explanation blue bibcodes open ADS page with paths to full text
Author name code: deubner
ADS astronomy entries on 2022-09-14
author:"Deubner, Franz-Ludwig"
---------------------------------------------------------
Title: Commission 12: Solar Radiation and Structure (Radiation et
Structure Solaires)
Authors: Foukal, Peter; Solanki, Sami; Mariska, J.; Baliunas, S.;
Dravins, D.; Duvall, T.; Fang, C.; Gaizauskas, V.; Heinzel, P.;
Kononovich, E.; Koutchmy, S.; Melrose, D.; Stix, M.; Suematsu, Y.;
Deubner, F.
2000IAUTA..24...73F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observers' Views of the Bustling Atmosphere of the Sun
Authors: Deubner, F. -L.; Steffens, S.
1999ESASP.448..149D Altcode: 1999ESPM....9..149D; 1999mfsp.conf..149D
No abstract at ADS
---------------------------------------------------------
Title: Observational Constraints on Models of the Solar Background
Spectrum
Authors: Straus, Th.; Severino, G.; Deubner, F. -L.; Fleck, B.;
Jefferies, S. M.; Tarbell, T.
1999ApJ...516..939S Altcode:
We discuss the properties of the solar background signal as observed in
high-quality, l-ν power and phase difference spectra of the continuum
(C), velocity (V), and line intensity (I) fluctuations of the Ni
I 6768 Å line. These spectra were generated from high-resolution
images acquired by the Michelson Doppler Imager on board SOHO. <P />We
confirm that the background signal in the velocity power spectra can be
reproduced by a composite model with two quasi-stationary components,
describing large-scale and small-scale convective motions, and a
periodic component. The line and continuum intensity power spectra
require additional quasi-stationary and periodic components. The
extra quasi-stationary component dominates the intensity and
continuum background signals over the spectral region where the I-V
phase difference spectra show essentially constant negative phase
difference: i.e., below and in between the p-mode ridges (called the
plateau-interridge regime by Deubner et al.). Since the I-V phase
between the p-mode ridges is not random, the solar background beneath
the p-modes must be considered as coherent. We thus speculate that
the negative phase regime may be the manifestation of a correlated
background. Such a background has been proposed to explain the opposite
sense of the asymmetries of the p-mode line profiles in velocity and
brightness oscillations.
---------------------------------------------------------
Title: υ - υ Phase Relations in the Vicinity of the Transition
Region Derived from SUMER Observations
Authors: Steffens, S.; Deubner, F.
1999ASPC..183..426S Altcode: 1999hrsp.conf..426S
No abstract at ADS
---------------------------------------------------------
Title: Astronomisches Institut der Universität
Würzburg. Jahresbericht für 1998.
Authors: Deubner, F. -L.
1999MitAG..82..751D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A wavelet analysis of solar atmospheric oscillations - on
the excitation of solar oscillations.
Authors: Yan, Yihua; Deubner, F. L.; Kleineisel, R.
1998ArBei..32...41Y Altcode:
The mechanism that keeps the surface of the Sun in 5-min oscillations
remains to be soundly confirmed by direct observations. The present
study aims at working out, with an alternative approach, the 2-D
response of the solar atmosphere to a local perturbation induced by
impulsive convective motions. Using the wavelet transform, the authors
provide an observed phase relationship between convective eddies and the
atmospheric wave that helps to understand the energy exchange process.
---------------------------------------------------------
Title: A spacial analysis of local sources of oscillations
Authors: Yan, Y.; Deubner, F. -L.; Kleineisel, R.
1998IAUS..185..461Y Altcode:
A continuous wavelet transform has been used to study the interaction
of impulsive and periodic perturbations in the solar atmosphere. The
transform allows the characterization of waveforms together with the
determination of the temporal delays that occur between the observed
fluctuations. Without selecting sample events but using the whole
observed data cubes, the research has confirmed the previous results of
the observational study (Deubner & Kleineisel 1996, etc.). Further,
the phase relationship between convective eddies and the atmospheric
waves is also studied with the help of the wavelet transform.
---------------------------------------------------------
Title: Physics of the Sun and Heliosphere in the ERA of Space Probes:
Scientific Highlights of SOHO, ULYSSES and Yohko
Authors: Engvold, O.; Deubner, F. L.; Ripken, H.
1998HiA....11..827E Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Phase relations and other diagnostics of solar atmospheric
strucutre and dynamics
Authors: Deubner, F. -L.
1998IAUS..185..427D Altcode:
Our perception of dynamical processes of the solar atmosphere
is presently characterized by the availability of highly advanced
radiation-hydrodynamic models and simulations, tackling also the effects
of small-scale magnetic fields, sunspots, canopies etc. on the one
hand. On the other hand, we are confronted with puzzling difficulties,
even under quiet solar surface conditions, in matching the observational
results with detailed predictions from 1-D simulations. Obviously,
momentum and energy transport in the real solar atmosphere cannot be
satisfactorily described in 1-D radiation-hydrodynamic studies. However,
the observations provide 3-D information on the amplitude, phase,
wave form etc. of brightness fluctuation and Doppler shift due to
wave motions, as function of frequency and wavenumber (viz. horizontal
component of wave vector). They help to clearly distinguish e.g. running
from standing waves, to detect reflected and scattered waves, and to
separate local events from global oscillations. We discuss examples,
how this large reservoir of experimental results may be utilized
to supplement the diagnostic inventory presently being applied
by theoretical studies, and to examine the productivity of current
concepts of chromospheric dynamics.
---------------------------------------------------------
Title: Astronomisches Institut der Universität
Würzburg. Jahresbericht für 1997.
Authors: Deubner, F. -L.
1998MitAG..81..737D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Phase spectra seen from space
Authors: Straus, Th.; Deubner, F. -L.; Fleck, B.; Marmolino, C.;
Severino, G.; Tarbell, T.
1998IAUS..185..455S Altcode:
We discuss preliminary results of a study of the dynamics of the solar
atmosphere including a first space based investigation of k-omega phase
difference spectra between velocity and intensity perturbations. The
data, including simultaneous line shift, line depth, and continuum
intensity measurements at disk center, have been obtained from a MDI
time series in its high resolution mode. Line depth and continuum
intensity are used to calculate the line intensity which is the more
frequently used parameter in phase difference studies. We compare the
results to ground based observations.
---------------------------------------------------------
Title: New eyes to see inside the sun and stars : pushing the limits
of helio- and asteroseismology with new observations from the ground
and from space
Authors: Deubner, Franz-Ludwig; Christensen-Dalsgaard, Joergen;
Kurtz, Don
1998IAUS..185.....D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: K-ϖ Phase Spectra Obtained from Space
Authors: Straus, Th.; Fleck, B.; Severino, G.; Deubner, F. -L.;
Marmolino, C.; Tarbell, T.
1998ESASP.417..293S Altcode: 1998cesh.conf..293S
No abstract at ADS
---------------------------------------------------------
Title: The influence of the solar atmospheric stratification on the
structure of the acoustic wave field
Authors: Steffens, S.; Schmitz, F.; Deubner, F. -L.
1997SoPh..172...85S Altcode: 1997ESPM....8...85S
We investigate the influence of the solar atmospheric temperature
stratification on the amplitude of waves at different heights and its
dependence on frequency and wave number. Special interest is taken in
the influence of atmospheric layers on the appearence of the recently
observed p-mode crossing features and their location in the Fourier
domain. We consider four stratification models. One of them is the
standard model with convection-zone, VAL-atmosphere and corona. The
others are modifications of this model in order to discuss the influence
of specific layers of the atmosphere. The changes in the temperature
structure significantly influence the velocity amplitude at certain
frequency-wave number combinations at certain heights.
---------------------------------------------------------
Title: Wave Propagation in the Chromosphere and Transition Region:
Where Have All the Shock Waves Gone?
Authors: Fleck, B.; Steffens, S.; Deubner, F. -L.; Wilhelm, K.;
Harrison, R.; Gurman, J.
1997SPD....28.0120F Altcode: 1997BAAS...29..882F
We present first results from a joint observing program (SOHO JOP 26)
involving SUMER, CDS and EIT on SOHO, coordinated with ground-based
observations at the Vacuum Tower Telescope at Iza{\ n}a, Tenerife. The
objective of this study is to characterize the wave propagation
properties in the solar atmosphere, from the photosphere through the
chromosphere up into the transition region. Particular emphasis is laid
on the 3-min shock waves observed in the Ca II K line. How do they
impact the transition region and what signature do they leave there
and in the lower corona? The ground-based measurements comprise high
resolution time series (both filtergrams and spectrograms) in Ca II K,
Hα and Mgb_2. With SUMER we ran four sequences covering different
temperature regimes: a) O I 1302, O I 1306, Si II 1309, C I 1311,
C II 1334, C II 1335, b) Si I 1256, N V 1242, O V 629 c) He I 584,
C III 1175, O I 1152, d) H I 1025, O VI 1031, O VI 1037. With CDS we
took spectral time series in O VI 554, He I 584, He II 607, Mg IX 368,
and O V 629 as well as wide-slit (90x240”) “movies” in He I 584,
Mg IX 368 and O V 629, while EIT ran sub-field high cadence sequences
in He II 304.
---------------------------------------------------------
Title: First Results from SOHO on Waves Near the Solar Transition
Region
Authors: Steffens, S.; Deubner, F. -L.; Fleck, B.; Wilhelm, K.;
Schuhle, U.; Curdt, W.; Harrison, R.; Gurman, J.; Thompson, B. J.;
Brekke, P.; Delaboudiniere, J. -P.; Lemaire, P.; Hessel, B.; Rutten,
R. J.
1997ASPC..118..284S Altcode: 1997fasp.conf..284S
We present first results from simultaneous observations with the
CDS, EIT and SUMER instruments {please see Solar Physics 162 (1995)
for a description of the instruments} onboard SOHO and the VTT at
Tenerife. Our aim is to study the wave propagation, shock formation,
and transmission properties of the upper chromosphere and transition
region. The preliminary results presented here include the variation
of velocity power spectra with height, difference in power between
internetwork and network regions, and variations in mean flows displayed
by different spectral lines.
---------------------------------------------------------
Title: Astronomisches Institut der Universität
Würzburg. Jahresbericht für 1996.
Authors: Deubner, F. -L.
1997MitAG..80..703D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: An observational study of the interaction of impulsive and
periodic perturbations in the solar atmosphere
Authors: Deubner, F. L.; Kleineisel, R.
1997IAUS..181..307D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Tracing CA K Grains Through the Chromosphere into the
Transition Region
Authors: Steffens, S.; Deubner, F. -L.; Fleck, B.; Wilhelm, K.
1997ESASP.404..685S Altcode: 1997cswn.conf..685S
No abstract at ADS
---------------------------------------------------------
Title: Wave Propagation in the Chromosphere and Transition Region
Authors: Steffens, S.; Deubner, F. -L.; Fleck, B.; Wilhelm, K.;
Harrison, R.; Gurman, J.
1997ESASP.404..679S Altcode: 1997cswn.conf..679S
No abstract at ADS
---------------------------------------------------------
Title: Division II: Sun & heliosphere. Reports 1996 from IAU
Commissions 10, 12 and 49.
Authors: Engvold, O.; Deubner, F. -L.; Ripken, H.
1997IAUTA..23..119E Altcode:
Commissions 10: Solar activity, 12: Solar radiation & structure,
49: The interplanetary plasma & the heliosphere.
---------------------------------------------------------
Title: Reports from IAU Commission 12: Solar radiation &
structure.
Authors: Deubner, F. -L.
1997IAUTA..23..149D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Evidence of K_2v_ grains being a non-magnetic phenomenon.
Authors: Remling, B.; Deubner, F. -L.; Steffens, S.
1996A&A...316..196R Altcode:
We present new data concerning the relation between locations of K_2v_
grain appearance and magnetic flux tubes. The data consist of a two hour
time series of simultaneous spectral scans in CaK and in the rotational
bands of cyanogen (CN) around 3883A. The intensity near the CN bandhead
at 3883.4A is used as a proxy for vertical magnetic flux (cf. Sheeley
(1971SPh....20...19S), Liu & Sheeley (1971SPh....20..282), Chapman
(1974SPh....37..151C)). We find no statistically significant increase
in CN intensity at locations of K_2v_ grain appearance. This indicates
that there is no relation between small scale magnetic flux tubes and
locations of bright K_2v_ grains in the internetwork region.
---------------------------------------------------------
Title: Observations of resonant nonradial modes of the solar
atmosphere
Authors: Deubner, F. -L.
1996BASI...24..117D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: K-grains as a three-dimensional phenomenon. II. Phase analysis
of the spatio-temporal pattern.
Authors: Hofmann, J.; Steffens, S.; Deubner, F. -L.
1996A&A...308..192H Altcode:
We have observed spatially one- and two-dimensional time series of CaiiK
spectra to study the spatio-temporal excitation pattern of the Ca K_2V_
grains. We compare the phases of chromospheric velocity fluctuations
(V) measured in K_3_ with those of spectral brightness measured at fixed
wavelength intervals in K_2V_ and K_2R_ (I). Temporal crosscorrelation
functions of prominent chromospheric (3min) wavetrains reproduce the
commonly observed coincidence of brightness maxima in K_2V_ and extreme
redshift of K_3_, whereas the corresponding V-I phases in the k-ν
diagrams reveal a distinct dichotomy: Only in the gaps between the
p-mode ridges do the spectra exhibit homogeneous areas with a stable
phase of approximately 180deg in agreement with the crosscorrelation
result. On the ridges the V-I phase switches to distinctly lower values
near -90deg, with K_3_ redshift preceding K_2V_ brightening. The latter
value is similar to the characteristic V-I phase measured in the core
of other chromospheric lines. Our findings support the contention that
a) K-grains are excited by superposition of resonant p-modes, and b)
that p-modes exhibit a uniform signature of their dynamic behaviour
throughout the full height range of the chromosphere.
---------------------------------------------------------
Title: Dynamics of the solar atmosphere. VI. Resonant oscillations
of an atmospheric cavity: observations.
Authors: Deubner, F. -L.; Waldschik, T.; Steffens, S.
1996A&A...307..936D Altcode:
We have evaluated new, spatially one- and two-dimensional time series
of photospheric and chromospheric Fraunhofer lines at a large number
of positions in the line profile, with the 'lambdameter' method. As
a result we have obtained the velocity and brightness fluctuations
corresponding to many closely staggered height levels in the atmosphere,
and their respective phase spectra as a diagnostic of the wave fields
involved. This material has not only served to define more accurately
and specifically the character of the 180deg phase jump observed before
in V-I spectra of the NaD_2_ line in internetwork regions, and to reveal
the narrow height interval that gives rise to this discontinuity in
the phase spectra. We have also discovered another discontinuity in
V-V spectra of the same Fraunhofer line at nearly the same frequency
(7.0mHz). Since neither running nor standing waves alone can explain
the observed solitary phase discontinuities, our results provide
strong evidence in favour of an atmosphere that supports (at least,
and probably more than) one eigenmode as a component of the wave field.
---------------------------------------------------------
Title: K-grains as a three-dimensional phenomenon. I. Statistics
and spatial evolution.
Authors: Steffens, S.; Hofmann, J.; Deubner, F. L.
1996A&A...307..288S Altcode:
We present new data concerning the statistics and motion of
chromospheric K-grains, in order to verify possible excitation
mechanisms. We have analysed a time-series of Ca K_2v_ filtergrams
obtained with the VTT at Observatorio del Teide, Tenerife. K-grains are
not only characterised by their brightness but also by their pointlike
appearance and in some cases by a horizontal motion. Our statistical
analysis of the spatial distribution of bright point emission reveals no
significant clustering at particular areas in the internetwork. Some of
the observed grains travel through the chromospheric internetwork cells
with a speed comparable to the phase speed of the solar p-modes. Both
results seem to be inconsistent with a causal relation between Ca K
bright points and magnetic flux tubes, and rather favour a mechanism
related to p-mode interference. Finally we present statistical evidence
showing that bright points do not dominate the emission of the quiet
chromosphere but rather contribute only about 9 percent of the K_2v_
intensity emitted from the internetwork areas in our data.
---------------------------------------------------------
Title: Astronomisches Institut der Universität
Würzburg. Jahresbericht für 1995.
Authors: Deubner, F. -L.
1996MitAG..79..669D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The effect of limited spatial resolution on the observed
power of solar oscillations.
Authors: Hofmann, J.; Deubner, F. -L.
1995A&AS..113..583H Altcode:
We present an analysis of the rms amplitude of p-mode oscillations for
different heights in the solar atmosphere, as a function of spatial
resolution. Two different reduction methods are used to simulate
limited spatial resolution. The dependence on spatial resolution can
be approximated by power laws. We do not find significant differences
between the exponents of the power laws obtained for the various
spectral lines we have analysed. Also, the results of the two reduction
methods differ only by a small amount.
---------------------------------------------------------
Title: Is there a chromospheric mode at 6 mHz?
Authors: Steffens, S.; Deubner, F. -L.; Hofmann, J.; Fleck, B.
1995A&A...302..277S Altcode:
We present time series of Na D_1_ and Ca K_2v_ filtergrams of the
quiet sun obtained simultaneously with the Vacuum Tower Telescope at
Observatorio del Teide, Tenerife. Special interest is taken in the
distribution of power in the Fourier domain. We distinguish power
"on" and "between" the ridges of the p-modes and pseudo p-modes. The
latter are found to extend beyond the acoustic cutoff frequency up to
12mHz in Na D_1_ and 8.5mHz in Ca K_2v_. Most of the power of the broad
chromospheric feature detected in Ca II K by Harvey et al. (???) in the
background of a one-dimensional power spectrum is found preferentially
between the p-mode ridges at about 6mHz, as our two-dimensional analysis
reveals. This behaviour would be consistent with the nature of "avoided
crossing" (Ulrich & Rhodes ???) of a chromospheric mode and the
p-modes. We note that the center frequency of the interridge feature
appears independent of height, whereas the power distribution of the
p-mode ridges extends to higher frequencies as height increases. We
suppose that different mechanisms are responsible for the generation of
these two wave fields. In our investigation the broad band of enhanced
power at 6mHz is even more conspicuous in Na D_1_ than in Ca K_2v_.
---------------------------------------------------------
Title: Phase Analysis of the K-Grain Excitation Pattern
Authors: Hofmann, J.; Deubner, F. –L.; Steffens, S.; Fleck, B.
1995ESASP.376b.493H Altcode: 1995help.confP.493H; 1995soho....2..493H
No abstract at ADS
---------------------------------------------------------
Title: On the Phenomenology of K-Grains
Authors: Steffens, S.; Deubner, F. –L.; Hofmann, J.; Fleck, B.
1995ESASP.376b.487S Altcode: 1995soho....2..487S; 1995help.confP.487S
No abstract at ADS
---------------------------------------------------------
Title: Is There an Atmospheric Mode Near 6 mHz?
Authors: Steffens, S.; Deubner, F. –L.; Hofmann, J.; Fleck, B.
1995ESASP.376b.481S Altcode: 1995soho....2..481S; 1995help.confP.481S
No abstract at ADS
---------------------------------------------------------
Title: Is there an atmospheric mode near 6 mHz?
Authors: Steffens, S.; Deubner, F. -L.; Hofmann, J.; Fleck, B.
1995AGAb...11..138S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: He 10830 Angstrom Confirms Non-Propagation Component of
Chromospheric Oscillations
Authors: Hofmann, J.; Deubner, F. -L.; Fleck, B.
1995ASPC...76..342H Altcode: 1995gong.conf..342H
No abstract at ADS
---------------------------------------------------------
Title: What Have We Learned About Chromospheric Oscillations from
HeI 10830Å?
Authors: Fleck, B.; Deubner, F. -L.; Hofmann, J.
1995itsa.conf..437F Altcode:
Time series of He I 10830 spectra taken simultaneously with spectra
of other chromospheric lines (Ca II 8542 Å and Ca II K) are analyzed
to study wave propagation in the solar chromosphere. Rather than
providing conclusive answers to some of the long standing questions
concerning chromospheric oscillations, the new results derived from
the He 10830 line raise new puzzling questions. The spatio-temporal
wave pattern deduced from the Doppler displacements of the He line
differs significantly from those of the two Ca II lines, while the
phase difference between the Doppler displacements of He 10830 and Ca
K_3 stays close to zero in the whole frequency range observed. This
is difficult to reconcile with the low oscillation amplitude observed
in the He 10830 line (RMS≈1100 m/s), which is less than half the
velocity amplitude derived from the core displacement of Ca K_3. Another
surprising result is that the Ca K “bright point” events are only
barely visible in the Doppler displacement of the He 10830 line.
---------------------------------------------------------
Title: Waves and Oscillations in the Solar Chromosphere
Authors: Deubner, F. -L.
1995ASPC...76..303D Altcode: 1995gong.conf..303D
No abstract at ADS
---------------------------------------------------------
Title: Resonant oscillations of the solar atmospheric cavity.
Authors: Deubner, F. -L.; Waldschik, T.; Steffens, S.
1995AGAb...11..139D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the phenomenology of K-grains.
Authors: Steffens, S.; Deubner, F. -L.; Hofmann, J.; Fleck, B.
1995AGAb...11..140S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Astronomisches Institut der Universität
Würzburg. Jahresbericht für 1994.
Authors: Deubner, F. -L.
1995MitAG..78..587D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the strength of solar intra-network fields.
Authors: Keller, C. U.; Deubner, F. -L.; Egger, U.; Fleck, B.; Povel,
H. P.
1994A&A...286..626K Altcode:
The combination of the German Vacuum Tower Telescope and the prototype
of ZIMPOL I (Zuerich Imaging Stokes Polarimeter I), a novel, very
sensitive imaging polarimeter, has resulted in the first spectra
of solar intra-network (IN) fields in circular polarization. The
sensitivity in terms of flux density is 0.7 Mx/cm^2^. While magnetic
fields in solar spots, pores, plages, and in the network have
predominantly kG field strengths, the magnetic field strength of
the IN flux is a controversial subject due to the absence of direct
measurements. We first summarize the current ideas on IN fields and
examine previous arguments for their field strength. Our measurements
of the magnetic line ratio formed between the amplitudes of the Stokes
V profiles of Fe I 5247.1 A and Fe I 5250.2 A are consistent with a
field strength well below 1 kG. Since the sensitivity of the magnetic
line ratio becomes low for small field strengths, we can only set an
upper limit on the field strength of IN fields of 500 G at the level
of line formation with a probability of 68% and an upper limit of 1
kG with a probability of 95%. We emphasize that these are the first
observations of a magnetic line ratio of unity near disk center.
---------------------------------------------------------
Title: On the correlation of magnetic field strength and inclination
with continuum brightness of a sunspot penumbra.
Authors: Hofmann, J.; Deubner, F. -L.; Fleck, B.; Schmidt, W.
1994A&A...284..269H Altcode:
A fairly regular sunspot penumbra has been observed near disk center
using a Stokes V polarimeter at the German Vacuum-Tower-Telescope in
Izana, Tenerife. We obtained two-dimensional spectral data by scanning
the limbside sector of the penumbra in steps of 1 arcsecond with the
slit oriented parallel to the solar limb. From Stokes V and Stokes I
spectra of four magnetically sensitive lines (FeI5247.1A, CrI5247.6A,
FeI5250.2A, and FeI5250.7A) recorded with 1024 x 1024 pixel CCD
cameras we have determined several magnetic parameters. The results
of a correlation analysis show a clear relation between continuum
brightness and magnetic field inclination, field lines beeing flatter
in the dark penumbral filaments. We also find a correlation between
field strength and brightness; this correlation is not uniform across
the penumbra, however.
---------------------------------------------------------
Title: Non-linearities of chromospheric oscillations
Authors: Deubner, F. -L.; Hofmann, J.; Kossack, E.; Fleck, B.
1994ASIC..433..155D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of Low Wavenumber Nonradial Eigenmodes of the Sun
Authors: Deubner, F. -L.
1994snft.book..402D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of Solar Oscillations in He 110830 Angstrom
Authors: Fleck, B.; Deubner, F. -L.; Maier, D.; Schmidt, W.
1994IAUS..154...65F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Wave propagation in the solar chromosphere: some new results
from CaII K, CaII 8542 and HeI 10830 observations
Authors: Fleck, B.; Deubner, F. -L.; Hofmann, J.; Steffens, S.
1994chdy.conf..103F Altcode:
Time series of spectra taken simultaneously in the three chromospheric
lines Ca II 8542 A, Ca II K, and He I 10830 AA are analyzed to study
the wave propagation behaviour in the solar chromosphere. The V-V
phase difference between the three chromospheric lines stays close to
0 deg in the whole frequency range observed and thus confirms previous
observations of a non-propagating component dominating the acoustic
wave spectrum in the solar chromosphere. In particular, the dominant
3-min oscillations observed in the core displacement of the Ca II
8542 and Ca K line are highly correlated, contrary to the numerical
NLTE radiating shock dynamic simulations of Carlsson and Stein (1993)
which revealed a significant phase delay between the two lines. The
oscillation amplitude observed in the He 10830 line (RMS ~ 1100 m/s)
is only about half the velocity amplitude derived from the core
displacement of Ca K3. We also present a first He 10830 k-omega diagram.
---------------------------------------------------------
Title: Ground — based instrumentation
Authors: Deubner, Franz Ludwig
1994LNP...432..285D Altcode: 1994LNPM...11..287D; 1994LNP...432..285L
In parallel with the development and deployment of solar space
instrumentation a substantial effort is being made at many ground
based observatories world-wide, not only to make better use of the
available hours of sunshine, but also to reach out to new frontiers of
solar research. Examples of novel instrumentation will be described,
and some of the observational results will be discussed in the light
of current problems in solar physics.
---------------------------------------------------------
Title: Line profile asymmetries in a sunspot penumbra
Authors: Hofmann, J.; Deubner, F. -L.; Fleck, B.
1994smf..conf..182H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Ground - based instrumentation.
Authors: Deubner, F. -L.
1994LNP...432..287D Altcode:
In parallel with the development and deployment of solar space
instrumentation a substantial effort is being made at many ground
based observatories world-wide, not only to make better use of the
available hours of sunshine, but also to reach out to new frontiers
of solar research. Examples of novel instrumentation are described,
and some of the observational results are discussed in the light of
current problems in solar physics.
---------------------------------------------------------
Title: Institut für Astronomie und Astrophysik der Universität
Würzburg. Jahresbericht für 1993.
Authors: Deubner, F. -L.
1994MitAG..77..505D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Phases and amplitudes of acoustic-gravity waves. 2: The
effects of reflection
Authors: Marmolino, C.; Severino, G.; Deubner, F. -L.; Fleck, B.
1993A&A...278..617M Altcode:
We study wave reflection caused by the temperature stratification
of the solar atmosphere, assumed to be a succession of two layers
of different temperatures and radiative decay times. Considering
waves which propagate energy upward in the atmosphere, we compute
the complex amplitude reflection and transmission coefficients and
investigate the effects that reflection introduces on the phases of
acoustic-gravity waves. In the evanescent region of the k<SUB>x</SUB>
- omega diagram, between the Lamb waves and the acoustic cut-off
frequency, the reflection coefficient is small, in particular zero on
the fundamental mode. Therefore, in this region, the reflected wave
has a small amplitude and its superposition to the incident wave does
not affect the latter in a significant way. In particular, the T - V
phase differences of the total wave are very similar to those of the
incident wave. Furthermore, a heruisitic formula is presented which
describes the observed coexistence of two different phase regimes
between velocity and intensity oscillations in the evanescent area
above the fundamental mode.
---------------------------------------------------------
Title: Polanmetric Measurements of the Fine Structure of a Sunspot
Penumbra
Authors: Hofmann, J.; Deubner, F. L.; Fleck, B.
1993ASPC...46...44H Altcode: 1993mvfs.conf...44H; 1993IAUCo.141...44H
No abstract at ADS
---------------------------------------------------------
Title: Observations of Waves and Oscillations in the Solar Magnetic
Fine Structure
Authors: Fleck, B.; Deubner, F. -L.; Schmidt, W.
1993ASPC...46..522F Altcode: 1993IAUCo.141..522F; 1993mvfs.conf..522F
No abstract at ADS
---------------------------------------------------------
Title: Institut für Astronomie und Astrophysik der Universität
Würzburg.
Authors: Deubner, F. -L.
1993MitAG..76..449D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Dynamics of the solar atmosphere. V - Partial reflection and
forced oscillation, and their signature in phase diagrams
Authors: Deubner, F. -L.; Fleck, B.; Schmitz, F.; Straus, Th.
1992A&A...266..560D Altcode:
An overview of several new dynamic phenomena detected by means of
velocity-brightness (V-I) and V-V phase diagrams is presented. The great
diagnostic value of this kind of data analysis is demonstrated and used
in order to develop a consistent description and interpretation of the
surprisingly broad spectrum of linear hydrodynamic wave motions that
occur in a stellar atmosphere. The significance of partial reflection
and the role of forced oscillations in practically all layers of the
solar atmosphere are demonstrated. With reference to the concept of
continuous partial reflection, a model of the 'background' of coherent
wave motions found at frequencies and wavenumbers in between the
well-known p-mode ridges is presented.
---------------------------------------------------------
Title: Is mesogranulation a distinct regime of convection?
Authors: Straus, Th.; Deubner, F. -L.; Fleck, B.
1992A&A...256..652S Altcode:
We investigate the dynamics of the mesogranulation phenomenon by
analyzing spatially 2D spectral time series taken at disk center
and cos Theta = 0.8. After a 3D Fourier transformation, we integrate
the power and crosspower spectra in azimuth, and calculate k - omega
power, phase difference, and cross-power spectra. The spatial power
spectra are compared with those obtained from numerical simulations of
stationary cell patterns. In the deepest atmospheric layers the V - I
phase difference spectra reveal a uniform regime of convective motions
at frequencies below the Lamb mode. The power spectra exhibit at all
levels a significant distinction between supergranulation and convective
patterns of smaller scales. On the other hand, the 'mesogranulation'
phenomenon cannot be identified as an independent convective regime
in the deep photosphere, distinct from granulation. Rather, the
mesostructures that appear to emerge in the middle photosphere and
temperature minimum seem to be a product of the overshoot driving only
the largest elements of an extended distribution of granular sizes
while the smaller elements have already died out at a lower level.
---------------------------------------------------------
Title: Polarimetric measurements of the fine structure of a sunspot
penumbra.
Authors: Hofmann, J.; Deubner, F. -L.; Fleck, B.; Schmidt, W.
1992AGAb....7..149H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: An analysis of non-linear oscillations in the solar
chromosphere.
Authors: Kossack, E.; Deubner, F. -L.; Fleck, B.
1992AGAb....7..148K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Institut für Astronomie and Astrophysik, Lehrstuhl
Astronomie. Jahresbericht für 1991.
Authors: Deubner, F. -L.
1992MitAG..75..405D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of Waves and Oscillations in Solar Magnetic
Fluxtube Concentrations (With 1 Figure)
Authors: Fleck, B.; Deubner, F. -L.
1991mcch.conf...19F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Oscillation observations.
Authors: Hill, Frank; Deubner, Franz-Ludwig; Isaak, George
1991sia..book..329H Altcode:
This chapter reviews recent observations of solar oscillations. The
oscillations discussed are global and local 5-min p-modes, the 160-min
oscillation and oscillations in the solar atmosphere. Experimental
and data reduction methods are described. Summaries of recent results
are provided, including measurements of frequencies, amplitudes, line
widths and splittings. Other topics include active-region tomography,
solar cycle changes, the chromospheric cavity and diameter measurements.
---------------------------------------------------------
Title: Observations of Waves and Oscillations (With 2 Figures)
Authors: Deubner, F. -L.
1991mcch.conf....6D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Institut für Astronomie und Astrophysik, Lehrstuhl
Astronomie. Jahresbericht für 1990.
Authors: Deubner, F. -L.
1991MitAG..74..379D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of solar oscillations
Authors: Deubner, Franz-Ludwig
1991GApFD..62..153D Altcode:
The most recent observational activities and results in the field
of solar oscillations are reviewed. We address the dynamics and
structure of the solar interior and of the atmosphere up to the
transition layer, while global, local and atmospheric oscillations
are being discussed. The topics of this review include: line width and
amplitude limits of the p-modes; cycle variations of frequencies and
amplitudes; internal solar rotation rate; p-mode absorption in spots
and antipodal focussing of p-modes; diagnostics in the UV and in the
IR; phase diagnostics in the atmosphere; chromospheric bright points.
---------------------------------------------------------
Title: Dynamics of the solar atmosphere. IV - Evanescent waves of
small amplitude
Authors: Deubner, F. -L.; Fleck, B.; Marmolino, C.; Severino, G.
1990A&A...236..509D Altcode:
The phase spectra of velocity and brightness perturbations in the quiet
photosphere have been studied in the evanescent domain of the k-omega
diagram. A regime of low-amplitude evanescent motions, occupying a
large sector of the diagnostic diagram bordered by the Lamb and the
fundamental mode, has been discovered. This regime forms a continuum
in the k-omega plane, in contrast to the 5-min oscillations. Beyond the
fundamental mode, it extends to much higher frequencies in between the
power ridges of the resonant p-modes. It is suggested that the observed
V-I phase is characteristic of evanescent waves, whose progressive
part carries energy downward, and that a continuum of such waves is
produced through scattering of ordinary resonant p-modes at higher
levels in the atmosphere.
---------------------------------------------------------
Title: Dynamics of the solar atmosphere. III - Cell-network
distinctions of chromospheric oscillations
Authors: Deubner, F. -L.; Fleck, B.
1990A&A...228..506D Altcode:
The propagation of waves in the chromosphere is analyzed, with
focus placed on the differences between the bright boundaries of the
chromospheric network and the dark cell interior. The logarithmic
velocity and intensity power spectra of Ca 8542 and Ca 8498 are
presented, along with the velocity fluctuations of Ca 8542 at a
spatially resolved point in a cell center. Attention is focused
on the phase difference and coherence spectra between the velocity
fluctuations of Ca 8542 and Ca 8498 and Ca 8542 and the photospheric
Fe 8496 line, as well as on the V - I phase and coherence spectra of
the Ca lines. Significant differences in both power and phase spectra
are found in the main power range from 3 to 6 mHz and also at low
frequencies below 3 mHz and in the high-frequency range up to at least
10 mHz. It is shown that the evanescent waves are influenced by the
magnetic field in the cell boundaries.
---------------------------------------------------------
Title: k-ω diagrams of the solar atmosphere revisited.
Authors: Deubner, F. -L.; Fleck, B.; Schmitz, F.; Straus, T.
1990AGAb....5...35D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Waves and Oscillations in the Non-Magnetic Photosphere
Authors: Deubner, F. -L.
1990IAUS..138..217D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Dynamics of mesogranulation.
Authors: Straus, T.; Deubner, F. -L.
1990AGAb....5...34S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Institut für Astronomie und Astrophysik, Lehrstuhl Astronomie.
Authors: Deubner, F. -L.
1990MitAG..73..325D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Comments on Solar Convection
Authors: Deubner, Franz-L.
1990ASSL..159..117D Altcode: 1990insu.conf..117D; 1990IAUCo.121..117D
No abstract at ADS
---------------------------------------------------------
Title: Observations of waves and oscillations in solar fluxtube
concentrations.
Authors: Fleck, B.; Deubner, F. -L.
1990PDHO....7..306F Altcode:
The authors investigate the dynamical behaviour of magnetic fluxtubes
concentrations by analyzing a high spatial resolution time series of
spectra taken simultaneously in left-hand and right-hand circularly
polarized light. All parameters extracted from the Stokes V and Stokes
I profiles reveal significant spatio-temporal variations.
---------------------------------------------------------
Title: Dynamics of the solar atmosphere. II - Standing waves in the
solar chromosphere
Authors: Fleck, B.; Deubner, F. -L.
1989A&A...224..245F Altcode:
A time series of brightness and velocity fluctuations measured
simultaneously in three Fraunhofer lines (Ca II 8542, Ca II 8498, Fe I
8496) is analyzed to investigate the oscillatory behavior of the solar
chromosphere. The propagation characteristics of waves in the average
chromosphere are examined. Apart from nonpropagating oscillations near
6 mHz, the results strongly suggest the existence of a standing wave
pattern for the whole continuum of acoustic waves with frequencies
beyond the acoustic cut-off frequency.
---------------------------------------------------------
Title: Mesogranulation - a convective phenomenon
Authors: Deubner, F. L.
1989hsrs.conf..489D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Gravity waves
Authors: Deubner, F. L.; Fleck, B.
1989hsrs.conf..339D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Mesogranulation - A convective phenomenon
Authors: Deubner, Franz-Ludwig
1989A&A...216..259D Altcode:
The dynamic behavior of mesogranulation at photospheric layers is
investigated. A distinct regime of coherent velocity and brightness
fluctuations is noted in the 4.5-10-arcsec range of spatial scales. The
observed phases are consistent with those that are expected for
hydrodynamic flows near the bottom of a stably stratified atmosphere. A
smooth transition of phases is noted between the granular and the
meso regime. The ratio of horizontal/radial flow velocity is shown
to gradually increase with the element size over the whole range,
suggesting that the mesogranules are convective in nature.
---------------------------------------------------------
Title: Dynamics of the solar atmosphere. I - Spatio-temporal analysis
of waves in the quiet solar atmosphere
Authors: Deubner, F. -L.; Fleck, B.
1989A&A...213..423D Altcode:
A time series of simultaneously measured velocity (V) and intensity
(I) fluctuations of different spectral lines formed in the photosphere
and low chromosphere is analyzed. In order to separate the different
patterns of motions, V-V and V-I phase difference spectra have been
computed not only with respect to frequency but also to the horizontal
wavenumber. The V-V phase difference spectra of the Na D1 line and two
photospheric Fe I lines clearly show the existence of gravity waves in
the solar atmosphere. The V-I phase spectra also exhibit the behavior
of gravity waves at high wavenumbers. At low wavenumbers one finds
positive V-I phase differences. This is taken as an indication for
convective motions with a typical spatial scale of more than 5 arcsec
(mesogranulation).
---------------------------------------------------------
Title: Spatio-Temporal Analysis of Waves in the Solar Atmosphere
Authors: Deubner, F. -L.; Fleck, B.
1989ASIC..263..325D Altcode: 1989ssg..conf..325D
No abstract at ADS
---------------------------------------------------------
Title: Institut für Astronomie und Astrophysik, Lehrstuhl
Astronomie. Jahresbericht für 1988.
Authors: Deubner, F. -L.
1989MitAG..72..309D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Granulation and Waves?
Authors: Deubner, F. -L.
1989ASIC..263..195D Altcode: 1989ssg..conf..195D
No abstract at ADS
---------------------------------------------------------
Title: GOLF: Global Oscillations at Low Frequencies for the SOHO
mission
Authors: Gabriel, A. H.; Bocchia, R.; Bonnet, R. M.; Cesarsky, C.;
Christensen-Dalsgaard, J.; Dame, L.; Delache, Ph.; Deubner, F. L.;
Foing, B.; Fossat, E.
1988sohi.rept...13G Altcode:
The GOLF (global oscillations at low frequencies) SOHO (solar
heliospheric observatory) mission is described. It aims to study
the internal structure of the Sun by measuring the spectrum of free
global oscillations. GOLF will measure both p and g mode oscillations,
with emphasis on low order long period waves which penetrate the
solar core. The instrument aims to measure frequencies between 10-7
and 6 10-3 Hz, with a sensitivity of 1 mm/s. The method involves an
extension to space of the ground based technique for measuring the mean
line-of-sight velocity of the solar surface. A sodium vapor resonance
scattering filter is used in a longitudinal magnetic field to sample the
two wings of the solar absorption line. The use of a modulating magnetic
field provides a continuous internal calibration of the sensitivity. By
adding an additional rotating polarizer, measurements are also made
of the average solar magnetic field. Efforts are made to correct the
data for the spurious effects caused by solar magnetic active regions.
---------------------------------------------------------
Title: Has turbulent granular decay been observed?
Authors: Deubner, F. -L.
1988A&A...204..301D Altcode:
Spatial wavenumber spectra of velocity and brightness fluctuations in
solar photospheric spectral lines have been studied with particular
attention to the range of spatial scales from 1arcsec.5 to 0arcsec.8,
where the coherence of the spectra drops significantly. The author
has found good coherence of brightness and outward velocity in the
low photosphere to k-values of at least 8 Mm<SUP>-1</SUP>. At higher
wavenumbers, the fluctuations are still correlated and an evidence of
turbulent motions is not seen. Loss of coherence at high wavenumbers
is likely to be caused by internal gravity waves.
---------------------------------------------------------
Title: Observations of Solar Oscillations
Authors: Deubner, Franz-Ludwig
1988ASSL..148..163D Altcode: 1988pmls.conf..163D
Recent progress in the field of helioseismology is reviewed. New
results from observations of the global p-mode spectrum and some of
their theoretical implications are considered as well as atmospheric
eigenmodes and running waves in the visible part of the solar
atmosphere.
---------------------------------------------------------
Title: On the Energy of Shortperiod Acoustic Waves in the Solar
Atmosphere
Authors: Deubner, F. L.; Reichling, M.; Langhanki, R.
1988IAUS..123..439D Altcode:
The apparent Doppler shift amplitudes measured in the cross power
spectra are compared with those of synthetic solar line profiles to
yield estimates of the energy carried by short period waves at various
photospheric/chromospheric levels.
---------------------------------------------------------
Title: Erfordernisse und Möglichkeiten zeitlicher Auflösung
Authors: Deubner, F. -L.
1987MitAG..68..166D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Raum-zeitliche Analyse hydrodynamischer Wellenfelder in der
Sonnenatmosphäre
Authors: Deubner, F. -L.; Fleck, B.
1987MitAG..70..326D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of gravity waves in the solar atmosphere
Authors: Deubner, F. -L.
1986ASIC..169...81D Altcode: 1986ssds.proc...81D
No abstract at ADS
---------------------------------------------------------
Title: Is there an anisotropy of p-modes?
Authors: Deubner, F. -L.
1986ASIC..169...83D Altcode: 1986ssds.proc...83D
No abstract at ADS
---------------------------------------------------------
Title: Detection of Magneto-Gravity Waves in the Chromosphere
Authors: Deubner, F. L.
1985tphr.conf..160D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Oscillations as a diagnostic of chromospheric structure.
Authors: Deubner, F. -L.
1985cdm..proc..279D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Detection of magneto-gravity waves in the chromosphere.
Authors: Deubner, F. -L.
1985MPARp.212..160D Altcode:
It has been shown that the brightness of the chromospheric network is
correlated to the local power of velocity and brightness oscillations
with periods longer than about 400 s, as measured in chromospheric
lines (Ca II, H, K or IR triplet). This correlation does not hold if
the oscillations are measured at a lower photospheric level.
---------------------------------------------------------
Title: Phase-spectra of solar oscillations
Authors: Staiger, J.; Mattig, W.; Schmieder, B.; Deubner, F. -L.
1984MmSAI..55..147S Altcode:
Diode array measurements of intensity- and velocity-oscillations
were made at the coude-telescope of Capri. From these observations
phase-spectra were calculated to identify different types of waves
within the solar atmosphere. The results indicate the existence of
atmospheric gravity modes in the frequency-range below 2.5 mHz. No
running acoustic waves were found in the photosphere for frequencies
beyond 7.5 mHz. Vertical propagation seems only to take place for
frequencies between 5 mHz and 7.5 mHz. No vertical propagation at
all was found in the upper chromosphere. This seems to be due to the
occurrence of wave reflection at the chromosphere-corona interface.
---------------------------------------------------------
Title: Phase relations of high degree modes revisited
Authors: Deubner, F. -L.; Endler, F.; Staiger, J.
1984MmSAI..55..135D Altcode:
Preliminary results of spectral analyses revealing short-period
oscillations of the solar atmosphere are reported. The numerical
techniques developed by Endler and Deubner (1983) to compensate for
the strongly nonrandom noise signal due to seeing effects in the phase
spectra of various Fraunhofer lines are summarized, and synthetic phase
spectra are presented and compared with observations. The signatures of
running and standing waves at frequencies above 8 mHz are detected, with
standing waves most evident in the highest atmospheric layers. Rough
estimates based on a simplified model give height difference of about
800 km between the sites of the Mg I 5173-A line and the Fe I 5383-A
line and about 3150 km between the site of the Na D(1) line and the
reflecting layer. It is inferred that the horizontal magnetic field
in this region is too disperse or too weak to affect the short-period
acoustic waves.
---------------------------------------------------------
Title: Helioseismology: Oscillations as a Diagnostic of the Solar
Interior
Authors: Deubner, Franz-Ludwig; Gough, Douglas
1984ARA&A..22..593D Altcode:
Contents: (1) Introduction. (2) Resonant cavities in the
Sun. (3) Observational methods. (4) High-degree modes: Solar
structure. Subphotospheric velocities. (5) Low-degree modes: High-order
p modes. Gravity modes. Solar structure. (6) Five-minute modes of
intermediate degree. (7) Limb observations. (8) Problems for the
immediate future. Appendix: Classification of stellar oscillations.
---------------------------------------------------------
Title: Powerspectra of Short-Period Oscillations
Authors: Deubner, F. -L.
1984ssdp.conf...14D Altcode:
As a result of the discussion of various hypotheses brought forward
to explain the existence of persistent subsidiary peaks in the high
frequency slope of the p-mode oscillations power spectra of the sun,
the author finds that all of them appear inadequate to account for
the properties of the spectra established so far.
---------------------------------------------------------
Title: On the Phase Relations of High Degree p-Modes (Keynote Talk)
Authors: Deubner, F. -L.
1984ssdp.conf....2D Altcode:
One of the long-standing problems in solar physics has been the
interpretation of phase spectra of velocity and intensity fluctuations
in the range of frequencies higher than about 5 mHz. Neither running
nor standing waves have clearly and consistently been identified. In
the last couple of years, however, considerable progress has been made
in this field on which the author focuses his presentation.
---------------------------------------------------------
Title: The detection limits in ground based measurements of stellar
microvariability.
Authors: Deubner, F. -L.; Isserstedt, J.
1983A&A...126..216D Altcode:
With photoelectric photometry in the VBLUW system the authors have
tried to detect short period brightness fluctuations in solar-like
stars. Although the result of this experiment is negative, the
r.m.s. noise level per frequency band of ca. 2.5×10<SUP>-5</SUP> mag
in the data appears low enough to encourage the ground-based search
for low-1 p-mode oscillations in F-type main sequence stars.
---------------------------------------------------------
Title: The influence of seeing on the observation of short period
fluctuations in the solar atmosphere
Authors: Endler, F.; Deubner, F. -L.
1983A&A...121..291E Altcode:
It is noted that the possibility exists for removing the effects of
seeing on the phase spectra from simultaneous observations of velocity
and intensity fluctuations in different photospheric and chromospheric
spectral lines, since seeing events in simultaneous data sets appear at
the same time with a preferred correlation. Image motion produces the
preferential contamination of the data at those solar disk locations
where solar signal spatial gradients are large. At periods larger than
40 sec, the corrected power spectra and phase spectra generally show
signals with significant coherence.
---------------------------------------------------------
Title: Short-Period Oscillations
Authors: Deubner, F. -L.; Laufer, J.
1983SoPh...82..151D Altcode: 1983IAUCo..66..151D
Short period oscillations (with periods less than 150 s) are shown to
be non-uniformly distributed on the solar surface, and in time. Rather,
they appear concentrated in short bursts which preferentially occur
in regions with strong instantaneous downflow motion throughout the
observed extent of the solar atmosphere.
---------------------------------------------------------
Title: Phasenspektren von kurzperiodischen solaren Oszillationen
Authors: Deubner, F. -L.; Endler, F.
1983MitAG..60..221D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Helioseismology with High Degree P-Modes
Authors: Deubner, F. -L.
1983SoPh...82..103D Altcode: 1983IAUCo..66..103D
The value of p-modes of high degree l as a diagnostic for the structure
and dynamics of the solar envelope is reviewed.
---------------------------------------------------------
Title: Spectral line transfer effects in Lambdameter measurements
of solar short-period oscillations
Authors: Deubner, F. -L.; Durrant, C. J.; Kaltenbacher, J.
1982A&A...114...85D Altcode:
Lambdameter records with different exit-slit settings yield power
spectra of short period oscillations in the solar atmosphere, observed
in the Na D(1) line and medium strong Fe I line, whose structure
is notably stable with regard to slit geometry changes. By means of
short period wavetrain numerical modeling, it is demonstrated that
while such a structure in the power spectra of photospheric lines
is absent for rms wave amplitudes lower than about 0.1 km/sec, it
emerges with higher amplitudes as a consequence of nonlinearities in
the line transfer process. It is emphasized that the nonlinear effect
presently investigated must also be considered in stronger chromospheric
lines. Linear correction factors cannot be applied to the observed power
in order to deduce the energy flux carried by the acoustic waves if
nonlinear effects are the only source of the observed spectral pattern.
---------------------------------------------------------
Title: On the magnitude and the height dependence of the granular
vertical flow velocity
Authors: Baessgen, M.; Deubner, F. -L.
1982A&A...111L...1B Altcode:
Granular velocities determined from excellent quality solar spectra
in two spectral lines are corrected for instrumental and atmospheric
image degrading effects by the application of a modulation transfer
function derived from the same material by comparing the observed
brightness fluctuation spectra with various true spectra from
the literature. k-omega spectra are used to separate granular and
oscillatory fluctuations. The results favor a rather flat gradient
with photospheric (C I 5380 line) rms granular velocities of at least
1.0 km/sec
---------------------------------------------------------
Title: Institut für Astronomie und Astrophysik, Lehrstuhl
Astronomie. Jahresbericht für 1981.
Authors: Deubner, F. -L.
1982MitAG..56..323D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Pulsations and oscillations.
Authors: Deubner, F. L.
1981NASSP.450...65D Altcode: 1981suas.nasa...65D
The observations of the oscillations of the solar atmosphere
are a powerful diagnostic tool for research into the structure
of the atmosphere from inside the convection zone to the upper
chromosphere. Interpretations of the global pulsations or oscillations
are presented with emphasis on using these observations to study the
structure of the interior of the Sun.
---------------------------------------------------------
Title: Solar granulation study in partial eclipse conditions using
speckle interferometric techniques
Authors: Ricort, G.; Aime, C.; Deubner, F.; Mattig, W.
1981A&A....97..114R Altcode:
During the partial eclipse of April 29, 1976, photoelectric
speckle-interferometric measurements of solar granulation were obtained
using the 35 cm domeless coudé refractor of the Kiepenheuer Institute,
operated at the Anacapri Island observatory. <P />A radial cut of
the two-dimensional power spectrum of the intensity distribution was
calculated and the empirical modulation transfer function (M.T.F.),
determined from the lunar limb profile, was used for correcting the
data. This experimental M.T.F. which contains the combined effects
of instrumental diffraction and atmospheric seeing is found to be
in very good agreement with Korff's theoretical model computed for
a Fried parameter r0 equal to 2.3 cm. <P />The corrected intensity
fluctuation (ΔI)r.m.s.= 16.5% for λ=5300 A. The maximum power is
found to be split into two components located respectively at 0.2 and
0.4 cycles per arc second. The shape of the power spectrum confirms
the fall in energy towards very low spatial frequencies, whereas the
poor precision obtained in the high frequency range cannot permit an
exponential decrease of the solar granulation power spectrum to be
confirmed or refuted.
---------------------------------------------------------
Title: Detection of low order p-modes in brightness fluctuations of
the Sun
Authors: Deubner, F. -L.
1981Natur.290..682D Altcode:
The discovery of radial and non-radial global oscillations of the Sun
through various types of detector systems has opened the field of solar
seismology. Of particular importance for studies of the deep interior of
stars are the detection and analysis of low harmonic order pulsations
such as the low order p-modes recently found on the Sun<SUP>1,2</SUP>
by line shift measurements. These pulsations have now also been detected
in the solar brightness fluctuations. Through the reflected light of
Uranus and Neptune the Sun was observed as though it were a distant
star. The positive results suggest that broad-band photometry has the
greatest potential for developing seismometry of main sequence stars.
---------------------------------------------------------
Title: Institut für Astronomie und Astrophysik, Lehrstuhl
Astronomie. Jahresbericht für 1980.
Authors: Deubner, F. -L.
1981MitAG..53..295D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Das Innere der Sterne bloßlegen.
Authors: Deubner, F. -L.
1981S&W....20....7D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Global oscillations of the sun.
Authors: Deubner, F. -L.
1980HiA.....5...75D Altcode:
A review is made of the progress achieved and the problems encountered
over the past three years in studies of solar global oscillations
and their interpretation with respect to the structure of the solar
interior. Topics covered include disk observations, measurements at
the limb, sources of signals other than global modes of oscillation,
and the coherence of p-modes on the disk.
---------------------------------------------------------
Title: Institut für Astronomie und Astrophysik, Lehrstuhl
Astronomie. Jahresbericht für 1979.
Authors: Deubner, F. -L.
1980MitAG..49..289D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of the hydrodynamic wave mode spectrum of the sun.
Authors: Deubner, F. -L.
1980vasg.meet...A2D Altcode: 1980vasg.meetQ....D
The spectrum of periods of hydrodynamic oscillations and waves in
the sun ranges from seconds to several hours. Although the p-mode
character of the 5-min oscillation has been established, there is still
considerable debate as to the significance and solar origin of signals
observed in the outer ranges of the spectrum. Recent developments in
studies of longer period oscillations observed at the solar limb or in
the integrated light of the disk are discussed. Improved resolution
and identification of low order solar p-modes has made it possible
to perform radial differential rotation measurements. Fluctuations
observed spectroscopically in the outer layers of the solar atmosphere
are less regular, and their energy flux appears insufficient for upper
chromospheric and coronal heating.
---------------------------------------------------------
Title: On the center to limb variation of the granular brightness
fluctuations.
Authors: Schmidt, W.; Deubner, F. -L.; Mattig, W.; Mehltretter, J. P.
1979A&A....75..223S Altcode:
The center to limb variation of the granular brightness contrast
was studied on the basis of slit-jaw photographs obtained with the
balloon-borne Spektro-Stratoskop telescope, flown at an altitude of
about 28 km on May 17, 1975 and during the partial solar eclipse of
April 26, 1976 on Tenerife. Positions concentrate at cosine theta
values of about 1, 0.6 and 0.2. The granular contrast was found to
decrease monotonically towards the solar limb, with the magnitude of
contrast about three times smaller at cosine theta 2 than at the disk
center. The relative center to limb variation was found to be 10.4%
(eclipse observations by a 40 cm evacuated Newtonian reflector at 422
nm) and 8.6% (Spektro-Stratoskop observations at 556 nm). Discrepancies
between these results and those reported by Deubner and Mattig (1975)
are thought to be due to corrections for photographic noise and other
factors.
---------------------------------------------------------
Title: Solar p-mode oscillations as a tracer of radial differential
rotation.
Authors: Deubner, F. -L.; Ulrich, R. K.; Rhodes, E. J., Jr.
1979A&A....72..177D Altcode:
Photoelectric observations of solar p-modes obtained with improved
wavenumber and frequency resolution are presented. The observations
are compared with model calculations of the p-modes, and the degree
of spatial and temporal coherence of the observed wave pattern is
investigated. It is found that the p-mode oscillations pervade the
visible surface of the sun with a high degree of coherence in space
and time, so that the whole complex pattern of standing waves with
its nodes and antinodes can be regarded as a fixed pattern corotating
with the solar surface layers. The p-modes are introduced as a tracer
of solar rotational flow velocities. The equatorial differential
rotation is estimated as a function of effective depth on the basis
of the theoretical contribution functions for the p-modes recently
derived by Ulrich et al. (1978). The results strongly indicate that
the angular speed of rotation is not uniform even in the relatively
shallow layer extending about 20,000 km below the photosphere.
---------------------------------------------------------
Title: A new technique for measuring solar rotation.
Authors: Rhodes, E. J., Jr.; Deubner, F. -L.; Ulrich, R. K.
1979ApJ...227..629R Altcode:
A new technique for measuring solar photospheric and subphotospheric
rotation rates is described. The technique utilizes the
standing-wave nature of the nonradial p-mode oscillations of the
whole sun. Specifically, the technique is based upon the observed
concentration of p-mode oscillatory power into well defined ridges in
two-dimensional wavenumber-frequency power spectra. The frequencies
of the ridges in the eastward- and westward-traveling portions of an
individual spectrum are systematically shifted in opposite directions
by a drift of the standing-wave pattern across the observing field
of view. The magnitudes of these frequency shifts are related to the
drift velocity and to the horizontal wavenumber in such a way that
measurement of the observed frequency shifts in a spectrum yields the
drift velocity for that observing run. By guiding on the solar limbs
and observing the velocity field at disk center, the observed drift
velocity obtained in this way is exactly the rotational velocity of
the solar p-mode pattern, and of the solar gas itself.
---------------------------------------------------------
Title: The effect of a radial rotational velocity gradient on p-mode
eigenfrequencies.
Authors: Ulrich, R. K.; Rhodes, E. J., Jr.; Deubner, F. -L.
1979ApJ...227..638U Altcode:
The splitting of p-mode eigenfrequencies due to a depth-dependent solar
rotation rate is considered. It is shown that to a first approximation
this splitting can be treated as resulting from the translation of
the wave pattern across the field of view with a velocity equal the
actual velocity at a depth called the effective depth. The effective
depths for a model solar envelope with l/H = 3 are presented as a
function of position on the (kh, omega)-plane. The combination of
omega near 0.025/s and kh near 0 yields the deepest probe of the solar
envelope. For this same combination of kh and omega it is possible
to resolve individual groups of eigenmodes in frequency but not in
spatial wavenumber. Achievement of this resolution observationally
may permit a determination of the lifetime of these particular modes.
---------------------------------------------------------
Title: Die Mitte-Rand-Variation des granularen Intensitätskontrastes
Authors: Schmidt, W.; Deubner, F. L.; Mattig, W.; Mehltretter, J. P.
1979MitAG..45..148S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Velocity fields in the solar atmosphere /Observations/
Authors: Deubner, F. L.
1977MmSAI..48..499D Altcode:
In the present paper, oscillatory and quasi-oscillatory motions observed
in the photosphere and lower chromosphere are discussed along with
convective motions on different horizontal scales. The discussion
covers global oscillatory modes with predominantly radial harmonic
motions and a coherent wave pattern across the entire solar surface,
implying global excitation; oscillatory modes with large coherent wave
systems, not necessarily globally excited (five minute oscillations);
locally excited short period waves (excited by the Lighthill mechanism,
no trapping, rapid dissipation); and nonoscillatory velocity (and
brightness) fluctuations, related to convective motions.
---------------------------------------------------------
Title: Is the Sun a Short Period Variable?
Authors: Deubner, F. -L.
1977A&A....57..317D Altcode:
SUMMARY Variations of the solar diameter and fluctuations of
the average surface velocity of the solar disc as observed by
various authors suggest the existence of low amplitude global solar
pulsations. Independent assessment of the order of magnitude and,
maybe, of the reality of these effects was attempted, monitoring
the solar luminosity by dual channel photometric observations of the
planets Uranus and Neptune. on the basis of a power spectrum analysis we
conclude that for periods shorter than 3 hours there is no luminosity
fluctuation detectable with amplitudes larger than 6 lO- rms per
independent frequency interval. Key wor : Solar global pulsations,
Luminosity fluctuations
---------------------------------------------------------
Title: INVITED PAPER - The Global Structure of the 5-min Oscillations
and its Implication for Differential Rotation.
Authors: Deubner, F. -L.
1977BAAS....9..374D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The global structure of the 5-min oscillations and its
implication for differential rotation.
Authors: Deubner, F. -L.
1977BAAS....9..375D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The small scale structure of solar magnetic fields. Joint
discussion at the XVIth General Assembly of the I.A.U., Grenoble,
1976.
Authors: Deubner, F. L.; Schmidt, H. U.
1977HiA.....4B.219D Altcode: 1977HiA.....4..219D
No abstract at ADS
---------------------------------------------------------
Title: Dynamics of the Solar Atmosphere. Review of Current
Observational Investigations in the Visible
Authors: Deubner, F.
1977ebhs.coll...45D Altcode: 1977IAUCo..36...45D
No abstract at ADS
---------------------------------------------------------
Title: The small scale structure of solar magnetic fields. Joint
discussion at the XVIth General Assembly of the I.A.U., Grenoble,
1976.
Authors: Deubner, F. L.; Schmidt, H. U.
1977ssss.conf.....D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar p-Mode Oscillations as a Tracer of Large-Scale Horizontal
Motions
Authors: Deubner, F. -L.
1977lsms.proc...77D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of short period acoustic waves bearing on the
interpretation of "microturbulence".
Authors: Deubner, F. -L.
1976A&A....51..189D Altcode:
Observational material and methods of analysis used to investigate
the detectability of short period waves in the solar atmosphere are
reviewed. The chief evidence for the presence of an acoustical wave
field is supplied by the power spectra of velocity fluctuations derived
from high spatial resolution solar spectra. The striking feature of
these spectra is that the kinetic power at higher frequencies does not
decrease monotonically, but rather cascades over a series of nearly
equidistant intermediate maxima and minima, which can be explained
in terms of a homogeneous layer of finite thickness where the line
contribution function is constant, but zero elsewhere. Calculations
based on this model show that the resulting short-period waves can
quantitatively account for the effects of nonthermal broadening.
---------------------------------------------------------
Title: Photospheric magnetic flux concentrations and the granular
velocity field.
Authors: Deubner, F. -L.
1976A&A....47..475D Altcode:
The discovery that magnetic flux in the solar photosphere outside of
sunspots occurs only in the form of highly concentrated flux elements
of subgranular size with high maximum fields of the order of 1.5 kG has
prompted a continuing discussion of how these fragile structures are
being produced and protected against rapid diffusion and dissipation. In
this context, an adequate quantitative picture of the photospheric
(granular) velocity field is of crucial importance. In particular, high
vertical velocities are required for models in which the magnetic-flux
elements are kept in a nonstationary dynamical equilibrium configuration
with reduced internal gas pressure by a pumping mechanism. It is of
interest to review some recent observations which indicate that the
granular velocities are locally much higher (as high as 6 km/s),
than the values commonly assumed.
---------------------------------------------------------
Title: Neue Beobachtungen zur Deutung der Mikroturbulenz
Authors: Deubner, F. L.
1976MitAG..38..203D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of low wavenumber non radial eigenmodes of the sun
Authors: Deubner, F. L.; Mc Intyre
1976pmas.conf..259D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Spatially Resolved Observations of Solar Global Relations
Authors: Deubner, F. L.
1976IAUTB..16..244D Altcode: 1976IAUT...16B.244D
No abstract at ADS
---------------------------------------------------------
Title: Observations of short period acoustic waves bearing on the
interpretation of "microturbulence"
Authors: Deubner, F. L.
1976pmas.conf..263D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: New observations of the granular intensity fluctuations.
Authors: Deubner, F. L.; Mattig, W.
1975A&A....45..167D Altcode:
White-light photographs of solar granulation obtained with a
40-cm evacuated reflector during the partial eclipse of June 30,
1973, are used for a statistical analysis of granular intensity
fluctuations. Two-dimensional power spectra of the intensity
distribution are calculated directly, and an instrument spread function
derived from photometric scans across the lunar limb is employed for
correcting the data. The mean FWHM of the spread function corresponded
to 0.52 sec. The corrected RMS intensity fluctuation is found to be
0.128 for a wavelength of 607 nm, and maximum power is found to occur
at the wave number corresponding to a wavelength of 1340 km or 1.85 sec.
---------------------------------------------------------
Title: La estructura fina de la rotación diferencial solar.
Authors: Deubner, F. -L.; Vázquez, M.
1975UrBar..60...39D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of low wavenumber nonradial eigenmodes of the sun.
Authors: Deubner, F. -L.
1975A&A....44..371D Altcode:
Photoelectric observations of the photospheric velocity field with high
resolution in horizontal wavenumber and frequency have been carried
out in the C I 5380-A line. Three or four discrete stable modes of
the five-minute oscillations are resolved in the wavenumber-frequency
diagram, which agree in many respects with the predicted fundamental
modes of subphotospheric standing acoustic waves. Some interesting
aspects of the confirmation of a 'global' excitation mechanism of the
five-minute oscillations are pointed out. Several apparently discordant
details of previous observations are rediscussed, and it is shown that
they can be reconciled with the present results.
---------------------------------------------------------
Title: Differential Rotation and the Spot Zones
Authors: Deubner, F. -L.; Vazquez, M.
1975SoPh...43...87D Altcode:
A minimum of angular velocity is not found at the equator as suggested
by Gilman, but at a latitude of 6° in both hemispheres.
---------------------------------------------------------
Title: Acoustic Waves and the Geometric Scale in the Solar Atmosphere
Authors: Deubner, F. -L.
1975SoPh...40..333D Altcode:
It is shown that the phase and group velocity of fluctuations in
different solar spectral lines are equal in the high-frequency
fluctuation tail where sound waves propagate. The motion of a
disturbance is described, the characteristics of which agree with those
of an acoustic wavefront traveling upward with gradually increasing
amplitude, and the frequency and velocity of the disturbance are plotted
as functions of time. Relative heights are found for regions where C I,
Fe I, Na I, and H-alpha lines form, and the results are shown to agree
with previous theoretical estimates.
---------------------------------------------------------
Title: Photospheric and Chromospheric Magnetic Structures
Authors: Deubner, F. L.
1975cesra...5...39D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Photospheric and chromospheric magnetic structures.
Authors: Deubner, F. L.
1975MmArc.105...39D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Die Intensitätsfluktuation der Granulation
Authors: Deubner, F. L.; Mattig, W.
1975MitAG..36..148D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Photospheric and chromospheric magnetic structures
Authors: Deubner, F. L.
1975esm..meet...39D Altcode:
Observations of the fine structure of the photospheric magnetic
field and its chromospheric extension are reviewed, and some models
of the flux concentrations and possible mechanisms for forming and
maintaining this structure are considered. Chromospheric structures
that are potentially of importance for constructing realistic models of
solar magnetic structures are described, including the facular network,
mottles, spicules, and filigrees. Photospheric structures described
include magnetic knots and anomalous granulation. Difficulties in the
interpretation of magnetic-field observations are discussed. Theoretical
models of the surface magnetic flux are examined, and it is shown
that turbulent pumping and the Bernoulli effect can be considered as
possible mechanisms for concentrating or confining magnetic flux in flux
ropes. Noting that the initial development of a magnetic configuration
driven by supergranular convection leads to a funnel-shape geometry
opening upwards, it is shown that such a configuration can be maintained
in the presence of a force-free field, a temperature variation, or a
dynamic effect.
---------------------------------------------------------
Title: Acoustic waves and the Geometric scale in the Solar atmosphere
Authors: Deubner, F. L.
1975MitAG..36..149D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Some Properties of Velocity Fields in the Solar Photosphere. V:
Spatio-Temporal Analysis of High Resolution Spectra
Authors: Deubner, F. -L.
1974SoPh...39...31D Altcode:
Series of high resolution spectrograms taken simultaneously in three
spectral regions were recorded with a lambda meter and subjected
to a statistical analysis of the fluctuations of Doppler shift and
brightness. The 5-min oscillations are confirmed to be `evanescent'
waves. Their horizontal wavelengths range from 9″ to 15″ and
probably still larger values.
---------------------------------------------------------
Title: On the Energy Distribution in Wavenumber Spectra of the
Granular Velocity Field
Authors: Deubner, Franz-Ludwig
1974SoPh...36..299D Altcode:
Wavenummer spectra of spatial velocity fluctuations measured in selected
high resolution solar photospheric spectrograms are presented. The
statistical stability of the power estimates of particular `peaks'
in these spectra is discussed.
---------------------------------------------------------
Title: Hα Fine Structure and the Dynamics of the Solar Atmosphere
Authors: Deubner, F. -L.
1974IAUS...56..263D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Eine Prozeßrechner im Dienste der Sonnenphysik. Moderne
Datenerfassung beim Fraunhofer Institut in Anacapri.
Authors: Deubner, F. -L.
1974S&W....13...47D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Is There Horizontal Phase Propagation of 5-min Oscillations
at High Velocities?
Authors: Deubner, Franz-Ludwig; Hayashi, Nobukazu
1973SoPh...30...39D Altcode:
New observations of the photospheric 5-min oscillations are presented
which prove that the physical reality of the very high horizontal phase
propagation velocities observed in connection with the oscillations
cannot be maintained. Instead, a statistical model is proposed to
explain the observed phase relations.
---------------------------------------------------------
Title: Eine statistische Deutung der horizontalen
Phasengeschwindigkeit der 5-Min.-Oszillationen
Authors: Deubner, F. -L.
1973MitAG..32..182D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the Powerspectrum of the Photospheric Resonance Oscillations
Authors: Deubner, Franz-Ludwig
1972SoPh...23..304D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Some Properties of Velocity Fields in the Solar
Photosphere. IV: Long Periods, Five Minute Oscillations, and the
Supergranulation at Lower Layers
Authors: Deubner, Franz-Ludwig
1972SoPh...22..263D Altcode:
Photoelectric measurements of photospheric velocity fields have been
carried out with the Sacramento Peak Doppler Zeeman Analyzer. Emphasis
was given to long periods and low spatial wavenumbers in deep
photospheric layers, where the 5-min oscillations are less dominant.
---------------------------------------------------------
Title: Some Properties of Velocity Fields in the Solar
Photosphere. III: Oscillatory and Supergranular Motions as a Function
of Height
Authors: Deubner, Franz-Ludwig
1971SoPh...17....6D Altcode:
Photoelectric measurements of Doppler shifts of various Fraunhofer
lines obtained with the Capri magnetograph were analysed. The height
dependence of the supergranular and oscillatory motions, as well as
the two dimensional structure of these velocity fields is investigated.
---------------------------------------------------------
Title: Photoelectric Measurements of Sunspot Magnetic Fields
Authors: Deubner, F. -L.; Göhring, R.
1971IAUS...43..190D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Photoelectric Polarimetry of a Dark Unipolar Sunspot
Authors: Deubner, F. -L.; Göhring, R.
1970SoPh...13..118D Altcode:
Photoelectric polarisation measurements in a stable sunspot (type H)
with a particularly dark umbra carried out with the Capri magnetograph
have been evaluated in terms of Unno's (1956) theory to give the
value and direction of the magnetic field vector. A linear increase of
the inclination angle with distance from the spot centre up tor ≈
1.2R<SUB>s</SUB> results, as originally found by Hale and Nicholson
(1938) with a different procedure. The field strength decreases from
the maximum value (about 3300Γ) to about 15% at the penumbral border,
still continuously decreasing outside the spot. The projected field
direction deviates considerably from the radial symmetry in several
parts of the spot region, but it is in good agreement with that of
the overlaying chromospheric structures.
---------------------------------------------------------
Title: Die unruhige Oberfläche der ruhigen Sonne.
Authors: Deubner, F. -L.
1970S&W.....9..285D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Some Properties of Velocity Fields in the Solar
Photosphere. II: The Spatial Distribution of the Oscillatory Field
Authors: Deubner, Franz-Ludwig
1969SoPh....9..343D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Vectormagnetograph of the Fraunhofer Institut
Authors: Deubner, Franz-Ludwig; Liedler, R.
1969SoPh....7...87D Altcode:
A new vectormagnetograph is described that measures all components of
the magnetic field vector strictly simultaneously. The azimuth of the
direction of the field is continuously obtained during the observation
by means of a servo circuit. As a first step of data recording
a photographic method is applied which presents all 5 quantities
(longitudinal and transverse component of the field vector, azimuth,
Doppler shift and intensity) in the form of maps.
---------------------------------------------------------
Title: Photoelektrische Magnetfeldmessungen an einem regulären
Sonnenfleck mit besonders dunkler Umbra
Authors: Deubner, F. -L.; Göhring, R.
1969MitAG..27..205D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Photoelektrische Registrierungen des photosphärischen
Netzwerks
Authors: Deubner, F. -L.
1969MitAG..27..204D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the Influence of Seeing on Photospheric Velocity
Measurements
Authors: Deubner, Franz Ludwig
1968SoPh....3..439D Altcode:
It is shown that the short-period fluctuations of photospheric velocity
records can be explained by the scanning effect of atmospheric seeing
(image motion) and the velocity gradients present on the solar
surface. Some observations supporting this explanation are presented.
---------------------------------------------------------
Title: Magnetic and Doppler Oscillations in Active Regions
Authors: Deubner, F. L.
1968IAUS...35..230D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Über die Vertikalkomponente der Supergranulationsströmung
Authors: Deubner, F. L.
1968MitAG..25..188D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Some Properties of Velocity Fields in the Solar Photosphere
Authors: Deubner, Franz Ludwig
1967SoPh....2..133D Altcode:
Photoelectric records of the Doppler effect (DE) and longitudinal
Zeeman effect (LZE) were obtained with the Capri magnetograph of the
Fraunhofer Institut photoelectric, using the FeI line λ 5250.22. Each
record consists of 65 scans repeated along the same line on the sun. The
analysis of 16 records covering a total of 485 oscillating regions
(period 300 sec) leads to the following results: The mean lifetime of
the DE-oscillations outside active regions is 20 min and 32 min in the
neighborhood of spotgroups. Discarding the weakest sporadic osculations,
one obtains 27 min and 43 min respectively. The most frequent lifetime
in both cases is 15 min.
---------------------------------------------------------
Title: On the reorganization of field lines during a flare
Authors: Deubner, F. L.
1965IAUS...22..369D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Eine Beobachtung zum Problem der Koinzidenz von Eruptionen
und magnetischen Neutrallinien. Mit 2 Textabbildungen
Authors: Deubner, F. L.
1962ZA.....55..123D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Über die Anwendung weiter Spektrographenspalte
beilichtelektrischen Polarisationsmessungen an Fraunhoferlinien. Mit
4 Textabbildungen
Authors: Deubner, F. L.
1962ZA.....56....1D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Der Magnetograph des Fraunhofer Instituts. Mit 5
Textabbildungen
Authors: Deubner, F. L.; Kiepenheuer, K. O.; Liedler, R.
1961ZA.....52..118D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Über die Verminderung des Streulichts in
Abbildungs-systemen. Mit 4 Textabbildungen
Authors: Deubner, F. -L.
1959ZA.....48...34D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Zur lichtelektrischen Registrierung und Photometrie von
Fackeln und Eruptionen. Mit 6 Textabbildungen
Authors: Kiepenheuer, K. O.; Deubner, F. L.
1958ZA.....45...17K Altcode:
No abstract at ADS
