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Author name code: schroeter
ADS astronomy entries on 2022-09-14
author:"Schroeter, Egon-Horst"
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Title: The lithium abundance in sunspots
Authors: Ritzenhoff, S.; Schroter, E. H.; Schmidt, W.
1997A&A...328..695R Altcode:
The solar lithium abundance was determined using an empirical model
for an observed sunspot umbra. The atmospheric model is deduced from a
number of spectral lines. In addition to the lithium (I) line doublets
from Li(6) and Li(7) at 670.8 nm eight different line profiles were
observed with high spectrographic resolution. A magnetically sensitive
line was included in order to determine the magnetic field strength. An
estimation for the influence of molecular blends caused by CN and
TiO was taken into account. Under the assumption of LTE a lithium
abundance of epsilon_Li =1.02 +/-0.12 was derived. Some evidence for the
existence of a small but notable amount of Li(6) is found, however only
an upper limit of Li(6/Li^7<=) 0.03 can be derived. A more precise
determination of the isotopic ratio is hampered by the uncertainties
induced by the presence of TiO blends. <P />On the logarithmic scale,
where the abundance of hydrogen is epsilon_H =12.
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Title: Polarimetry of Solar Pores
Authors: Sütterlin, P.; Schröter, E. H.; Muglach, K.
1996SoPh..164..311S Altcode:
We address the magnetic field structure of solar pores. The data
were obtained at the Gregory Coudè telescope at Izaña using
the AT1 CCD camera system to observe pores with three spectral
lines: one magnetically sensitive line, recording all 4 Stokes
profiles, and two g = 0 lines where only the intensity profiles
were measured. The data reduction included the standard procedure
(removing dark current and flatfielding) as well as destretching of
the polarimetric spectra and removing the non-magnetic straylight by
means of a 2-d deconvolution of the observed intensity variation using
a Lucy-Richardson restoration algorithm. In the following analysis we
first determined the temperature- and pressure stratification of the
pore using the g = 0 lines and then applied an inversion of the Stokes
profiles to get the parameters of the magnetic field. Across the pore
we find a strong variation of the resulting field strength as well as
of the inclination and the azimuth, consistent with the assumption of
a canopy forming in the higher atmosphere.
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Title: Kiepenheuer-Institut für Sonnenphysik. Jahresbericht für
1993.
Authors: Schröter, E. H.; Stix, M.
1994MitAG..77..121S Altcode:
No abstract at ADS
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Title: On the magneto-thermodynamical structure of a solar pore
Authors: Sütterlin, P.; Thim, F.; Schröter, E. H.
1994smf..conf..213S Altcode:
No abstract at ADS
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Title: Kiepenheuer-Institut für Sonnenphysik. Jahresbericht für
1992.
Authors: Schröter, E. H.
1993MitAG..76..101S Altcode:
No abstract at ADS
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Title: Kiepenheuer-Institut für Sonnenphysik. Jahresbericht für
1991.
Authors: Schröter, E. H.
1992MitAG..75...99S Altcode:
No abstract at ADS
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Title: Interferometric measurements of the solar line Fe I 5576.1
A and its centre-to-limb variation
Authors: Kentischer, T. J.; Schroeter, E. H.
1991A&A...245..279K Altcode:
This paper reports on interferometric absolute wavelength measurements
of the solar line Fe I 5576.1 A at the solar disk center and along the
solar meridian. The measurements have been performed in 1985 using a
LASER-controlled Fabry-Perot interferometer with multilayer coatings,
placed in front of the Littrow spectrograph of the Schauinsland
Observatory near Freiburg (Germany). The resulting channeled spectra
were recorded on film and digitized. The data reduction includes
a correction for the phase dispersion of the Fabry-Perot multilayer
coatings. The main results are: (1) a value for the absolute wavelength
of 5576.090 + or - 0.001 A at the solar disk center; (2) a limb shift
curve with a monotonic increase of the wavelength toward the solar limb
(i.e., there is no sag for cos theta about 0.8, as reported by some
authors); and (3) a possible super-gravity red shift at the limb.
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Title: Kiepenheuer-Institut für Sonnenphysik. Jahresbericht für
1990.
Authors: Schröter, E. H.
1991MitAG..74...99S Altcode:
No abstract at ADS
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Title: Laudatio auf Reinhard W. Hanuschik zur Verleihung des
Ludwig-Biermann-Förderpreises.
Authors: Schröter, E. H.
1991MitAG..74..407S Altcode:
No abstract at ADS
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Title: Laudatio auf Eugene N. Parker zur
20. Karl-Schwarzschild-Vorlesung.
Authors: Schröter, E. H.
1991MitAG..74..405S Altcode:
No abstract at ADS
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Title: Kiepenheuer-Institut für Sonnenphysik. Jahresbericht für
1989.
Authors: Schröter, E. H.
1990MitAG..73...83S Altcode:
No abstract at ADS
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Title: High spatial resolution observations of the Evershed flow
with the German VTT on Teneriffe
Authors: Schröter, E. H.; Kentischer, Th.; Münzer, H.
1989hsrs.conf..299S Altcode:
No abstract at ADS
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Title: The variation of the cell size and velocities of the
supergranulation with heliographic latitude
Authors: Rimmele, T.; Schroeter, E. H.
1989A&A...221..137R Altcode:
A Fourier analysis of supergranular velocity fields measured
at different heliographic latitudes is discussed. Line-of-sight
components of the supergranular velocity field were measured with the
aid of Doppler shifts of the photospheric absorption line Fe I lambda =
5576 A determined using a Doppler-compensating servosystem. Evidence is
found for a decrease of the mean cell diameter of the supergranulation
toward higher latitudes. The results show a mean cell size of 37,800 +
or - 460 km for the equator belt, a minimum value of 33,700 + or - 330
km for latitudes around 45 deg, and increasing cell size values toward
higher latitudes. No variation of rms velocities with latitude is noted.
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Title: Kiepenheuer Institute's Space Spectrograph (poster)
Authors: Schmidt, W.; Schröter, E. H.
1989hsrs.conf..359S Altcode:
No abstract at ADS
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Title: Pole-equator-difference of the size of the chromospheric CA
II-K-network in quiet and active solar regions
Authors: Muenzer, H.; Schroeter, E. H.; Woehl, H.; Hanslmeier, A.
1989A&A...213..431M Altcode:
The dependence of the size of chromospheric network cells on latitude
was investigated for quiet and active solar regions. Calibrated
photographic Ca II K-filtergrams were used and a Fast Fourier Transform
analysis was performed to obtain the cell size. Among other reductions
the results had to be corrected for seeing effects. A significant
decrease of the cell size toward higher latitudes and an increase with
locally increasing magnetic activity was found.
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Title: Kiepenheuer-Institut für Sonnenphysik. Jahresbericht für
1988.
Authors: Schröter, E. H.
1989MitAG..72...91S Altcode:
No abstract at ADS
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Title: Report on the Session: Position and Discussion - Solar Data
Authors: Righini, A.; Schröter, E. H.
1989ASIC..263..295R Altcode: 1989ssg..conf..295R
No abstract at ADS
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Title: A high resolution spectrograph for the Orbiting Solar
Laboratory.
Authors: Schmidt, W.; Schröter, E. H.
1989AGAb....2...22S Altcode: 1989amt..conf...22S
No abstract at ADS
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Title: Book-Review - Solar and Stellar Physics - 5TH European Solar
Meeting - Titisee / Schwarzwald - Germany - 1987APR27-30
Authors: Schroter, E. H.; Schussler, M.; Staude, J.
1989AN....310...66S Altcode:
No abstract at ADS
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Title: Book-Review - the Role of Finescale Magnetic Fields on the
Structure of the Solar Atmosphere
Authors: Schroter, E. H.; Vazquez, M.; Wyller, A. A.; Wiedemann, E.
1989AN....310..318S Altcode:
No abstract at ADS
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Title: Pole-Equator Difference of the Size of the Chromospheric Ca
II-K Network in Quiet and Active Solar Regions
Authors: Münzer, H.; Hanslmeier, A.; Schröter, E. H.; Wöhl, H.
1989ASIC..263..217M Altcode: 1989ssg..conf..217M
No abstract at ADS
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Title: The behavior of asymmetry and other profile parameters of
the Fe I lambda 5576.1 A line in solar regions of varying magnetic
activity
Authors: Immerschitt, S.; Schroeter, E. H.
1989A&A...208..307I Altcode:
Spectra of the magnetic insensitive line Fe I 5576.1 A from one of
the most active regions of the last solar cycle are used to study the
influence of varying magnetic field strength on the convective structure
of the photosheric layers. A simplified heuristic model is constructed
for the modified convective structure of the solar granulation within
active regions. The photospheric atmosphere is divided into upstreaming
granular, downstreaming intergranular, and state filigree columns. The
observations are best reproduced by a restricted granular upflow,
accompanied by increasing surface density of filigree elements in
plage regions of increasing Ca(+)-brightness.
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Title: Book-Review - Solar and Stellar Physics / 5TH European Solar
Meeting / Titisee / Schwarzwald Germany - 1987APR
Authors: Schroter, E. H.; Schussler, M.; Venkatakrishnan, P.
1988BASI...16..248S Altcode:
No abstract at ADS
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Title: Book-Review - the Role of Finescale Magnetic Fields on the
Structure of the Solar Atmosphere
Authors: Schroter, E. H.; Vazquez, M.; Wyller, A. A.
1988S&T....76R.264S Altcode:
No abstract at ADS
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Title: Book-Review - Solar and Stellar Physics
Authors: Schroter, E. H.; Schussler, M.
1988JBAA...98..262S Altcode:
No abstract at ADS
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Title: Book-Review - Solar and Stellar Physics
Authors: Schroter, E. H.; Schussler, M.
1988S&T....75S.498S Altcode:
No abstract at ADS
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Title: The solar granulation in the vicinity of sunspots
Authors: Schmidt, W.; Grossmann-Doerth, U.; Schroeter, E. H.
1988A&A...197..306S Altcode:
The mean size of the granulation close to sunspots is about 10 percent
smaller than the corresponding value in the normal photosphere. The
percentage of small granules increases steadily over a distance of
about 30 arcsedc, as one approaches the sunspots. The observed rms
intensity-contrast of the granulation at distances of less than 10
arcse to the penumbra is lower than in the quiet photosphere. This is
the result of a power spectrum analysis of 11 white light pictures of
different sunspots taken in 1980 with the 40 cm Newtonian Telescope
of the Kiepenheuer-Institut operated at the Observatorio del Teide,
Tenerife.
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Title: Solar and Stellar Physics
Authors: Schröter, Egon-Horst; Schüssler, Manfred
1987LNP...292.....S Altcode: 1987ssp..conf.....S
These proceedings bring together ideas from solar and stellar
physics. The sun is near enough for rather detailed observations and
one chapter is devoted to the more recent experimental data from
observations from space. On the other hand the multitude of stars
provides a wide range of physical parameters to test hypotheses in
solar and stellar astrophysics. The reader will find an illuminating
overview of these fields ranging from the dynamo in the convection zone
to the stellar envelopes and winds in the outer regions. In particular
the importance of small-scale magnetohydrodynamic processes for the
activity phenomena plays an important role in the contributions to this
volume. For both students and researchers the general introduction
by N. O. Weiss makes an excellent guide to this very active field of
research. (See also Lecture Notes in Physics Vol. 291.)
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Title: Recommendations for the LEST site testing campaign.
Authors: Schröter, E. H.
1987LFTR...26...11S Altcode:
No abstract at ADS
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Title: On the Correlation of the C-Shape of the FeI-Line 5576 Å
with the Brightness of Ca<SUP>+</SUP> K-Faculae
Authors: Immerschitt, S.; Schröter, E. -H.
1987rfsm.conf...53I Altcode:
The authors inquired the basic properties of the line-profile of Fe
I λ5576 Å, particularly the c-shape, in a large active region. They
find that systematic changes of the form of the c-shape, of the residual
intensity, of the full-width-at-half-minimum and of the equivalent-width
take place in active regions. These results constitute strong evidence
that magnetic activity modifies the convective temperature and velocity
pattern within the photosphere.
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Title: The role of fine-scale magnetic fields on the structure of
the solar atmosphere
Authors: Schröter, E. -H.; Vázquez, M.; Wyller, A. A.
1987rfsm.conf.....S Altcode:
No abstract at ADS
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Title: Size and temperature of umbral dots
Authors: Grossmann-Doerth, U.; Schmidt, W.; Schroeter, E. H.
1986A&A...156..347G Altcode:
In 12 white light broad band pictures of 6 different sunspots, taken
in 1980 and 1981 with the 40 cm Newtonian Vacuum Telescope operated at
the Observatorio del Teide (Iazaña), the authors identified nearly 100
umbral dots and attempted to derive their temperature and diameter. They
found strong evidence that the diameter of the dots is in the range
0arcsec.4 to 0arcsec.9 and the temperature is several 100K up to more
than 1000K cooler than the photosphere.
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Title: Korrelation des C-Shape der Linie Fe-5576 mit der Helligkeit
von Calcium-K<SUP>+</SUP>-Fackeln
Authors: Immerschitt, S.; Schröter, E. H.
1986MitAG..67..278I Altcode:
Der Einfluß solarer Magnetfelder auf die Struktur konvektiver
Bewegungen der Granulation der Sonne wird untersucht.
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Title: Zum Pol-Äquator Unterschied des Chromosphärischen
Ca<SUP>+</SUP>- Netzwerks und des supergranularen
Geschwindigkeitsfeldes
Authors: Münzer, H.; Rimmele, T.; Schröter, E. H.; Wöhl, H.
1986MitAG..67..281M Altcode:
No abstract at ADS
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Title: Some Impressions I took home with Me
Authors: Schröter, E. H.
1986ssmf.conf..225S Altcode:
No abstract at ADS
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Title: The Solar Differential Rotation - Present Status of
Observations
Authors: Schroeter, E. H.
1985SoPh..100..141S Altcode:
The present status of observations regarding the solar differential
rotation is reviewed from contributions published in the last two
decades. The paper does not deal with the theory; it mentions
theoretical aspects only where they are needed to guide and to
understand observational efforts and results.
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Title: Die deutschen Sonnenteleskope des Observatorio del Teide
auf Teneriffa.
Authors: Schröter, E. H.; Wiehr, E.
1985S&W....24..319S Altcode:
No abstract at ADS
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Title: The German solar telescopes at the observatorio del Teide
Authors: Schroeter, E. H.; Soltau, D.; Wiehr, E.
1985VA.....28..519S Altcode:
This article gives a survey of the German solar telescope installations
which are going to be operational in 1985 (Gregory Coudé Telescope)
and in 1986 (Vacuum Tower Telescope) respectively.
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Title: The German Solar Telescopes to be Installed in the Spanish
Observatorio del Teide/Tenerife; Present Status
Authors: Schröter, E. H.
1985spit.conf.1184S Altcode:
No abstract at ADS
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Title: The longitudinal distribution of solar active regions and
solar global oscillation measurements
Authors: Schroeter, E. H.
1984A&A...139..538S Altcode:
The recently discovered 13.1-day periodicity in solar global oscillation
measurements as reported by Claverie et al. (1982) is shown to be
produced by the rotation of active regions occurring predominantly
in long lived active longitudes 180° apart. They cause an artificial
oscillatory Doppler signal for long periods whenever the solar activity
exceeds a critical minimum value (R<SUB>M</SUB> ≥ 40). It is further
shown that the properly calibrated active region-weighted Doppler signal
for the period July 10 to July 24, 1981 agrees with the measurements
of Claverie et al. within the error limits. It is thus concluded that
Claverie's observations contain no direct evidence for a fast rotating
solar core as was speculated by the authors and by Dicke (1983).
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Title: The Asymmetry of Photospheric Absorption Lines in Quiet and
Active Regions of the Sun
Authors: Kaisig, M.; Durrant, C. J.; Schroter, E. H.
1984ssdp.conf..360K Altcode:
Photoelectric scans of Fe I lines in quiet and active regions of the
sun yield significant differences of the line asymmetry and wavelength
shifts of the line centers. These differences are interpreted
in terms of a modification of the hydrodynamic structure beneath
Ca<SUP>+</SUP>-plage regions. To demonstrate this, the authors used a
second-order perturbation analysis and the classical "two-stream model".
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Title: On Line Asymmetries in Quiet and Plage Regions on the Sun
Authors: Brandt, P. N.; Schroter, E. H.
1984ssdp.conf..371B Altcode:
The centre-to-limb variation of the bisector shapes of the Fe I lines
λ5576.1 Å and λ5250.2 Å is measured in quiet and plage regions
on the sun. At disk centre the smaller curvature of the bisector
in plage regions found in λ5576.1 Å and other lines by Kaisig and
Schröter (1983) and in λ5250.6 Å by Livingston (1982) are essentially
confirmed. While for λ5576.1 Å the differences in bisector shapes tend
to decrease towards the limb they increase for λ5250.2 Å. Due to the
lack of a wavelength reference no discrimination can be made between the
red-shift of biscectors in the line-centres in plage-regions compared to
non-active regions as found by Livingston (1982) and the corresponding
relative blue-shift as reported by Kaisig and Schröter (1983).
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Title: Solar global velocity oscillations and active region rotation
Authors: Durrant, C. J.; Schroeter, E. H.
1983Natur.301..589D Altcode:
Claverie et al.<SUP>1</SUP> have recently reported the detection
of an approximately 13-day periodicity in measurements of the mean
Doppler velocity shift of the integrated solar disk. They attribute
this signal to the presence of a rapidly rotating core. Here we draw
attention to the close correlation between this periodicity and the
rotation of solar active regions across the disk. The presence of
an active region should modulate the measured velocities due to the
temperature sensitivity of the line measured. It seems likely that
this is the origin of the signal observed by Claverie et al.
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Title: Zum Einfluß chromosphärischer Fackelgebiete auf Messungen
globaler Oszillationen der Sonne
Authors: Schröter, E. H.
1983MitAG..60..223S Altcode:
No abstract at ADS
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Title: The asymmetry of photospheric absorption lines. II - The
asymmetry of medium-strong Fe I lines in quiet and active regions
of the sun
Authors: Kaisig, M.; Schroeter, E. H.
1983A&A...117..305K Altcode:
Significant differences in line asymmetry and wavelength shifts of line
centers are obtained by photoelectric scans of six medium-strong Fe I
lines in quiet and active regions close to the solar disk center. An
I2-absorption tube was used for wavelength calibration. In addition,
stronger line core blueshifts and smaller line flank blue bulges were
shown by the bisectors in active regions around sunspots. These
differences are interpreted in terms of a modification of the
hydrodynamic structure of the photospheric layers beneath Ca(-)-plage
regions. This interpretation is supported by both a second-order
perturbation analysis quadratically relating line profile parameter
variations with atmospheric quality variations, and a two-stream
model representing atmospheric fluctuations by positive and negative
rms values.
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Title: On the centre-to-limb variation and latitude dependence of
the asymmetry and wavelength shift of the solar line λ 5576
Authors: Brandt, P. N.; Schroeter, E. H.
1982SoPh...79....3B Altcode:
Low noise photoelectric measurements of the line profile of the g =
0 Fe line gl 5576.097 combined with determinations of the wavelength
shift of its centre calibrated by use of an I<SUB>2</SUB> absorption
tube are reported. Measurements taken at various limb distances
(1.0 ≤ cos ϑ ≤ 0.2) and along 4 different diameters of the Sun
are used to investigate the behaviour of the line asymmetry (C-shape)
and wavelength shift of the line centre as functions of cos ϑ and of
latitude and to search for possible pole-equator differences.
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Title: Kiepenheuer-Institut für Sonnenphysik. Jahresbericht für
1981.
Authors: Schröter, E. H.
1982MitAG..56..115S Altcode:
No abstract at ADS
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Title: Rms-value and power spectrum of the photospheric
intensity-fluctuations
Authors: Schmidt, W.; Knoelker, M.; Schroeter, E. H.
1981SoPh...73..217S Altcode:
The power spectrum and the rms-value of the granular intensity
fluctuations were studied using granulation photographs of
excellent quality obtained during the JOSO site testing campaign
1979 at Izaña. The observed power spectrum was corrected using
various effective modulation transfer functions of the system:
telescope+aberrations+atmospheric seeing, assuming different
contributions of the atmospheric seeing. With this procedure a
lower and upper limit for the `true' power spectrum of the granular
intensity fluctuations and thus for the rms-value could be derived:
7.2% <I<SUB>rms</SUB> <12% at λ = 550 nm, with a most probable
value of I<SUB>rms</SUB> = 10.5%. We checked the validity of the
upper limit by applying to our data a MTF (Deubner and Mattig, 1975),
which certainly must lead to an overcorrection. This procedure lead
to I<SUB>rms</SUB> = 13.4%. Thus we can state that the true rms-value
of the granular intensity fluctuations does certainly not exceed 13%
at λ = 550 nm.
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Title: On Diurnal Variations of the Solar Rotation Rate as Derived
from Sunspot Tracings
Authors: Koch, A.; Woehl, H.; Schroeter, E. H.
1981SoPh...71..395K Altcode:
The heliographic positions of more than 100 sunspots were accurately
measured several times a day from 1974 until 1979 by means of the
computer-controlled tracing method described by Schröter and Wöhl
(1975). A striking degree of constancy of the solar rotation rate (about
0.15% or 3 m s<SUP>−1</SUP>) is found, when east-west proper motion
components of each individual stable sunspot is considered. However,
large differences of the rotation rate are observed (up to 7% or 130
m s<SUP>−1</SUP>) when comparing different sunspots. We found no
significant correlation of these fluctuations with characteristics of
the sunspots (age, evolution, etc.).
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Title: Über die Pol-Äquator-Differenz des Limb-Effekts und der
Linien-Asymmetrie einer photosphärischen Linie
Authors: Brandt, P. N.; Schröter, E. H.
1981MitAG..52...31B Altcode:
No abstract at ADS
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Title: Kiepenheuer-Institut für Sonnenphysik. Jahresbericht für
1980.
Authors: Schröter, E. H.
1981MitAG..53..119S Altcode:
No abstract at ADS
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Title: Ergebnisse der Site-Test-Messungen auf den Kanarischen Inseln
Authors: Brandt, P. N.; Schröter, E. H.
1981MitAG..52Q..32B Altcode:
No abstract at ADS
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Title: Powerspektrum und rms-Wert der photosphärischen
Intensitätsfluktuationen
Authors: Schmidt, W.; Knölker, M.; Schröter, E. H.
1981MitAG..52Q.127S Altcode:
No abstract at ADS
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Title: Computergesteuerte Tracermessungen an Sonnenflecken
Authors: Koch, A.; Wöhl, H.; Schröter, E. H.
1981MitAG..52..105K Altcode:
No abstract at ADS
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Title: Kiepenheuer-Institut für Sonnenphysik. Jahresbericht für
1979.
Authors: Schröter, E. H.
1980MitAG..49..111S Altcode:
No abstract at ADS
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Title: On Depth-Dependence of Photospheric Oscillations
Authors: Koch, A.; Kueveler, G.; Schroeter, E. H.
1979SoPh...64...13K Altcode:
We report on results from photographic observations of photospheric
oscillations as a function of depth. Using rms-values and power-spectra
from shifts of entire line-profiles, we find qualitatively an
increase of the velocity-amplitude with increasing height. We get
more quantitative informations by comparing measured asymmetries
of line-profiles with calculated ones derived from Voigt-functions
containing a depth dependent velocity-field.
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Title: Small scale motions on the sun
Authors: Schröter, E. H.
1979ssms.conf.....S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Kiepenheuer-Institut für Sonnenphysik. Jahresbericht für
1978.
Authors: Schröter, E. H.
1979MitAG..46..101S Altcode:
No abstract at ADS
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Title: An attempt to compare the differential rotation of the
Ca<SUP>+</SUP>-network with that of the photospheric plasma.
Authors: Schroeter, E. H.; Woehl, H.; Soltau, D.; Vazquez, M.
1978SoPh...60..181S Altcode:
In this third paper of a series we report on results obtained
from almost simultaneous observations of the differential
rotation of the Ca<SUP>+</SUP>-chromosphere and the photospheric
plasma. The observations (tracings of Ca<SUP>+</SUP>-mottles,
Doppler-shift-measurements in a photospheric line) were performed
at the Locarno station during two extended periods in 1976. Both
data sets were used to search for a large scale circulation
pattern. A regular long-lived pattern could not be detected, but a
single cell with radial outflow (∼40 ms<SUP>-1</SUP>) extending
over more than 50° in longitude has been found. Statistically
significant temporal changes of the differential rotation law of the
Ca<SUP>+</SUP>-chromosphere correlated with changes of meridional
motions and differences in the rotation of the two hemispheres
were observed. The data of 1976 show no significant difference in
the equatorial velocity of the Ca<SUP>+</SUP>-chromosphere and the
photosphere. A comparison of temporal variations of the rotation
velocity of the Ca<SUP>+</SUP>-mottles and the photospheric plasma
yielded no significant correlation. Finally, we correlated the
measurements of the photospheric rotation performed within the
equatorial belts at Locarno with those obtained at Mt. Wilson by a
different method during the same periods. The Locarno data show small
temporal variations (±50 m<SUP>-1</SUP>s) with no correlation between
the two hemispheres, while from the Mt. Wilson data larger variations
(±100 m s<SUP>-1</SUP>) with a very high correlation between the two
hemispheres have been found. A comparison of both sets of data yielded
no correlation at all demonstrating the need for further coordinated
observations and a drastic increase of internal accuracy.
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Title: Fraunhofer-Institut mit den Observatorien Schauinsland und
Anacapri. Jahresbericht für 1977.
Authors: Schröter, E. H.
1978MitAG..44...80S Altcode: 1978MitAG..44...80.
No abstract at ADS
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Title: Gleissberg's problem of the sunspot maxima revisited.
Authors: Schroeter, E. H.
1977JICR....8..218S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Fraunhofer-Institut mit den Observatorien Schauinsland und
Anacapri. Report for 1976.
Authors: Mattig, W.; Schroeter, E. H.
1977MitAG..41...81M Altcode:
No abstract at ADS
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Title: On velocity oscillations in sunspot umbrae.
Authors: Soltau, D.; Schroeter, E. H.; Woehl, H.
1976A&A....50..367S Altcode:
We report results from a power spectrum analysis of photographic
measurements of velocity oscillations in two sunspot umbrae. We find
oscillations with 3 regimes, of periods: 470-300 s, 196-164 s and
123-110 s with a peak to peak amplitude of about 0.6 km/sec. Whereas
the two long period oscillations agree well with the findings of
previous authors the detection of the short period oscillations is
new. We find significant power for the 300 s oscillations in a purely
umbral molecular line, 6496.2 A (TiO), which establishes the umbral
origin of this oscillation mode.
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Title: Differential rotation and giant cell circulation of solar
Ca<SUP>+</SUP>-network.
Authors: Schroeter, E. H.; Woehl, H.
1976SoPh...49...19S Altcode:
We report new results obtained from high precision computer controlled
tracings of ca. 400 bright Ca<SUP>+</SUP>-mottles made during summer
1975 in continuation of our 1974 program (Schröter and Wöhl, 1975). In
particular, we looked in 1975 for the existence of a giant circulation
pattern in the equatorial zone. We find for the differential rotation:
ω = 13.93 − 2.90 sin<SUP>2</SUP>B (deg/day, sidereal) when combining
the new measurements with those obtained in 1974. Observations from
26th April until June 19th give strong evidence that at that time
four giant circulation cells, crossing the solar equator, (i.e. a
nonaxisymmetric velocity field pattern with respect to the solar
equator) did exist. This yields two more rapid and two slower rotating
sectors with Δv = ±80 m s<SUP>−1</SUP>. These giant cells transport
angular momentum towards the equator.
---------------------------------------------------------
Title: On the time behaviour of oscillations in sunspot umbrae.
Authors: Schroeter, E. H.; Soltau, D.
1976A&A....49..463S Altcode:
The time behavior of oscillations in a sunspot umbra is studied using
Doppler-compensator velocity records with high time resolution. A
power-spectrum analysis yields modes with different periods. It is
found that during time periods when the spot umbra oscillated with the
180-s period, the 300-s period was strongly suppressed and vice versa.
---------------------------------------------------------
Title: Differentielle Rotation und meridionale Bewegungen des solaren
Ca<SUP>+</SUP>-Netzwerkes
Authors: Wöhl, H.; Schröter, E. H.
1976MitAG..38..208W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Differential Rotation and Giant Cell Circulation of the Solar
CA^{+}- Network
Authors: Schröter, E. H.; Wöhl, H.
1976IAUS...71...37S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Differential rotation, meridional and random motions of the
solar Ca<SUP>+</SUP> network
Authors: Schroeter, E. H.; Woehl, H.
1975SoPh...42....3S Altcode:
From high precision computer controlled tracings of bright
Ca<SUP>+</SUP>-mottles we investigated differential rotation, meridional
and random motions of these chromospheric fine structures. The
equatorial angular velocity of the Ca<SUP>+</SUP>-mottles agrees well
with that of sunspots (14°.50 per day, sidereal) and is 5 % higher than
for the photosphere. The slowing down with increasing latitude is larger
than for sunspots. Hence in higher latitudes Ca<SUP>+</SUP>-mottles
rotate as fast as the photospheric plasma. A systematic meridional
motion of about 0.1 km s<SUP>−1</SUP> for latitudes around 10° was
found. The Ca<SUP>+</SUP>-mottles show horizontal random motions due
to the supergranular flow pattern with an rms velocity of about 0.15
km s<SUP>−1</SUP>. We finally investigated the correctness of the
solar rotation elements i and Ω derived by Carrington (1863).
---------------------------------------------------------
Title: Differentielle Rotation und meridionale Strömungen des
solaren Ca<SUP>+</SUP>-networks
Authors: Schröter, E. H.; Wöhl, H.
1975MitAG..36..141S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Universitäts-Sternwarte Göttingen mit Institut für
Sonnenforschung Locarno-Orselina (Tessin). Report 1973.
Authors: Deinzer, W.; Kippenhahn, R.; Schröter, E. H.; Voigt, H. H.
1974MitAG..35...66D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solare Magnetfeldmessungen
Authors: Schröter, E. H.
1973MitAG..32...55S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Universitäts-Sternwarte Göttingen mit Institut für
Sonnenforschung Locarno-Orselina (Tessin). Report 1971.
Authors: Deinzer, W.; Kippenhahn, R.; Schröter, E. H.; Voigt, H. H.
1972MitAG..31..285D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On Equivalent Widths in a Penumbral Spectrum (A Test of the
Moe-Maltby Model)
Authors: Schleicher, H.; Schröter, E. H.
1971SoPh...17...31S Altcode:
From new observational material we made a curve of growth
analysis of the penumbra of a large, stable sunspot. The analysis
was done relative to the undisturbed photosphere and gave the
following results (⊙ denotes photosphere, * denotes penumbra):
(θ<SUP>*</SUP> - θ<SUP>⊙</SUP>)<SUB>exe</SUB> = 0.051 ± 0.007 \
{ξ<SUB>t</SUB><SUP>*</SUP>}/{ξ<SUB>t</SUB><SUP>⊙</SUP>} = 1.3 ±
0.1 \ {P<SUB>e</SUB><SUP>*</SUP>}/{P<SUB>e</SUB><SUP>⊙</SUP>} = 0.6
± 0.1 \ {P<SUB>g</SUB><SUP>*</SUP>}/{P<SUB>g</SUB><SUP>⊙</SUP>}
= 1.0 ± 0.2. The results of the analysis are in satisfactory
agreement with the penumbral model as published by Kjeldseth Moe and
Maltby (1969). Additionally we tested this model by computing the
equivalent widths of 28 well selected lines and comparing them with
our observations.
---------------------------------------------------------
Title: Universitäts-Sternwarte Göttingen und Institut für
Sonnenforschung Locarno-Orselina (Tessin). Report 1970.
Authors: Deinzer, W.; Kippenhahn, R.; Schröter, E.; Voigt, H. H.
1971MitAG..29...55D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Ziele und Aufgaben der Schulkommission der Astronomischen
Gesellschaft.
Authors: Schröter, E. H.
1971S&W....10..115S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On Magnetic Fields in Sunspots and Active Regions
Authors: Schröter, E. H.
1971IAUS...43..167S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A complete photoelectric sunspot spectrum: An atlas from 3900
8000 Å
Authors: Wöhl, H.; Wittmann, A.; Schröter, E. H.
1970SoPh...13..104W Altcode:
Complete photoelectric spectra of the photosphere as well as of both
umbra and penumbra of a typical sunspot, ranging from 3900-8000 Å, have
been obtained at the Locarno observatory. An automatic scanning device,
a high precision electronic divider and an on-line Oscillomink penless
recorder enabled us to eliminate the noise produced by image distortion
and to scan the entire visible spectrum within just 5 h. The recordings
have a linear dispersion of about 50 mm/Å and a spectral resolution of
40 mÅ or better. Simultaneously with these observations the momentary
continuous spot intensity and its fast variation with time due to seeing
variations have been recorded with a frequency resolution up to 100
Hz. In order to provide as much data as possible for the correction
of the umbral spectrum for parasitic light, we also measured the limb
profile and the aureola intensity at several wavelengths.
---------------------------------------------------------
Title: On the Dependence of Sunspot Minimum Intensity on Area
Authors: Rossbach, M.; Schröter, E. H.
1970SoPh...12...95R Altcode:
Highly resolved photographs of 25 sunspots and pores of different areas
in 2 continuous wavelengths, obtained in summer 1966 at the Sacramento
Peak Observatory, have been used to reinvestigate the dependence of
sunspot minimum intensity on area. Special care was taken to correct
for parasitic light caused by blurring or image motion and by light
scattering in the instrument and atmosphere. We find a very small,
if any, dependence ofI<SUB>min</SUB> on sunspot area in contradiction
to older measurements but in agreement with Sitnik's and Zwaan's
statements.
---------------------------------------------------------
Title: Universitäts-Sternwarte Göttingen, Institut für
Sonnenforschung Locarno-Orselina (Tessin). Report 1969.
Authors: Deinzer, W.; Kippenhahn, R.; Schröter, E.; Voigt, H. H.
1970MitAG..28...53D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Intensity, Velocity and Magnetic Structure of a Sunspot
Region. IV: Properties of a Unipolar Sunspot
Authors: Beckers, J. M.; Schröter, E. H.
1969SoPh...10..384B Altcode:
From an investigation of spectra in a magnetically sensitive (λ 6173,
g = 2.5) and insensitive line (λ 5576, g = 0), we derived the following
properties for a symmetrical sunspot: The magnetic field strength varies
with the distance ρ(ρ ⩽ 1) from the sunspot center like H(ρ) = H(0)
(1 + ρ<SUP>2</SUP>)<SUP>-1</SUP>
---------------------------------------------------------
Title: The Intensity, Velocity and Magnetic Structure of a Sunspot
Region. V: On the Gradients of Temperature and Pressure in Sunspots
Authors: Wittmann, A.; Schröter, E. H.
1969SoPh...10..357W Altcode:
High resolution sunspot photographs in the blue, red and
infrared continuum exposed on various days were used to derive the
center-to-limb variation of the intensity ratio φ = I<SUB>sp</SUB> /
I<SUB>ph</SUB>. Special care was taken to correct for image blurring,
scattered light and the influence of line absorption.
---------------------------------------------------------
Title: The Intensity, Velocity and Magnetic Structure of a Sunspot
Region. III: On the Origin of the Apparent π Component in Sunspot
Umbrae
Authors: Beckers, J. M.; Schröter, E. H.
1969SoPh....7...22B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Fleckenkontrast als Funktion der Fleckenfläche einige
Eigenschaften der Granulation in unmittelbarer Fleckennähe
Authors: Rossbach, M.; Schröter, E. H.
1969MitAG..27..208R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Intensity, Velocity and Magnetic Structure of a Sunspot
Region. II: Some Properties of Umbral Dots
Authors: Beckers, J. M.; Schröter, E. H.
1968SoPh....4..303B Altcode:
A time sequence of high-resolution sunspot photographs, exposed
almost simultaneously in two continuum wavelengths (4680 Å and 6400
Å), was used to study some properties of umbral fine structures
(`umbral dots'). The lifetime of the umbral dots is found to be 1500
sec. Photometry of some bright dots leads to an observed intensity
excess of 0.129 I<SUB>phot</SUB> and 0.134 I<SUB>phot</SUB> in the
blue and red respectively. The observed mean diameter of the dots is
found to be 420 km. These values still include the action of image
blurring. From the color index the true intensity and diameter of the
dots are estimated. It appears that the umbral dots are in reality
of photospheric brightness having true diameters of 150-200 km. The
spatial distribution of the dots in sunspot umbrae is discussed. Some
peculiarities in recent sunspot magnetic-field observations may be
explained by magnetic inhomogeneities associated with umbral dots.
---------------------------------------------------------
Title: A Statistical Analysis of Large-Scale Brightness and Velocity
Fluctuations in the Solar Atmosphere
Authors: Appenzeller, I.; Schröter, E. H.
1968SoPh....4..131A Altcode:
Simultaneous photoelectric recordings of the intensities and the
Doppler shifts in 5 Fraunhofer lines (Hβ, Na D<SUB>1</SUB>,
Mg b<SUB>2</SUB>, Feλ5123, Feλ5223) were used to study the
structure of local large-scale fluctuations of the intensity and
velocity in different layers of the solar atmosphere. We derived the
autocorrelation and cross-correlation functions and the powerspectra
of the fluctuations. Fluctuation patterns with a characteristic size
of 3-4 × 10<SUP>4</SUP> km were found in all observed lines. The
intensity of the fluctuations decreases sharply from the chromospheric
Hβ-core to the weak iron lines. The results are discussed in terms
of the solar supergranulation pattern.
---------------------------------------------------------
Title: The Intensity, Velocity and Magnetic Structure of a Sunspot
Region. I: Observational Technique; Properties of Magnetic Knots
Authors: Beckers, J. M.; Schröter, E. H.
1968SoPh....4..142B Altcode:
The observational set-up for a detailed study of the velocity,
intensity and magnetic-field fine structure in and around a sunspot is
described. On highly resolved spectra we detected in the vicinity of a
sunspot a large number of points with strong magnetic fields (magnetic
knots). The magnetic field in these knots causes a striking decrease of
the line depth (or a `line gap' after SHEELEY, 1967). The properties
of the magnetic knots are: (1) magnetic fields up to 1400 gauss; (2)
diameter ≈ 1100 km; (3) coincidence with dark intergranular spaces;
(4) generally downward material motion; (5) lifetime>30min; (6)
estimated total number around an unipolar spot ⩾ 2000; (7) combined
magnetic flux comparable to the sunspot flux; (8) coincidence with
Ca<SUP>+</SUP> plages.
---------------------------------------------------------
Title: On the Relation between the Photospheric Intensity, Velocity
and Magnetic Fields
Authors: Beckers, J. M.; Schröter, E. H.
1968SoPh....4..165B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Instrumentelle und technische Neuerungen der Sonnenstation
Locarno
Authors: Schröter, E. H.; Wiehr, E.
1968MitAG..25..187S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On Lithium in Sunspots
Authors: Wiehr, E.; Stellmacher, G.; Schröter, E. H.
1968ApL.....1..181W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetfeld und Materieströmungen in symmetrischen
Einzelflecken
Authors: Beckers, J. M.; Schröter, E. H.
1968MitAG..25..197B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Intensity, Velocity and Magnetic Structure in and around
a Sunspot
Authors: Beckers, J. M.; Schröter, E. H.
1968IAUS...35..178B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Temperaturschichtung und Wilson-Effekt in symmetrischen
Einzelflecken
Authors: Wittmann, A.; Schröter, E. H.
1968MitAG..25..191W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Solar Work at the Göttingen Observatory
Authors: Brückner, G.; Schröter, E.; Voigt, H. H.
1967SoPh....1..487B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Center-To-Limb Variations of the Intensity and the Wavelength
of Several Fraunhofer Lines Along the SUN's Polar and Equatorial
Diameter
Authors: Appenzeller, I.; Schröter, E. H.
1967ApJ...147.1100A Altcode:
The center-to-limb variations for the continuum, for two faint iron
lines, and for the cores of several strong Fraunhofer lines have been
measured along polar and equatorial diameters of the solar disk. A
photoelectric device was used attached to the Gregory-coude' solar
telescope of the University Observatory, , at Locarno. The temperature
difference between the polar and the equatorial limb has been found
not to exceed 6 K during August, 1965. Simultaneous recordings of the
variations of the wavelength were used to determine the so-called limb
effect on these lines.
---------------------------------------------------------
Title: The Evershed-Effect in Sunspots
Authors: Schröter, E. H.
1967sp...conf..325S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Ein Versuch zur Deutung des Evershed-Effektes als Folge von
Strömungen in penumbralen Feinstrukturen
Authors: Schröter, E. H.
1965ZA.....62..256S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Der Evershed-Effekt in einem inaktiven symmetrischen
Einzelfleck. Mit 9 Textabbildungen
Authors: Schröter, E. H.
1965ZA.....62..228S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Die Li-Häufigkeit und das Isotopenverhältnis
Li<SUP>6</SUP>/Li<SUP>7</SUP> in Sonnenflecken. Mit 2 Abbildungen
Authors: Schmahl, G.; Schröter, E. H.
1965ZA.....62..143S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Is There Radiative Equilibrium in Sunspots?.
Authors: Mattig, W.; Schröter, E. H.
1964ApJ...140..804M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Evershed-effect for an isolated, symmetrical sunspot
Authors: Schröter, E. H.
1964susp.conf..190S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A remark concerning the electrical conductivity in visible
layers of sunspots
Authors: Schröter, E. H.
1964susp.conf..222S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Einige Beobachtungen und Messungen an Stratoskop
I-Negativen. Mit 1 Textabbildung
Authors: Schröter, E. H.
1963ZA.....56..183S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Die Mitte-Rand-Variation des Kontinuums für λbar =
5893 Å und der Flügel der NaD-Linien im Sonnenspektrum. Mit 13
Textabbildungen
Authors: Mattig, W.; Schröter, E. H.
1961ZA.....52..195M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Intensity measurements in the wings of the NaD-lines
Authors: Mattig, W.; Schröter, E. H.
1960AnAp...23..913M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Chromosphärische Strukturen in den Balmerlinien. Mit 4
Textabbildungen
Authors: Schröter, E. H.
1958ZA.....45...68S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Polaritäten und Maximalwerte magnetischer Feldstärken von
Sonnenflecken im Zeitraum 1957 Januar I bis März 31
Authors: Künzel, H.; Mattig, W.; Schröter, E. H.
1957AN....284...33K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Polaritäten und Maximalwerte magnetischer Feldstärken von
Sonnenflecken im Zeitraum 1956 Juli I bis August 31
Authors: Künzel, H.; Mattig, W.; Schröter, E. H.
1957AN....283..251K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Polaritäten und Maximalwerte magnetischer Feldstärken von
Sonnenflecken im Zeitraum 1956 September I bis Dezember 31
Authors: Künzel, H.; Mattig, W.; Schröter, E. H.
1957AN....283..263K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Zur Deutung der Rotverschiebung und der Mitte-Rand-Variation
der Fraunhoferlinien bei Berücksichtigung der Temperaturschwankungen
der Sonnenatmosphäre. Mit 9 Textabbildungen
Authors: Schröter, E. H.
1957ZA.....41..141S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Polaritäten und Maximalwerte magnetischer Feldstärken von
Sonnenflecken im Zeitraum 1956 April I bis Juni 30
Authors: Künzel, H.; Mattig, W.; Schröter, E. H.
1956AN....283..159K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Polaritäten und Maximalwerte magnetischer Feldstärken von
Sonnenflecken in dem Zeitraum 1956 Januar I-März 31
Authors: Künzel, H.; Mattig, W.; Schröter, E. H.
1956AN....283...89K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Polaritäten und Maximalwerte magnetischer Feldstärken von
Sonnenflecken in den Jahren 1954-1955
Authors: Künzel, H.; Mattig, W.; Schröter, E. H.
1956AN....283...28K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Ein Versuch zur Bestimmung des Verlaufes der magnetischen
Feldstärke über die Fläche eines Sonnenflekes. Mit 5
Textabbildungen
Authors: Schröter, E. H.
1953ZA.....33...20S Altcode:
No abstract at ADS
