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Author name code: stellmacher
ADS astronomy entries on 2022-09-14
author:"Stellmacher, Goetz"
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Title: Velocity Difference of Ions and Neutrals in Solar Prominences
Authors: Wiehr, E.; Stellmacher, G.; Balthasar, H.; Bianda, M.
2021ApJ...920...47W Altcode: 2021arXiv210813103W
Marked velocity excesses of ions relative to neutrals are obtained
from two time series of the neighboring emission lines He I 5015
Å and Fe II 5018 Å in a quiescent prominence. Their Doppler
shifts show time variations of quasi-periodic character where the
ions are faster than the neutrals, 1.0 ≤ V<SUB>macro</SUB>(Fe
II)/V<SUB>macro</SUB>(He I) ≤ 1.35 in series A and ≤1.25 in
series B. This "ratio excess" confirms our earlier findings of a 1.22
ion velocity excess, but the present study shows a restriction in
space and time of typically 5 Mm and 5 minutes. The ratio excess is
superposed by a time- and velocity-independent "difference excess"
of -0.3 ≤ V<SUB>macro</SUB>(Fe II)-V<SUB>macro</SUB>(He I) ≤
+0.7 km s<SUP>-1</SUP> in series A (also indicated in series B). The
high repetition rate of 3.9 s enables the detection of high-frequency
oscillations with several damped 22 s periods in series A. These show
a ratio excess with a maximum of 1.7. We confirm the absence of a
significant phase delay of He neutrals with respect to the Fe ions.
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Title: Evidence for the Two-fluid Scenario in Solar Prominences
Authors: Wiehr, E.; Stellmacher, G.; Bianda, M.
2019ApJ...873..125W Altcode: 2019arXiv190401536W
This paper presents observational evidence of the different dynamical
behavior of neutral and ionized species in solar prominences. The
analysis of a time-series of Sr II 4078 Å and Na D spectra in a
quiescent prominence yields systematically larger Doppler shifts
(line-of-sight velocities) for the ions V <SUB>LOS</SUB>(Sr II) = 1.22
× V <SUB>LOS</SUB>(Na D). Both lines show a 30 minute oscillation of
good coherence. Sixteen hours later the same prominence underwent marked
morphological changes (with a rising dome), and the Sr II velocity
excess dropped to V <SUB>LOS</SUB>(Sr II) = 1.11 ×V <SUB>LOS</SUB>(Na
D). The same excess is found for the line pair Fe II 5018 Å and He I
5015 Å. The widths of the ionic lines, mainly non-thermally broadened,
are not related to the macro-velocities. The emission ratio of Na D
and Sr II, a measure of the electron density, yields n <SUB>e</SUB>
= 4 × 10<SUP>10</SUP> cm<SUP>-3</SUP>, shows no relation with the V
<SUB>LOS</SUB> variation or with height above the limb, and seems to be
reduced 16 hr later during the active phase. We apply a new wavelength
reference from aureola spectra, which is independent of photospheric
velocity fields.
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Title: The Na I and Sr II Resonance Lines in Solar Prominences
Authors: Stellmacher, G.; Wiehr, E.
2017SoPh..292...83S Altcode: 2017arXiv170502475S
We estimate the electron density, n<SUB>e</SUB>, and its spatial
variation in quiescent prominences from the observed emission ratio
of the resonance lines Na I 5890 Å (D<SUB>2</SUB>) and Sr II 4078
Å. For a bright prominence (τ<SUB>α</SUB>≈25 ) we obtain
a mean n<SUB>e</SUB>≈2 ×10<SUP>10</SUP>cm−<SUP>3</SUP>;
for a faint one (τ<SUB>α</SUB>≈4 ) n<SUB>e</SUB>≈4
×10<SUP>10</SUP>cm−<SUP>3</SUP> on two consecutive days with
moderate internal fluctuation and no systematic variation with height
above the solar limb. The thermal and non-thermal contributions to
the line broadening, T<SUB>kin</SUB> and V<SUB>nth</SUB>, required
to deduce n<SUB>e</SUB> from the emission ratio Na I/Sr II cannot be
unambiguously determined from observed widths of lines from atoms of
different mass. The reduced widths, Δ λ<SUB>D</SUB>/λ<SUB>0</SUB>,
of Sr II 4078 Å show an excess over those from Na D<SUB>2</SUB> and
Hδ 4101 Å, assuming the same T<SUB>kin</SUB> and V<SUB>nth</SUB>. We
attribute this excess broadening to higher non-thermal broadening
induced by interaction of ions with the prominence magnetic field. This
is suggested by the finding of higher macro-shifts of Sr II 4078 Å
as compared to those from Na D<SUB>2</SUB>.
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Title: The Electron Density in a Quiescent Prominence
Authors: Wiehr, E.; Stellmacher, G.; Bianda, M.
2016CEAB...40...79W Altcode:
We estimate the electron density, n_e, from the emission ratio of the
Na I D_2 and Sr II 4078 Å resonance lines. For a quiescent prominence,
we find a range 1.7≤ n_e≤3.4\cdot 10^{10}cm^{-3} with significant
differences between neighboring structures but not with height above
the solar limb. After seven hours of moderate evolutionary changes,
the prominence shows the same n_e range.
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Title: Non-thermal line-broadening in solar prominences
Authors: Stellmacher, G.; Wiehr, E.
2015A&A...581A.141S Altcode: 2016arXiv160507923S
<BR /> Aims: We show that the line broadening in quiescent solar
prominences is mainly due to non-thermal velocities. <BR /> Methods:
We have simultaneously observed a wide range of optically thin lines
in quiescent prominences, selected for bright and narrow Mg b emission
without line satellites from macro-shifts. <BR /> Results: We find a
ratio of reduced widths, Δλ<SUB>D</SUB>/λ<SUB>0</SUB>, of Hγ and Hδ
of 1.05 ± 0.03, which can hardly be attributed to saturation, since
both are optically thin for the prominences observed: τ<SUB>γ</SUB>
≤ 0.3, τ<SUB>δ</SUB> ≤ 0.15. We confirm the ratio of reduced
widths of He 4772 (triplet) and He 5015 (singlet) of 1.1 ± 0.05 at
higher significance and detect a width ratio of Mg b<SUB>2</SUB>
and Mg 4571 (both from the triplet system) of 1.3 ± 0.1. <BR />
Conclusions: The discrepant widths of lines from different atoms,
and even from the same atom, cannot be represented by a unique pair
[T<SUB>kin</SUB>; V<SUB>nth</SUB>]. Values of T<SUB>kin</SUB> deduced
from observed line radiances using models indicate low temperatures
down to T<SUB>kin</SUB> ≈ 5000 K. Non-thermal velocities, related to
different physical states of the respective emitting prominence region,
seem to be the most important line broadening mechanism.
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Title: The Temperature of Quiescent Prominences
Authors: Wiehr, E.; Stellmacher, G.
2015CEAB...39...35W Altcode:
We simultaneously observed in solar prominences faint metallic
emission lines together with Hγand two He I lines from the singlet
and triplet systems, respectively. We find that the reduced widths
Δλ<SUB>D</SUB>/λ<SUB>0</SUB> are not linearly related to the
square-root of the inverse atomic mass, as is expected from the Doppler
formula. Instead, each emission line is individually broadened. The
gradients in the V<SUB>D</SUB><SUP>2</SUP>(1/μ) diagrams correspond
to unrealistically high T<SUB>kin</SUB>≥10<SUP>4</SUP> K, which
contradict values deduced from line radiance observations yielding
temperatures down to at most 5000 K. A scenario of down-falling gas
clumps by Low et al. (2012) offers a plausible explanation for these
discrepancies.
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Title: The Hot Skin of Prominence Structures
Authors: Wiehr, E.; Stellmacher, G.; Ramelli, R.; Bianda, M.
2013CEAB...37..487W Altcode:
We observe various emission lines in solar prominences and compare
the widths of He II 4686 Å, He I 4472 Å (triplet) and He I 5015 Å
(singlet) with those of the optically thin Hγ and Mg b_2 lines. The
latter two yield a thermal line broadening of 9000<T_{kin}<11
000 K, which fits the width of He I 5015 Å (singlet). However, He I
4471 Å (triplet) shows an excess of 1.1 indicating an excitation of
the triplet in 1.2 times hotter prominence regions. He II 4686 Å is
1.65 times broader and thus emitted in 2.73 times hotter regions of the
prominence-corona transition layer, PCTR. The linear radiance relations
He tripl/He II=50 and Hγ/He tripl=11.8 suggest a PCTR between each
fine-structure thread and the surrounding hot coronal gas.
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Title: Helium Emissions Observed in Ground-Based Spectra of Solar
Prominences
Authors: Ramelli, R.; Stellmacher, G.; Wiehr, E.; Bianda, M.
2012SoPh..281..697R Altcode: 2012SoPh..tmp..221R; 2012arXiv1208.2153R
The only prominent line of singly ionized helium in the visible
spectral range, He II 4686 Å, is observed together with the He I 5015
Å singlet and the He I 4471 Å triplet line in solar prominences. The
Na D<SUB>2</SUB> emission is used as a tracer for He II emissions which
are sufficiently bright to exceed the noise level near 10<SUP>−6</SUP>
of the disk-center intensity. The prominences thus selected are
characterized by small non-thermal line broadening and almost absent
velocity shifts, yielding narrow line profiles without wiggles. The
reduced widths [Δλ<SUB>D</SUB>/λ] of He II 4686 Å are 1.5 times
broader than those of the He I 4471 Å triplet and 1.65 times broader
than those of the He I 5015 Å singlet. This indicates that the He
lines originate in a prominence-corona transition region with outwards
increasing temperature.
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Title: Balmer and Lyman Emission Lines in Solar Prominences
Authors: Wiehr, E.; Stellmacher, G.
2009CEAB...33...99W Altcode:
Space observations of Lyman lines are compared with ground-based
observations of Balmer lines for quiescent solar prominences of
comparable brightness defined by their Hβ emission. The integrated
spectral line radiances of the Lyman and the Balmer emissions show
differences which diminish with increasing upper level u and converge
toward highest level numbers. Lyman lines emitted from u=5 originate
from 250 times less emitters than the corresponding Balmer lines from
the same upper level. For u=8 this difference still amounts to a factor
of 65, supporting the idea of a distinct origin of the emissions of
both hydrogen series.
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Title: On the origin of the Balmer and Lyman emission lines in
solar prominences
Authors: Stellmacher, G.; Wiehr, E.
2008A&A...489..773S Altcode: 2012arXiv1209.6264S
Aims: We show how the observed hydrogen Balmer and Lyman emission lines
constrain the modeling of quiescent solar prominences. <BR />Methods:
We compare space observations of Lyman lines with ground-based
observations of Balmer lines for quiescent solar prominences of
comparable brightness defined by their Hβ emission. <BR />Results:
The effective number densities of hydrogen atoms emitting from the
same upper level u deduced from the corresponding emerging Lyman
and Balmer line emissions show large differences that diminish
with increasing level number and converge at the highest level
numbers. Hydrogen atoms excited in u=5 contribute 250 times less,
and those in u=8 still contribute 65 times less to the Lyman than to
the corresponding Balmer emission, supporting the idea of distinct
spatial origin of the emissions of both series. This is also indicated
by the line widths. The high optical thickness of all Lyman members
allows the brightness temperature T<SUB>b</SUB> to be estimated from
the spectral radiance at line center, where T<SUB>b</SUB> is found to
be largely independent of the upper level number, in contrast to the
(known) behavior of the Balmer lines.
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Title: Imaging of the He D<SUB>3</SUB>/Hβ Emission Ratio in Quiescent
Solar Prominences
Authors: Hirzberger, J.; Wiehr, E.; Stellmacher, G.
2007ASPC..368..321H Altcode:
Quiescent solar prominences have been observed simultaneously in
profile-integrated He D<SUB>3</SUB> and Hβ emission with the SST on
La Palma. The two-dimensional ratio maps of the He D<SUB>3</SUB> and
Hβ intensities are used to study temporal variations of intrinsic
prominence parameters. Sub-areas with substantial variation of
the intensity distribution indicate the evolution of prominence
structures. When the emission ratio remains unchanged, the evolving
threads are of largely equal physical state. Other regions which show
a temporal varying emission ratio indicate substancial evolution of
the intrinsic physical conditions. We propose that distance variation
between the threads affects different penetration of the EUV irradiation
required for populating of the He triplet system.
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Title: Two-dimensional imaging of the He D_3/Hbeta emission ratio
in quiescent solar prominences .
Authors: Stellmacher, G.; Wiehr, E.; Hirzberger, J.
2007MmSAI..78..108S Altcode:
Simultaneous prominences spectroscopy with THEMIS in the emission
lines H-alpha, H-beta, HeD3, NaD2, Mgb2 and He(singlet)5015 lead to
an extended study of two-dimensional images simultaneously in H-beta
and HeD3. The spatial variation of the integrated line intensities and
their ratio shows mainly two characteristics: (a) A constant emission
ratio (even) in regions with substantial intensity variations; this
can be explained by a varying number of superposing threads with equal
physical states. (b) A varying emission ratio (often) tightly related
to intensity changes; this indicates a superposition of threads with
different physical states (most likely the gas-pressure). We also
observe temporal changes of the emission ratio which seem to be too
fast for a variation of the gas-pressure; here, we suppose a change of
the packing density of threads along the line-of-sight which affects
the penetration of ionizing UV radiation required for the He triplet
excitation.
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Title: Two-Dimensional Mapping of the He D<SUB>3</SUB>/Hβ Emission
Ratio in Solar Prominences
Authors: Wiehr, Eberhard; Stellmacher, Goetz; Hirzberger, Johann
2007SoPh..240...25W Altcode:
Solar prominences have been simultaneously observed in the integrated
light of the He D<SUB>3</SUB> and the Hβ emissions on two successive
days, using the SST on La Palma with its tip-tilt mirror locked on a
nearby white-light limb facular grain. The spatial and the temporal
variation of the integrated line intensities and their ratio shows
mainly two characteristics: (A) Constant emission ratio (even)
in regions with substantial intensity variations and (B) varying
emission ratio (often) tightly related to intensity structures of the
prominence. (A) May be explained by a different number of superposing
threads along the line of sight having very similar physical state. (B)
Indicates threads with different intrinsic physical states; these
may depend on the gas pressure or the inner structure of each thread,
i.e., the "packing density," affecting the penetration of ionizing EUV
radiation, which affects the He I level populations and thus the rate
of the triplet excitation.
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Title: Two-dimensional imaging of the HeD3/H[Beta] emission ratio
in quiescent solar prominences
Authors: Wiehr, E.; Stellmacher, G.; Hirzberger, J.
2007msfa.conf..261W Altcode:
We extend our earlier studies of two-dimensional prominence imaging
by simultaneous observations of the HeD3 and H[Beta] emissions at
the 1m SST on La Palma. The observed small spatial variations of the
HeD3/H[Beta] ratio indicate rather homogeneous physical conditions
within prominences. Sub-regions do exist which show a largely uniform
ratio in spite of substantial spatial intensity variations. Here, the
fine-structures will exhibit almost uniform physical conditions. In
other regions with variations of the ratio parallel to the emissions,
the structures will have different intrinsic physical state.
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Title: Solar prominences with Na and Mg emissions and centrally
reversed Balmer lines
Authors: Stellmacher, G.; Wiehr, E.
2005A&A...431.1069S Altcode: 2012arXiv1210.5643S
We observed bright solar limb prominences with significant emission
of NaD2 and Mgb2 simultaneously with the Hα, Hβ, HeD3, He^+4685,
and the He^singl 5015 Å lines, using the THEMIS telescope on
Tenerife. We find that most prominences with significant NaD2 and
Mgb2 emissions show pronounced centrally reversed Hα profiles, and
occasionally even of Hβ; the strongest emissions reach integrated
intensities Eβ>16×{}10<SUP>4</SUP> [ erg/(cm<SUP>2</SUP> s str)]
. The centrally reversed profiles are well reproduced by semi-infinite
models. The source function reaches Sα≤{}36 × {}10<SUP>4</SUP>
[ erg/(cm<SUP>2</SUP> s str Å)] corresponding to an excitation
temperature T_ex<SUP>α</SUP>≈3950 K; here, the optically thickness of
Hα amounts τ^0<SUB>α</SUB>≈{}10. The line widths of the NaD2, Mgb2,
and HeD3 profiles yield kinetic temperatures 7000≤{}T_kin<8000
K and non-thermal broadening v_tu=5 km s<SUP>-1</SUP>.
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Title: Spectroscopy of Solar Prominences Simultaneously From Space
and Ground
Authors: Stellmacher, G.; Wiehr, E.; Dammasch, I. E.
2003SoPh..217..133S Altcode: 2013arXiv1303.1126S
We present a comprehensive set of spectral data from two quiescent
solar prominences observed in parallel from space and ground: with
the VTT, simultaneous two-dimensional imaging of Hβ4862 Å and Caii
8542 Å yields a constant ratio, indicating small spatial pressure
variations over the prominence. With the Gregory, simultaneous spectra
of Caii 8542 Å and Hei 10830 Å were taken, their widths yielding
8000 K <T<SUB>kin</SUB><9000 K and 3<v<SUB>nth</SUB><8
km s<SUP>−1</SUP>. The integrated line intensities show a distinct
relation E(Hei) versus E(Caii) for each prominence (`branching'). The
intensity ratio of the helium triplet components is used for a
simple estimate of the optical thickness, which is τ<1.0 for the
fainter prominence but reaches up to τ=2.0 for the brighter one. The
τ<SUB>0</SUB> values allow us to deduce the source function from
the central line intensities and thus a mean excitation temperature
T<SUB>ex</SUB><SUP>mean</SUP>=3750 K, which determines the relative
populations of the helium <SUP>3</SUP>S and <SUP>3</SUP>P levels. With
SUMER, we sequentially observed six spectral windows containing
higher Lyman lines, `cool' emission lines from neutrals and singly
charged atoms, as well as `hot' emission lines from ions like Oiv,
Sv, Nv, Ov, and Svi. The spatial variation of the EUV lines along the
SUMER slit shows a pronounced maximum at the main prominence body and
`side-regions' where the `hot' lines are significantly enhanced with
respect to the `cool' lines from neutral and singly-ionized atoms. These
selected locations were averaged over 7” and the resulting mean EUV
lines were fitted by Gaussians yielding realistic widths and integrated
line intensities. The intensities of `hot' lines blue-wards of the
Lyman series limit appear reduced in the main prominence body but
enhanced in the `side-regions'. This absorption is also visible in TRACE
images of Feix/x171 Å as fine dark structure which covers only parts
of the main (`cool') prominence body. The Lyman lines show a smooth
decrease of both line widths and integrated emission, with increasing
upper level k=5 to k=19; the widths are smaller for the prominence
that yields lower T<SUB>kin</SUB> from the ground-based spectra. The
level populations along the line of sight follow for 5 lekle a smooth
Boltzmann distribution with T<SUB>ex</SUB>>6×10<SUP>4</SUP> K, the
levels k>8 appearing more and more overpopulated. The larger widths
of the Lyman lines require high non-thermal broadening close to that of
`hot' EUV lines. In contrast, the Heii emission is more related to the
`cool' lines.
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Title: Spectroscopy of solar prominences from space and ground
Authors: Dammasch, I. E.; Stellmacher, G.; Wiehr, E.
2003AN....324..338D Altcode:
Two quiescent solar prominences were observed in July 2000 from
SUMER aboard SOHO and from the two German solar telescopes at
Tenerife. Two-dimensional images taken at the VTT simultaneously in the
spectral lines Hβ at 4862 Å and Ca II at 8542 Å show no significant
spatial variation of their pressure-sensitive emission ratio. Slit
spectra of the Ca II 8542 Å and He i 10830 Å lines obtained at the
Gregory-Coudé telescope yield 8000 K < T_kin < 9000 K and 3 km/s
< V_n-th < 8 km/s. Among the various spectral ranges observed with
SUMER, we first investigate the Lyman emission lines, which were fitted
by Gaussians yielding reliable spectral radiances and line widths for
the series members 5<k<18. A determination of the level population
gives for the lower series members a Boltzmann temperature of 60 000 K,
the higher members being over-populated. This temperature indicates an
origin of the Lyman lines from hot surroundings of the cool prominence
body seen in the ground-based data; this also holds for the `hotter'
SUMER lines.
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Title: Spatial offsets between lines and continuum in limb faculae
Authors: Stellmacher, G.; Wiehr, E.
2001SoPh..202..259S Altcode:
High-spatial-resolution spectra of limb faculae show spatial
displacements of line cores relative to the adjacent continuum at cos
θ<0.35, confirming results from earlier photographic analyses. The
observed displacements are geometric measures which probe the upper
atmospheric layers of fluxtubes forming facular grains. We selected
spectra with highest contrast and smallest width of the facular
continuum streaks, in order to avoid clustered structures. The spatial
displacements of Stokes-Q and -V maxima were also measured: we find
Q-signals spatially located near the continuum, as is expected from
their origin in line wings; V-signals - which should give evidence
for the existence of horizontal fields - are not found, except for
one case of a 'hidden' pore.
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Title: Two-dimensional photometric analysis of emission lines in
quiescent prominences
Authors: Stellmacher, G.; Wiehr, E.
2000SoPh..196..357S Altcode:
Emission lines from quiescent prominences were observed simultaneously
through narrow-band interference filters, thus integrating the total
line intensities without the use of a spectrograph. Simultaneous
exposures (50 ms) on three electronically connected CCD cameras at
the 70 cm VTT on Tenerife assured almost identical influence of the
Earth's atmosphere and a spatial resolution of ≤ 1 arc sec. The
resulting spatially high-resolution two-dimensional images in Hβ,
Hα, and Ca<SUP>+</SUP>8542, calibrated in units of the disk-center
intensities, allow a two-dimensional mapping of emission ratios yielding
relevant physical parameters. The emission relation between Hα and
Hβ, which depends on the total optical thickness, confirms earlier
photometric results from spectra, however, with a large sample of data
points from six prominences. It demonstrates the saturation effects
towards brighter prominences or prominence locations. The relation
between Ca<SUP>+</SUP>8542 and Hβ, which depends on the gas pressure,
is found to vary between different prominences but is nearly constant
within one prominence. Its mean spatial variation of ≤ 30% within
one prominence may be interpreted in terms of a magnetic field with
variations of ≤5%. The brightness distribution in most prominences
is not smooth but indicates preferred values, which are interpreted
as superpositions of several fine structures.
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Title: Two-dimensional Mapping of Emission Ratios in Quiescent
Prominences
Authors: Wiehr, E.; Stellmacher, G.
1999ESASP.448..435W Altcode: 1999ESPM....9..435W; 1999mfsp.conf..435W
No abstract at ADS
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Title: Continuum photometry of solar white-light faculae
Authors: Sütterlin, P.; Wiehr, E.; Stellmacher, G.
1999SoPh..189...57S Altcode:
We have determined absolute continuum intensities and brightness
temperatures of individual facular grains at a spatial resolution
limited by the φ=50 cm aperture of the SVST on La Palma. A facular
region at θ≈57° was observed simultaneously in three narrow
continuum windows at 450.5, 658.7, and 863.5 nm. We corrected for
image degradation by the Earth's atmosphere using the speckle masking
method. The brightness temperatures do not exactly follow the Planck
law. The differences of T<SUB>blue</SUB>−T<SUB>red</SUB>=220
K and T<SUB>ir</SUB>−T<SUB>red</SUB>=−42 K reflect the
wavelength dependence of the continuum formation depth. The (red)
temperatures of 250 facular grains show excesses between 250
and 450 K above their undisturbed neighborhood. The wavelength
dependence of the relative intensity ratios C<SUB>λ</SUB>=
[I<SUP>fac</SUP>/I<SUP>phot</SUP>] <SUB>λ</SUB>show a large scatter
around mean values of C<SUB>blue</SUB>/C<SUB>red</SUB>=1.075 and
C<SUB>ir</SUB>/C<SUB>red</SUB>=0.98. We determined the center-to-limb
variation of the 863.5 nm continuum contrast for 0.17>cosθ>0.39
by measuring 270 grains in reconstructed facular images. The
upper envelope of the data points increases linearly to 1.5 at
cos θ=0.17. Application of the mean color dependence yields green
contrasts up to C<SUB>550</SUB>=1.7, which is far higher than previously
observed values. The behaviour for cos θ>0.17 is estimated from
(unreconstructed) frame-selected best images taken over a time interval
of 7 hours. Six distinct facular regions clearly discernible during
the whole time interval indicate a slight contrast decrease towards
the extreme limb. The observed quantities are useful for an adjustment
of model calculations and for a discrimination of competing models.
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Title: The hot prominence periphery in EUV lines
Authors: de Boer, C. R.; Stellmacher, G.; Wiehr, E.
1998A&A...334..280D Altcode:
Two sets of He I and metallic lines were observed with the EUV
spectrograph SUMER in a quiescent prominence. H, He, and Ca II
lines were observed simultaneously with both German telescopes on
Tenerife. The visible lines from elements with different atomic
weights yield thermal and non-thermal broadening parameters of 7500
<= T<SUB>kin</SUB> <= 8000 K and 2.5 <xi <5.0 km/s for the
cool prominence body. The EUV lines, however, show line widths which
correspond to much higher temperatures and non-thermal velocities. If
the calculated formation temperature for every individual ion is
assumed, the observed line widths require non-thermal velocities of 14 -
25 km/s. The narrowest reduced widths of the EUV He I 584 and He I 537
lines are 3.1 and 2.9 times broader than those of the visible He D_3
and He 3888 lines. If this is due to optical depth effects in the EUV
lines, one obtains tau_0 (584) ~ 8*10(3) and tau_0 (537) ~ 2*10(3)
, respectively. The emission ratios of the Ca II-to-Balmer lines
vary little inside the prominence, indicating a largely constant gas
pressure. The ratios of the visual He-to-Balmer lines as well as those
of the EUV He-to-metallic lines show a significant branching between
peripheral and central prominence regions. The total emissions in the
main prominence body amount to 13, 0.3, and 4 [Watt/ (m(2*) ster)]
for the 584, 537, and D_3 lines, respectively. The observed emission
ratio E(He 584)/E(He 537)= 45 agrees with model calculations whereas
their total emissions are about 37 times higher than calculated. The
observed ratio E(He D_3)/ E(He 584)~0.3 is about 15 times smaller
than model predictions. The observations indicate that the emissions
of different ions originate from individual (isothermal) threads with
different temperatures between 10(4) and 10(5) K.
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Title: Prominence Emissions with SUMER and Optical Telescopes
Authors: Wiehr, E.; Stellmacher, G.; de Boer, C. R.; Sütterlin, P.
1998ASPC..155..331W Altcode: 1998sasp.conf..331W
No abstract at ADS
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Title: About polar ejection events and surges
Authors: Loucif, M. L.; Koutchmy, S.; Stellmacher, G.; Georgakilas,
A.; Bocchialini, K.; Delaboudinière, J. -P.
1998ESASP.421..299L Altcode: 1998sjcp.conf..299L
No abstract at ADS
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Title: Wave Activity and Prominence Eruption
Authors: Baudin, F.; Bocchialini, K.; Delannee, C.; Koutchmy, S.;
Stellmacher, G.; Shibata, K.; Veselovsky, I. S.; Panasenko, O. A.;
Zhukov, A. N.
1998ASPC..150..314B Altcode: 1998IAUCo.167..314B; 1998npsp.conf..314B
No abstract at ADS
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Title: Prominence Emission Lines Observed with SUMER and Two
Ground-Based Telescopes
Authors: de Boer, C. R.; Stellmacher, G.; Wiehr, E.
1998ASPC..150..196D Altcode: 1998npsp.conf..196D; 1998IAUCo.167..196D
No abstract at ADS
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Title: Three colour photometry of solar limb faculae.
Authors: de Boer, C. R.; Stellmacher, G.; Wiehr, E.
1997A&A...324.1179D Altcode:
The contrasts of limb faculae at various heliocentric angles are
observed in three continuum windows largely free of absorption
lines. Observations with interference filters show a contrast decrease
with wavelength which is not found when using an `UBF' to select the
shortest continuum window. Limb faculae in speckle-reconstructed images
yield contrasts being typically 1.2 times higher than those deduced from
the `best images' of the corresponding bursts. The fit of the wavelength
dependence (`colour index') to a black-body law is significantly better
for the contrasts deduced from the reconstructed images than for the
contrasts from the best images. The uncorrected contrasts yield a mean
facular temperature excess of 200-300K; those from the reconstructed
images yield about 470 K. The center-to-limb variation is found to be
much smaller than the fluctuations between individual faculae.
---------------------------------------------------------
Title: The helium singlet-to-triplet line ratio in solar prominences.
Authors: Stellmacher, G.; Wiehr, E.
1997A&A...319..669S Altcode:
The emissions of the He singlet line at 6678Å and the He triplet line
at 4471Å are simultaneously observed in three solar prominences. For
two of them, the line pairs He-D_3_/H<SUB>beta</SUB>_ and
Ca^+^8662/H<SUB>beta</SUB>_ were also observed. Comparisons with model
calculations show that the emission line ratios require low densities
(n_H_=~3.10^10^cm^-3^), low gas pressures (P_g_=~0.02dyn/cm^2^),
and large physical slab widths. The relative He-to-H number density
cannot be much lower than y=0.1.
---------------------------------------------------------
Title: Emission Lines in a Quiescent Prominence Observed with the
SUMER, VTT, a nd Gregory Telescopes
Authors: Wiehr, E.; de Boer, C. R.; Stellmacher, G.; Sutterlin, P.
1997ASPC..118..294W Altcode: 1997fasp.conf..294W
A number of emission lines have been observed in a quiescent prominence
with the two German telescopes on Tenerife and with SUMER. The Gregory
telescope monitored simultaneously the lines H_8 3889, He 3888, Ca(+\:)
8498, the VTT simultaneously the lines H_β, He-D_3, Ca(+\:) 8542, and
H_α slit jaw pictures on 1024 x 1024 CCDs. At the same time, SUMER
monitored successively three combinations of EUV lines containing He
584, He 537 in the second, and Ar, N(+) , C, C(++) , O, O(+) , O(++)
, S(++) , S(+++) lines in the first order. Two dimensional images in
the various EUV lines establish the anti-relation between temperature
and Balmer brightness.
---------------------------------------------------------
Title: Branching of the helium-to-Balmer emission ratio in solar
prominence structures.
Authors: Stellmacher, G.; Wiehr, E.
1995A&A...299..921S Altcode:
The H<SUB>alpha</SUB>_, H<SUB>beta</SUB>_, and He D_3_ emission
lines are simultaneously observed with high spatial resolution at
the VTT on Tenerife. It is found that the emission ratios He D_3_/
H<SUB>beta</SUB>_ and He D_3_/H<SUB>alpha</SUB>_ show typical mean
values for each individual prominence. This branching is related
to the mean kinetic temperature and to the structuring of each
prominence. Whereas the Balmer excitation is almost uniformly
distributed throughout prominences, the He excitation is enhanced
in structured prominences of low Balmer brightness or outer parts
of unstructured bright prominences, where exciting and ionizing EUV
radiation can freely penetrate. In these regions the He ionization
may exceed that of hydrogen. The atmospheric prominence parameters
are not yet sufficiently known to allow a reliable determination of
the solar Helium abundance.
---------------------------------------------------------
Title: The Hα and Hβ emissions in solar prominence structures.
Authors: Stellmacher, G.; Wiehr, E.
1994A&A...290..655S Altcode:
High precision photometry of the H<SUB>alpha</SUB>_ and
H<SUB>beta</SUB>_ emissions is performed from spectra of four
spatially high resolved quiescent prominences. The data are
compared with recent observations and calculations. It is
found that for faint emissions the observed Balmer decrement
D=E_tot_(H<SUB>alpha</SUB>_)/E_tot_(H<SUB>beta</SUB>_) significantly
exceeds the limiting value D=10.0 calculated for slab models. In
contrast to former observations, the spatially and spectrally high
resolved emission profiles do not require a hot and a cool component
for an optimal fit. The deduced source functions do not yield a common
value for different prominences, but show an individual mean for each
prominence with a tendency for an increase with the optical thickness
of H<SUB>alpha</SUB>_. Optically thick H<SUB>alpha</SUB>_ emissions with
central absorptions are spatially related with narrow H<SUB>beta</SUB>_
emissions and hence with small kinetic temperatures. The narrow
H<SUB>beta</SUB>_ emissions exist over a large range of optical
thickness and show equal macroscopic shifts for individual emission
features favouring a picture of closely tied bundles of threads.
---------------------------------------------------------
Title: Dependence of the He/H_8_ emission ratio on brightness,
temperature, and structuring of prominences
Authors: Stellmacher, G.; Wiehr, E.
1994A&A...286..302S Altcode: 2012arXiv1211.3636S
The line pair He 3888 and H_8_ 3889 has been observed simultaneously
with the Ca^+^8498 line in a number of quiescent prominences. The
He/H_8_ emission ratio R is found to cover defined parts of a general
anti-correlation with the total H_8_ emission, depending on the
kinetic temperature, T_kin_, of the individual prominence: High H_8_
brightness is related to small R and Tkin values and preferably occurs
in prominences with less significant fine-structure.
---------------------------------------------------------
Title: Chromospheric Faculae as Filaments Feet?
Authors: Koutchmy, S.; Stellmacher, G.
1994emsp.conf...91K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Influence of non-thermal broadening on the He 3889/H8 emission
ratio in prominence fine-structures
Authors: Stellmacher, G.; Wiehr, E.; Grupe, D.
1992A&A...265..781S Altcode:
The neighboring emission lines H8 and He near 3889 A were observed in a
quiescent prominence at high spatial resolution. The systematic increase
of the He/H8 emission ratio R towards the edges of the prominence is
found to be largely cospatial with a corresponding behavior of the
nonthermal line-broadening parameter Xi while the thermal broadening
does not increase. The good relation between R and Xi also exists in
the fine-structures. This is explained by broadening of the absorption
coefficient increasing the efficiency of the exciting UV radiation
preferably for the (heavier) helium. Interpretation of the nonthermal
broadening parameter in terms of a velocity dispersion may favor the
influence of waves.
---------------------------------------------------------
Title: Structural changes in the solar corona during the July
1991 eclipse
Authors: Zirker, J. B.; Koutchmy, S.; Nitschelm, C.; Stellmacher, G.;
Zimmermann, J. P.; Martinez, P.; Kim, I.; Dzyubenko, N.; Kurochka,
L.; Makarov, V.
1992A&A...258L...1Z Altcode:
Preliminary results of the analysis of radially filtered pictures
obtained at several hours interval during the July 11, 1991 total
solar eclipse are given. Instrumental parameters and method are
outlined. Structural changes are discussed.
---------------------------------------------------------
Title: Modelling the moustache phenomenon in network regions
Authors: Stellmacher, G.; Wiehr, E.
1991A&A...251..675S Altcode:
The intensity enhancement in the inner line wings (moustache) of
Mgb1 5183 and Fe 5434.5 A observed in Ca(+) K bright points outside
active regions is found to result from a superposition of a hot
component (representing the magnetic structure) surrounded by a cool
(intergranular) region. The I + V and I - V profiles of the magnetically
sensitive line Fe 6302.5, observed strictly simultaneously with Mgb1,
are equally well modeled by the same procedure (which in an earlier
paper had successfully been used to explain the gap effect of Zeeman
insensitive lines in plages). The Mgb1 moustaches are cospatial with
the simultaneously observed Fe 6302.5 gaps. Their equal spatial extent
indicates equal width of the temperature and the magnetic structures
of the Ca(+) K region.
---------------------------------------------------------
Title: Geometric line elevation in solar limb faculae
Authors: Stellmacher, G.; Wiehr, E.
1991A&A...248..227S Altcode:
Spectra of markedly visible white light faculae near the solar limb are
used to determine the geometric displacement, Delta-h, of line cores
with respect to their adjacent continuum. The observed Delta-h are
plotted as a function of the excitation potential and, respectively,
equivalent width of the different lines. Comparison with calculated
Delta-h from a photospheric LTE model shows that the observed facula
values significantly exceed the photospheric ones.
---------------------------------------------------------
Title: Stokes-V in an active prominence
Authors: Wiehr, E.; Stellmacher, G.
1991A&A...247..379W Altcode:
Stokes-V spectra of the Ca(+)8542 emission were taken with a CCD in
an active prominence showing extremely high line-of-sight velocities
up to 25 km/s. The spatial resolution allows detecting prominence
fine-structures as small as 1.1 arcsec. Exact field strengths were
determined from the measured steepness of the individual emission line
flanks. Values between 75 and 180 Gs are obtained. No indication is
found for a dependence of the field strength on the spatial resolution
or on the line-of-sight velocity, nor on the emission brightness.
---------------------------------------------------------
Title: The magnetic-field polarity of quiescent prominences
Authors: Kim, I. S.; Klepikov, V. Y.; Koutchmy, S.; Stepanov, A. I.;
Stellmacher, G.
1990PAZh...16..545K Altcode:
A statistical analysis of magnetographic data on quiescent solar
prominences is presented. The existence of two different magnetic
field systems in quiescent prominences is suggested. The first system
is oriented opposite to the underlying photospheric field; the angle
between the long axis of the filament and the field direction is
equal to 15 deg and B-parallel equals 15-18 G. The polarities of the
second system and of the underlying photospheric field are the same,
B-parallel = 5-7 G.
---------------------------------------------------------
Title: Magnetic Field Polarity of Quiescent Prominences
Authors: Kim, I. S.; Klepikov, V. Y.; Koutchmy, S.; Stepanov, A. I.;
Stellmacher, G.
1990SvAL...16..234K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Doppler Velocity Oscillations in Quiescent Prominences
Authors: Wiehr, E.; Balthasar, H.; Stellmacher, G.
1990LNP...363..255W Altcode: 1990IAUCo.117..255W; 1990doqp.coll..255W
No abstract at ADS
---------------------------------------------------------
Title: Velocity and magnetic field fluctuations in penumbral
fine-structures
Authors: Wiehr, E.; Stellmacher, G.
1989A&A...225..528W Altcode:
Spatially very highly resolved spectra of sunspot penumbrae show that
the Evershed effect is not spatially related to the continuum intensity
fluctuations. The line asymmetry and the core shift (both a signature
of the Evershed effect) show fluctuations at a larger horizontal scale
than the continuum and a trend for an anticorrelation, in the sense
that locations with smaller asymmetry trend to show larger shifts. The
Zeeman broadening also shows variations at a larger spatial scale
than the continuum. There is no indication for field enhancements
in dark continuum streaks, some spots even show a certain trend for
enhanced field strengths in bright streaks. The absence of a general
relation to continuum streaks might be explained by the finding that
the continuum structures in the spectrum are almost invisible at
the formation height of the Fe 5576-A line, where a coarser spatial
structure of a few arcsec width occurs.
---------------------------------------------------------
Title: Magnetic fields of solar prominences: strength and latitude
distribution.
Authors: Kim, I. S.; Klepikov, V. Yu.; Koutchmy, S.; Stepanov, A. I.;
Stellmacher, G.
1989BSolD..11...98K Altcode:
According to the data obtained by a Nikolsky-type magnetograph
during 1979 - 1986 there are two maxima in histograms
"occurrence-B<SUB>∥</SUB>": O - 21 G and 27 - 36 G. The probability of
the minimum between these maxima is equal to 82%. The first maximum may
be divided into three distributions with peaks at 8, 15 and 20 G. The
second maximum refers to active latitude prominences. The major part
of the data (80%) belongs to the pre-minimum and minimum epochs. For
this period the average latitude of prominence formation is less than
20°. The authors believe that the peak at 15 G characterizes the
critical field strength of prominence formation.
---------------------------------------------------------
Title: Doppler Velocity Oscillations in Quiescent Prominences
Authors: Wiehr, E.; Balthasar, H.; Stellmacher, G.
1989HvaOB..13..131W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Oscillations in presence of local magnetic fields.
Authors: Wiehr, E.; Balthasar, H.; Stellmacher, G.
1988ESASP.286..269W Altcode: 1988ssls.rept..269W
Oscillatory Doppler shifts in sunspots and in small fluxtubes are
observed using either the intensity profile of lines with negligible
magnetic splitting or the circular Zeeman profile (Stokes-V inversion
point) of lines with strong Zeeman splitting. Sunspot umbrae
show local 5 min oscillations of reduced amplitude as compared to
the neighbouring photosphere. Occasionally the authors find 5 min
oscillations of opposite phase at both outer penumbral borders. This
could be interpreted as tilting and bobbing of the spot as a whole
on the oscillating solar surface. In contrast to these larger scale
sunspot fluxtubes the gas in the small fluxtubes of a few hundred km
diameter seems to fully participate in the photospheric oscillations
without any interaction with the magnetic field. Prominence magnetic
fields show sometimes a reaction to the photospheric 5 min and to the
chromospheric 3 min oscillations, in addition several other periods
are found. Indication is found for eigenmodes of Alfvén waves.
---------------------------------------------------------
Title: Periodic and quasiperiodic Doppler velocity variations in
solar prominences along one spatial direction
Authors: Balthasar, H.; Wiehr, E.; Stellmacher, G.
1988A&A...204..286B Altcode:
Temporal variations of the Doppler displacement of the Hα-emission
line were measured in four quiescent prominences in autumn 1986 at
the recently installed Gregory telescope on Tenerife. As detector,
a 100×100 pixel diode array was used. The length of the time series
was up to seven hours. The slit was oriented parallel to the solar
limb in the first case and perpendicular in the others. In November
1987 another prominence was observed with a 256×256 pixel camera
simultaneously in Ca<SUP>+</SUP>H and Hɛ over five hours. In this case,
the slit was oriented parallel to the solar limb. The result for the
two lines are in good agreement. The authors earlier result of periods
near one hour is confirmed. Short periods near five and three minutes
are found in some parts of the prominences. They might be interpreted
as a reaction of the prominence on the photospheric and chromospheric
oscillations. For the time series of more than five hours indications
of eigenmodes of the prominences are found.
---------------------------------------------------------
Title: Spectroscopic analysis of prominence emissions
Authors: Bendlin, C.; Wiehr, E.; Stellmacher, G.
1988A&A...197..274B Altcode:
Prominence spectra of fairly high spatial resolution of 3arcsec
to 4arcsec are analysed. The total optical thickness of the
Ca<SUP>+</SUP>K emission is determined from the self-absorption
factor, using the true upper level population obtained from the
Ca<SUP>+</SUP>8542 emission. Turbulence values determined from the
widths of optically thin lines show fair agreement with microturbulence
values obtained from the emission relation of the optically thick
Ca<SUP>+</SUP>H and K lines. Variations of the emission ratio
E<SUB>8542</SUB>/E<SUB>&</SUB>beta; in prominences may be related
to different gas pressures.
---------------------------------------------------------
Title: On variation of prominence heights with the solar cycle.
Authors: Kim, I. S.; Klepikov, V. Yu.; Koutchmy, S.; Stepanov, A. I.;
Stellmacher, G.
1988BSolD...5...77K Altcode:
The behaviour of prominence heights with the solar cycle is
studied. Prominence pictures taken by the Nikolsky magnetograph in
1979 - 1986 are used. A dependence of the average height with time
is analysed. The minimum height took place in the fall of 1984, 2
years before the solar activity minimum. Histograms of "prominence
occurrence versus height" were constructed for different phases of
the solar cycle. It is pointed out that the behaviour of the average
prominence height depends on the variation of the distribution of
prominence heights with the solar cycle. The minimum height is due to
a relative increase of the number of prominences which is less than
25 arcsec. The occurrence of these prominences has a peak before the
minimum of solar activity. Such prominences are predominantly located
at the latitudes 0 - 20°.
---------------------------------------------------------
Title: Spectrophotometric analysis of small sunspots
Authors: Stellmacher, G.; Wiehr, E.
1988A&A...191..149S Altcode:
High resolution spectra of two small sunspots were obtained with the
Gregory Vacuum Telescope at Izaña (Tenerife) on 1986 Oct. 8 and 9. The
two lines Fe<SUP>+</SUP> 6149 and Li<SUP>7</SUP> 6707 (doublet) were
chosen for their very different behaviour in umbra atmospheres. Detailed
shape analysis shows that cold spot models (T<SUB>eff</SUB> ≅ 4000K)
cannot explain the present observations; a higher T<SUB>eff</SUB> ≅
4600K has to be assumed. The influence of parasitic light produced by
penumbral blurring and the contribution of dots is discussed.
---------------------------------------------------------
Title: On the distribution of prominence heights.
Authors: Kim, I. S.; Klepikov, V. Yu.; Koutchmy, S.; Stepanov, A. I.;
Stellmacher, G.
1988BSolD1988...75K Altcode:
The distribution of prominence heights is studied. Prominence
pictures obtained in 1979 - 1986 by the Nikolsky magnetograph are
used. Discreteness in the distribution of heights is found. There are
two peaks: the first narrow peak at 20 - 25 arc sec and the second
one at 35 - 45 arc sec. One finds that the prominences with heights
less than 25 arc sec locate mainly at the latitude interval 0 <
φ ≤ 20°. During the preminimum and minimum of solar activity the
average latitude of the filaments (prominences) formation is 18 -
21°. The most likely height interval for prominence formation is at
20 - 25 arc sec (which is the critical height).
---------------------------------------------------------
Title: Velocity variations of prominences.
Authors: Balthasar, H.; Wiehr, E.; Stellmacher, G.
1988AGAb....1R..12B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Oscillatory motions of the H<SUB>α</SUB>-emission line in
quiescent prominences.
Authors: Balthasar, H.; Wiehr, E.; Stellmacher, G.
1988dssp.conf...63B Altcode:
Temporal variations of the Doppler displacement of the
H<SUB>α</SUB>-emission were measured in 4 prominences (September 28
through October 5, 1986) at the recently installed Gregory telescope at
Tenerife, using a 100×100 pixel diode array. Long periods near one hour
confirm former results. The amplitude of these long periods vary with
height and also in the direction parallel to the limb. Short periods
near 5 minutes and near 3 minutes are found which might be interpreted
as perturbations by the photospheric and chromospheric oscillations.
---------------------------------------------------------
Title: Spectroscopic analysis of prominence emissions.
Authors: Wiehr, E.; Bendlin, C.; Stellmacher, G.
1988dssp.conf...67W Altcode:
Spatially well resolved prominence spectra of Ca<SUP>+</SUP> and H lines
are used to determine (1) optical thickness of Ca<SUP>+</SUP>K from
the self-absorption factor, taking the true upper level population from
Ca<SUP>+</SUP>8542; (2) turbulence values from the emission relations
of the thick Ca<SUP>+</SUP>H and K lines yielding results similar to
those from the widths of optically thin lines; (3) gas pressure from
the emission ratio Ca<SUP>+</SUP>8542/H<SUB>β</SUB>.
---------------------------------------------------------
Title: Some Statistical Properties of the Magnetic Field in
Prominences
Authors: Kim, I.; Koutchmy, S.; Stellmacher, G.; Stepanow, A. I.
1987rfsm.conf..289K Altcode:
Magnetic field observations based on the Zeeman effect, measuring the
longitudinal component B<SUB>∥</SUB> of the field with an entrance
hole of 6.4 arcsec diameter, were obtained for a great number of
prominences during 1979 to 1985.
---------------------------------------------------------
Title: Spectroscopic Analysis of Prominence Emissions
Authors: Wiehr, E.; Bendlin, C.; Stellmacher, G.
1987dssp.work...67W Altcode: 1987ASSL..150...67W
No abstract at ADS
---------------------------------------------------------
Title: Properties of a Concentrated Magnetic Field Region
Authors: Koutchmy, S.; Stellmacher, G.
1987rfsm.conf..103K Altcode:
Further results concerning the fine structure of concentrated magnetic
field regions or network elements, observed near disk center well
outside of active regions, are presented.
---------------------------------------------------------
Title: High Resolution Spectroscopy of Sunspot Penumbrae
Authors: Wiehr, E.; Knölker, M.; Grosser, H.; Stellmacher, G.
1987rfsm.conf..162W Altcode:
The spatial variation of velocity- and magnetic field within penumbral
finestructures is investigated from two very highly resolved spectra.
---------------------------------------------------------
Title: The 1981 total solar eclipse. III - Photometric study of the
prominence remnant in the reversing south polar field
Authors: Stellmacher, G.; Koutchmy, S.; Lebecq, C.
1986A&A...162..307S Altcode:
High resolution white light colour pictures obtained during the
1981 total solar eclipse were used for a photometric analysis of
the S-pole region. A small helmet-like streamer was visible over
the S-polar limb overlying a faint polar prominence from the polar
crown belt of filament channels that reached 87° latitude at the
eclipse date. Typical electron densities deduced are n<SUB>e</SUB>
≅ 2×10<SUP>9</SUP>cm<SUP>-3</SUP> for the activated top of the
prominence and n<SUB>e</SUB> ≅ 6×10<SUP>8</SUP>cm<SUP>-3</SUP>
for the associated coronal structures. Upward velocities up to 160 km
s<SUP>-1</SUP> are obtained for the eruptive prominence parts. The
authors found that dynamic processes are controlled by magnetic
forces for fields B ≥ 3.5 Gauss, and that the coronal structures
are apparently connected with the faintest and most dynamic parts of
the prominence.
---------------------------------------------------------
Title: Evidence for quasi-periodic Doppler motions in solar
prominences
Authors: Balthasar, H.; Knoelker, M.; Wiehr, E.; Stellmacher, G.
1986A&A...163..343B Altcode:
Observations of Doppler displacements in solar prominences have been
performed using the Hα emission line. Evidence is found for the
existence of quasi-periodic line-of-sight velocities in the range of
2.5 - 4.7 mHz. Former findings of long time variations near one hour
are confirmed. Possible influences by misguiding and by image motion
can be excluded. Scattered light from the solar aureola cannot produce
the observed amplitudes.
---------------------------------------------------------
Title: The sharp decrease of Evershed effect and magnetic field at
the outer sunspot border
Authors: Wiehr, E.; Knoelker, M.; Grosser, H.; Stellmacher, G.
1986A&A...155..402W Altcode:
Spatially high-resolved spectra of a small split line (g = 0.5) in
four sunspots at different heliographic angles show that the combined
effect of line core velocities and line asymmetries (defined as Evershed
effect) is strongly limited to the sunspot area defined by the continuum
intensity step. Occasionally observed 'adjoining velocity maxima'
just outside the sunspot edges are not related to line asymmetries,
thus indicating a different origin than that of the classical Evershed
effect. A similar concentration of the very spot area is found for
the magnetic line broadening of two large split lines. Both results
indicate that magnetic field and velocity field are sharply restricted
to the visible sunspot, the often observed smooth discontinuity of
both quantities are thus considered to be due to seeing.
---------------------------------------------------------
Title: Measurement of Magnetic Fields in Solar Prominences
Authors: Nikolskii, G. M.; Kim, I. S.; Koutchmy, S.; Stepanov, A. I.;
Stellmacher, G.
1985SvA....29..669N Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The 1981 total solar eclipse corona. II. Global absolute
photometric analysis.
Authors: Lebecq, C.; Koutchmy, S.; Stellmacher, G.
1985A&A...152..157L Altcode:
Detailed results of the absolute photometry of the solar corona
during the July 31, 1981 total eclipse are presented together with
a morphological analysis. The basic calibration method uses the
detailed photometry of images of stars present on the same coronal
picture. Both sky intensity and coronal aureola variations over the
field are carefully evaluated. The recent axi-symmetric non-spherical
model of the F-corona is introduced and the relevant K-corona intensity
variations are derived. The determinations of the Ludendorf index of
flattening and the integrated total brightness of the K-corona alone
are made and discussed in relation to the phase of the sunspot cycle
of activity.
---------------------------------------------------------
Title: Evershed Effect and Magnetic Field in Penumbral Finestructures
Authors: Wiehr, E.; Stellmacher, G.
1985LNP...233..198W Altcode: 1985hrsp.proc..198W
A highly resolved penumbra spectrum obtained from the Locarno telescope
on July 4, 1982 is studied. It is observed that line core shifts are
predominant in dark spectrum streaks and line asymmetries in bright
spectrum streaks. The relationship between line widths and continuum
brightness is investigated. A continuous dependence of these line
parameters on the continuum brightness is detected; decreasing continuum
brightness results in increasing line widths. Explanations for this
increase are discussed. The effect of line widths/brightness variations
on magnetic field fluctuations in penumbral fine structures is examined.
---------------------------------------------------------
Title: Influence of Umbral Dots on Sunspot Models
Authors: Wiehr, E.; Stellmacher, G.
1985LNP...233..254W Altcode: 1985hrsp.proc..254W
A photoelectric investigation was conducted of umbrae of different
brightness in three clean continuum windows at 4365 + or - 1/8, 6305 +
or - 1/4, and 8089 + or - 1/2. These were conducted simultaneously
in the 13th, 9th and 7th order of the f = 10 m echelle grating
spectrograph. It was found that the presence of umbral dots could
not account for observed differences in umbral brightness. In effect,
it is proposed that the dots represent a less important additive for
umbrae of different temperatures.
---------------------------------------------------------
Title: The gas pressure in solar prominences
Authors: Hellwig, J.; Wiehr, E.; Stellmacher, G.
1984A&A...140..449H Altcode:
Attention is given to the results of new measurements of the emission
relation of Ca(+)8542 and H-beta, which indicate that the emission
ratio E(Ca/+/8542)/E(H-beta), at about 0.16, is significantly lower
than the value of about 0.3 obtained by Landsman et al. (1977). The
presently undertaken comparison of these results with those of the
Heasley and Milkey (1978) model indicates that a much higher value
of the gas pressure, approximately 0.1 dyn/sq cm, must be assumed in
order to match the observed lower ratio.
---------------------------------------------------------
Title: The influence of penumbral fine structures on line profiles
Authors: Wiehr, E.; Koch, A.; Knoelker, M.; Kueveler, G.; Stellmacher,
G.
1984A&A...140..352W Altcode:
An experimental investigation of the effect of penumbral fine structure
on the line profiles of Ti 5222.7 A and Fe(+) 5264.8 is presented. The
highly resolved penumbral spectrum was observed with the evacuated
Locarno telescope of the Goettingen observatory. It is shown that the
highly excited Fe(+) line has a strong correlation in its line symmetry
to bright spectrum streaks. Line core shift was correlated with dark
spectrum streaks. The Doppler shift of the Be(+) line increased by 1.2
km/s, and that of the Ti line by 0.7 km/s for a continuum brightness
decrease of 20 percent. On the basis of the observational data, it
is concluded that the two-component model of sunspot penumbrae is
unlikely. It is suggested that Evershed asymmetry originates mainly
from a mixture of fine structure.
---------------------------------------------------------
Title: Comparative magnetographic observations in different prominence
lines
Authors: Nikolsky, G. M.; Kim, I. S.; Koutchmy, S.; Stellmacher, G.
1984A&A...140..112N Altcode: 1984A&A...140..112K
Analysis of the longitudinal field strength in prominences obtained
by measurements of Zeeman polarization in HeD3, Hα, and Hβ is
presented. The measurements were performed with the spectrally scanning
magnetograph installed at the 53 cm coronograph of the Kislovodsk high
altitude station. The observations allow to correlate the values of
the equivalent widths and those of the half widths with magnetographic
data. No systematic dependence of field strengths on line widths is
found. High field strengths persist for large Doppler shifts and low
emissions. In the histogram showing the distribution of observed field
strengths two peaks near B<SUB>∥</SUB> ≅ 8 Gauss and B<SUB>∥</SUB>
≅ 20 Gauss appear. The second peak corresponds to prominences
mainly related to active regions for latitudes <±35°. A similar
distribution is obtained from a set of data deduced from observation
of the Hanle effect and corresponding to the same epoch.
---------------------------------------------------------
Title: Oscillations of the Hα Emission in Solar Prominences
Authors: Wiehr, E.; Stellmacher, G.; Balthasar, H.
1984SoPh...94..285W Altcode:
The time dependence of Doppler shift and line-center intensity
is simultaneously observed for the Hα emission of three solar
prominences, each one during about two hours. Doppler oscillations
with periods near one hour and amplitudes between 1 and 2 km
s<SUP>−1</SUP> are conspicuously visible in the recordings of all
three prominences. Fourier analysis yields periods of 50, 60, and
64 min, as well as slight indications of short periods near 3 and 5
min. No oscillations are found in the line-center brightness.
---------------------------------------------------------
Title: The electron density of faint prominences observed during
the solar eclipse of July 31, 1981
Authors: Koutchmy, S.; Lebecq, C.; Stellmacher, G.
1983A&A...119..261K Altcode:
Prominences visible on the narrow band filtergrams of the
eclipsed Sun, July 3t, 1981, are analysed. The ratio of the Hβ
line intensity to the continuum intensity at λ=6073 Å is used to
derive the electron density n<SUB>e</SUB> as a function of electron
temperature T<SUB>e</SUB>. The prominences present on that day were
of low brightness: E<SUB>β,max</SUB> ≃ 0.2 10<SUP>4</SUP> [erg
cm<SUP>-2</SUP> s<SUP>-1</SUP> sterad<SUP>-1</SUP>]. An electron density
n<SUB>e</SUB> = 5.7 10<SUP>9</SUP> [cm<SUP>-3</SUP>] at T<SUB>e</SUB>
= 10,000° is obtained, being typical for prominence edges.
---------------------------------------------------------
Title: Magnetic field in solar prominences measured with a new
spectrally scanning magnetograph
Authors: Kim, I. S.; Nikolsky, G. M.; Koutchmy, S.; Stellmacher, G.
1982A&A...114..347K Altcode:
Observations of the longitudinal field strength in quiescent prominences
obtained with the new redesigned spectrally scanning magnetograph
installed in the Coude focus of the 53 cm coronograph of the Kislovodsk
station are presented. With the instrument one can obtain magnetographic
data as well as central intensities, equivalent widths, line widths,
and shifts of the analyzed prominence lines. A first discussion,
correlating magnetographic and spectroscopic data, is given
---------------------------------------------------------
Title: Magnetfeld, Intensität und Strömung in
Penumbra-Feinstrukturen
Authors: Stellmacher, G.; Wiehr, E.; Knölker, M.
1982MitAG..55...68S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Line profiles and magnetic field in penumbral fine structures
Authors: Stellmacher, G.; Wiehr, E.
1981A&A...103..211S Altcode:
Spectra at high spatial resolution are taken in a sunspot penumbra at
disc center. The magnetic low sensitive lines Fe (+) 5264.8 (g equals
0.1) and Ti 5222.7 (g equals 0) as well as the large split line Fe
6302.3 are analyzed by comparison with model calculations. No systematic
fluctuations of the magnetic field strength and inclination are found
in the bright and dark spectral streaks, b and d. It is shown that this
result is still compatible with actual field fluctuations of less than
or equal to 1,000 G between the individual penumbral bright and dark
regions, BR and DR. The observed fluctuations of the central intensity
of the two oppositely temperature sensitive Fe(+) and Ti lines are
essentially smaller than expected from the continuum fluctuations. The
DR model requires a larger macro turbulence parameter than the BR model
in agreement with a spatially low resolved Evershed flow in the DR.
---------------------------------------------------------
Title: Joint Soviet - French Investigations of the Solar Corona -
Part Three - Structure and Some Dynamic Features of the Solar Corona
of 1973JUN30
Authors: Vsekhsvyatskii, S. K.; Dzyubenko, N. I.; Ivanchuk, V. I.;
Popov, O. S.; Rubo, G. A.; Koutchmy, S.; Koutchmy, O.; Stellmacher, G.
1981SvA....25..463V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the branching in the emission relations of Ca<SUP>+</SUP>
in prominences
Authors: Stellmacher, G.; Wiehr, E.
1981SoPh...71..299S Altcode: 2012arXiv1211.3641S
Spatially well resolved prominence spectra of the three lines
Ca<SUP>+</SUP> K, Hβ, and Ca<SUP>+</SUP> 8542 are analysed. It is
confirmed that the branching in the emission relations of Ca<SUP>+</SUP>
versus Hβ correlates with the magnitude of non-thermal (turbulent)
broadening.
---------------------------------------------------------
Title: Joint Soviet / French Investigations of the Solar Corona -
Part Two - Photometry of the Solar Corona of 1973JUN30
Authors: Vsekhsvyatskii, S. K.; Dzyubenko, N. I.; Ivanchuk, V. I.;
Popov, O. S.; Rubo, G. A.; Koutchmy, S.; Koutchmy, O.; Stellmacher, G.
1981SvA....25..211V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Umbral Models with Enhanced Continuum Opacity
Authors: Stellmacher, G.; Wiehr, E.
1981A&A....95..229S Altcode:
Umbral models based on the assumption of an additional continuum opacity
(Zwaan, 1974; Kollatschny et al., 1979: M4) are compared with model M3
by Stellmacher and Wiehr (1975) which is based on the standard continuum
opacity. <P />The strong Fe 4063.6 lime is observed in several sunspot
umbrae. An upper limit of parasitic light is estimated on the basis
of vanishing Fe+ limes in umbrae. It is shown that the wings of the
so corrected Fe 4063.6 line cannot be reproduced by model M3. The
recent model M4 requires an opacity enhancement q<SUB>4063</SUB> =
2.5 ± 0.2; Zwaan's model needs q<SUB>4063</SUB> = 2.7. The relative
umbral intensity at λλ4063 is obtained to 0.026 I<SUP>phot</SUP>
using model M4 with q<SUB>4063</SUB> = 2.5. Assuming line haze as
origin for q<SUB>λ</SUB> the true continuum would amount to 0.065
I<SUP>phot</SUP>. Measurements of umbral continuum contrasts near
the peaks of the opacity curve q(λ) suggested by Gaur et al. (1979)
do not show the marked contrast depressions predicted and are thus
at variance with the idea that the additional opacity arises from
electronic transitions of CN, CaB, MgH and TiO molecules.
---------------------------------------------------------
Title: On TV Observations of Polarization of Green Coronal Line at
the Eclipse Time of 1981JUL31
Authors: Popov, O. S.; Ivchenko, V. N.; Lapchuk, V. P.; Milinevsky,
G. P.; Osminkina, K. I.; Koutchmy, S.; Begot, J.; Lebeq, C.;
Stellmacher, G.
1981ATsir1202....1P Altcode: 1981ATsir1202Q...1P
No abstract at ADS
---------------------------------------------------------
Title: Zusatz-Opazität für Sonnenflecken und späte Sterne
Authors: Wiehr, E.; Kollatschny, W.; Stellmacher, G.
1981MitAG..52..162W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The infrared Ca/+/ lines in sunspot umbrae
Authors: Kollatschny, W.; Wiehr, E.; Stellmacher, G.; Falipou, M. A.
1980A&A....86..245K Altcode: 2012arXiv1210.3336K
We present an empirical working model for sunspot umbrae which equally
describes observed continuum intensities and line profiles. The wings
of the infrared Ca II lines depend sensitively on the temperature
gradient at -0.6 < log(tau-0.5) < +0.3 but not essentially on
the absolute value of T. These lines are observed to remain almost
unchanged from photosphere to umbra and are thus insensitive to
parasitic light. It is also shown that the infrared K I 7699 line is
suitable for umbral spectroscopy since it is not seriously blended, its
continuum is well defined and it is less influenced by parasitic light
as compared to lines in the visible spectrum, due to the smaller umbral
contrast. Calculations show that the umbral gradient dT/d(tau), required
to fit the Ca II triplet lines, strongly conflicts with the observed
profiles of K I 7699, NaD2 and Fe I 5434 (g=0), even when assuming
vanishing Fe II lines for a maximum correction of parasitic light. It
is shown that this discrepancy from the different line profiles may
be removed by adopting an opacity enhancement as introduced by Zwaan
(1974) from a discussion of continuum contrasts alone. The finally
proposed umbral working model is very close to a scaled model of the
quiet sun with T(eff)= 4000 K thus resembling a M0 rather than a K5
stellar atmosphere
---------------------------------------------------------
Title: Line shifts and asymmetries in sunspot penumbrae
Authors: Stellmacher, G.; Wiehr, E.
1980A&A....82..157S Altcode:
The paper considers the line shifts and asymmetries in sunspot
penumbrae. Spatially unresolved spectra show decreasing shifts of
line cores and increasing symmetries with height; it is shown that
a decomposition of the asymmetric profiles into a main component and
a satellite yields contradictory results when considering the depth
dependence and the center-to-limb variation of different lines. Line
profiles from the bright and dark spectral streaks are analyzed, showing
that line widths, residual intensities, and asymmetries increase with
increasing line shift. Finally, an attempt is made to simulate the
bright and dark line profiles by simple superposition of intrinsic
profiles from the bright and dark penumbral regions calculated with
the corresponding models given by Kjeldseth-Moe and Maltby (1974).
---------------------------------------------------------
Title: A common model for solar filigree and faculae.
Authors: Stellmacher, G.; Wiehr, E.
1979A&A....75..263S Altcode:
A disk-center filigree model for facular plages is examined by
using photographic spectra of solar lines with a reasonably small
Zeeman splitting. The results fully confirm previously reported line
weakenings as well as a previously observed decrease in the line
weakenings toward the limb. It is found that the highly excited lines
of Fe II at 5264 A, Ti II at 4568 A, and Si I at 6145 A exhibit line
strengthenings for most limb faculae but that the absolute intensities
of the line cores are always higher than those of the neighboring
photosphere. Photoelectric measurements of the wavelength dependence of
the contrast in true continuum windows and in facular spectra obtained
at various heliocentric angles reveal that the contrast decreases with
wavelength, as reported earlier.
---------------------------------------------------------
Title: Simultaneous measurements of Ca<SUP>+</SUP> K, Ca<SUP>+</SUP>
H, Hα, Hβ, and He D<SUB>3</SUB> emission in prominences
Authors: Stellmacher, G.
1979SoPh...61...61S Altcode:
Simultaneously measured line intensities of Ca<SUP>+</SUP> K and H,
Hα, Hβ and He D<SUB>3</SUB> are presented and compared with recent
model calculations by Heasley and Milkey (1978). The model calculations
are compatible with the observations. There is indication that the
observed branching of the relation E(Ca<SUP>+</SUP> K and H) ∼ E(Hβ)
depends on the widths of the Ca<SUP>+</SUP>-lines.
---------------------------------------------------------
Title: Discussion
Authors: Maltby, P.; Stellmacher, G.
1979phsp.coll...35M Altcode: 1979IAUCo..44...35M
No abstract at ADS
---------------------------------------------------------
Title: Ein Modell für solare Filigrees und Fackeln
Authors: Wiehr, E.; Stellmacher, G.
1979MitAG..45..149W Altcode:
Previous measurements of magnetically nonsplit lines are extended to
slightly magnetically split lines to gather data on low ionization
lines of Fe(+), Ti(+), and Si. Attention is given to Schmahl's model
in determining the rest-intensity effect, as well as to correlations
between solar filigrees and faculae.
---------------------------------------------------------
Title: Ca^{+} (h and K), Hα and Hβ Emission Observed Simultaneously
in Quiescent Prominences.
Authors: Stellmacher, G.
1979phsp.coll...33S Altcode: 1979phsp.conf...33S; 1979IAUCo..44...33S
No abstract at ADS
---------------------------------------------------------
Title: Photometrical analysis of the June 30, 1973 solar corona.
Authors: Koutchmy, S.; Stellmacher, G.; Koutchmy, O.; Dzubenko, N. I.;
Ivanchuk, V. I.; Popov, O. S.; Rubo, G. A.; Vsekhsviatskii, S. K.;
Lamy, P.
1978A&A....69...35K Altcode:
In order to deduce reliable values of the K and F coronal, a method
of photographic photometry has been applied to study compensated
high-resolution pictures obtained during the June 30, 1973, solar
total eclipse, including a color one. The correctly exposed images of
calibration stars are used to obtain intensities in units of the mean
brightness of the sun. An account is made, in both the blue and the
red spectral ranges, for the sky background as well as for the coronal
aureola effects. The N-polar and E-equatorial regions are shown to be
relatively homogeneous; their intensities are especially studied in
the radial direction and compared with published values of the K and F
coronae. No flattening and no color effect are found in the inner part
(distance less than 2.5 solar radii) of the F corona.
---------------------------------------------------------
Title: Photospheric faculae. II. Line profiles and magnetic field
in the bright network of the quiet sun.
Authors: Koutchmy, S.; Stellmacher, G.
1978A&A....67...93K Altcode:
Smnmary. Spatially high resolution spectra ( 0"75) of the three
iron lines. Fe 5576 A (non split), Fe 6301.5 A and Fe 6302.5 A
(triplet) observed in maguetic regions (network) of the quiet Sun,
were analysed. For the model computations, recent values of filigree
continuum contrast and diameter were used [1f/1P -18, 4) -0"24 (174
km), =6000 A]. High values of the maguetic field strength (10001500
Gauss) are found for the quiet network regions. A fit of the observed
profiles with the calculated proffles can be obtained only when a
strong maguetic field is also assumed in the intergranular regions
that surround the filigrees; the dimension of the magnetic field patch
is found to be structured and larger than that of the proper line gap
(ffligree). For the model calculations, a good fit is obtained when
the filigree width r is assumed to increase with height h as r =0.12
h+87 [km]. Key words: Sun - photo sphere - filigrees - facularpoints -
gap-profiles - concentrated magnetic fields
---------------------------------------------------------
Title: The Contrast of Solar Filigrees
Authors: Koutchmy, S.; Stellmacher, G.
1977MitAG..42..142K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Zum Problem der Evershedströmungen in Penumbra-Feinstrukturen
Authors: Wiehr, E.; Stellmacher, G.; Soltau, D.
1977MitAG..42..117W Altcode:
The use of a two-flow model in the interpretation of the solar
Evershed flows reported by Schroeter (1965) leads to contradictions
with respect to recent measurements regarding the flow characteristics
in the penumbra fine structures. Stellmacher and Wiehr (1971) have
found in an analysis of line asymmetries based on such a model that
the line main component must be related to slow-flowing bright penumbra
structures. The line satellite, on the other hand, must be related to
fast-flowing dark penumbra structures. A series of nonsplitting lines
in two long-term individual spots were recorded in connection with a
more detailed investigation of this model concept. The asymmetrical
penumbral line profiles were decomposed with the aid of a computer
calculation into a main component and a satellite. The significance of
the results is discussed. It is found that the observational phenomena
can be very well reconciled with a depth-dependent flow concept for
the penumbra proposed by Maltby (1964).
---------------------------------------------------------
Title: Photometric study of chromospheric and coronal spikes observed
during the total solar eclipse of 30 June 1973.
Authors: Koutchmy, S.; Stellmacher, G.
1976SoPh...49..253K Altcode:
A photometric and colorimetric analysis of a color picture of the very
inner solar corona, near the South pole region, is performed. Dimensions
and average electron densities of both chromospheric and very fine
resolved coronal spikes are deduced. For the coronal spike a half
width of 1″.67 is measured, the estimate of electron density yields
n<SUB>e</SUB> = 10<SUP>10</SUP> cm<SUP>−3</SUP>. Some conclusions
are attempted on the light of a simultaneously observed spectrum of
the same region which appeared to be a "disappearing coronal hole." The
observations seem to support the concept of a "striated" corona.
---------------------------------------------------------
Title: Erratum; The Deep Layers of Sunspot Umbrae
Authors: Stellmacher, G.; Wiehr, E.
1976A&A....47..479S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Ein empirisches Modell für die tiefen Umbra-Schichten
Authors: Wiehr, E.; Stellmacher, G.; Schleicher, H.
1976MitAG..38..217W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The deep layers of sunspot umbrae.
Authors: Stellmacher, G.; Wiehr, E.
1975A&A....45...69S Altcode: 2012arXiv1210.4393S
We model the deepest observable layers of dark sunspot umbral
atmospheres in terms of an empirical model which equally describes
observed near infrared continuum intensities and line profiles. We
use the umbral continuum intensity at 1.67 nm and the three C I
lines at 1,6888, 1,7449 and 1,7456 nm to model the deep layers near
the minimum of H- absorption. We find that a radiative equilibrium
stratification yields the best compromise between continuum and C I line
observations. We determine the effective temperature from the umbral and
photospheric flux ratio by down-scaling the monochromatic photospheric
flux with the umbral contrast for each frequency. The thus obtained
monochromatic umbral flux and the photospheric one are integratied
over the whole frequency range, yielding the ratio of total umbral and
photospheric flux, which gives 3560 K < T_eff < 3780 K. We assume
for our model M3 T_eff=3750 K and fit M3 to the theoretical model by
Meyer et al. (1974). Comparison of the model's 'nabla' gradient with
the adiabatic one shows that umbral convection, if existing at all,
can only occur at considerably deeper layers than in the photosphere.
---------------------------------------------------------
Title: Zum Problem des Kontinuum-Kontrastes solarer Fackeln
Authors: Wiehr, E.; Stellmacher, G.
1975MitAG..36..148W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Study of low dispersion eclipse spectra: observation of weak
low excitation emission lines in the corona.
Authors: Stellmacher, G.; Koutchmy, S.
1974A&A....35...43S Altcode:
Summary. A spectroscopic experiment, set up to observe simultaneously
the electronic, emission line and F-corona, near the equator between
0.1 and 0.8 R0 above the sun's limb, was carried out successfully
during the total solar eclipse on June 30, 1973 in the Republic of
Tchad. The low excitation line emission in Ca+, H and K, H , H ,
H is observed superimposed over the entire spectrum, including the
lunar background. No radial dependence is observed for the equivalent
width of these lines. The emission is interpreted in terms of double
scattered light of chromospheric origin in the earth's atmosphere. The
color dependence of the double scattered light is correctly reproduced
by a quasi quantitative model confirming the parasitic origin of these
lines. Key words: sun - total solar eclipse chromospheric emission
lines double scattered parasitic light atmospheric optics
---------------------------------------------------------
Title: Sur les premiers signes de la reprise de l'activité solaire.
Authors: Koutchmy, S.; Bareau, C.; Stellmacher, G.
1974CRASB.278..873K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A Facula Model and its Application to Facula Fine Structures
Authors: Wiehr, E.; Stellmacher, G.
1974IAUS...56..179W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observed Facula Line Profiles and Contrasts, Comparison
with Models
Authors: Stellmacher, G.; Wiehr, E.
1973A&A....29...13S Altcode:
Summary. Profiles of magnetically insensitive lines are measured
together with contrasts in real continuum windows for solar facula
regions at different positions on the disc with a spatial resolution
of about 3". The contrast measurements earlier observations (Fig. 1);
the line profiles show the "rest-intensity effect" (discussed in a
previous paper) to decrease towards the limb (Fig. 2). Calculations
with a number of reasonable facula models indicate that a homogeneous
LTE model fails to represent simultaneously the observed contrasts
and line profiles, without further assumptions. Key words: facula models
---------------------------------------------------------
Title: Observatino of an Instability in a "Quiescent" Prominence
Authors: Stellmacher, G.; Wiehr, E.
1973A&A....24..321S Altcode: 2012arXiv1210.6779S
Summary. A cavity-like instability has been observed in a"quiescent"
prominence. -yaw pictures (Fig. 1) are shown together with Ca+ 8542
spectra (Fig. 2) taken with an image intensifier. The instability
propagates almost with the phase velocity of MHD compres sive waves. A
violation of the lateral stability criterion in the Kippenhahn-
model is indicated, producing a material outflow along the lines of
force. Key words: prominences - magnetic instability
---------------------------------------------------------
Title: Protuberanzen-Spektroskopie hoher Auflösung mit Hilfe des
Bildverstärkers
Authors: Stellmacher, G.; Wiehr, E.
1973MitAG..32..166S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the Line Intensity Ratios E(Hα)/ E(D3) and E(Hβ)/ E(D3)
in Prominences
Authors: Stellmacher, G.
1972SoPh...25..104S Altcode:
The intensity ratios E(Hα)/E(D3) and E(Hβ)/E(D3) in prominences depend
on the total optical thickness in Hα of the layer. The emission of
the He D3 line appears relatively enhanced in thin layers and in outer
parts of the prominences.
---------------------------------------------------------
Title: A Working Model for Sunspot Umbrae
Authors: Stellmacher, G.; Wiehr, E.
1972A&A....19..293S Altcode:
Comparison of magnetically non-split line profiles with the predictions
of several umbra models (Stell macher and Wiehr, 1970) resulted in
the selection of three "best umbra models", those by Zwaan, Henoux
and Stellmacher-Wiehr. These models have now been tested by the
much stronger criterion of the center-to-limb variation (CLV) of the
non-split line Fe 5434.5 and the Na D-lines. The Stellmacher-Wiehr
model best represents these observations. This model is thus able to
simultaneously represent the observations of wavelength dependence
and CLV of umbra continuum contrasts, the profiles of non-split lines
including their CLV, and the Na D-lines. This model is proposed as
a "working model" for reductions of umbra observations. Key words:
umbra of line proflles in umbrae
---------------------------------------------------------
Title: The Influence of the Sunspot Model on the Li-Abundance
Authors: Stellmacher, G.; Wiehr, E.
1971SoPh...21...96S Altcode:
The dependence of the Li-abundance on the equivalent width of the
Li-resonance doublet at λ 6708 Å is calculated for different umbral
models. The choice of the model strongly influences the deduced
Li-abundance (up to a factor 8 or Δ log ɛ<SUB>Li</SUB> = 0.9) even
when using recent umbral models. Detailed discussion of the observations
and reduction with the most suitable umbral model (Stellmacher and
Wiehr, 1970) leads to an abundance of log ɛ<SUB>Li</SUB> = 1.1±0.05
(in the log ɛ<SUB>H</SUB> = 12.0 scale).
---------------------------------------------------------
Title: Magnetically Non-Split Lines in Faculae
Authors: Stellmacher, G.; Wiehr, E.
1971SoPh...18..220S Altcode:
Profile changes of five magnetically non-split lines going from the
photosphere to faculae are investigated. The observations show that
the profiles normalized to the continuum differ from those of the
undisturbed photosphere only in the core. The outer parts of the
profiles remain unchanged. Calculations using two recent facular
models do not represent these observed profile changes. It is shown
that a temperature increase in outer layers h≳ 250 km does explain
the observations. The problem of photospheric magnetograph calibration
for facula magnetic field measurements is discussed.
---------------------------------------------------------
Title: Magnetically Non Split Lines in Penumbrae
Authors: Stellmacher, G.; Wiehr, E.
1971SoPh...17...21S Altcode:
Line asymmetries of five magnetically insensitive lines in penumbrae
are investigated in detail.
---------------------------------------------------------
Title: Magnetically Non Split Lines in Sunspots
Authors: Stellmacher, G.; Wiehr, E.
1970A&A.....7..432S Altcode:
Three magnetically non split lines are measured photographically
in sunspot umbrae and penumbrae by means of & "spot contrast
discriminator", which is described and tested. The origin of parasitic
light is investigated in detail, its upper limit is determined by means
of a non split Fe+ line being absent in umbrae. These observational data
are compared with calculations for six umbra models and one penumbra
model. Concerning the wavelength dependence and the center-to-limb
variation of the continuum contrast, the umbra models "Zwaan
preliminary", "Wittmann.Schr6ter" and " " are in accordance with the
observations. Concerning the proffles of the three non split lines, the
models "Zwaan preliminary" and " " show a fairly good agreement, which
is improved by slight alteration of Henoux's temperature stratffication
in the outer layers (T0 < 1). From the unchanged non split line Fe
A 4065.4 the best agreement between observed and calculated umbral
proffles is obtained with a microturbulent velocity 1 km/s being of
the same order as the photospheric value from recent works. The good
agreement between measured and calculated umbral proffles indicates that
inhomogenities are less important for umbrae than for the photosphere.
---------------------------------------------------------
Title: Indium, Rubidium, and Caesium in Sunspots
Authors: Stellmacher, G.; Wiehr, E.
1969ApL.....3...91S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Spectroscopic Analysis of Faint Prominences
Authors: Stellmacher, G.
1969A&A.....1...62S Altcode:
The following results were obtained from a spectroscopic analysis 9f
faint prominences: kinetic temperature from linewidths: 6000 - 7000 K;
turbulent velocity = 5 km s-1 electron density ne = 3. 1010 cm- . For
all observed prominences a common state of excitation was found with
considerable departures from L.T.E. For the H atom, these departures
are characterised by = 40, b5,3 = 2, bs.b = 1 (k 4). The higher levels
of the H atom and He atom are found to be in equilibrium with the free
electrons at a temperature Te = 6000-6250 K. The Balmer decrement gave
EH/E = 12 (after correction for sell-absorption). For the 3 8D level
of He is found `D = 1.25. The populations of the 3 8D level and the
third level (0,3) of the H atom are influenced by resonance-scattering
of the visible photospheric radiation.
---------------------------------------------------------
Title: On Lithium in Sunspots
Authors: Wiehr, E.; Stellmacher, G.; Schröter, E. H.
1968ApL.....1..181W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Die Häufigkeiten einiger leichter Elemente abgeleitet aus
Fleckenspektren
Authors: Stellmacher, G.; Wiehr, E.
1968MitAG..25Q.199S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Spektroskopische Analyse einiger schwacher Protuberanzen
Authors: Stellmacher, G.
1968MitAG..25..190S Altcode:
No abstract at ADS
