explanation blue bibcodes open ADS page with paths to full text
Author name code: firstova
ADS astronomy entries on 2022-09-14
author:"Firstova, N. M."
---------------------------------------------------------
Title: Structure and physical conditions in the Hα loops of an M7.7
solar flare
Authors: Firstova, N. M.; Polyakov, V. I.
2017AstL...43..768F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Connection between the appearance of γ-ray sources and H α
line impact linear polarization in the July 23, 2002 flare
Authors: Firstova, N. M.
2015AstL...41..593F Altcode:
During our spectropolarimetric observations of the 2B/4.8X flare
on July 23, 2002, with the Large Solar Vacuum Telescope (LSVT),
we detected impact linear polarization in the southern ribbon. The
maximum polarization exceeded 10%. On the whole, the polarization
was observed only for ~6 min out of almost 2 h of observations of
this flare. At this time, the H α line profiles had a deep central
self-reversal. We have compared the LSVT observations with the Reuven
Ramaty High Energy Solar Spectroscopic Imager (RHESSI) data, where
the locations of γ-ray emission were obtained for the first time. A
careful comparison has revealed that the effects in the H α line were
observed in a region <10″ located between two X-ray sources in
the southern ribbon. According to the RHESSI data, a γ-ray source
attributable to a beam of high-energy (~1 MeV) electrons was observed
at the same place. The events in the corona and the upper chromosphere
also coincide in time with the observed effects in the H α line. The
two X-ray sources are assumed to represent a common footpoint of
the southern foot of the loop bifurcated due to the precipitation of
high-energy electrons. It is suggested that the penetration of these
electrons into the dense layers of the chromosphere could lead to
impact polarization and a decrease of the H α line intensity in the
southern ribbon of the flare, in contrast to the northern ribbon where
a typical hard X-ray source with an energy ~20-120 keV was observed;
there were no self-reversal at the H α line center and polarization.
---------------------------------------------------------
Title: Observation of H α line impact polarization in solar flares
Authors: Firstova, N. M.; Polyakov, V. I.; Firstova, A. V.
2014AstL...40..449F Altcode:
We present the results of studying the impact linear polarization of 32
solar flares of X-ray classes C, M, and X (two flares) observed with the
Large Solar Vacuum Telescope. It has turned out that there is evidence
for impact polarization only in 13 of them. The newly obtained data
have confirmed that the linear Stokes parameters are predominantly
2-7%, while the spatial sizes of flaring points with nonzero Stokes
parameters are small (1″-2″). Two features of the manifestation
of impact polarization in flares revealed by these studies are of
greatest interest: (1) at the two foot points of a single flare loop
or an arcade of loops, both the H α intensity profiles and the Stokes
profiles differ in behavior; (2) based on the H α line, we have found
for the first time that the sign of the Stokes parameters changes not
only across the flare ribbon but also with depth of the chromosphere.
---------------------------------------------------------
Title: Hα Line Impact Linear Polarization Observed in the 23 July
2002 Flare with the Large Solar Vacuum Telescope (LSVT)
Authors: Firstova, N. M.; Polyakov, V. I.; Firstova, A. V.
2012SoPh..279..453F Altcode:
We present the results of studying the proton flare 2B/X4.8 on 23
July 2002, observed with the Large Solar Vacuum Telescope (LSVT) at
the Baikal Astrophysical Observatory in spectropolarimetric mode with
high spatial and spectral resolution. We have found some evidence for
Hα line impact linear polarization, predominantly during the initial
moments of the flare. For the Hα line 606 cuts were made along the
dispersion in 53 spectrograms, and a polarization signal was found
more or less confidently in 60 cuts (13 spectrograms). Polarization
was mainly observed in one of the kernels of the flare. A particular
feature of this kernel was that the Hα line was observed to show
a reversal in the central part of this kernel, which created a dip
in the kernel center in the photometric cut. The size of these dips
and the size of the sites with the linear polarization coincide and
are equal to 3 - 6 arcsec. The maximum polarization degree in this
kernel reached 15 %. The direction of the polarization in the kernel
is radial, except for the first two frames, where the direction of
the polarization was both radial and tangential. Furthermore, we found
an analogy between the effects observed at the chromospheric level in
this kernel (polarization and depression in Hα line) and the temporal
variation of the HXR sources.
---------------------------------------------------------
Title: Observing solar phenomenas with the large solar vacuum
telescope
Authors: Firstova, N. M.; Polyakov, V. I.
2011Ge&Ae..51..888F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Studying instrumental linear polarization at the Large Solar
Vacuum Telescope (LSVT)
Authors: Firstova, N. M.; Polyakov, V. I.; Skomorovsky, V. I.;
Grigoriev, V. M.
2009Ge&Ae..49..927F Altcode:
Impact linear polarization in solar flares is studied with the
Large Solar Vacuum Telescope (LSVT) using the spectral polarimetric
method. This method makes it possible to minimize the effect of
instrumental polarization with an error of up to 10<SUP>-2</SUP> owing
to the normalization of the spectral line intensity to the continuum
spectrum intensity with negligible linear polarization. As a result,
the Hα line intensity in two orthogonally polarized spectral stripes
coincides in the absence of solar polarization. However, in the presence
of linear polarization in a flare, the spectral polarimetric method does
not rule out that the error can be present in determining the Stokes
parameters Q and U because of their possible relative “leakage.”
Linear instrumental polarization of LSVT has been performed using
polaroid rotation before the major mirror. Twelve elements of a
telescope matrix, characterizing linear polarization, have been
determined. The usage of a matrix makes it possible to specify the
observed Q and U values accurate to 10<SUP>-3</SUP> of their magnitude.
---------------------------------------------------------
Title: Impact Linear Polarization on Impulsive Phase of Proton Flare
Observations with High Spatial Resolution
Authors: Firstova, N. M.; Polyakov, V. I.; Firstova, A. V.
2009ASPC..405..131F Altcode:
We describe the results of the observations of the 23 July 2002 2B/X4.8
proton flare impulsive phase at the Irkutsk Large Solar Vacuum Telescope
(LSVT) using the spectropolarimetric mode. 18 regions of the flare
in the Hα line were observed with high spatial, spectroscopic and
time resolution. In the six processed flare regions we obtained the
evidence of impact linear polarization in the Hα line center. We
noted that the general structure of the polarization profiles during
the observation of a single flare region is kept in time. On the other
hand, polarization across flare ribbons changes significantly. In all
the flare regions we observed a deviation of the polarization peak
position from the location of maximum intensity.
---------------------------------------------------------
Title: Impact Linear Polarization of the H α Line Observed in a
Proton Flare with the Irkutsk Large Solar Vacuum Telescope
Authors: Firstova, N. M.; Polyakov, V. I.; Firstova, A. V.
2008SoPh..249...53F Altcode: 2008SoPh..tmp...60F
The impulsive phase of the 23 July 2002 2B/X4.8 proton flare with a
classical two-ribbon structure was observed with the Irkutsk Large Solar
Vacuum Telescope (LSVT) in spectropolarimetric mode, with high spatial,
spectral, and time resolution. On the basis of 49 spectrograms and 1200
spectral cuts across the flare ribbons, evidence for Hα line impact
polarization has been obtained. A systematic change of the Stokes Q
and U parameters has been detected across the ribbons for different
flare regions measured with a scanning step of 0.85″. In the eastern
side of the ribbons, the degree of polarization is 4 - 8%; its plane
is oriented toward the solar disk center (radial direction). In the
western side, the polarization degree runs up to 25%, and its plane is
perpendicular to the disk center direction (tangential direction). A
comparison of these results with hard X-ray data (RHESSI) allows us
to conclude that high-energy electron beams reached the chromosphere
during this flare. The observed changes of the direction of polarization
and the vanishing polarization within the ribbons mean that, at the
chromospheric level, the energy of electrons remaining in the beam is
about 200 eV. A shift of the peak position of polarization relative to
the intensity maximum in the ribbons may result from the inclination
of the electron beam axis with respect to the solar surface.
---------------------------------------------------------
Title: Hα Line Polarization in the Major Flare of 2002 July
23. I. Observations and Data Analysis
Authors: Firstova, N. M.; Xu, Z.; Fang, C.
2003ApJ...595L.131F Altcode:
On 2002 July 23, a major 2B/X4.8-class flare was observed in Hα lines
with the Large Solar Vacuum Telescope of the Baikal Astrophysical
Observatory using the spectropolarimetric method. Linear polarization
of 3%-10% has been detected in Hα lines of the flare, particularly
in the Hα lines with a central reversal. They are mainly radial on
the solar disk and appear at the impulsive phase of hard X-ray and
γ-ray bursts. The polarization changes its direction in a spatially
limited small region (~4"-5") and within a short period of time
(~10 s). Moreover, the linear polarization is limited to only some
relatively small regions of the flare.
---------------------------------------------------------
Title: Hα Line Polarization in the 2B/X4.8 Flare of 2002 July 23
Authors: Xu, Zhi; Firstova, N. M.; Chen, Qing-Rong; Fang, Cheng
2003ChJAA...3..266X Altcode:
On 2002 July 23, a 2B/X4.8 flare was observed in the Hα line
spectropolarimetrically by the Large Solar Vacuum Telescope of Baikal
Astrophysical Observatory. Linear polarization of 3%-10% was detected in
the Hα line, particularly where the line showed central reversal. The
linear polarization is mainly radial on the solar disk and appears at
the impulsive phase of the hard X-ray and γ-ray bursts. It is limited
to some relatively small regions of the flare. The polarization in
a limited small region (∼ 4”-5”) changed its direction within a
short period of time (∼10 s)
---------------------------------------------------------
Title: Measurement and processing of linear polarization in solar
flares - a comparison of two methods
Authors: Kotrč, P.; Firstova, N. M.; Kashapova, L. K.; Kupryakov,
Yu. A.
2002ESASP.506..947K Altcode: 2002svco.conf..947K; 2002ESPM...10..947K
Linear polarization measurement in solar flares is discussed from the
point of view of the processing technique. Usually, spectropolarimetric
investigation of the linear polarization in solar flares is carried
out for the line profiles. The results obtained by two methods
(either processing of individual profiles or the whole spectral
strips) are compared and applied to the observations obtained at the
Large Solar Vacuum Telescope (the Baikal Astrophysial obseratory)
and at the Ondřejov Multichannel Flare Spectrograph. The results
obtained by the second method are comparable by accuracy with the
results obtained by the first one. Moreover, it allows to check the
instrumental polarization and the polarization behaviour in the nearby
objects. However, the profile operating method allows to investigate
the polarization effects along the dispersion more carefully.
---------------------------------------------------------
Title: Observation of the linear polarization in the flare with a
powerful surge
Authors: Firstova, N. M.; Kashapova, L. K.
2002A&A...388L..17F Altcode:
An investigation of the linear polarization in the flare with a
powerful surge revealed an unusual behavior of the Stokes parameter
profiles along the dispersion. We discuss the probability that photons
propagating from the flare and passing through the surge generate a
linearly polarized radiation of the surge.
---------------------------------------------------------
Title: The results of spectropolarimetric observations of solar
flares followed by surge
Authors: Firstova, N. M.; Kashapova, L. K.
2002ESASP.477..103F Altcode: 2002scsw.conf..103F
An investigation of the linear polarization in the June 29, 1999 flare
with a powerful surge (the maximum velocity was about 160 km/sec)
revealed an unusual behavior of the Stokes parameter profiles along the
dispersion. We discuss the probability that photons propagating from
the flare and passing through the surge generate a linearly polarized
radiation of the surge.
---------------------------------------------------------
Title: Investigation of He I 10 830 Å `Dark Points' at the Sayan
Solar Observatory and the Baikal Astrophysical Observatory
Authors: Skomorovsky, V. I.; Firstova, N. M.; Kashapova, L. K.;
Kushtal, G. I.; Boulatov, A. V.
2001SoPh..199...37S Altcode:
A new two-bandpass birefringent filter has been produced at
ISTP, Irkutsk for the investigation of the fine structure of the
chromosphere. One filter passband is centered on the He i 10 830 Å
line, the second one is centered on Hα. The FWHM of the He i 10 830 Å
passband is 0.46 Å and of the Hα passband is 0.3 Å. A large number of
filtergrams were obtained with the filter at the Sayan observatory. At
the same time, spectral observations with high spatial and spectral
resolution were carried out by the large solar vacuum telescope at the
Baikal Observatory. We selected 29 `dark point' spectra with sizes from
2” to 13”, as well as `dark points' on the filtergrams. Comparison of
spectrograms and filtergrams has shown a good agreement of their size
and intensity in relation with the surrounding chromosphere as well
as the absence of primary line-of-sight velocities in both observation
types. From spectral observations, the depth of 10 830 Å is over 30%
for some `dark points', and the FWHM is more than 1 Å. He i 10 830 Å
line profiles in `dark points' are more deep and wide than in quiet
regions. The optical depth of the chromosphere in `dark points' is
estimated. Comparison with the unperturbed chromosphere showed that
`dark points' in He i 10 830 Å are more optically thin than the
nearby chromosphere.
---------------------------------------------------------
Title: The Today's Investigations on Large Solar Vacuum Telescope
Authors: Skomorovsky, V. I.; Firstova, N. M.; Kashapova, L. K.;
Firstova, A. V.; Kushtal, G. I.
2001AGM....18.P221S Altcode:
The contribution presents the prospective observations obtained with
the Large Solar Vacuum Telescope (Baikal astrophysical observatory,
Irkutsk) from 1997 after its re-equipment by CCD-camera. During the
latest years we carried out basically the spectropolarimetric Hα
observations of the emission objects of different sizes from the solar
flares to the Ellerman bombs. The flares followed by a surges have
aroused a special interest. The observations and preliminary results are
shown. The Ellerman bombs or moustaches were devoted much attention. We
obtained the extensive observational data( more than 200 objects) and
the various mechanisms of their arising have been analyzed. Besides
the investigation of the linear polarization in Hα line the spectral
observations in IR region (HeI 10830 Å line) were carried out. Also
we obtain the observation of the pores in the several Fe lines for the
latest two years. This work was supported by Russian Foundation for
Basic Research grants 00-02-16068-a and 01-02-06203. Thanks are also
due the State Support of Leading Scientific Schools of the Russian
Federation grant 00-15-96659 and the State Scientific and Technical
Program “Astronomy” for their support.
---------------------------------------------------------
Title: First-order adaptive system for correction of images in solar
ground-based telescopes
Authors: Antoshkin, Leonid V.; Borovik, A. B.; Botygina, Nina N.;
Bulatov, Alexei V.; Emaleev, Oleg N.; Firstova, N. M.; Fortes, Boris
V.; Grigoryev, Victor M.; Kovadlo, P. G.; Lavrinova, L. N.; Lukin,
Vladimir P.; Petrov, A. I.; Skomorovsky, Valery I.; Yankov, A. P.
2000SPIE.4007..232A Altcode:
The possibility of applying adaptive-optics devices to ground- based
solar astronomy and high-resolution spectroscopy is considered. Due
to atmospheric turbulence the resolution of ground-based solar
telescopes are limited to 1 arcsec on the average with short period
of subarcsecond resolution at good sites. Application of adaptive
correction is a ground-based telescope to improve image quality is
possible to improve whole performance of telescope to obtain images
with resolution about 0.3' and to improve resolution for spectral
measurements of the Sun. Adaptive Optics represent a visible tool for
increasing the resolution of ground-based telescopes to the level that
will be needed to understand the physical processes occurring on the
Sun. An experimental adaptive- optics system for image stabilization is
described, as well as the results of its tests. Different ways of the
further development of the adaptive-optics system for use in the Big
Solar Vacuum Telescope (BSVT) of the Baikal Astrophysical Observatory
are discussed.
---------------------------------------------------------
Title: The linear polarization in moustaches
Authors: Firstova, N. M.; Boulatov, A. V.; Kashapova, L. K.
1999ASSL..243..451F Altcode: 1999sopo.conf..451F
No abstract at ADS
---------------------------------------------------------
Title: A spectropolarimetric study of the Hα radiation from
Ellerman bombs.
Authors: Kazantsev, S. A.; Firstova, N. M.; Kashapova, L. K.; Bulatov,
A. V.; Petrashen', A. G.
1998RuPhJ..41.1258K Altcode:
Polarization data are given for three whiskers recorded with the
large solar vacuum telescope at Baikal Observatory, Institute of
Solar-Terrestrial Physics, Russian Academy of Sciences. The observed
degree of polarization varies from 2 to 13%. The direction of the
polarization plane for the medium intensity whisker was tangential,
while that for the weakest one was radial. The brightest whisker had
a polarization plane direction close to radial at the center of the
line but tangential at the flanks. It is assumed that the polarization
is due to impact excitation of a hydrogen-atom ensemble in the solar
chromosphere by an electron beam, and estimates are made of the
beam energy.
---------------------------------------------------------
Title: Spectropolarimetric studies of H<SUB> alpha </SUB> emission
in "solar moustaches": Observations and calculation of the Stokes
parameters
Authors: Kazantsev, S. A.; Firstova, N. M.; Kashapova, L. K.; Bulatov,
A. V.; Petrashen', A. G.; Henoux, J. -C.
1998ARep...42..702K Altcode:
The results of spectropolarimetric observations of three solar
`moustaches' carried out on the Large Vacuum Solar Telescope of
Baikal Observatory of the Institute of Solar-Terrestrial Physics are
presented. The observed degree of polarization varies from 2-13%. The
direction of the plane of polarization for a moustache with moderate
intensity is tangential, and is radial for the weakest moustache. In
the brightest moustache, the plane of polarization is close to radial
at the line center, and is tangential in the wings.
---------------------------------------------------------
Title: Spectropolarimetric studies of H<SUB> alpha </SUB> emission in
"solar moustaches": Energy of the excited electron beam
Authors: Kazantsev, S. A.; Firstova, N. M.; Petrashen', A. G.; Henoux,
J. =C.
1998ARep...42..707K Altcode:
Spectropolarimetric observations of the Hα emission of `solar
moustaches' are used to estimate the energy of the beam of electrons
that is assumed to give rise to the observed polarization during
its shock excitation of an ensemble of hydrogen atoms in the solar
chromosphere.
---------------------------------------------------------
Title: Spectroscopolarimetric Sensing of Energy Deposition Into the
Chromosphere during Solar Flares - I. Observations
Authors: Firstova, N. M.; Hénoux, J. -C.; Kazantsev, S. A.; Bulatov,
A. V.
1997SoPh..171..123F Altcode:
Measurements of linear polarization in hydrogen Hα and Hβ lines,
made with the Large Solar Vacuum Telescope of Baikal Astrophysical
Observatory and Automated Solar Telescope of Sayan Solar Observatory,
affiliated with the Russian Institute of Solar and Terrestrial Physics,
are reported in this paper. Short-term polarization associated with
solar flares is found to be present in active regions. There is
a significant tendency for the Hα polarization vector to be radial,
i.e., in the flare-to-disk-center direction. This polarization may be
due to atmospheric bombardment by hecta keV protons. On the other hand,
the polarization vector is found to be perpendicular to the radial
direction at some locations where the line profile has a typical
mustache shape suggesting a bombardment by energetic electrons. The
Hβ line is also linearly polarized. However, no preferential direction
of polarization is found in this line, which is formed more deeply in
the solar atmosphere.
---------------------------------------------------------
Title: Spectropolarimetry of solar flare based on measurements of
the H<SUB> beta </SUB> hydrogen line
Authors: Kazantsev, S. A.; Petrashen', A. G.; Firstova, N. M.; Henoux,
J. -C.
1996OptSp..80..635K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Determination of energy transfer to the chromospheric region of
solar flare on the basis of spectropolarimetric data on hydrogen lines
Authors: Kazantsev, S. A.; Petrashen', A. G.; Firstova, N. M.; Enu,
Zh. -K.
1996OptSp..80..532K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Characteristics of the Linear Polarization Observed in the
16 May 1991 Solar Flare
Authors: Firstova, N. M.; Boulatov, A. V.
1996SoPh..164..361F Altcode:
In a search for linear polarization effects, 37 profiles of the
H<SUB>α</SUB> line emitted in the 16 May 1991 flare have been
analyzed. Linear polarization is clearly present in the central
part of line. On average, the degree of polarization is 7 %, but it
reaches 20 % in regions with lower H<SUB>ga</SUB> emission. Generally
the orientation of the plane of polarization coincides with the flare
to disk center direction, except for sections where the H<SUB>ga</SUB>
line has the characteristic form observed in moustaches. We believe that
the linear polarization observed in the 16 May 1991 flare was caused
by bombardment of the chromosphere by beams of accelerated particles,
protons in the main part of the flare and electrons at locations where
the H<SUB>ga</SUB> line has the characteristic moustache structure.
---------------------------------------------------------
Title: The Large Solar Vacuum Telescope: the Optical System, and
First Spectral Observations
Authors: Skomorovsky, V. I.; Firstova, N. M.
1996SoPh..163..209S Altcode:
The performance of the optics of the Large Solar Vacuum Telescope
(LSVT) and examples of the spectrograms taken with the spectrograph are
presented. A new pneumo-mechanical support system for the siderostat
mirror and monitoring system of the telescope optics is described.
---------------------------------------------------------
Title: Determination of the energy of the proton beam formed in a
solar flare on the basis of spectropolarimetric data
Authors: Kazantsev, S. A.; Firstova, N. M.; Petrashen', A. G.; Henoux,
J. -C.; Bulatov, A. V.
1995OptSp..78..655K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Spectropolarimetric determination of the energy contribution
to the optically active region of the chromosphere
Authors: Kazantsev, S. A.; Petrashen, A. G.; Firstova, N. M.; Hénoux,
J. C.
1993OptSp..75..382K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Possibilities of spectropolarimetrically studying eruptive
formations in the solar atmosphere
Authors: Kazantsev, S. A.; Firstova, N. M.; Gubin, A. V.; Lankevich,
N. A.
1991OptSp..70..580K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observational aspects of the study of plasma turbulence in
solar flares.
Authors: Firstova, N. M.
1990JQSRT..44..177F Altcode:
Using two techniques (the polarization method and the Baranger-Mozer
method) a study has been made of plasma turbulence in solar emission
features. The study suggests the conclusion that the 0.02 - 0.03 plasma
turbulence level (E = 1 - 2 kV cm<SUP>-1</SUP>) seems to be the highest
achieved in flares.
---------------------------------------------------------
Title: On the Presence of High-frequency Turbulent Electric Fields
in the August 7, 1960 Flare
Authors: Firstova, N. M.; Heinzel, P.; Kotrc, P.
1990BAICz..41...88F Altcode:
According to Oks (1978), the wings of some hydrogen Balmer lines
observed in the spectrum of the moustache-like flare of August 7,
1960 do exhibit theoretically predicted dips, which should indicate
the presence of Langmuir turbulence. However, these features are rather
subtle and thus several difficulties arise if one tries to identify them
in the noisy spectra with typically many blends. Moreover, the Balmer
profiles used for Oks' analysis were already 'filtered' in a special
manner, which strongly affects the results. In view of these problems,
consideration is given to whether these dips in this particular flare
were real, starting with newly obtained microphotometric records. Using
the same lines as Oks (i.e., H7, H8, H11-13), together with H14,
none of the expected dips in the line wings were identified. All
observational aspects of this analysis are discussed in detail, and
new special observations are proposed. The role of electron density
variations within the flare volume is also briefly discussed.
---------------------------------------------------------
Title: A Search for a Plasma Turbulence in the Flare of September 15,
1981, 00:09 UT
Authors: Firstova, N. M.; Kotrc, P.
1987BAICz..38..257F Altcode:
The linear polarization in the H-alpha and H-beta lines in the flare
of Sept. 15, 1981, is studied by a photographic method which enables
instrumental polarization to be eliminated. Considerable values of
the degree of polarization occur in the cores of the lines, at some
points as much as 17 percent. However, an objective analysis of all
the profiles indicates that the polarization in this flare cannot be
demonstrated as the degree of polarization does not exceed, on the
average, the inaccuracy of the photographic method used. A blue shift
corresponding to the velocities -2.5 km/s and -1.3 km/s has been found
in the cores of the H-alpha and H-beta lines, respectively. The blue
shift changes into red at about the full width of the half maximum of
the lines.
---------------------------------------------------------
Title: An Investigation of the Linear Polarization in Emission
Features of Active Regions
Authors: Firstova, N. M.
1986SoPh..103...11F Altcode:
A study has been made of linear polarization in `moustaches' using
the Hα and Hβ lines. A Wollaston prism and an achromatic λ/2-plate
were employed in the study. In the course of the observations, the
major axis of the plate was placed at 0° and 22°.5 with respect to
the horizontal axis of the installation. The Stokes parameters J, Q,
and U were recorded, thus enabling the degree of polarization and
the field azimuth to be determined. During the first three minutes
of the existence of the moustaches, the two lines revealed a linear
polarization of about 7% located at the center of the lines. No
polarization was found during the later stage of the moustaches'
lifetimes. Whenever the linear polarization is present, there is a
tendency for the polarization to decrease rapidly, in accompaniment
of a turning of the azimuth. Several mechanisms for interpreting
the polarization observed in the moustaches are examined. Some
suggestions are made in support of the excitation of hydrogen atoms
in the moustaches initiated by a high-energy electron flux or vertical
heat conduction.
---------------------------------------------------------
Title: Observational aspects in investigating the plasma turbulence
in solarflares.
Authors: Firstova, N. M.
1986psf..conf...65F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: An evaluation of the possibility of studying flare plasma
turbulence using the satellites of He i line forbidden components
Authors: Firstova, N. M.
1984SoPh...90..269F Altcode:
Using the Baranger-Mozer method, we explore the possibility of
diagnosing the flare plasma of forbidden HeI lines, that permits
the determination of the plasma oscillation frequency and noise
level. Examination of the HeI lines observed in solar flare has led us
to conclude that: the appearance of satellites of forbidden components
in the flares spectrum, due to turbulent electric fields, is the most
probable for HeI 3819.606 Å lines;
---------------------------------------------------------
Title: Review of Observational Techniques and Data on Turbulent
Electric Fields in Solar Flares
Authors: Firstova, N. M.
1984IGAFS..68...31F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Evaluation of the Possible Investigation of Flare Plasma
Turbulence Using Satellites of Forbidden Components of the Hei Lines
Authors: Firstova, N. M.
1983IGAFS..65..194F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Ratio of maximum intensities of CA II H and K lines in
umbral flashes
Authors: Firstova, N. M.
1980AZh....57..666F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Ratio of Maximum Intensities of CAII H and K Lines in Umbral
Flashes
Authors: Firstova, N. M.
1980SvA....24..384F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Concerning the Big Solar Vacuum Telescope Spectrograph
Scheme Choosing
Authors: Firstova, N. M.
1980IGAFS..52..122F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Variation of sunspot umbra sizes with height.
Authors: Firstova, N. M.; Turova, I. P.
1979IGAFS..45...49F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Oscillations regime in the chromosphere above a large sunspot
umbra.
Authors: Teplitskaya, R. B.; Turova, I. P.; Firstova, N. M.
1979IGAFS..49...21T Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Bright emission in H and K Ca II lines in a sunspot umbra.
Authors: Firstova, N. M.
1978BSolD1978...77F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Shapes and centre-to-limb variation of the H and K lines in
sunspot umbrae.
Authors: Teplitskaia, R. B.; Firstova, N. M.
1976SoPh...48..103T Altcode:
The shapes of the Ca II H and K lines in sunspot umbral spectra
vary from single asymmetric peaks near the centre of the disk to
almost symmetric double peaks at the limb. In addition, there are
other differences in the behaviour of both H and K lines in sunspots
compared to the quiet Sun. The whole complex of the phenomena observed
can not be explained by large scale chromosphere motions. Instead, a
satisfactory model reproducing in detail peculiarities of the umbral
emission reversals contains a cloud of emitting and absorbing gas
located above the chromosphere, which flows into the sunspot. The
radiation field parameters in such a cloud are consistent with the
concept of weak quiescent prominences above the umbra.
---------------------------------------------------------
Title: The sphape of the H and K Ca II line profiles in the spectra
of sunspot umbrae and its center-to-limb variation.
Authors: Teplitskaya, R. B.; Firstova, N. M.
1976fsp..conf...84T Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Extraction of scattered light on sunspot spectrograms obtained
by means of a Wollaston prism.
Authors: Firstova, N. M.; Kuklin, G. V.
1973BSolD1973...94F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Dependence of temperature on the magnetic field intensity in
the region of a sunspot.
Authors: Firstova, N. M.
1973BSolD1973...91F Altcode:
No abstract at ADS
