Author name code: stodilka
ADS astronomy entries on 2022-09-14
author:"Stodilka, Miroslav I."
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Title: Statistical Analysis of the Orbital Motion of Selected
Artificial Earth Satellites during Solar Cycle 24
Authors: Bilinsky, A. I.; Baran, O. A.; Stodilka, M. I.; Vovchyk,
Ye. B.; Koval'chuk, M. M.
Bibcode: 2021KPCB...37..310B
Altcode:
No abstract at ADS
Title: Comparison of physical conditions in two phases of the solar
flare of July 19, 2000 of M6.4/3N class
Authors: Lozitsky, V. G.; Stodilka, M. I.
Bibcode: 2021Ap&SS.366...30L
Altcode:
We study the solar flare of July 19, 2000 of M6.4/3N class, which
occurred in the active region NOAA 9087. Echelle Zeeman spectrograms
of this flare were obtained with the horizontal solar telescope of the
Astronomical Observatory of Taras Shevchenko National University of
Kyiv. Physical conditions were compared for two times corresponding to
the pre-peak and peak phases of the flare in area of a small sunspot. It
was found that the effective magnetic field B eff by Fe I
6301.5 and Fe I 6302.5 lines was almost the same for both times and
both spectral lines. However, B eff in peak phase measured
by the splitting of the emission peaks of Fe II and Hβ lines turned
out to be 300-500 G stronger than those by the above-mentioned Fe I
lines, whereas by D3 He I line it was found to be close to zero. This
may indicate a local magnetic field increase in height range from
temperature minimum region to the lower chromosphere. A semi-empirical
model of the photospheric layers of the flare, constructed on a base
of observations of Fe I 5123.7 and Fe I 5434.5 lines by solving the
inverse problem for non-equilibrium radiative transfer using Tikhonov
stabilizers, shows the moderate increasing of temperature (∼300 K)
in altitude range 250-500 km. The radial velocities were decreased
during peak phase. The micro-turbulent velocity was increased in the
photosphere layers before the flare peak, while during the peak phase
it was significantly decreased. The obtained results indicate that in
the pre-peak phase the altitude perturbations in the photosphere were
larger than in the peak phase.
Title: Solar Faculae: Microturbulence as an Indicator of Inclined
Magnetic Fields
Authors: Stodilka, M. I.; Kostyk, R. I.
Bibcode: 2020KPCB...36..153S
Altcode:
The observations of the solar facula in the Ba II λ 455.403
Å line are used to construct a 3D model of the facula area by
solving the inverse nonequilibrium radiative transfer problem and to
investigate the fine structure of the field of unresolved velocities
(microturbulence). New turbulent structures are formed in the layers
of the upper photosphere. They are localized mainly between upward
and downward flows with the formation of ring-shaped structures of
increased turbulence around these flows. The mechanism of magnetic
anisotropy of microturbulent velocity is proposed (small-scale eddy-type
plasma motions mainly occur in the planes perpendicular to the magnetic
field), which explains the height dependence of the field of unresolved
velocities. Anisotropy of microturbulence begins to manifest itself in
the lower photospheric layers outside the upward and downward flows,
while it manifests itself in the higher layers inside these flows. The
increase of microturbulence in the layers of the upper photosphere and
the lower chromosphere in the areas between matter flows indicates the
presence of inclined magnetic fields, which, along with the blurring
of its spatial structure, indicates the existence of a magnetic
canopy region. Microturbulence can be used as an additional tool for
diagnostics of inclined magnetic fields.
Title: Solar faculae: microturbulence as an indicator of inclined
magnetic fields
Authors: Stodilka, M. I.; Kostyk, R. I.
Bibcode: 2020KFNT...36d...3S
Altcode:
No abstract at ADS
Title: Anomalous Widening of 5434.5 Line in Sunspots: Super-Strong
Magnetic Fields?
Authors: Lozitsky, V. G.; Osipov, S. M.; Stodilka, M. I.
Bibcode: 2020OAP....33...89L
Altcode:
We present results of spectral observations of two sunspots in six
metal lines near Fe I 5434.5 Å, which have effective Lande factors
geff from 0.014 to 2.14. The observations were made on July
8 and August 25, 2015, with the ATsU-5 telescope of GAO NAS of Ukraine
using a circular polarization analyzer and spectra registration with the
SBIG ST-8300 CCD camera. The following line parameters are compared:
observed splitting of I ± V profiles, the width and depth of the
Stokes I profiles. Significant differences of the measured magnetic
field strengths Beff were found in separate places of the
spots and by lines with different geff values. The Fe I
5434.5 Å line (geff = -0.014) shows measurable splitting
in some locations of the sunspots, which corresponds to the magnetic
field Bobs ≍ 20 kG. Comparison of the widths and depths
of the line profiles revealed several special places in the sunspots,
where the Fe I 5434.5 Å line was expanded additionally by ≍ 15-35%,
whereas other lines with larger Lande factors did not have such a
feature. One of the reasons for this expansion could be a sharp and
local increase of turbulent velocities, but no active processes such
as solar flares or significant Doppler flows were observed at these
locations. A semi-empirical model constructed for the first sunspot by
FeI 5434.5 line using inverse code with Tikhonov`s stabilizers shows
an anomalous feature - the maximum of microturbulent velocities in the
upper photosphere and the temperature minimum zone instead of the usual
small increase of microturbulence at these heights. This may be the
effect of very strong magnetic fields of mixed polarity or unresolved
turbulent structures. As to first case, the estimated value of the
magnetic field in such locations of sunspots is ∼105 G,
which requires additional careful verification.
Title: Long-term monitoring of spectral line variations with the
11-year cycle. Quiet Sun.
Authors: Osipov, S. N.; Shchukina, N. G.; Kostyk, R. I.; Stodilka,
M. I.
Bibcode: 2020A&AT...31..465O
Altcode:
The monitoring program of long-term variation of selected solar
spectral lines is described. The aim of the program is to study
how the physical parameters of the quiet solar atmosphere change
over the last solar cycle 24. The research is based on high spectral
resolution observations of the quiet Sun using the Ernest Gurtovenko
horizontal solar telescope of the Main Astronomical Observatory of the
National Academy of Sciences of Ukraine. Since 2012 the observations
are performed daily, when the weather conditions allow. We found that
the line core depths and full widths at half maximum of the Fe I solar
spectral lines correlate with the cycle modulation of the total unsigned
magnetic field and the Wolf numbers of the Sun. The behaviour of these
line parameters can be explained by variations of the temperature of
the quiet photosphere during the 11-year cycle.
Title: Features of Convection in the Atmospheric Layers of the
Solar Facula
Authors: Stodilka, M. I.; Prysiazhnyi, A. I.; Kostyk, R. I.
Bibcode: 2019KPCB...35..261S
Altcode:
According to the data of complex 2D observations on the VTT telescope
of the solar facula, a 3D model of the solar atmosphere in the facular
region was obtained by solving the inverse radiative transfer problem
in the Ba II 4554 A line. The magnetic field was estimated using the
Stokes V profiles of the Fe I 15648 A line. The influence of magnetic
field on photospheric convection was investigated: spatial variations
in temperature and velocities at different heights were considered. It
is shown that the mutual transformation of the mechanical and thermal
energy of the solar plasma into magnetic energy occurs in the layers of
the middle photosphere. The integral effect of a small-scale magnetic
dynamo leads to lowering the temperature and slowing down the motion of
the predominant downward flows in the layers of the middle photosphere
in the facular regions with a strong field (greater than 1 kG),
while there is an increase in temperature and acceleration of the
motion of the predominant upward flows in the layers of the middle
photosphere in the facular regions with a weak field (less than 1
kG). It is shown that the magnetic field of the facula stabilizes
photospheric convection, and the small-scale magnetic dynamo causes
a double temperature inversion in the photospheric layers of the facula.
Title: Features of convection in the atmosphere layers of the
solar facula
Authors: Stodilka, M. I.; Prysiazhnyi, A. I.; Kostyk, R. I.
Bibcode: 2019KFNT...35f..18S
Altcode:
No abstract at ADS
Title: Diagnostics of photospheric jets of the quiet Sun atmosphere
Authors: Stodilka, M. I.; Sukhorukov, A. V.; Prysiazhnyi, A. I.
Bibcode: 2019KFNT...35e..48S
Altcode:
No abstract at ADS
Title: Diagnostics of the Quiet Sun Atmosphere's Photospheric Jets
Authors: Stodilka, M. I.; Sukhorukov, A. V.; Prysiazhnyi, A. I.
Bibcode: 2019KPCB...35..231S
Altcode:
From 2D-spectral observation data of a quiet region of the solar
disk center in the Fe I λ 557.609 nm line, 3D hydrodynamic models of
photospheric jets are built by solving the inverse radiative transfer
problem. The obtained models describe thermodynamic parameters and the
complete velocity field (vertical and horizontal). It is shown that the
photospheric jets under consideration arise from the interaction of
the surrounding environment with the field of the magnetic tube. The
jets are located in a region of a unipolar magnetized downflow at
the impact point of two horizontal flows, and they tend to occur at
the edge of magnetic tubes. The observed gas velocities are subsonic
in downflows of the jets. Energy release in the photospheric jets
is predominantly localized in the middle photosphere layers, where
the excess pressure is maximal. Compared with the surrounding media,
mass density in the jets is significantly increased in the upper layers
and slightly decreased in the lower layers of the photosphere.
Title: Magnetic fields and thermodynamic conditions in the pre-peak
phase of M6.4 / 3N solar flare
Authors: Lozitsky, M.; Stodilka, M.
Bibcode: 2019BTSNU..59...22L
Altcode:
We present a study of the pre-peak phase of the solar flare of M6.4
/ 3N class which arose on July 19, 2000 in the NOAA 9087 active
region. The effective magnetic field Beff was measured using the FeI
6301.5 Å, FeI 6302.5 Å, Hα and Hβ spectral lines. It was found
that at the brightest place of the flare, which was projected onto
a small sunspot of N polarity, Beff was close to each other on all
four lines and corresponded to 1.0-1.2 kG. At the same time, the
modulus of the magnetic field at the level of FeI 6302.5 formation,
determined by the splitting of peaks V of the Stokes parameter and the
localization of the σ-components in the I ± V profiles, was in the
range 1.6-2.6 kG. The bisectors of the I + V and I - V profiles of
the FeI 6301.5 line are parallel to each other, indicating a simple
one-component structure of the magnetic field at the level of the
middle photosphere under the flare. The Balmer decrement of Imax (Hα)
/ Imax (Hβ) by Hα and Hβ lines was 1.16. The semi-empirical model
of the photospheric layers of the flare was constructed using Stokes
I observations of non-magneticsensitive FeI 5123.7 and 5434.5 lines
by solving the inverse equilibrium transfer problem using Tikhonov
stabilizers. For the distribution of temperature with height, the
effects of deviation from the LTE were found to be significant for
the layers of the lower photosphere corresponding to the heights h
≥ 0 (i.e. τ 5 ≤ 1). In the entire thickness of the photosphere
(h = 0-500 km), the flare temperature is lower compared to the
non-perturbed atmosphere, while it is slightly higher for h>
500 km. The micro-turbulent velocity is increased at altitudes h>
200-500 km, while at altitudes h <200 km it is reduced. The obtained
results indicate that the upper photosphere and the lower chromosphere
are perturbed during solar flares, even when the magnetic field is
quasi-homogeneous in the lower layers (middle photosphere).
Title: Robust method for determination of magnetic field strength
in solar photosphere
Authors: Prysiazhnyi, A. I.; Stodilka, M. I.; Shchukina, N. G.
Bibcode: 2018KFNT...34f...3P
Altcode:
No abstract at ADS
Title: Robust Method for Determination of Magnetic Field Strength
in the Solar Photosphere
Authors: Prysiazhnyi, A. I.; Stodilka, M. I.; Shchukina, N. G.
Bibcode: 2018KPCB...34..277P
Altcode:
The classical method for determining the magnetic field strength from
the distance between the peaks of blue and red wings of the Stokes
V profile of a magnetically sensitive spectral line is modified. To
reduce the influence of noise and to more accurately measure the
distance between these peaks, the observed Stokes V profile was
approximated by a modified wavelet-function. The parameters of the
best fitted approximation function were determined by multidimensional
optimization. Following such an approach, the magnetic field strength
can be found analytically using such an approximation. We investigate
the modified method by means of calculations of the Fe I λ 1564.8
nm Stokes V and I profiles in a three-dimensional snapshot model
atmosphere. Magneto-convection snapshot model with small-scale dynamo
action performed by Rempel was used. It was found that the method
proposed is less sensitive to noise and the shape of the observed
V-signal of the line. This makes it possible to conclude that the
approach of determining of the magnetic field strength from the observed
splitting of the Fe I λ 1564.8 nm Stokes V profile is more reliable
in comparison with the classical one.
Title: Structure of the Long-Living Elements of Solar Granulation
Authors: Baran, O. A.; Stodilka, M. I.; Prysiazhnyi, A. I.
Bibcode: 2018KPCB...34...13B
Altcode:
No abstract at ADS
Title: Structure of the long-living elements of the solar granulation
Authors: Baran, O. A.; Stodilka, M. I.; Prysiazhnyi, A. I.
Bibcode: 2018KFNT...34a..21B
Altcode:
No abstract at ADS
Title: Role of the solar wind parameters in changing orbital motion
of the Earth's satellites
Authors: Koval'chuk, M. M.; Hirnyak, M. B.; Baran, O. A.; Stodilka,
M. I.; Vovchyk, Ye. B.; Bilinsky, A. I.; Blahodyr, Ya. T.; Virun,
N. V.; Apunevych, S. V.
Bibcode: 2017KPCB...33..295K
Altcode:
No abstract at ADS
Title: Role of the parameters of solar wind in the changing of
orbital motion of the artificial satellites of the Earth
Authors: Koval'chuk, M. M.; Hirnyak, M. B.; Baran, O. A.; Stodilka,
M. I.; Vovchyk, Y. B.; Bilinsky, A. I.; Blahodyr, Y. T.; Virun, N. V.;
Apunevych, S. V.
Bibcode: 2017KFNT...33f..61K
Altcode:
No abstract at ADS
Title: Investigation of the influence of heliogeoactivity on the
dynamics of orbital parameters of artificial satellites of the Earth
Authors: Koval'chuk, M. M.; Hirnyak, M. B.; Baran, O. A.; Stodilka,
M. I.; Vovchyk, Y. B.; Bilinsky, A. I.; Blahodyr, Y. T.; Virun, N. V.;
Apunevych, S. V.
Bibcode: 2017KFNT...33e..68K
Altcode:
No abstract at ADS
Title: Investigation of heliogeoactivity impact on the dynamics of
orbital parameters of Earth's artificial satellites. I
Authors: Koval'chuk, M. M.; Hirnyak, M. B.; Baran, O. A.; Stodilka,
M. I.; Vovchyk, Ye. B.; Bilinsky, A. I.; Blahodyr, Ya. T.; Virun,
N. V.; Apunevych, S. V.
Bibcode: 2017KPCB...33..245K
Altcode:
No abstract at ADS
Title: Estimation of the lifetime of artificail satellites of the
Earth depending on their elements of orbit
Authors: Koval'chuk, M.; Vovchyk, Ye.; Stodilka, M.; Bilinsky, A.;
Baran, O.; Hirnyak, M.; Martynyuk-Lototsky, K.
Bibcode: 2017BTSNU..55...39K
Altcode:
Lagrange equations for the elements of orbit are used for description of
the motion of artificial satellites of the Earth in noncentral Earth's
gravity field at the presence of atmospheric drag. Relation between
the elements of orbit of satellites at a certain time and further
duration of the existence of satellites is investigated. We described
the method that enables to define quickly and reliably the lifetime of
satellites on an orbit. For comparison, the actual lifetimes of the
selected satellites are brought, it gave an opportunity to test the
presented calculation method. The error of the calculated and observed
times of an existence of satellites does not exceed 2-3 days, so it is
sufficiently for predictions of the lifetime of satellites on an orbit.
Title: The development of convective structures in the solar
photosphere
Authors: Baran, O.; Stodilka, M.
Bibcode: 2016BTSNU..54...46B
Altcode: 2016BTSNU...54...46
We study the development of convective structures in the solar
photosphere on the basis of the photospheric convection models obtained
using data from VTT by the solving of the inverse nonequilibrium
radiative transfer problem. Temporal changes of the variations
of vertical velocity and temperature within granular cells are
analyzed. Features of the appearance and the disappearance of granules
according to their size, the formation of "trees" of fragmenting
granules are investigated.
Title: Diagnostics of horizontal velocity field in the solar
atmosphere: Line Ba II λ 455.403 nm
Authors: Stodilka, M. I.
Bibcode: 2016KPCB...32..145S
Altcode:
No abstract at ADS
Title: Diagnostics of the solar atmosphere by the Non-LTE inversion
method: Line of Ba II λ 455.403 nm
Authors: Stodilka, M. I.; Prysiazhnyi, A. I.
Bibcode: 2016KPCB...32...23S
Altcode:
No abstract at ADS
Title: Convection structure in the solar photosphere at granulation
and mesogranulation scales
Authors: Baran, O. A.; Stodilka, M. I.
Bibcode: 2015KPCB...31...65B
Altcode:
No abstract at ADS
Title: On the diagnostics of solar small scale magnetic fields
Authors: Stodilka, M. I.
Bibcode: 2015AdSpR..55..891S
Altcode:
The model of small scale magnetic fields was proposed. The fields
are described by two distribution functions: for unsigned magnetic
field and for field vectors directions. The distribution functions
were used to derive expressions for elements of the line absorption
matrix and to deduce function that characterizes mutual cancellation
of magnetic fields. We received the solutions for polarized radiative
transfer problem within 3D MHD model of the solar photosphere and
determined Stokes profiles parameters for two magnetosensitive lines Fe
I λ 525.0 nm and λ 524.7 nm. The Stokes profiles parameters of the
lines were used for further test diagnostics of small scale magnetic
fields. A regression approach to diagnostics of the magnetic fields was
proposed. The correlation between theoretical and reproduced parameters
of small scale magnetic fields is greater than 0.95.
Title: The Observed Evolution of Convective Flows in the Solar
Photosphere (Velocity Field)
Authors: Baran, O.; Stodilka, M.
Bibcode: 2014BTSNU..51...25B
Altcode:
We investigate the evolution of the vertical velocity field by
solving the inverse problem of nonequilibrium radiative transfer
using neutral iron lineλ≈639.3nm profiles. The profiles were
taken with high spatial resolution around the centre of the solar
disc in the non-perturbed region. The acoustic waves were removed
by k-ω filtration. We analyze the spatial variations of vertical
velocity at different heights of the solar photosphere (h=-25÷550km):
the correlation coefficient of velocities at different heights with
velocities at h=0km is significantly reduced in the upper photosphere;
at heights h>200km the velocity inversion is detected for 12% of
convective cells (granules and intergranules). We found that upflows
usually arise in the lower photosphere and eventually perturbation
extends upwards; downflows mostly originate in the upper layers of
the photosphere and later the perturbation region goes down.
Title: Spatial variations of Stokes profiles of magnetoactive lines
Fe I
Authors: Stodilka, M. I.
Bibcode: 2014KPCB...30..261S
Altcode:
No abstract at ADS
Title: Specifics of the solar photospheric convection at granulation,
mesogranulation, and supergranulation scales
Authors: Baran, O. A.; Stodilka, M. I.
Bibcode: 2014KPCB...30..173B
Altcode:
No abstract at ADS
Title: Phase velocities of gravity waves in the solar photosphere
Authors: Stodilka, M. I.
Bibcode: 2013KPCB...29..157S
Altcode:
No abstract at ADS
Title: Spatial structure of gravity waves in the solar photosphere
Authors: Stodilka, M. I.
Bibcode: 2012KPCB...28..162S
Altcode:
No abstract at ADS
Title: Some peculiarities in excitation and propagation of the
gravity waves in solar photosphere
Authors: Stodilka, M. I.
Bibcode: 2012KPCB...28..149S
Altcode:
No abstract at ADS
Title: Effect of small-scale magnetic fields on magnetically sensitive
Fe I λ 525.02 and λ 1564.85 nm line profiles in the quiet solar
photosphere
Authors: Stodilka, M. I.
Bibcode: 2011KPCB...27..161S
Altcode:
No abstract at ADS
Title: Global isothermal oscillations in the solar photosphere
Authors: Stodilka, M. I.
Bibcode: 2011KPCB...27..124S
Altcode:
No abstract at ADS
Title: Horizontal convective velocity field obtained from the
observations of the solar limb
Authors: Baran, O. A.; Stodilka, M. I.
Bibcode: 2010KPCB...26..117B
Altcode:
No abstract at ADS
Title: Reflection of acoustic waves in the real solar atmosphere
Authors: Stodilka, M. I.
Bibcode: 2010KPCB...26...71S
Altcode:
No abstract at ADS
Title: On 2D radiative transfer in solar granulation. The case of
Fe I lines
Authors: Stodilka, M. I.
Bibcode: 2008Ap&SS.318...93S
Altcode: 2008Ap&SS.tmp..201S
The effects have been investigated of non-vertical radiative transfer
on the formation of neutral iron spectral lines in inhomogeneous
photosphere of the Sun. The non-vertical effects, as well as deviations
from LTE, smooth the contrast of solar granulation in equivalent
widths of solar absorption lines. For the central residual intensities
of moderate and strong lines, on the contrary to weak lines, these
effects enhance the granulation contrast. It was found, that the
negative dependency of equivalent width on intensity in continuous
spectrum decays due to the non-vertical effects for Fe I lines.
Title: On the detection of internal gravity waves in the solar
photosphere
Authors: Stodilka, M. I.
Bibcode: 2008MNRAS.390L..83S
Altcode: 2008MNRAS.tmpL..95S; 2008MNRAS.tmpL..94S
The distribution of temperature perturbations over the solar photosphere
was reconstructed. The k-ω and phase filtering was applied to Fourier
image of space-time variations of temperature in order to find the
signatures of local internal gravity waves. Within the convectively
stable photospheric layers, the structures have been identified
featuring the following properties: quasi-periodicity in space (at
scales of mesogranulation) and time, mostly horizontal propagation
with subsonic velocities, the group velocity of and the wavepacket
perpendicular to its phase velocity. Such properties are exactly those
of internal gravity waves.
Title: Structure of the solar photospheric convection on
subgranulation scales
Authors: Stodilka, M. I.; Baran, O. A.
Bibcode: 2008KPCB...24...70S
Altcode:
No abstract at ADS
Title: On the nature of solar irradiance five-minute oscillations
Authors: Stodilka, M. I.
Bibcode: 2007KosNT..13c..67S
Altcode:
A possible nature and the origin of solar irradiance five-minute
oscillations is examined. Using solar radiation observations (DIFOS-F,
VIRGO SPM, the line λ 532.418 nm Fe I of a high spatial resolution) the
authors solved inverse radiative transfer problem and reproduced height
stratification of the local and global temperature oscillations of low
l in the solar photosphere. Pseudoglobal oscillations of temperature
were extracted from photosphere oscillations, which enabled to study
the contribution of acoustic and internal gravity modes into the solar
irradiance oscillations. It is shown that the latter ones originate
probably from the scattering p-modes of low l on the solar granulation
with the subsequent constructive interference.
Title: Spatial variations in the velocity field and real solar
granulation
Authors: Stodilka, M. I.; Malynych, S. Z.
Bibcode: 2006MNRAS.373.1523S
Altcode: 2006astro.ph.12436S; 2006MNRAS.tmp.1296S
In this paper, the physical conditions within the inhomogeneous solar
atmosphere have been reconstructed by means of solving the inverse
problem of non-local thermodynamic equilibrium (NLTE) radiative
transfer. The profiles of the λ = 523.42nm FeI spectral line of high
spatial and time resolution were used as observational data. The
velocity field has been studied for the real solar granulation in
the superadiabatic layer and overshooting convection region. Also,
we investigate the vertical structure of the inhomogeneous solar
photosphere and consider the penetration of granules from the
convective region into the upper layers of the stable atmosphere. The
microturbulent velocity appears to be minimal at the bottom of the
overshooting convection region and increases sharply through the
superadiabatic layer and upper photosphere. High-turbulence layers
emerge either in the central part of a flow or at the boundary of
an incipient flow with subsequent drift towards the centre of the
flow. Wide descending flows tend to disintegrate into structures
having turbulence augmented and these structures correspond to the
flows of matter. High microturbulence of the intensive flows provokes
steep temperature depression in the upper photosphere leading to the
second inversion of temperature for the intergranules. The inversion
of vertical velocities is observed to be frequent in the solar
granulation. Some of the convective flows reach the minimum temperature
region. Vertical convective velocities of the matter flows are found
to be smaller in the middle and upper photosphere. Also, the effect
of finite resolution on spatial variations of the velocities in the
solar photosphere has been estimated.
Title: Structure of convective motions in the solar photosphere
Authors: Stodilka, M. I.
Bibcode: 2006KFNT...22..260S
Altcode:
Solving the inverse non-equilibrium radiative transfer problem with
subsequent k -ω and phase filtering, we investigated the convective
field of the temperature and velocities as well as their energetics. We
revealed small-scale inhomogeneities in the middle photosphere and
the temperature inversion of large convective flows in the middle and
upper photosphere layers. Power spectrum of the velocity variations
of convective flows decreases with height monotonously. The maximum
of the temperature variation power is concentrated in the lower
photosphere; the power decreases with height, reaching the minimum
at the beginning of the overshooting convection region; in the middle
and upper photosphere the power of the variations grows up again, and
that is due to temperature inversion and formation of a small-scale
component. The temperature inversion and small-scale inhomogeneities
are of convective origin.
Title: Convection peculiarities in the solar photosphere
Authors: Stodilka, M. I.; Baran, O. A.; Malynych, S. Z.
Bibcode: 2006KFNT...22..173S
Altcode:
Peculiarities of the photospheric convection are investigated by
means of reproduced spatio-time variations of the temperature and
line of sight velocity. The investigations were performed by solving
nonequilibrium inverse radiation transfer problem using the neutral
iron line λ ≈ 523.4 nm profiles obtained with a high spatial and
time resolution. In the middle and upper photosphere, the inversion of
temperature fluctuations becomes apparent clearly in large granules and
intergranules; for small granules the inversion is found seldom. The
discovered large granules are generated by a few ascending flows, which
interact between themself in the process of their development. Large
granules reach the temperature minimum layers, but the granules of less
sizes, that achieve these layers, are found too. The line of sight
velocity decreases with height reaching zero in the layers not lower
the temperature minimum. We detected sufficient horizontal shifts of
the granules and intergranules (500...1000 km) with a velocity of 3
to 5 km/s; that is due to rise up of a new cell.
Title: Diagnostics of the solar atmosphere by inverse methods:
hydrogen absorption lines
Authors: Stodilka, M. I.
Bibcode: 2005KFNT...21..461S
Altcode:
We solved non-equilibrium inverse radiation transfer problem in
hydrogen lines, that allows one to carry out the diagnostics of the
solar photosphere and chromosphere layers. The Tikhonov stabilizers
ensure solution stability to noise and input guesses of the reproduced
parameters, suppress false oscillations of the solutions. Using hydrogen
lines, we performed test diagnostics of the solar photosphere and
chromosphere layers: the maximum absolute error of the temperature
recovering does not exceed 70 K. When studying non-LTE hydrogen line
formation, we used the quantum-mechanical approach to take into account
the linear Stark effect.
Title: Spatial stratification of acoustic oscillations in the solar
photosphere
Authors: Stodilka, M. I.
Bibcode: 2005KFNTS...5..124S
Altcode:
Space-time variations of solar atmosphere parameters are derived
by solving non-equilibrium radiation transfer problem. Acoustic
oscillations were extracted using k-ω filtration of variations. In the
lower photosphere there are evanescent remnants of underphotosphere
oscillations; in the middle and high photosphere there are discrete
sources of oscillations, which are excited by granule decay and
formation of a new intergranule. The photosphere is penetrated by narrow
``channels'', by which energy of fluctuations tunnels with minimal
losses into the higher atmosphere layers; such ``channels'' arise
mostly between ascending and descending flows. Particularities of the
wave propagation in the solar atmosphere are determined by relationship
between wavelength and the effective size of inhomogeneities.
Title: Diagnostics of internal gravity waves in the solar photosphere
Authors: Stodilka, M. I.
Bibcode: 2005KFNT...21..197S
Altcode:
Internal gravity waves (IGW) are separated by k-ω filtering of
time-spatial temperature variations in the solar photosphere layers;
the temperature variations are reproduced by solving the nonequilibrium
inverse radiation transfer problem using neutral iron line profiles with
a high spatial and time resolution. IGW exist in all the photosphere
layers, but they are suppressed in the thin transition layer to the
overshooting convection region. The power for middle photosphere
sources is less by the order of magnitude than for the sources below
the top of the convective zone. We revealed two types of gravity
waves: 1) the waves without horizontal propagation are standing
waves trapped by the convective structure; 2) running waves with
moderate amplitude. Turbulent flows with high horizontal gradients
of convective motions strengthen oscillations, and intensive gravity
waves are excited in such layers.
Title: Power spectra of acoustic oscillations in the solar photosphere
Authors: Stodilka, M. I.
Bibcode: 2005KFNT...21...99S
Altcode:
We reproduced energetics of oscillations in the solar photosphere based
on power spectra of temperature and velocity fluctuations. Acoustic
oscillations of temperature and velocity in the solar photosphere are
separated by k-ω filtering of time-spatial variations reproduced by
solving the nonequilibrium inverse radiation transfer problem. Acoustic
oscillation power is localized on meso-supergranulation scales in the
range of five-minute oscillations. At the beginning of the overshooting
convection region the power of temperature oscillations is suppressed
by the wave scattering on convective nonuniformities. The power of the
observed velocity spectrum is increased in the high-frequency range at
these heights; that is due to distortion of wave fronts. High-frequency
oscillations are trapped by the convective structure of the middle
photosphere. The sources of five-minute and high-frequency oscillations
are localized.
Title: Investigation of the five-minute solar brightness oscillations:
DIFOS-F experiment
Authors: Stodilka, M. I.
Bibcode: 2005KosNT..11a..30S
Altcode:
Using observational data on solar continuous radiation flows in six
spectral regions, we solved radiation transfer problem and reproduced
global temperature oscillations in the low photosphere of the Sun. The
accuracy of the reproduction of oscillations by DIFOS data is two or
three times higher than that by SOHO data. It is shown that five-minute
oscillations of the solar brightness are generated by global standing
waves and one of their knots lies at the beginning of the overshooting
convection region.
Title: Temperature structure of a real solar granulation
Authors: Stodilka, M. I.
Bibcode: 2003KFNT...19..407S
Altcode:
We investigated the temperature structure of a real solar
granulation. Parameters of the inhomogeneous atmosphere are derived by
means of the inverse NLTE problem solution of radiation transfer using
modified response functions and implementing Tikhonov's stabilizers,
which enables one to obtain smooth solution and reduce considerably
its sensitivity to initial guesses. Temperature profiles along two
spatial coordinates are obtained. We also investigated temperature
fluctuations at different depths of the photosphere and pecularities
of a real solar convection, namely a superadiabatic layer and an
overshooting convection region. Using our temperature distribution,
we localized fluctuations generating oscillatory motions and estimated
the velocity of horizontal flows.
Title: Tikhonov stabilizers in inverse problems of spectral studies
Authors: Stodilka, M. I.
Bibcode: 2003KFNT...19..334S
Altcode:
Results of the reproduction of parameter stratification in the solar
or a star atmosphere models, which are based on Fraunhofer line
profiles, depend on starting guesses. Solutions feature substantial
oscillations. We suggest specific Tikhonov stabilizers substitution
of which into a corresponding merit function enables one to decrease
substantially the dependence of the reproduced parameters on the
starting guesses, to eliminate practically solution oscillations and
to obtain both LTE and non-LTE semiempirical models of inhomogeneities
including those of the solar granulation. Based on profiles with a
high spatial resolution, the temperature stratification in granules
and intergranules was obtained. It is shown that the first temperature
inversion in the solar granulation occurs at heights of 50 to 180 km.
Title: The role of collisions with neutral hydrogen atoms in the
formation of neutral iron lines in the quiet solar atmosphere:
Fe I lines
Authors: Stodilka, M. I.
Bibcode: 2002KFNT...18..330S
Altcode:
A redistribution of atoms on Fe I levels occurs due to collisions with
neutral hydrogen. The sensitivity of central line depth to collisions
with hydrogen is determined by the depth of formation of the line
center and the excitation potential of the lower level; the moderate
and strong lines which arise from metastable and semistable levels in
the upper photosphere are most sensitive. The collisions with hydrogen
have a weak influence on equivalent linewidths at the center of the
solar disk; the influence is stronger for stronger photospheric lines
closer to the limb. The equivalent widths and central depths of the
chromospheric lines which arise from metastable and semistable levels
have a faint response to collisions with hydrogen.
Title: The Inverse Problem for a Study of Solar and Stellar Atmosphere
Inhomogeneities
Authors: Stodilka, M.
Bibcode: 2002JPhSt...6..435S
Altcode:
No abstract at ADS
Title: Nonequilibrium polarized radiation transfer in the solar spots:
Fe I
Authors: Stodilka, M. I.
Bibcode: 2001KFNT...17..331S
Altcode:
Using accelerated Lambda-iteration method we solved unequilibrium
polarized radiation transfer problem for Fe I lines in the cool and hot
spot models. In low layers of the cool model the conditions of line
formation are close to equilibrium, where as in the hot model slight
neutral iron overionization by UV-radiation occurs. We investigated
NLTE-effects and magnetic field influense on Fe I lines formation
in the solar spots. It is shown that polarization of the radiation
sufficiently decreases formation depths of magnetically sensitive lines.
Title: Spatial variations of the equivalent widths of neutral iron
lines in the solar granulation
Authors: Stodilka, M. I.
Bibcode: 2001KFNT...17...24S
Altcode: 2001KFNT...17..024S
Using accelerated Lambda-iteration method, we solved 2D nonequilibrium
radiation transfer problem for quasi-stationary and fully nonstationary
solar granulation models. Neutral iron lines were calculated for a
21-level atom model. We took into account the Doppler shifts of the
absorption coefficient profiles (due to convective motions) along the
ray path. We studied the spatial variations of the equivalent widths (W)
for four lines: lambdalambda 388.625, 525.021, 670.357, and 671.032 nm -
strong, moderate, and two weak ones, correspondingly, which are formed
in different layers of the solar atmosphere. The spatial variations of
the equivalent widths over granular-intergranular regions are sensitive
to non-LTE effects due to photoionization processes: the non-LTE
modelling produces a small negative slope in the equivalent width -
continuum intensity dependence, while the LTE calculation produces a
positive slope. It is shown that the interaction of descending flows is
overestimated, which leads to a stronger negative correlation between
the equivalent width and intensity in the non-LTE modelling. The non-LTE
effects make weaker the equivalent widths of spectral lines in granules
and filter their fluctuations. The depletion of Fe I levels by the UV
radiation leads to a smaller height interval where the line is formed,
and that is why the non-LTE line profiles for forbidden transitions
are more sensitive to local conditions and reflect the conditions in
deeper atmosphere layers.
Title: Non-equilibrium formation of rare-earth elements weak spectra
in the solar atmosphere: CeII
Authors: Kovalchuk, M. M.; Stodilka, M. I.; Blagodyr, Ja. T.; Girnyak,
M. B.
Bibcode: 2001JPhSt...5...91K
Altcode:
No abstract at ADS
Title: Multidimensional radiation transfer in the inhomogeneous
stellar atmospheres
Authors: Stodilka, M. I.
Bibcode: 2000KFNTS...3..466S
Altcode:
We solved 2D non-equilibrium radiation transfer problem for different
atmosphere models. 2D NLTE radiation transfer problem is solved by
using multigrid techniques. On the each grid the solution is found
by the accelerated Λ-iteration method. For the formal solution of
the radiation transfer problem the short characteristics method is
used; we also used the linear convergence improvement procedure. The
solution convergence is fast for all the atmosphere models that were
tested. We considered influence of NLTE effects on the Fe I equivalent
width spatial variations over granular intergranular layers in the
solar atmosphere.
Title: Nonequilibrium two-dimensional radiation transfer in the
solar granulation: non-LTE and horizontal effects for neutral iron
Authors: Stodilka, M. I.
Bibcode: 2000KFNT...16..291S
Altcode:
The multilevel two-dimensional radiation transfer problem for modelled
solar granulation was solved with the help of the powerful accelerated
Λ-iteration method. We investigated the NLTE and horizontal radiation
transfer effects on the level populations and source function
for bound-bound transitions of neutral iron in the granular and
intergranular regions. The ultraviolet overionization leads to the
depletion of neutral iron in hot and cool areas of the photosphere,
with the granular areas in the upper photosphere being depleted more
than slightly hotter layers of intergranular areas. The horizontal
fluctuations in the line source function are greatly filtered by the
NLTE and horizontal effects for transitions between the levels with
high excitation potentials. The NLTE amplification of the horizontal
gradients of upper level populations occurs in nonuniform regions, which
may be used for the detection of shock waves in the solar photosphere.
Title: The linear Stark effect for hydrogen lines in the solar
atmosphere.
Authors: Stodilka, M. I.; Olijnyk, P. A.; Hirnyak, M. B.
Bibcode: 1998KPCB...14..414S
Altcode:
Proposes a simple and efficient method for calculating the Stark profile
of line absorption coefficient. The method involves the expansion
of the profile into series on the orthogonal basic set of functions
generated by the Voigt function. The profiles were calculated for
the hydrogen Paschen lines λλ1093.8, 1004.9 nm. Experimental line
profiles fit better the theoretical profiles with the Stark effect than
the Voigt profiles. Under the solar atmosphere conditions both lines
are most sensitive (among the Paschen series lines) to the linear Stark
effect. The wings of these lines are shown to be formed by nonelastic
collisions of hydrogen atoms with free electrons.
Title: The problem of two-dimensional radiative transfer for
multilevel atoms.
Authors: Stodilka, M.; Rykaliuk, R.
Bibcode: 1998JPhS....2..427S
Altcode:
The present paper deals with detailed analyses of radiative transfer
and statistical equilibrium equations solution problem. The problem
is solved by using multigrid techniques. This approach guarantees
convergence to true solution since long periodical oscillations
of the solution are being filtered, and the convergence itself
becomes essentially improved. On each grid the solution is found
by the accelerated h-iteration method. For the formal solution of
the radiative transfer equation the short characteristics method is
used. The method under the linear interpolation of source function
gives a simple recurrent relationship for the radiation intensity
which is spread in a given direction. For the statistical equilibrium
equations the preconditioning procedure is used. Such a procedure
ensures positive solutions and the equations themselves linearly
depend on level populations which results in linear convergence. The
ways of linear convergence improvement are described. Using the short
characteristics approach the coefficients for local and quasilocal
approximate Λ-operators have been obtained. In the latter the nearest
neighbouring points conditions have been taken into account and that
improves the operator quality. Described techniques allow to study
inhomogeneous astrophysical plasma.
Title: Effects of partial frequency redistribution on the formation
of Na I and Mg I resonance lines in the quiet solar atmosphere.
Authors: Babij, B. T.; Stodilka, M. I.
Bibcode: 1993KPCB....9d..52B
Altcode: 1993KPCB....9...52B
Comparative analysis is carried out for the effect of redistribution
functions of different types on the Na I and Mg I resonance line
profiles. Best results are obtained using the redistribution function
RII-A. The partial frequency redistribution is shown to
affect the center-to-limb relationship for central intensities of the
sodium D lines only, shifting them down the intensity scale. The
HSRA model gives better results as compared to VAL-80 C. When
RII-A is used in this case, the center-to-limb relationship
shifts still further by approximately 1% down the intensity scale, the
central intensities of D lines being 4 - 7%. For the partial frequency
redistribution case, the line Mg I λ285.2 nm has inverse peaks near
Δλ ≍ 0.01 nm, as in observed profiles. Calculations of this line for
the complete frequency redistribution case revealed no emission peaks.
Title: Theoretical Profiles of Fraunhofer Lines of the Solar Spectrum
for a 6-LEVEL Model of the Sodium Atom
Authors: Babii, B. T.; Stodilka, M. I.
Bibcode: 1989SvA....33..331B
Altcode:
No abstract at ADS
Title: Analysis of neutral magnesium line profiles in the solar
spectrum with the assumption of complete and partial frequency
redistribution.
Authors: Babii, B. T.; Stodilka, M. I.
Bibcode: 1988KFNT....4....3B
Altcode:
Profiles of neutral magnesium lines at the centre and at the limb of
the solar disc are calculated with the assumption of partial frequency
redistribution. The complete and partial redistribution is studied
for its effect on source functions of some lines. Menzel parameters
of examined lines are defined.
Title: Calculations of sodium D line profiles accounting for departure
from LTE.
Authors: Babii, B. T.; Stodilka, M. I.
Bibcode: 1987KFNT....3Q..34B
Altcode: 1987KNFT....3Q..34B
The populations of four levels of the Na I atom (3S, 3P, 4S, 4P)
at various heights in the solar atmosphere are determined using the
differential method of equivalent two-level atoms and the modified
method of linearization. Observed and calculated profiles of the
D1 and D2 lines for different positions on the
solar disk agree well. The calculated profiles of subordinate lines
at 330.3 and 1139.9 nm are deeper than observed ones.
Title: Depths of the intensity formation in the sodium D-lines at
different positions on the solar disc.
Authors: Babij, B. T.; Stodilka, M. I.
Bibcode: 1987BSolD1986...80B
Altcode:
Depths of the intensity formation in sodium D-lines at various
distance of line centers at different positions on the solar disc
are determined. It is shown that only very deep parts of line cores
are formed in the chromosphere. The rest radiation outside the cores
(Δλ ≥ 0.1 Å) has a photospheric nature.
Title: On a direct method of obtaining information from faint
Fraunhofer lines.
Authors: Babij, B. T.; Stodilka, M. I.
Bibcode: 1986BSolD1986...54B
Altcode:
A method of a simultaneous determination of important characteristics of
the solar atmosphere: abundance, damping constant, unresolved turbulence
velocity, is proposed on the basis of an analysis of faint Fraunhofer
line profiles.
Title: On steadying the monthly fluctuations of heliophysical indices
Authors: Voichishin, K. S.; Stodilka, M. I.
Bibcode: 1984AZh....61..976V
Altcode:
The statistical stability of the 11-yr cycles in the average-monthly
observed Wolf numbers is investigated, modifying the parametric model
of Voichishin and Stodilka (1982) by the addition of a steadying
technique to account for the nonstationary nature of the fluctuation
component of the signal without obscuring the principal microstructural
and macrostructural features. The results are presented graphically
and discussed. The statistical features of the as-observed data are
preserved in the steadied and smoothed data, confirming the validity
of conclusions drawn from analysis of the observed data.
Title: On Steadying the Monthly Fluctuations of Heliophysical Indices
Authors: Voichishin, K. S.; Stodilka, M. I.
Bibcode: 1984SvA....28..569V
Altcode:
No abstract at ADS
Title: Determination and estimation of the parameters of cyclic
signals of complex structure
Authors: Voichishin, K. S.; Stodilka, M. I.
Bibcode: 1983OtPeI..68...15V
Altcode:
The paper describes algorithms for estimating cyclic signals with
breakdowns in the statistical stability of the form of the cycles
characteristic for solar-activity indices. The proposed algorithms
resemble Rastrigin's (1979) stochastic minimization algorithm and,
besides solar-activity indices, can be used to analyze other types of
signals with breakdowns in the statistical stability of cycle form.
Title: On the statistical stability of solar cyclicity
Authors: Voichisin, K. S.; Stodilka, M. I.
Bibcode: 1982AZh....59.1171V
Altcode:
A form function for the 11-year solar-activity cycles is introduced
for an interval equal to the duration of the cycles, with allowance
for the asymmetry of the latter. A mathematical model is proposed
to describe the time structure of solar cyclicity. A method and
algorithm for optimal estimation (in the sense of the minimum of
the root-mean-square deviation) of its parameters are described. The
statistical correlation of parameters of 11 year cycles is discussed
and the stability of their fine structure is illustrated. The residual
dispersion is calculated with allowance for all 20 cycles of the Zurich
numbering (after subtracting from the initial data their approximated
values). Attention is drawn to the uniformity of its variation from
cycle to cycle as a test of the statistical stability of the shape
of the latter. The sources of disruption of the indicated uniformity
for monthly average observed Wolf numbers are calculated and ways of
eliminating them are indicated. It is concluded that the statistical
stability of the shape of the 11-year solar-activity cycles is real
to within the variation of their asymmetry.
Title: On the Statistical Stability of Solar Cyclicity
Authors: Voichishin, K. S.; Stodilka, M. I.
Bibcode: 1982SvA....26..705V
Altcode:
No abstract at ADS