe I in the Sun and A Stars and
Systematic Errors in the gf Scale
Authors: Elste, Guenther
1969BAAS....1R.340E Altcode:
No abstract at ADS
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Title: Comments on the Bilderberg Continuum Atmosphere
Authors: Elste, Günther
1968SoPh....3..106E Altcode:
The Bilderberg Continuum Atmosphere fails to reproduce the observed
limb-darkening throughout the range of wavelengths 4500 Å<λ<
25 000 Å. The temperature-pressure diagram for the deep layers of this
model is a curve which is flatter than the relation predicted from
the mixing length theory. A modification of the Bilderberg Continuum
Atmosphere that improves representation of the observations and
theoretical results is proposed.
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Title: The Distinction Between - and Macroturbulence in the Solar
Photosphere Using Line Profiles
Authors: Elste, Guenther H. E.
1967ApJ...148..857E Altcode:
On the basis of line-profile studies of sixty-two weak and medium-strong
lines of Fe I, whose excitation potentials lie above 3 eV, a distinction
between macro- and microturbulence is sought by comparing the observed
relation between the half-widths and the equivalent widths with model
computations. The shape of the lines near their cores as well as the
curves of growth supports the result that the microturbulence velocity
must be as low as 1 km/sec, while macroturbulent velocities of at least
1.5 km/sec are needed to explain the observations These conclusions are
drawn from spectra of the center of the disk only. The more extensive
study of the velocity field using the complete center-to4imb variation
of the line profiles is in progress.
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Title: An atmsphere analysis of the magnetic star Gamma Equulei
Authors: Evans, J. C.; Elste, G.
1967AJ.....72S.298E Altcode:
No abstract at ADS
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Title: Direct observational evidence for a small value of the
turbulence in sunspot umbrae
Authors: Elste, G.
1963JQSRT...3..185E Altcode:
No abstract at ADS
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Title: Difficulties in the explanation of the wings of the Balmer
lines in sunspot umbrae
Authors: Elste, G.
1963JQSRT...3..187E Altcode:
No abstract at ADS
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Title: Der Einfluβ von Streulicht auf die Photometrie der
Sonnenoberfläche. Mit 4 Textabbildungen
Authors: David, K. H.; Elste, G.
1962ZA.....54...12D Altcode:
No abstract at ADS
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Title: Die Mitte-Rand-Variation schwacher bis mittelstarker
Fraunhoferlinien auf der Sonnenscheibe
Authors: Elste, Günther
1960VeGoe...6..287E Altcode:
No abstract at ADS
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Title: The centre-limb-variation of weak and moderately strong
Fraunhofer lines on the solar disc (Die Mitte-Rand-Variation schwacher
bis mittelstarker Fraunhoferlinien auf der Sonnenscheibe)
Authors: Elste, Günther
1960VeGoe...6..285E Altcode:
No abstract at ADS
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Title: Temperatur und Turbulenz in ruhenden Protuberanzen, bestimmt
aus Linien-Breiten
Authors: ten Bruggencate, Paul; Elste, Günther
1959VeGoe...7..257T Altcode:
in English precedes German text
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Title: Die Entzerrung von Spektrallinien unter Verwendung von
Voigtfunktionen
Authors: Elste, Günther
1958VeGoe...6..157E Altcode:
No abstract at ADS
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Title: Atmospheres of the B Stars.IV. The Calculation of Partition
Functions.
Authors: Elste, Günther; Jugaku, Jun
1957ApJ...125..742E Altcode:
Formulae for the calculation of partition functions are presented in
a form appropriate for numerical calculations. Detailed applications
are given for neutral and ionized helium for a range of temperatures
and densities appropriate to the B stars.
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Title: The Atmospheres of the B Stars. III. The Composition of
Tau Scorpii.
Authors: Aller, L. H.; Elste, G.; Jugaku, J.
1957ApJS....3....1A Altcode:
New measurements of line intensities in the spectrum of r Scorp ,
based on coude' plates secured at the Mount Wilson and McDonald
Ohservatories, are discussed with the aid of a model atmosphere and
Pecker's theory for medium-strong lines. The computational procedures
are described in detail, with a view to their application to other
stellar atmospheres. he abundances derived differ from those and by
Traving for three reasons: (1) the newer equivalent widths differ
systematically from those found with the older McDonald spectrographs;
(2) a slightly different model atmosphere is employed; and (3) a precise
theory of line formation is utilized. Different ions of the same element
yield different curves of growth, whereas lines formed in the same
layers tend to have similar curves of growth. The agreement between
theory and observation is improved with the aid of a differential
correction to the model atmosphere, but all ions of all elements
cannot be equally well represented by the same model atmosphere. The
largest uncertainties appear to come from poor f-values. Helium, carbon,
nitrogen, oxygen, and silicon are observed in two stages of ionization;
other elements are observed in only one stage of ionization.
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Title: The composition of τ Scorpii.
Authors: Aller, L. H.; Elste, G.; Jugaku, J.
1957AJ.....62R...2A Altcode: 1957AJ.....62....2A
Measurements of line intensities in the spectrum of r Scorpii are
discussed with th~ aid of a model atmosphere and Pecker's theory for
lines of medium strength. The abundances derived differ from those found
by Unsold and by Traving for three reasons: (i) the newer equivalent
widths are systematically smaller, (2) a slightly different model
atmosphere is employed, and (3) a precise theory of line formation is
utilized. As has been noted previously for silicon, different ions
of the same element have different curves of growth. This effect is
strikingly exhibited in ~ Pegasi where silicon is observed in three
stages of ionization. Differential corrections may be applied when
the model does not quite represent the observations. The largest
uncertainties arise from poor J-values. The abundance of helium is
particularly difficult to establish because of uncertainties in the
line-broadening theory and in the damping constants. The abundances
of the heavier elements, expressed as log NeIern~t~Nhydr0g~, are
as follows: Carbon' -4.3 Neon -3.14 Nitrogen -3.74 Magnesium - 3.7
Oxygen -3.37 Aluminum -5.6 Silicon -4.37 Helium, carbon, nitrogen,
oxygen, and silicon are observed in two stages of ionization; other
elements are observed in only one stage of ionization. The Observatory,
University of i~Iichigan, Ann Arbor, AIThh.
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Title: Computation of individual curves of growth.
Authors: Elste, G.
1957AJ.....62S..14E Altcode:
It is shown that when theoretical equivalent widths of absorption
lines are calculated precisely for a model atmosphere on the mechanism
of pure absorption and following the theory of Pecker, the resulting
curve of growth depends on the variation of the number of absorbing
atoms with depth as well as on the Doppler width and on the wave
length. Calculations performed for the solar spectrum are based on a
model atmosphere derived from A. K. Pierce's photoelectric observations
of the limb-darkening and energy distribution. Fifteen elements
were selected for which f-values and equivalent widths are known with
sufficient accuracy. For each element the lines were arranged in groups
according to excitation potential and wave length. A pair of points
defining a theoretical curve of growth in the transition region was
then computed for each line group. The computations were carried out
with the electronic computers, MIDAC and IBM 650 of the University of
Michigan. Corresponding calculations for model atmospheres of B stars
were carried out using graphical integration methods. The results show
that the shape and position of the curve of growth depend strongly
on the stage of ionization as well as on the excitation potential and
wave length. University of Michigan, Ann Arbor, Mich.
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Title: Theoretical Line Intensities and the Spectrum of Tau Scorpii
Authors: Elste, Günther; Jugaku, Jun; Aller, L. H.
1956PASP...68...23E Altcode:
No abstract at ADS
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Title: Theoretical line intensities and spectrum of τ: Scorpii.
Authors: Aller, L. H.; Elste, G.; Jugaku, J.
1956AJ.....61....1A Altcode:
The model atmosphere for r Scorpii, recently calculated by G. Traving,
is revised using the same temperature distribution but a surface
gravity 2 X io4 dynes/cm2. The profile of H~, calculated with
the absorption coefficients given by the new Kolb theory shows a
satisfactory agreement with the observations. The equivalent widths
of the Silil and Siiv lines, computed by the corrected Pecker theory
and checked by precise numerical integrations, give the same silicon/
hydrogen ratio substantiating the adopted model. The Sjiii and Siiv
lines follow different curves of growth, not merely because of the
different damping constants but also because of the changing numbers
of atoms with depth. The silicon/hydrogen ratio is smaller than that
found by Traving and more nearly in accord with that found for the
sun. Untversity of Alich?gan Observatory, Ann Arbor, Mich.
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Title: Die Mitte-Rand-Variation schwacher bis mittelstarker
Fraunhoferlinien auf der Sonnenscheibe. Mit 16 Textabbildungen
Authors: Elste, G.
1955ZA.....37..184E Altcode:
No abstract at ADS
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Title: Die Entzerrung von Spektrallinien unter Verwendung von
Voigtfunktionen
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Title: Die Entzerrung von Spektrallinien unter
Verwendung von Voigtfunktionen
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Title: Equalization of spectral lines
using Voigt functions;
Authors: Elste, Günther H.
1954PhDT........15E Altcode:
No abstract at ADS
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Title: The correction of spectral lines by using Voigt functions (Die
Entzerrung von Spektrallinien unter Verwendung von Voigtfunktionen)
Authors: Elste, Günther
1953VeGoe...6..194E Altcode:
No abstract at ADS
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Title: Die Entzerrung von Spektrallinien unter Verwendung von
Voigtfunktionen. Mit 8 Textabbildungen
Authors: Elste, G.
1953ZA.....33...39E Altcode:
No abstract at ADS
