Author name code: kashapova
ADS astronomy entries on 2022-09-14
author:"Kashapova, Larisa K."
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Title: Analysis of the Properties of SEP Events and Their
Solar Sources Taking Into Account of the Magneto-Morphological
Classification of Active Regions
Authors: Kashapova, L. K.; Zhukova, A. V.; Miteva, R.; Zhdanov, D. A.;
Myagkova, I. N.; Meshalkina, N. S.
Bibcode: 2021Ge&Ae..61.1022K
Altcode:
We studied 87 events of solar cosmic rays, i.e., solar energetic
particle (SEP) emissions associated with solar flares of at least
M5 class (according to the GOES classification) that occurred during
solar cycle 23. A relationship between the spectral parameters of the
SEP events and the microwave (MW) emission properties of the related
solar flares was analysed. The peak frequency of the MW spectrum
was used as an indicator of the acceleration processes during solar
flares, which may characterize both the strength of magnetic field
in the emission source and the intensity of the accelerated particle
flux. The magneto-morphological classification (MMC) was applied to
take into account the features of the magnetic topology of the active
regions (ARs) that generated flares. Our analysis showed that most
of ARs, associated with SEP events with large proton flux, violated
at least one of the empirical laws established for sunspot groups
(Hale's law, Joy's law, or another). The relationships between the
spectral properties of electrons and protons and the properties of MW
radiation were analyzed and discussed, taking into account the MMC of
ARs generated flares associated with SEP events.
Title: Common Origin of Quasi-Periodic Pulsations in Microwave and
Decimetric Solar Radio Bursts
Authors: Kashapova, Larisa K.; Kolotkov, Dmitrii Y.; Kupriyanova, Elena
G.; Kudriavtseva, Anastasiia V.; Tan, Chengming; Reid, Hamish A. S.
Bibcode: 2021SoPh..296..185K
Altcode: 2021arXiv211007880K
We analyse quasi-periodic pulsations (QPP) detected in the
microwave and decimetre radio emission of the 5 May 2017 7:04 UT
(SOL2017-09-05T07:04) solar flare, using simultaneous observations
by the Siberian Radioheliograph 48 (SRH-48, 4 - 8 GHz) and Mingantu
Spectral Radioheliograph (MUSER-I, 0.4 - 2 GHz). The microwave
emission was broadband with a typical gyrosynchrotron spectrum, while
a quasi-periodic enhancement of the decimetric emission appeared
in a narrow spectral band (500 - 700 MHz), consistent with the
coherent-plasma-emission mechanism. The periodicity that we found
in microwaves is about 30 seconds, coming from a compact loop-like
source with a typical height of about 31 Mm. The decimetric emission
exhibited a periodicity of about 6 seconds. We suggest a qualitative
scenario linking the QPPs observed in both incoherent and coherent
spectral bands and their generation mechanisms. The properties of the
QPPs found in the microwave signal are typical for perturbations of the
flare loop by the standing sausage mode of a fast magnetohydrodynamic
(MHD) wave. Our analysis indicated that this sausage-oscillating
flare loop was the primary source of oscillations in the discussed
event. The suggested scenario is that a fundamental sausage harmonic is
the dominant cause for the observed QPPs in the microwave emission. The
initiation of oscillations in the decimetric emission is caused by the
third sausage harmonic via periodic and nonlinear triggering of the
acceleration processes in the current sheets, formed at the interface
between the sausage-oscillating flare loop and the external coronal loop
that extended to higher altitudes. Our results demonstrate the possible
role of MHD wave processes in the release and transport of energy during
solar flares, linking coherent and incoherent radio emission mechanisms.
Title: Analysis of the Eruptive Event after the Solar Flare of June
7, 2011
Authors: Kupryakov, Yu. A.; Gorshkov, A. B.; Kotrč, P.; Kashapova,
L. K.
Bibcode: 2021ARep...65..876K
Altcode:
We present the results of the analysis of the observational data
for the eruptive event of June 7, 2011 obtained both on spacecraft
(SDO, LASCO) and using ground-based solar instruments. The event was
characterized by deceleration of the shock front during the first
minutes of the evolution from 1150 to 710 km/s. According to the
LASCO data, the velocity of the coronal mass ejection (CME) on time
scales of more than an hour did not exceed 285 km/s. According to the
spectral observations of the ground-based instrument, we found the
radial velocities of the fastest features of the exploding prominence
to be between 200 and 190 km/s. We paid special attention to studying
the physical characteristics of a blob—a separate drop of coronal
rain that accompanied the event. The line-of-sight velocity of the
blob increased in 5 min from 207 to 263 km/s, its diameter was 5900
km, and the estimated mass was 1.8 × 1012 g; the values
of temperature and turbulent velocity of 7880 K and Vturb
= 18.7 km/s were obtained,correspondingly. We should note that the
finding and measurement of velocities were limited by the capabilities
of narrow-band filters and a small wavelength range in most solar
instruments. This paper is based on the report made at the conference
"Ideas of S.B. Pikelner and S.A. Kaplan and Modern Astrophysics"
(Sternberg Astronomical Institute, Moscow State University, February
8-12, 2021).
Title: The morphology of average solar flare time profiles from
observations of the Sun's lower atmosphere
Authors: Kashapova, Larisa K.; Broomhall, Anne-Marie; Larionova,
Alena I.; Kupriyanova, Elena G.; Motyk, Ilya D.
Bibcode: 2021MNRAS.502.3922K
Altcode: 2021MNRAS.tmp..301K; 2021arXiv210202596K
We study the decay phase of solar flares in several spectral bands
using a method based on that successfully applied to white light flares
observed on an M4 dwarf. We selected and processed 102 events detected
in the Sun-as-a-star flux obtained with SDO/AIA images in the 1600 and
304 Å channels and 54 events detected in the 1700 Å channel. The main
criterion for the selection of time profiles was a slow, continuous
flux decay without significant new bursts. The obtained averaged time
profiles were fitted with analytical templates, using different time
intervals, that consisted of a combination of two independent exponents
or a broken power law. The average flare profile observed in the 1700
Å channel decayed more slowly than the average flare profile observed
on the M4 dwarf. As the 1700 Å emission is associated with a similar
temperature to that usually ascribed to M dwarf flares, this implies
that the M dwarf flare emission comes from a more dense layer than
solar flare emission in the 1700 Å band. The cooling processes in solar
flares were best described by the two exponents model, fitted over the
intervals t1 = [0, 0.5]t1/2 and t2 = [3, 10]t1/2,
where t1/2 is time taken for the profile to decay to half
the maximum value. The broken power-law model provided a good fit to
the first decay phase, as it was able to account for the impact of
chromospheric plasma evaporation, but it did not successfully fit the
second decay phase.
Title: Analysis of Properties of SEP Events and their Solar Sources
Considering the Magneto- Morphology Classification of Active Regions
Authors: Zhukova, A. V.; Kashapova, L. K.; Miteva, R.; Zhdanov, D. A.;
Meshalkina, N. S.; Myagkova, I. N.
Bibcode: 2020acsp.conf..105Z
Altcode:
No abstract at ADS
Title: The origin of quasi-periodicities during circular ribbon flares
Authors: Kashapova, L. K.; Kupriyanova, E. G.; Xu, Z.; Reid, H. A. S.;
Kolotkov, D. Y.
Bibcode: 2020A&A...642A.195K
Altcode: 2020arXiv200802010K
Context. Solar flares with a fan-spine magnetic topology are able to
form circular ribbons. A previous study based on Hα line observations
of the solar flares on 5 March 2014 revealed a uniform and continuous
rotation of the magnetic fan-spine. A preliminary analysis of the flare
time profiles revealed quasi-periodic pulsations (QPPs) with similar
properties in hard X-rays, Hα, and microwaves.
Aims: In this
work, we address the question of whether the observed periodicities are
related to periodic acceleration of electrons or plasma heating.
Methods: We analysed QPPs in the Hα emission from the centre of the
fan (inner ribbon R1), a circular ribbon (R2), a remote source (R3),
and an elongated ribbon (R4) located between R2 and R3. We used methods
of correlation, Fourier, wavelet, and empirical mode decomposition. We
compared the QPPs in Hα emission with those in microwave and X-ray
emission.
Results: We found multi-wavelength QPPs with periods
around 150 s, 125 s, and 190 s. The 150 s period is seen to co-exist
in Hα, hard X-rays, and microwave emissions, which allowed us to
connect it with flare kernels R1 and R2. These kernels spatially
coincide with the site of the primary flare energy release. The 125
s period is found in the Hα emission of the elongated ribbon R4 and
the microwave emission at 5.7 GHz during the decay phase. The 190
s period is present in the emission during all flare phases in the
Hα emission of both the remote source, R3, and the elongated ribbon,
R4, in soft X-rays and in microwaves at 4-8 GHz.
Conclusions:
We connected the dominant 150 s QPPs with the slipping reconnection
mechanism occurring in the fan. We suggested that the period of 125
s in the elongated ribbon can be caused by a kink oscillation of the
outer spine, connecting the primary reconnection site with the remote
footpoint. The period of 190 s is associated with the three-minute
sunspot oscillations.
Title: Calculation of the intensity of Mg I spectral lines in solar
prominences using the Cloudy code model
Authors: Kupryakov, Yu. A.; Dodin, A. V.; Schwartz, P.; Kashapova,
L. K.
Bibcode: 2020A&AT...31..459K
Altcode:
Spectroscopical observations of several prominences in the MgI lines
were carried out from 2014 to 2017. These lines from visible part of
the solar spectrum play an important diagnostic role, complementing the
UV Mg II resonance lines regularly observed by the IRIS satellite. We
found that a rather weak Mg I emission, e.g., in the 5172.6 Å line
correlates well with the presence of extended bright areas on the solar
disk observed in the 1600 Å SDO / AIA band. However, in many cases
the radiation in the 5172.6 Å line is very low, even not detectable,
although a bright prominence above the limb or are
on the solar
disc were observed. To explain this phenomenon, we have calculated
spectra of optically thin plasma using Cloudy code and found that
observed ratio of optical lines and UV continuum is possible and the
presence of heel processes stimulates luminescence in Mg I and 1600
Å lines.
Title: The Calculation of the Intensity of The Mg I Spectral Lines
in Solar Prominences Using the Cloudy code Model
Authors: Kupryakov, Yu. A.; Dodin, A. V.; Schwartz, P.; Kashapova,
L. K.
Bibcode: 2019simi.conf..139K
Altcode: 2019simi.conf..139D
Spectroscopical observations of several prominences in the MgI lines
were carried out from 2014 to 2017. These lines from visible part of
the solar spectrum play an important diagnostic role, complementing the
UV Mg II resonance lines regularly observed by the IRIS satellite. We
found that a rather weak Mg I emission, e.g., in the 5172.6 Å line
correlates well with the presence of extended bright areas on the
solar disk observed in the 1600 Å SDO/AIA band. However, in many cases
the radiation in the 5172.6 Å line is very low, even not detectable,
although a bright prominence above the limb or flare on the solar disc
were observed. To explain this phenomenon, we have calculated spectra
of optically thin plasma using Cloudy code and found that observed
ratio of optical lines and UV continuum is possible and the presence
of heel processes stimulates luminescence in Mg I and 1600 Å lines.
Title: Features of Solar Energetic Particle Events During the 23rd
Cycle Of Solar Activity and Their Relationship with Solar X-ray,
Gamma-Emission and Coronal Mass Ejections
Authors: Myagkova, I. N.; Miteva, R.; Kashapova, L.; Bogomolov, A. V.;
Danov, D.
Bibcode: 2019simi.conf..201M
Altcode:
The study on the relationship of solar cosmic ray events (in
particular, the ratio of the maximum between the proton and
electron fluxes) with X-ray and gamma radiation from solar
flares, as well as with parameters of coronal mass ejections
was carried out. It was done on the basis of SOHO/ERNE proton
event catalog (http://newserver.stil.bas.bg/SEPcatalog/)
and Solar Flares Catalog based on measurements of X- and
gamma-emission (>50 keV) detected by SONG (CORONAS-F –
Russian solar observatory) from August, 2001 till December, 2003
(http://swx.sinp.msu.ru/apps/solar_flares_cat/index.php). Solar electron
flux (> 300 keV) were measured in the polar caps by MKL-instrument
on board CORONAS-F satellite.
Title: About Productivity of the Solar Energetic Particle Events
Authors: Zhdanov, D. A.; Kashapova, L. K.; Myshyakov, I. I.; Miteva, R.
Bibcode: 2019simi.conf..211Z
Altcode:
We present an analysis of 22 SEPs events related to flares that
demonstrate significant microwave emission. We analyzed the microwave
burst parameters characterizing acceleration processes for each
event. In some events, despite the significant microwave signatures,
powerful SEPs were not produced. The current study aimed to check
the correlation of the SEP event productivity of active regions based
on features of their magnetic field topology and the presence of type
III radio bursts as an additional indicator of open magnetic field
lines. The magnetic field during the pre-flare stage was extrapolated
by a potential approximation. The obtained results are discussed.
Title: Results of work of new spectropolarimeter for solar radio
emission observations in the range 50-500 MHz
Authors: Muratova, Nataliia; Muratov, Anatoliy; Kashapova, Larisa
Bibcode: 2019STP.....5c...3M
Altcode: 2019SZF.....5c...3M
Ground-based observations within meter radio range are of importance
for understanding processes occurring in the solar corona. We present
concepts, block diagram, and results of first observations of the
Solar Spectropolarimeter of Meter Range (SSMD), launched for solar
observations in the range 50-500 MHz in April 2016. The main purpose of
this work was to develop an up-to-date digital radio spectropolarimeter
able to record the full Stokes vector for sporadic solar phenomena
taking place in the 50-500 MHz range. We use a crossed log periodic
antenna to detect solar radio emission. This antenna can simultaneously
obtain horizontal and vertical polarization components. The main part of
SSMD is a digital receiver based on an FX correlator architecture. We
use the Fast Fourier Transform (FFT) algorithm based on the real-time
pipeline circuit to construct amplitude dynamic spectra (intensity vs
frequency and time). SSMD has 4608 frequency channels with 97.66 kHz
channel bandwidth and 97.66 kHz spacing. Time resolution is 1 s. The
spectropolarimeter has a 50-500 MHz range. It can record the full
Stokes vector. At present, SSMD observes two of four parameters in
regular mode (I and V). We have observational data since 2016. The
catalog development is in progress. We plan to improve time and
frequency characteristics, record all Stokes parameters, and conduct
a calibration. We are working on providing access to the data archive
via the Internet.
Title: Study on the Features of the SEP Solar Origin Based on
Microwave Observations
Authors: Kashapova, L. K.; Meshalkina, N. S.; Miteva, R.; Zhukova,
A. V.; Myagkova, I. N.
Bibcode: 2019simi.conf..185K
Altcode:
We present the results on the analysis of microwave (MW) emission
in solar flares related to strong solar energetic particle (SEP)
events observed during the 23rd solar cycle. The parameters of the
MW spectrum were used as indicators of acceleration processes during
solar flares. The magnetic topology of the active regions (ARs) that
produced the flares were taken into account by the approach suggested
by Abrameko et al. [2018]. We found that during their evolution most
of the ARs related to proton-rich SEP events violated at least one
of the classical sunspot group evolution laws (Hale's law, Joy's law
et cetera). However, the statistical study of all ARs of the cycle
revealed the domination of normal ARs. The dependences between SEP
events and MW indicators of the acceleration process for different
groups are studied and discussed.
Title: Parameters of Thermal and Non-thermal X-ray and Gamma Ray
Emission of Solar Flares, Observed onboard CORONAS-F
Authors: Bogomolov, A. V.; Myagkova, I. N.; Miteva, R.; Danov, D.;
Kashapova, L. K.
Bibcode: 2019simi.conf..179B
Altcode:
Based on data from the SPR-N and SONG multi-channel hard electromagnetic
radiation detectors onboard the CORONAS-F space observatory and
the X-ray monitors onboard GOES satellites, we have distinguished
the thermal and non-thermal components in the X-ray spectrum of a
number of powerful flares of 23rd solar activity cycle. Temporal,
spectral and energetic parameters of the flares were analyzed using
the catalogs of Solar Energetic Particles and Related Phenomena
(http://newserver.stil.bas.bg/SEPcatalog/).
Title: Quasi-periodic pulsations in a solar flare with an unusual
phase shift
Authors: Kupriyanova, Elena G.; Kashapova, Larisa K.; Van Doorsselaere,
Tom; Chowdhury, Partha; Srivastava, Abhishek K.; Moon, Yong-Jae
Bibcode: 2019MNRAS.483.5499K
Altcode: 2018arXiv181209868K; 2018MNRAS.tmp.3312K
Two kinds of processes could occur during the flare decay
phase: processes of energy release or processes of energy
relaxation. Quasi-periodic pulsations (QPPs) of the broad-band
emission are a good tool for the verification of mechanisms. We aim
to study the processes during the decay phase of the X-class solar
flare SOL2014-03-29T17:48. The observations in X-ray, microwave, and
extreme ultraviolet bands are exploited to study the fine temporal,
spatial, and spectral structures of the flare. The periods, amplitudes,
and phases of both the fluxes and physical parameters [emission measure
(EM), temperature] are studied using standard methods of correlation,
Fourier, and wavelet analyses. It is found that the source of the QPPs
is associated with the uniform post-flare loop. The X-ray source is
located at the top of the arcade. QPPs with the similar characteristic
time scales of P ≈ 74-80 s are found in the X-ray (3-25 keV) and
microwave (15.7 GHz) emissions. Besides, QPPs with the same period are
found in the time profiles of both the temperature (Te) and
EM. The QPPs in temperature and the QPPs in EM demonstrate antiphase
behaviour. The analysis reveals the quasi-periodic process of energy
relaxation, without any additional source of energy during the decay
phase. The periods of the QPPs are in a good agreement with second
harmonic of standing slow magneto-acoustic wave in the arcade that
could be triggered by a Moreton wave initiated by the flare in the
direct vicinity of the arcade.
Title: Onset Time of the GLE 72 Observed at Neutron Monitors and
its Relation to Electromagnetic Emissions
Authors: Kurt, V.; Belov, A.; Kudela, K.; Mavromichalaki, H.;
Kashapova, L.; Yushkov, B.; Sgouropoulos, C.
Bibcode: 2019SoPh..294...22K
Altcode:
We present an overview of the ground-level enhancement (GLE 72) of the
cosmic-ray intensity associated with the recent powerful solar flare
SOL2017-09-10 (X-ray class X8.9) based on the available neutron monitor
(NM) network observations and on data from the satellite GOES 13. The
maximum increase at high-latitude near-sea-level NMs was ≈6 -7 %
(2-min averages), greater with better time resolution. A scatter plot
of the maximum increase of the GLE versus solar energetic-particle
(SEP, proton) flux >100 MeV shows one of the softest spectra
among GLEs relative to the SEP fluxes. However, at two high-mountain
middle-latitude NMs the increase was ≈1 % , indicating the possibility
of proton acceleration up to 6 GeV. Among the analyzed NM data the Fort
Smith (FSMT) NM shows the earliest and the rather high increase between
16:06 - 16:08 UT. This indicates an anisotropy in the first phase of
the GLE event. We calculate the acceptance cones of several NM stations
at high latitudes and contours of pitch angles corresponding to the
interplanetary magnetic field (IMF). When employing the available data
we find that pion-decay γ -ray emission onset is in accordance with the
time of the main flare energy release. The observed time interval of the
impulsive burst of >100 MeVγ -ray emission probably corresponds to
the time of a turbulent current sheet creation. The observed location
of the impulsive burst pion-decay emission source coincides with the
active region and the cusp-shaped structure. It seems that models
assuming sub-relativistic proton production beginning in a turbulent
reconnecting current sheet are consistent with the observations. If
these particles were released from the Sun during a type III emission
with a pion-decay maximum at 16 :00 :30 ±30 UT, we get a plausible
path length equal to 1.5 ±0.3 AU of the particles responsible for the
onset of the SEP event and GLE. The time lag of GLE 72 corresponds to
the most probable interval of the time difference between GLE onset and
main flare energy release. Although other scenarios are not excluded
we attribute the protons that create the pion-decay emission and
the protons responsible for the GLE and SEP event onset to a general
population of accelerated particles.
Title: On the role of preflares in tornado-type prominences
Authors: Kupryakov, Yu. A.; Kotrc, P.; Kashapova, L. K.
Bibcode: 2019A&AT...31..177K
Altcode:
We present first results of a study of rotation parameters of the
tornado-type promi- nences using Hα line spectra and filtergrams. The
prominences of the tornado-type were observed by ground-based
spectrographs MFS and HSFA 2 in the Ondrejov Observatory (Astronomical
Institute of AS CR) from 2000 to 2017. The analysis took into account
the structure and dynamics of selected prominences and a comparison
of the data of Hα with the EUV observations of SDO (304 Å, 193 Å,
171 Å), as well as information about the emission of flares in the
X-ray range. We found that most of the analyzed events were associated
with solar flares of classes from B5 to M5 by GOES classification. We
revealed two types of motions in the prominences. The first type
shows the Doppler velocity quasi-symmetry of the values in the "blue"
and "red" Hα line wings. The events of the other type demonstrate
a difference of up to one order of velocities in the direction of,
and towards, the observer.
Title: Characteristics of SEP Events and Their Solar Origin During
the Evolution of Active Region NOAA 10069
Authors: Kashapova, L. K.; Miteva, R.; Myagkova, I. N.; Bogomolov,
A. V.
Bibcode: 2019SoPh..294....9K
Altcode:
We present the results of a comparative analysis of the properties of
a series of successive solar flares, which occurred in active region
(AR) 10069 in August 2002, and the associated solar energetic particle
(SEP) events. The active region was extremely flare productive
during its evolution. The solar flare characteristics are based on
X-ray and radio emission data: maximum detected photon energies and
spectral index, delays between microwave, metric-radio and, hard
X-ray emissions. The coronal mass ejections (CMEs) are characterized
by their projected speed. The SEP properties are described by the
relative electron to proton abundance as well as by the abundance of
lower relative to higher energy particles. The analysis carried out
supports some previous results obtained by large statistical studies,
but at the same time refutes others. For example, the set of analyzed
events that occurred in the AR did not show clear evidence of the big
flare syndrome though the large proton events observed near Earth were
always accompanied by CMEs. Some of the peculiar observations could
be the result of the magnetic topology of the AR.
Title: Comparative analysis of the proton generation efficiency
during 17 March 2003 and 11 April 2004 solar flares
Authors: Bogomolov, A. V.; Myagkova, I. N.; Myshyakov, I.; Tsvetkov,
Ts; Kashapova, L.; Miteva, R.
Bibcode: 2018JASTP.179..517B
Altcode:
We present the comparative analysis of the solar energetic particle
(SEP) event properties and the indicators of acceleration processes
in solar flares - the hard X-rays (HXR) and radio emission from
microwaves to the meter-range. We focus our study on the two SEP
events associated with solar flares with similar characteristics in
HXR emission and the close location on solar disk. The proton flux
in the SEP event associated with the weaker flare by GOES class in
soft X-ray (SXR) (C9.6/SOL2004-Apr-11) was more than an order higher
than in the SEP event associated with the more powerful solar flare
(X1.5/SOL2003-Mar-17). At the same time, the electron fluxes in both SEP
events were comparable. Both flares were followed by CMEs with speed
above 1000 km s-1. The analysis of SEP fluxes and flare
plasma parameters was done taking into account the magnetic topology
of the active region (AR) and its evolution before and during the
solar flares. The 3D reconstruction of the potential magnetic field
showed the existence of an arcade of high loops covering the active
region where the more powerful flare occurred. The flare associated
with the proton-rich SEP event occurred in the active region where
3D reconstruction revealed a fan of high loops associated with open
magnetic field lines. We suppose that the arcade of high loops could be
the factor which prevents an escape of the accelerated particles into
the interplanetary space (IPS) while the fan of high loops facilitates
the production of the more proton-rich SEP events. Results of the
analysis show a necessity to use topology of ARs as a parameter in
statistical studies of SEP event origins.
Title: Radio, Hard X-Ray, and Gamma-Ray Emissions Associated with
a Far-Side Solar Event
Authors: Grechnev, V. V.; Kiselev, V. I.; Kashapova, L. K.; Kochanov,
A. A.; Zimovets, I. V.; Uralov, A. M.; Nizamov, B. A.; Grigorieva,
I. Y.; Golovin, D. V.; Litvak, M. L.; Mitrofanov, I. G.; Sanin, A. B.
Bibcode: 2018SoPh..293..133G
Altcode: 2018arXiv180810103G
The far-side solar eruptive event SOL2014-09-01 produced hard
electromagnetic and radio emissions that were observed with detectors at
near-Earth vantage points. Especially challenging was a long-duration
> 100 MeV γ -ray burst that was probably produced by accelerated
protons exceeding 300 MeV. This observation raised the question how
high-energy protons could reach the Earth-facing solar surface. Some
preceding studies discussed a scenario in which protons accelerated by a
shock driven by a coronal mass ejection high in the corona return to the
solar surface. We continue with the analysis of this challenging event,
involving radio images from the Nançay Radioheliograph and hard X-ray
data from the High Energy Neutron Detector (HEND) of the Gamma-Ray
Spectrometer onboard the Mars Odyssey space observatory located near
Mars. HEND recorded unocculted flare emission. The results indicate
that the emissions observed from the Earth's direction were generated by
flare-accelerated electrons and protons trapped in static long coronal
loops. They can be reaccelerated in these loops by a shock wave that was
excited by the eruption, being initially not driven by a coronal mass
ejection. The results highlight ways to address the remaining questions.
Title: Multi-instrument view on solar eruptive events observed with
the Siberian Radioheliograph: From detection of small jets up to
development of a shock wave and CME
Authors: Grechnev, V. V.; Lesovoi, S. V.; Kochanov, A. A.; Uralov,
A. M.; Altyntsev, A. T.; Gubin, A. V.; Zhdanov, D. A.; Ivanov, E. F.;
Smolkov, G. Ya.; Kashapova, L. K.
Bibcode: 2018JASTP.174...46G
Altcode: 2018arXiv180502564G
The first 48-antenna stage of the Siberian Radioheliograph (SRH)
started single-frequency test observations early in 2016, and since
August 2016 it routinely observes the Sun at several frequencies in
the 4-8 GHz range with an angular resolution of 1-2 arc minutes and
an imaging interval of about 12 s. With limited opportunities of the
incomplete antenna configuration, a high sensitivity of about 100
Jy allows the SRH to contribute to the studies of eruptive phenomena
along three lines. First, some eruptions are directly visible in SRH
images. Second, some small eruptions are detectable even without a
detailed imaging information from microwave depressions caused by
screening the background emission by cool erupted plasma. Third,
SRH observations reveal new aspects of some events to be studied
with different instruments. We focus on an eruptive C2.2 flare on
16 March 2016 around 06:40, one of the first flares observed by the
SRH. Proceeding from SRH observations, we analyze this event using
extreme-ultraviolet, hard X-ray, white-light, and metric radio data. An
eruptive prominence expanded, brightened, and twisted, which indicates
a time-extended process of the flux-rope formation together with the
development of a large coronal mass ejection (CME). The observations
rule out a passive role of the prominence in the CME formation. The
abrupt prominence eruption impulsively excited a blast-wave-like
shock, which appeared during the microwave burst and was manifested
in an "EUV wave" and Type II radio burst. The shock wave decayed and
did not transform into a bow shock because of the low speed of the
CME. Nevertheless, this event produced a clear proton enhancement near
Earth. Comparison with our previous studies of several events confirms
that the impulsive-piston shock-excitation scenario is typical of
various events.
Title: Results of comparative analysis of the SEP events and the
microwave bursts observed by 2-24 GHz and 4-8 GHz spectropolarimeters
in 2010-2016
Authors: Zhdanov, D.; Kashapova, L. K.; Miteva, R.
Bibcode: 2018simi.conf..105Z
Altcode:
We present a relationship analysis between the solar energetic particle
(SEP) events and the microwave (MW) spectral observations of the solar
bursts detected in 2010-2016. The information about the SEP events
is taken from the Wind/EPACT catalog based on data in the period
1996-2016. We use MW data from the archive of MW observations in the
range 2-24 GHz. Observations were made by spectropolarimeters of the
SSRT observatory (Russia). We found that 40 events are present in both
catalogs. We tested the relationships between the proton spectral index
of SEP events and the peak frequency of the MW bursts and presence of
circular polarization in MW emission of selected events. The results
are finally discussed.
Title: Analysing of the SEP origins based on microwave emission of
solar flares
Authors: Kashapova, L.; Mehsalkina, N.; Miteva, R.; Myagkova, I.;
Bogomolov, A.
Bibcode: 2018simi.conf..119K
Altcode:
We present the results on the analysis of microwave emission in
solar flares related to strong solar energetic particle (SEP) events
observed during the previous solar cycle. The target of the work is
to find criteria based on the solar flare features that would allow
us to separate the SEP events into groups with more homogeneous
physical/topological properties. In the current study, we compared
peak frequency of microwave spectra and spectral index with spectral
characteristics of SEP proton fluxes. The two groups of events related
to the value of the peak frequency are found. We discuss revealed
tendencies and physical reasons of the two population appearances.
Title: The efficiency of solar energetic particle generation:
CORONAS-F mission data analysis
Authors: Myagkova, I. N.; Miteva, R.; Kashapova, L.; Bogomolov, A. V.;
Petrov, V.; Tsvetkov, Ts.; Meshalkina, N.; Myshyakov, I.
Bibcode: 2018simi.conf..114M
Altcode:
We present the results of a comparative analysis on the efficiency
of the solar energetic particle events (SEP) and related solar
flares. Both SEP events and solar flares were detected by the CORONAS-F
solar mission. We selected the SEP events based on the presence of
simultaneous observations from the hard X-ray (HXR) instrument SONG
(CORONAS-F satellite) with radio emission ranging from microwaves
to the meter-range, as evidence of accelerated particles generated
during the events and solar proton and electron data measured by MKL
instrument on board CORONAS-F satellite in polar caps. The results
are discussed from point of using solar flare emission features as
the criteria of generation of SEP event with high proton abundance.
Title: Homologous Circular-ribbon Flares Driven by Twisted Flux
Emergence
Authors: Xu, Z.; Yang, K.; Guo, Y.; Zhao, J.; Zhao, Z. J.; Kashapova,
L.
Bibcode: 2017ApJ...851...30X
Altcode:
In this paper, we report two homologous circular-ribbon flares
associated with two filament eruptions. They were well observed by the
New Vacuum Solar Telescope and the Solar Dynamics Observatory on 2014
March 5. Prior to the flare, two small-scale filaments enclosed by a
circular pre-flare brightening lie along the circular polarity inversion
line around the parasitic polarity, which has shown a continuous
rotation since its first appearance. Two filaments eventually erupt
in sequence associated with two homologous circular-ribbon flares and
display an apparent writhing signature. Supplemented by the nonlinear
force-free field extrapolation and the magnetic field squashing factor
investigation, the following are revealed. (1) This event involves
the emergence of magnetic flux ropes into a pre-existing polarity
area, which yields the formation of a 3D null-point topology in
the corona. (2) Continuous input of the free energy in the form of
a flux rope from beneath the photosphere may drive a breakout-type
reconnection occurring high in the corona, supported by the pre-flare
brightening. (3) This initiation reconnection could release the
constraint on the flux rope and trigger the MHD instability to first
make filament F1 lose equilibrium. The subsequent more violent magnetic
reconnection with the overlying flux is driven during the filament
rising. In return, the eruption of filament F2 is further facilitated by
the reduction of the magnetic tension force above. These two processes
form a positive feedback to each other to cause the energetic mass
eruption and flare.
Title: The origin of SEP events: New research collaboration and
network on space weather
Authors: Miteva, Rositsa; Kashapova, Larisa; Myagkova, Irina;
Meshalkina, Nataliia; Petrov, Nikola; Bogomolov, Andrey; Myshyakov,
Ivan; Tsvetkov, Tsvetan; Danov, Dimitar; Zdanov, Dmitriy
Bibcode: 2017ses..conf...57M
Altcode:
A new project on the solar energetic particles (SEPs) and their solar
origins (flares and coronal mass ejections) is described here. The
main aim of this project is to answer the question - whether the SEPs
observed in situ are driven by flares, by CMEs or both accelerators
contribute to an extent which varies from event to event - by deducing
a quantitative measure of the flare vs. CME contribution, duration
and efficiency. New observations (SONG/Koronas-F, Relec/Vernov) and
new approaches of analysis will be utilized (e.g., magnetic topology
of active regions using 3D extrapolation techniques of detailed
case studies together with statistical analysis of the phenomena). In
addition, the identification of the uncertainty limits of SEP injection,
onset time and testing the validity of assumptions often taken for
granted (association procedures, solar activity longitudinal effects,
correlation analysis, etc.) are planned. The project outcomes have
the capacity to contribute to other research fields for improvement
of modeling schemes and forecasting methods of space weather events.
Title: CORONAS-F observation of gamma-ray emission from the solar
flare on 2003 October 29
Authors: Kurt, Victoria G.; Yushkov, Boris Yu.; Galkin, Vladimir I.;
Kudela, Karel; Kashapova, Larisa K.
Bibcode: 2017NewA...56..102K
Altcode: 2018arXiv180802627K
Appreciable hard X-ray (HXR) and gamma-ray emissions in the 0.04-150 MeV
energy range associated with the 2003 October 29 solar flare (X10/3B)
were observed at 20:38-20:58 UT by the SONG instrument onboard the
CORONAS-F mission. To restore flare gamma-ray spectra we fitted the
SONG energy loss spectra with a three-component model of the incident
spectrum: (1) a power law in energy, assumed to be due to electron
bremsstrahlung; (2) a broad continuum produced by prompt nuclear
de-excitation gamma-lines; and (3) a broad gamma-line generated from
pion-decay. We also restored spectra from the RHESSI data, compared
them with the SONG spectra and found a reasonable agreement between
these spectra in the 0.1-10 MeV energy range. The pion-decay emission
was observed from 20:44:20 UT and had its maximum at 20:48-20:51 UT. The
power-law spectral index of accelerated protons estimated from the ratio
between intensities of different components of gamma rays changed with
time. The hardest spectrum with a power-law index S = -3.5 - 3.6 was
observed at 20:48-20:51 UT. Time histories of the pion-decay emission
and proton spectrum were compared with changes of the locations
of flare energy release as shown by RHESSI hard X-ray images and
remote and remote Hα brightenings. An apparent temporal correlation
between processes of particle acceleration and restructuring of flare
magnetic field was found. In particular, the protons were accelerated
to subrelativistic energies after radical change of the character of
footpoint motion from a converging motion to a separation motion.
Title: Siberian Radioheliograph: first results
Authors: Lesovoi, Sergey; Altyntsev, Alexander; Kochanov, Aleksey;
Grechnev, Victor; Gubin, Aleksey; Zhdanov, Dmitriy; Ivanov, Evgeniy;
Uralov, Arkadiy; Kashapova, Larisa; Kuznetsov, Aleksey; Meshalkina,
Nataliya; Sych, Robert
Bibcode: 2017STP.....3a...3L
Altcode: 2017SZF.....3a...3L; 2017arXiv170407100L
Regular observations of active processes in the solar atmosphere
have been started using the first stage of the multiwave Siberian
Radioheliograph (SRH), a T-shaped 48-antenna array with a 4-8 GHz
operating frequency range and a 10 MHz instantaneous receiving
band. Antennas are mounted on the central antenna posts of the
Siberian Solar Radio Telescope. The maximum baseline is 107.4 m,
and the angular resolution is up to 70". We present examples of
observations of the solar disk at different frequencies, "negative"
bursts, and solar flares. The sensitivity to compact sources reaches
0.01 solar flux units (≈10-4 of the total solar flux)
with an accumulation time of about 0.3 s. The high sensitivity of
SRH enables monitoring of solar activity and allows studying active
processes from characteristics of their microwave emission, including
faint events, which could not be detected previously.
Title: Fermi-LAT Observations of High-energy Behind-the-limb Solar
Flares
Authors: Ackermann, M.; Allafort, A.; Baldini, L.; Barbiellini, G.;
Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Bonino, R.; Bottacini, E.;
Bregeon, J.; Bruel, P.; Buehler, R.; Cameron, R. A.; Caragiulo, M.;
Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Ciprini, S.;
Costanza, F.; Cutini, S.; D'Ammando, F.; de Palma, F.; Desiante, R.;
Digel, S. W.; Di Lalla, N.; Di Mauro, M.; Di Venere, L.; Drell, P. S.;
Favuzzi, C.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Giglietto, N.;
Giordano, F.; Giroletti, M.; Grenier, I. A.; Guillemot, L.; Guiriec,
S.; Jogler, T.; Jóhannesson, G.; Kashapova, L.; Krucker, S.; Kuss,
M.; La Mura, G.; Larsson, S.; Latronico, L.; Li, J.; Liu, W.; Longo,
F.; Loparco, F.; Lubrano, P.; Magill, J. D.; Maldera, S.; Manfreda,
A.; Mazziotta, M. N.; Mitthumsiri, W.; Mizuno, T.; Monzani, M. E.;
Morselli, A.; Moskalenko, I. V.; Negro, M.; Nuss, E.; Ohsugi, T.;
Omodei, N.; Orlando, E.; Pal'shin, V.; Paneque, D.; Perkins, J. S.;
Pesce-Rollins, M.; Petrosian, V.; Piron, F.; Principe, G.; Rainò,
S.; Rando, R.; Razzano, M.; Reimer, O.; Rubio da Costa, F.; Sgrò,
C.; Simone, D.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli,
P.; Tajima, H.; Thayer, J. B.; Torres, D. F.; Troja, E.; Vianello, G.
Bibcode: 2017ApJ...835..219A
Altcode: 2017arXiv170200577A
We report on the Fermi-LAT detection of high-energy emission from the
behind-the-limb (BTL) solar flares that occurred on 2013 October 11,
and 2014 January 6 and September 1. The Fermi-LAT observations are
associated with flares from active regions originating behind both
the eastern and western limbs, as determined by STEREO. All three
flares are associated with very fast coronal mass ejections (CMEs)
and strong solar energetic particle events. We present updated
localizations of the >100 MeV photon emission, hard X-ray (HXR)
and EUV images, and broadband spectra from 10 keV to 10 GeV, as well
as microwave spectra. We also provide a comparison of the BTL flares
detected by Fermi-LAT with three on-disk flares and present a study
of some of the significant quantities of these flares as an attempt
to better understand the acceleration mechanisms at work during these
occulted flares. We interpret the HXR emission to be due to electron
bremsstrahlung from a coronal thin-target loop top with the accelerated
electron spectra steepening at semirelativistic energies. The >100
MeV gamma-rays are best described by a pion-decay model resulting
from the interaction of protons (and other ions) in a thick-target
photospheric source. The protons are believed to have been accelerated
(to energies >10 GeV) in the CME environment and precipitate down to
the photosphere from the downstream side of the CME shock and landed
on the front side of the Sun, away from the original flare site and
the HXR emission.
Title: Fermi Large Area Telescope Observations of High-Energy
Gamma-ray Emission From Behind-the-limb Solar Flares
Authors: Omodei, Nicola; Pesce-Rollins, Melissa; Petrosian, Vahe;
Liu, Wei; Rubio da Costa, Fatima; Golenetskii, Sergei; Kashapova,
Larisa; Krucker, Sam; Palshin, Valentin; Fermi Large Area Telescope
Collaboration
Bibcode: 2017APS..APR.Y3005O
Altcode:
Fermi LAT >30 MeV observations of the active Sun have increased
the number of detected solar flares by almost a factor of 10 with
respect to previous space observations. Of particular interest are the
recent detections of three solar flares whose position behind the limb
was confirmed by the STEREO-B spacecraft. These observations sample
flares from active regions originating from behind both the eastern
and western limbs and include an event associated with the second
ground level enhancement event (GLE) of the 24th Solar Cycle. While
gamma-ray emission up to tens of MeV resulting from proton interactions
has been detected before from occulted solar flares, the significance
of these particular events lies in the fact that these are the first
detections of >100 MeV gamma-ray emission from footpoint-occulted
flares. These detections present an unique opportunity to diagnose
the mechanisms of high-energy emission and particle acceleration and
transport in solar flares. We will present the Fermi-LAT, RHESSI and
STEREO observations of these flares and discuss the various emission
scenarios for these sources.
Title: Solar X-ray Emission Measured by the Vernov Mission During
September - October of 2014
Authors: Myagkova, I. N.; Bogomolov, A. V.; Kashapova, L. K.;
Bogomolov, V. V.; Svertilov, S. I.; Panasyuk, M. I.; Kuznetsova,
E. A.; Rozhkov, G. V.
Bibcode: 2016SoPh..291.3439M
Altcode: 2016SoPh..tmp..128M
Solar hard X-ray and γ -ray emissions were measured by the Detector
of the Roentgen and Gamma-ray Emissions (DRGE) instrument, which is
part of the RELEC set of instruments operated onboard the Russian
satellite Vernov, from July 8, 2014 until December 10, 2014 (on a
solar-synchronous orbit with an apogee of 830 km, perigee of 640 km,
and an inclination of 98.4∘). RELEC measurements of 18
flares with X-ray energy >30 keV, taken in September - October
2014, were connected with the same active region with the number AR
12172 during the first rotation and AR 12192 during the next one. These
measurements were compared to the data obtained with RHESSI, Konus-Wind,
Fermi Observatory, Radio Solar Telescope Net (RSTN), and the Nobeyama
Radioheliograph (NoRH) operating at the same time. Quasi-periodicities
with similar periods of 7 ±2 s were found in about one third of all
flares measured by RELEC (Vernov) from September 24 until October
30, 2014.
Title: Relationship of Type III Radio Bursts with Quasi-periodic
Pulsations in a Solar Flare
Authors: Kupriyanova, E. G.; Kashapova, L. K.; Reid, H. A. S.;
Myagkova, I. N.
Bibcode: 2016SoPh..291.3427K
Altcode: 2016arXiv160800129K; 2016SoPh..tmp..127K
We studied a solar flare with pronounced quasi-periodic pulsations
detected in the microwave, X-ray, and radio bands. We used correlation,
Fourier, and wavelet analyses methods to examine the temporal fine
structures and relationships between the time profiles in each wave
band. We found that the time profiles of the microwaves, hard X-rays,
and type III radio bursts vary quasi-periodically with a common period
of 40 - 50 s. The average amplitude of the variations is high, above
30 % of the background flux level, and reaches 80 % after the flare
maximum. We did not find this periodicity in either the thermal X-ray
flux component or in the source size dynamics. Our findings indicate
that the detected periodicity is probably associated with periodic
dynamics in the injection of non-thermal electrons, which can be
produced by periodic modulation of magnetic reconnection.
Title: Diagnosing the Source Region of a Solar Burst on 26 September
2011 by Using Microwave Type-III Pairs
Authors: Tan, B. L.; Karlický, M.; Mészárosová, H.; Kashapova,
L.; Huang, J.; Yan, Y.; Kontar, E. P.
Bibcode: 2016SoPh..291.2407T
Altcode: 2016SoPh..tmp..143T; 2016arXiv160605410T
We report a peculiar and interesting train of microwave Type-III pair
bursts in the impulsive rising phase of a solar flare on 26 September
2011. The observations include radio spectrometers at frequencies
of 0.80 - 2.00 GHz from the Ondřejov radiospectrograph in the
Czech Republic (ORSC), hard X-ray from the Ramaty High-Energy Solar
Spectroscopic Imager (RHESSI) and Gamma-Ray Burst Monitor onboard
the Fermi Space Telescope (Fermi/GRB), EUV images from the Sun
Watcher using APS detectors and image Processing instrument onboard
the Project for Onboard Autonomy 2 (SWAP/PROBA2), and magnetograms
from the Helioseismic and Magnetic Imager onboard the Solar Dynamic
Observatory (SDO/HMI). By using a recently developed method (Tan et al.,
Res. Astron. Astrophys.16, 82, 2016a), we diagnosed the plasma density,
temperature, plasma-β , magnetic field near the source region, the
energy of energetic electrons, and the distance between the acceleration
region and the emission start sites of Type-III bursts. From the
diagnostics, we find that i) The plasma density, temperature, magnetic
field, and the distance between the acceleration region and the emission
start sites have almost no obvious variations during the period of
Type-III pair trains, while the energy of electrons has an obvious
peak value that is consistent with the hard X-ray emission. ii) The
plasma-β is much higher than unity, showing a highly dynamic process
near the emission start site of Type-III bursts. iii) Although the
reversed-slope Type-III branches drift more slowly by one order of
magnitude than that of the normal Type-IIIs, the related descending
and ascending electrons still could have energy of the same order of
magnitude. These facts indicate that both the ascending and descending
electrons are possibly accelerated by a similar mechanism and in a
small source region. These diagnostics can help us to understand the
physics in the source region of solar bursts.
Title: Broadband microwave sub-second pulsations in an expanding
coronal loop of the 2011 August 10 flare
Authors: Mészárosová, H.; Rybák, J.; Kashapova, L.; Gömöry,
P.; Tokhchukova, S.; Myshyakov, I.
Bibcode: 2016A&A...593A..80M
Altcode: 2016arXiv160904217M
Aims: We studied the characteristic physical properties and
behavior of broadband microwave sub-second pulsations observed in
an expanding coronal loop during the GOES C2.4 solar flare on 2011
August 10.
Methods: The complex microwave dynamic spectrum and
the expanding loop images were analyzed with the help of SDO/AIA/HMI,
RHESSI, and the STEREO/SECCHI-EUVI data processing software, wavelet
analysis methods, the GX Simulator tool, and the NAFE method.
Results: We found sub-second pulsations and other different burst
groups in the complex radio spectrum. The broadband (bandwidth about
1 GHz) sub-second pulsations (temporal period range 0.07-1.49 s,
no characteristic dominant period) lasted 70 s in the frequency
range 4-7 GHz. These pulsations were not correlated at their
individual frequencies, had no measurable frequency drift, and zero
polarization. In these pulsations, we found the signatures of fast
sausage magnetoacoustic waves with the characteristic periods of 0.7
and 2 s. The other radio bursts showed their characteristic frequency
drifts in the range of -262-520 MHz s-1. They helped us to
derive average values of 20-80 G for the coronal magnetic field strength
in the place of radio emission. It was revealed that the microwave
event belongs to an expanding coronal loop with twisted sub-structures
observed in the 131, 94, and 193 Å SDO/AIA channels. Their slit-time
diagrams were compared with the location of the radio source at 5.7 GHz
to realize that the EUV intensity of the expanding loop increased just
before the radio source triggering. We reveal two EUV bidirectional
flows that are linked with the start time of the loop expansion. Their
positions were close to the radio source and propagated with velocities
within a range of 30-117 km s-1.
Conclusions: We
demonstrate that periodic regime of the electron acceleration in a model
of the quasi-periodic magnetic reconnection might be able to explain
physical properties and behavior of the sub-second pulsations. The
depolarization process of the microwave emission might be caused by
a plasma turbulence in the radio source. Finally, the observed EUV
flows might be linked with reconnection outflows.
Title: Time delays in the nonthermal radiation of solar flares
according to observations of the CORONAS-F satellite
Authors: Tsap, Yu. T.; Stepanov, A. V.; Kashapova, L. K.; Myagkova,
I. N.; Bogomolov, A. V.; Kopylova, Yu. G.; Goldvarg, T. B.
Bibcode: 2016CosRe..54..285T
Altcode:
In 2001-2003, the X-ray and microwave observations of ten solar flares
of M- and X-classes were carried out by the CORONAS-F orbital station,
the RSTN Sun service, and Nobeyama radio polarimeters. Based on these
observations, a correlation analysis of time profiles of nonthermal
radiation was performed. On average, hard X-ray radiation outstrips the
microwave radiation in 9 events, i.e., time delays are positive. The
appearance of negative delays is associated with effective scattering
of accelerated electrons in pitch angles, where the length of the free
path of a particle is less than the half-length of a flare loop. The
additional indications are obtained in favor of the need to account for
the effect of magnetic mirrors on the dynamics of energetic particles
in the coronal arches.
Title: A Cold Flare with Delayed Heating
Authors: Fleishman, Gregory D.; Pal'shin, Valentin D.; Meshalkina,
Natalia; Lysenko, Alexandra L.; Kashapova, Larisa K.; Altyntsev,
Alexander T.
Bibcode: 2016ApJ...822...71F
Altcode: 2016arXiv160307273F
Recently, a number of peculiar flares have been reported that
demonstrate significant nonthermal particle signatures with low,
if any, thermal emission, which implies a close association of the
observed emission with the primary energy release/electron acceleration
region. This paper presents a flare that appears “cold” at the
impulsive phase, while displaying delayed heating later on. Using
hard X-ray data from Konus-Wind, microwave observations by SSRT, RSTN,
NoRH, and NoRP, context observations, and three-dimensional modeling,
we study the energy release, particle acceleration, and transport, and
the relationships between the nonthermal and thermal signatures. The
flaring process is found to involve the interaction between a small
loop and a big loop with the accelerated particles divided roughly
equally between them. Precipitation of the electrons from the small loop
produced only a weak thermal response because the loop volume was small,
while the electrons trapped in the big loop lost most of their energy in
the coronal part of the loop, which resulted in coronal plasma heating
but no or only weak chromospheric evaporation, and thus unusually
weak soft X-ray emission. The energy losses of the fast electrons in
the big tenuous loop were slow, which resulted in the observed delay
of the plasma heating. We determined that the impulsively accelerated
electron population had a beamed angular distribution in the direction
of the electric force along the magnetic field of the small loop. The
accelerated particle transport in the big loop was primarily mediated
by turbulent waves, which is similar to other reported cold flares.
Title: A Tiny Eruptive Filament as a Flux-Rope Progenitor and Driver
of a Large-Scale CME and Wave
Authors: Grechnev, V. V.; Uralov, A. M.; Kochanov, A. A.; Kuzmenko,
I. V.; Prosovetsky, D. V.; Egorov, Y. I.; Fainshtein, V. G.; Kashapova,
L. K.
Bibcode: 2016SoPh..291.1173G
Altcode: 2016SoPh..tmp...57G; 2016arXiv160400800G
A solar eruptive event SOL2010-06-13 observed with the Atmospheric
Imaging Assembly (AIA) of the Solar Dynamics Observatory (SDO) has been
extensively discussed in the contexts of the CME development and an
associated extreme-ultraviolet (EUV) wave-like transient in terms of a
shock driven by the apparent CME rim. Continuing the analysis of this
event, we have revealed an erupting flux rope, studied its properties,
and detected wave signatures inside the developing CME. These findings
have allowed us to establish new features in the genesis of the CME and
associated EUV wave and to reconcile all of the episodes into a single
causally related sequence. i) A hot 11 MK flux rope developed from the
structures initially associated with a compact filament system. The flux
rope expanded with an acceleration of up to 3 km s−2 one
minute before a hard X-ray burst and earlier than any other structures,
reached a velocity of 420 km s−1, and then decelerated
to about 50 km s−1. ii) The CME development was driven
by the expanding flux rope. Closed coronal structures above the rope
got sequentially involved in the expansion from below upwards, came
closer together, and apparently disappeared to reveal their common
envelope, the visible rim, which became the outer boundary of the
cavity. The rim was probably associated with the separatrix surface of
a magnetic domain, which contained the pre-eruptive filament. iii) The
rim formation was associated with a successive compression of the upper
active-region structures into the CME frontal structure (FS). When the
rim was formed, it resembled a piston. iv) The disturbance responsible
for the consecutive CME formation episodes was excited by the flux rope
inside the rim, and then propagated outward. EUV structures arranged
at different heights started to accelerate, when their trajectories
in the distance-time diagram were crossed by that of the fast front of
this disturbance. v) Outside the rim and FS, the disturbance propagated
like a blast wave, manifesting in a type II radio burst and a leading
part of the EUV transient. Its main, trailing part was the FS, which
consisted of swept-up 2 MK coronal loops enveloping the expanding
rim. The wave decelerated and decayed into a weak disturbance soon
afterwards, being not driven by the trailing piston, which slowed down.
Title: Sunspot waves and flare energy release
Authors: Sych, R.; Karlický, M.; Altyntsev, A.; Dudík, J.;
Kashapova, L.
Bibcode: 2015A&A...577A..43S
Altcode: 2014arXiv1409.2947S
Context. We study the possibility of flare process triggering by
waves propagating from the sunspot along a magnetic loop (channel)
to a nearby flare site.
Aims: We present a relationship between
the dynamics of ~3-min slow magnetoacoustic waves in the sunspot and
flare emergence process. Waves propagating in the magnetic channel
whose one foot is anchored in the umbra represent the disturbing agent
responsible for triggering the flare energy release.
Methods:
We applied time-distance plots and pixel wavelet filtration methods
to obtain spatio-temporal distribution of wave power variations in
radio and SDO/AIA data. To find the magnetic channel, we used potential
magnetic field extrapolation of SDO/HMI magnetograms. The propagation
velocity of wave fronts was measured from wave locations at specific
times.
Results: In the correlation curves of the 17 GHz (NoRH)
radio emission, we found a monotonous energy amplification of the
3-min waves in the sunspot umbra before the 2012 June 7 flare. This
amplification was associated with an increase in the length of the
oscillatory wakes in coronal loops (SDO/AIA, 171 Å) prior to the flare
onset. A peculiarity of the flare is the constant level of the flare
emission in soft X-rays (RHESSI, 3-25 keV) for ~10 min after the short
impulsive phase, which indicates continuing energy release. Throughout
this time, we found transverse oscillations of the flare loop with a
30 s period in the radio-frequency range (NoRH, 17 GHz). This period
appears to be related to the 3-min waves from the sunspot. The magnetic
field extrapolation based on SDO/HMI magnetograms shows the existence
of the magnetic channel (waveguide) connecting the sunspot with the
energy release region.
Conclusions: We analysed the sunspot
3-min wave dynamics and found a correlation between the oscillation
power amplification and flare triggering in the region connected to the
sunspot through the magnetic channel. We propose that this amplified
wave flux triggered the flare. The flare occurred because of this
amplified flux, however, and because a sufficient amount of free
magnetic energy was accumulated in close vicinity to the magnetic
channel prior to the flare. Furthermore, because of loop heating,
the wave velocity (sound velocity) increased with the penetration of
waves into the energy release site. The heating is shown to be able to
proceed after the flare main peak owing to a further energy pumping
in the form of waves from the sunspot and additional reconnection
episodes in the flare region.
Title: CORONAS-F observation of HXR and gamma-ray emissions from
the solar flare X10 on 29 October 2003 as a probe of accelerated
proton spectrum
Authors: Kurt, V. G.; Yushkov, B. Yu.; Kudela, K.; Galkin, V. I.;
Kashapova, L. K.
Bibcode: 2015CoSka..45...42K
Altcode:
HXR and gamma-ray emissions in the 0.04—150 MeV energy range
associated with the solar flare on 29 October 2003 (X10/3B) were
observed at 20:38—20:58 UT by the SONG instrument aboard the CORONAS-F
mission. We restored consecutive flare gamma-emission spectra from
SONG and RHESSI data and found a good agreement of these spectra in
the 0.1—10 MeV energy range. Two phases were identified which showed
major changes in the spectral shape of flare emission: 20:38:00-20:44:20
UT and 20:44:20-20:58:00 UT. During the second phase an efficiency of
proton acceleration increased considerably relatively to the efficiency
of acceleration of high energy electrons. The pion-decay component of
the flare gamma-emission was elicited statistically significant only
during the second phase since 20:47:40 UT. A power law spectrum index of
accelerated protons was estimated from the ratio between intensities of
the pion-decay and gamma-line components. The hardest spectrum (power
law index S=3.7) was at 20:48—20:51 UT when the intensity of the
pion-decay emission was maximal. Our subdivision of the flare into two
phases is consistent with sharp changes in the structure of the flare
found by Ji et al. (2008) and Liu et al. (2009). This flare was
accompanied by GLE 66. The time profile of the pion-decay gamma-emission
was compared with the GLE onset time. It was shown that both protons
interacting at the Sun and the particles responsible for the GLE onset
could belong to the same population of accelerated particles.
Title: Editorial: solar radiophysics — recent results on
observations and theories
Authors: Nakariakov, Valery M.; Kashapova, Larisa K.; Yan, Yi-Hua
Bibcode: 2014RAA....14....1N
Altcode:
Solar radiophysics is a rapidly developing branch of solar physics
and plasma astrophysics. Solar radiophysics has the goal of analyzing
observations of radio emissions from the Sun and understanding basic
physical processes operating in quiet and active regions of the solar
corona. In the near future, the commissioning of a new generation
of solar radio observational facilities, which include the Chinese
Spectral Radio Heliograph (CSRH) and the upgrade of the Siberian
Solar Radio Telescope (SSRT), and the beginning of solar observations
with the Atacama Large Millimeter/submillimeter Array (ALMA), is
expected to bring us new breakthrough results of a transformative
nature. The Marie-Curie International Research Staff Exchange (MC
IRSES) “RadioSun” international network aims to create a solid
foundation for the successful exploitation of upcoming solar radio
observational facilities, as well as intensive use of the existing
observational tools, advanced theoretical modeling of relevant physical
processes and observables, and training a new generation of solar
radio physicists. The RadioSun network links research teams from China,
Czech Republic, Poland, Russia and the UK. This mini-volume presents
research papers based on invited reviews and contributed talks at
the 1st RadioSun workshop in China. These papers cover a broad range
of research topics and include recent observational and theoretical
advances in solar radiophysics, MHD seismology of the solar corona,
physics of solar flares, generation of radio emission, numerical
modeling of MHD and plasma physics processes, charged-particle
acceleration and novel instrumentation.
Title: Dynamics of the hard X-ray, gamma-ray, and microwave emission
of solar flares produced by the active region NOAA 0069 in August 2002
Authors: Bogomolov, A. V.; Kashapova, L. K.; Myagkova, I. N.; Tsap,
Yu. T.
Bibcode: 2014ARep...58..156B
Altcode:
Regularities have been searched for in the dynamics of characteristics
of flare solar radiation during the development of the active region
NOAA 0069 in the interval of August 14-24, 2002. The SONG (Solar
Neutrons and Gamma rays) instrument onboard the Russian CORONAS-F Solar
Observatory recorded hard X-ray and gamma-ray radiation in nine of the
30 flares of class above C5 in this active region within the indicated
time interval. It was obtained that, in accordance with the development
of the active region, the X- and gamma-ray flux tended to increase at
the flare maxima while the hard X-ray spectral index tended to decrease;
flares with a harder radiation spectrum occurred in the sunspot umbra,
i.e., in the region with the strongest magnetic fields.
Title: Analysis of time structure of the radio and HXR-emission
of solar flares produced by AR0069 and their connection with
characteristics of SEP events
Authors: Myagkova, Irina; Kashapova, Larisa; Miteva, Rositsa;
Bogomolov, Andrew
Bibcode: 2014cosp...40E2212M
Altcode:
The results of the experimental investigation of solar energetic
particles acceleration and propagation based on the study of delays
between radio and X-rays emission of flares produced by the active
region 0069 in August 2002 are present. Parameters of SXR and HXR photon
spectrum as characteristics of acceleration processes were compared with
SEP flux, their maximal energy and spectral index. Structure analysis
of delays between microwave, meter and X-ray emission was carried
out in order to study processes of accelerated at the Sun particle
propagation and possible mechanisms of additional acceleration. It was
obtained that during this series of flares more powerful SEP events
with higher energies were observed in time flares with the minimal
delay between microwave and HXR emission. The obtained results are
discussed in respect to possible models of the SEP propagation.
Title: On the Flat Gradual Phase of the 21 July 2013 Flare
Authors: Kashapova, Larisa; Sych, Robert; Zhdanov, Dmitrii;
Tokhchukova, Susanna
Bibcode: 2014cosp...40E1413K
Altcode:
We present results of study of energy release process in the C3.1
solar flare occurred on July 21, 2013. This event demonstrated about
30-minutes duration flat period in the X-ray flux curve in the 3-12
keV energy band during the gradual phase of the flare. Existence of
this particular shape period was confirmed by EUV observations by
EVE/SDO and microwave data. The reasons of such long suppression of
plasma cooling are studied using the analysis of temporal profiles of
EUV, X-ray, microwave emission and plasma parameters (temperature and
emission measure). The aim of the study is the revealing and analysis
of quasi-periodic pulsations which could be an indicator of the energy
input or cooling suppressing during the studied period. Special
attention is given to the analysis of microwave spectra obtained
by RATAN-600 and Badary Broadband Microwave Spectropolarimeters
(BBMS). The obtained results are discussed from the point of view of
different mechanisms explaining the long duration events (LDE).
Title: CORONAS-F detection of gamma-ray emission from the solar
flare on 29 October 2003
Authors: Kurt, Victoria; Kashapova, Larisa; Yushkov, Boris; Kudela,
Karel; Galkin, Vladimir
Bibcode: 2014cosp...40E1705K
Altcode:
Appreciable HXR/gamma-ray emissions in the 0.015-150 MeV energy
range associated with the solar flare on 29 October 2003 (X10/3B) were
observed at 20:41-20:58 with the SPR-N and SONG instruments onboard the
CORONAS-F mission. Two time intervals were identified which showed major
changes in the intensity of these emissions. To specify the details
of the spectral changes with time, we fitted the SONG energy loss
spectra with a three-component model of incident gamma-ray spectrum:
(1) a power law in energy, assumed to be due to electron bremsstrahlung;
(2) a broad continuum produced by nuclear de-excitation gamma-lines;
and (3) a broad gamma-line generated from pion decay. We study the
relationship between non-imaging observations, particularly between time
of pion-decay emission onset and motions in this solar flare, using HXR
foot points (FP) separation and flare shear temporal behavior presented
by (Ji et al., 2008). In this work it was shown that significant
FP converging and unshearing motion occurred during the first flare
interval. During this interval the primary bremsstrahlung extended to
tens of MeV and de-excitation gamma-lines dominated. During the second
interval after 20:45 the FPs began to move apart. We found out that
starting from 20:46, the gamma-emission spectrum revealed a feature
attributed to pion-decay. It means that the effective acceleration of
protons to energies above 300 MeV (pion-production threshold) occurred
coincidently with a change of the flare magnetic structure. The maximum
intensity of the pion-decay gamma emission was observed at 20:49 and
proved to be 2.0•10-4 photons cm-2 s-1 MeV-1 at 100 MeV. This flare
was accompanied by GLE-66. Using the data of the world neutron monitor
network, we found its onset as 20:59 which corresponds to a reasonable
propagation time of protons with ~ 0.5-2 GeV energy on the assumption
that proton acceleration began at 20:46.
Title: The subsecond pulses during the August 10, 2011 flare
by observations of RATAN-600 and the 4-8 GHz Siberian solar
spectropolarimeter
Authors: Kashapova, L. K.; Tokhchukova, S. Kh.; Zhdanov, D. A.; Bogod,
V. M.; Rudenko, G. V.
Bibcode: 2013Ge&Ae..53.1021K
Altcode:
We present the results of a study of the subsecond pulses (SSPs)
registered in the microwaves during the C2.4 solar flare. The event
occurred on August 10, 2011, in the 11236 active region near the
western limb and reached a maximum at 0935 UT. Subsecond pulses
were registered by RATAN-600 for the first time when this flare
reached its maximum. The fact of detection of SSPs was confirmed by
simultaneous observations carried out with a spectropolarimeter at
the Radio Astrophysical Observatory, Institute of Solar-Terrestrial
Physics. A former analysis of the emission nature of the main flare
source revealed the presence of a high-temperature ( T > 30 MK)
source that determined both the microwave and X-ray emission parameters
of this event. We have compared the temporal variations of the SSPs
microwave emission with the variations of the plasma parameters
(temperature and emission measure) taken from observations with the
FERMI space telescope with a subsecond time resolution. The obtained
results suggest that the nature of SSP generation, as well as of the
flare itself, was determined by the high-temperature source.
Title: First results of radio observations of the sun and powerful
discrete radio sources using the Irkutsk Radar
Authors: Vasil'ev, R. V.; Kushnarev, D. S.; Kashapova, L. K.; Lebedev,
V. P.; Medvedev, A. V.; Nevedimov, N. I.; Ratovskii, K. G.
Bibcode: 2013ARep...57..872V
Altcode:
Using the Irkutsk Incoherent Scattering Radar, it is demonstrated that
the high sensitivity of such radars, which are usually used for studies
of the Earth's ionosphere, also enables their use in a passive mode for
observations of astronomical radio sources. Observations of solar flares
accompanied by coronal mass ejections and of quasi-stationary radio
sources on the Sun have been carried out. In addition, scintillations of
several of the brightest discrete radio sources (Cygnus A, Cassiopeia A,
and the Crab Nebula) have been studied over several months. These data
can also be useful for studies of the ionosphere and interplanetary
space.
Title: Coronal mass ejections in July 2005 and an unusual heliospheric
event
Authors: Livshits, M. A.; Belov, A. V.; Shakhovskaya, A. I.; Eroshenko,
E. A.; Osokin, A. R.; Kashapova, L. K.
Bibcode: 2013CosRe..51..326L
Altcode:
Using the events in July 2005 as an example, the causes and
peculiarities of Forbush effects produced by solar sources remote
from the central zone are discussed. The event in question differs
from other effects observed at the periphery of interplanetary
disturbances by strong variations in cosmic rays on the background
of weak disturbances in the solar wind and magnetic field of the
Earth. The cloud of magnetized plasma ejected from the Sun was large
and fast, but it passed to the west from the Sun-Earth line. According
to performed estimates, the mass of the ejected substance was close to
the upper boundary of mass for coronal mass ejections (CMEs). Anomalous
parameters and high modulation capability of the formed solar wind
disturbance are explained, in particular, by the fact that it combined
several CMEs and that the last fast disturbance was prepared by a series
of impulsive events in the active region of the Sun. Usually, such a
great mass is ejected directly after the main energy release in strong
solar flares. In the given case, a powerful MHD disturbance occurred
approximately half an hour after a maximum of hard X-ray burst under
the conditions when gas pressure in the flare loops became close to
magnetic pressure, which was just a premise of the largescale ejection.
Title: Modeling of Hα Eruptive Events Observed at the Solar Limb
Authors: Kotrč, P.; Bárta, M.; Schwartz, P.; Kupryakov, Y. A.;
Kashapova, L. K.; Karlický, M.
Bibcode: 2013SoPh..284..447K
Altcode: 2012SoPh..tmp..290K; 2012SoPh..tmp..269K
We present spectra and slit-jaw images of limb and on-disk eruptive
events observed with a high temporal resolution by the Ondřejov
Observatory optical spectrograph. Analysis of the time series of
full width at half-maximum (FWHM) in Hα, Hβ, and radio and soft
X-ray (SXR) fluxes indicates two phenomenologically distinct types
of observations which differ significantly in the timing of FWHM
and SXR/radio fluxes. We investigated one such unusual case of a
limb eruptive event in more detail. Synthesis of all observed data
supports the interpretation of the Hα broadening in the sense of
regular macroscopic plasma motions, contrary to the traditional
view (emission from warm dense plasma). The timing and observed
characteristics indicate that we may have actually observed the
initiation of a prominence eruption. We test this scenario via modeling
of the initial phase of the flux rope eruption in a magnetohydrodynamic
(MHD) simulation, calculating subsequently - under some simplifying
assumptions - the modeled Hα emission and spectrum. The modeled and
observed data correspond well. Nevertheless, the following question
arises: To what extent is the resulting emission sensitive to the
underlying model of plasma dynamics? To address this issue, we have
computed a grid of kinematic models with various arbitrary plasma
flow patterns and then calculated their resulting emission. Finally,
we suggest a diagnostics based on the model and demonstrate that it
can be used to estimate the Alfvén velocity and plasma beta in the
prominence, which are otherwise hard to obtain.
Title: Microwave Quasi-periodic Radio Pulsations in the 2012 March
08 Solar Flare
Authors: Zhdanov, D. A.; Kashapova, L. K.; Altyntsev, A. T.; Myshyakov,
I. I.; Zandanov, V. V.
Bibcode: 2013CEAB...37..563Z
Altcode:
We describe microwave observations of quasi-periodic pulsations
from the C6.8 flare on 2012 March 08. The radio observations were
made by the Siberian Solar Radio Telescope and Siberian Solar Radio
Spectropolarimeter. The microwave quasi-periodic pulsations were
accompanied by hard X-ray emissions which were obtained by the Fermi
Gamma-ray Space Telescope. We considered both magnetohydrodynamic
oscillations and injection of accelerated electrons as the possible
cause of microwave pulsations.
Title: On the Possible Mechanisms of Energy Release in a C-class Flare
Authors: Kashapova, L. K.; Tokhchukova, S. K.; Rudenko, G. V.; Bogod,
V. M.; Muratov, A. A.
Bibcode: 2013CEAB...37..573K
Altcode:
We present the study of the C2.4 flare which occurred at 9:35 UT, 2011
August 10 in the AR 11263 near the western limb. It was observed by
RATAN-600 and the Siberian Solar Radio Spectropolarimeter in microwaves
(MW) and by RHESSI and FERMI in hard X-rays (HXR). A peculiarity of
this event was the detection of HXR flux with energies above 25 keV
that is not typical for such weak flares. The good correlation between
HXR and MW time profiles indicates the generation of both HXR and MW
emission by a common population of electrons. Results of fitting the
HXR spectra revealed that the flare emission of energies above 25 keV
could be generated both by non-thermal electrons and a high-temperature
source (T> 30 MK). We reconstructed the microwave spectra using the
GX_Simulator code for 3D modeling of gyrosynchrotron microwave emission
(Fleischmann et al., 2011) . The input flare plasma parameters were
obtained from HXR spectra and the magnetic field structure was obtained
by extrapolation of the photospheric magnetic field from HMI/SDO. The
results were compared with existing theoretical models and observations
of other authors.
Title: On a Signature of a Flux-rope Formation by Vortex Motions in
its Footpoint
Authors: Kotrč, P.; Bárta, M.; Kupryakov, Yu. A.; Kashapova, L. K.
Bibcode: 2013CEAB...37..513K
Altcode:
We analyzed Hα spectrograms and slit-jaw filtergrams of active regions
NOAA 10311 and 10314 observed by the Ondřejov flare spectrograph near
the western limb on March 19, 2003. Several pre-flares and medium
flares C, M, X (according to GOES classification) occurred in this
active region during our period of observation. We observed a process
of intensive creation of an active region filament. Then the filament
changed its contrast in relation to the surrounding chromosphere. From
details observed in the filtergrams and spectra we conclude that during
this process the filament/flux-rope was twisted by vortex motions in
its footpoint. The energy accumulated gradually in the configuration of
magnetic field was then released during a series of flares. We discuss
the observed phenomena and try to explain them in frame of generally
accepted models of physical processes in solar flares.
Title: On a Flat-shape Emission in the Solar Flare on 7th June 2012
Authors: Kotrč, P.; Kupryakov, Yu. A.; Kashapova, L. K.; Bárta, M.
Bibcode: 2013CEAB...37..555K
Altcode:
We present results of the study of the C1.5 solar
flare~(SOL2012-06-07T05:56) which occurred on June 7, 2012. This weak
flare showed an extraordinary long flat emission in the X-ray flux curve
in the 3-12 keV energy band. Duration of this flat period was about 10
minutes while the duration of the flare was almost 20 minutes. As this
particular shape was observed both by RHESSI and FERMI, it could not
be caused by an instrumental effect. We analyzed the optical spectra
and slit-jaw images from the solar spectrograph in Ondřejov and in
the hard X-ray by RHESSI as well as EUV data obtained by SDO and all
available microwave data. We found that the "flat emission" period was
also observed in microwaves (5-17 GHz). During this period the motion
of the flare source from the spot to south direction was revealed. A
localized maximum of the chromospheric emission was also shifting in the
same direction. Quasi-periodic pulsations with periods of about
5 minutes were detected in evolution of the electron temperature that
is an evidence of the energy input during the "flat emission" period.
Title: Relationship between nonthermal and gasdynamic processes in
powerful solar flares
Authors: Livshits, M. A.; Kashapova, L. K.
Bibcode: 2012Ge&Ae..52..892L
Altcode:
The relationship between gas-dynamic processes and particle acceleration
is illustrated using three examples. For the flare of July 6, 2006,
observations show that explosive evaporation of the chromosphere occurs
in the pulse phase. In addition, the coronal mass emission (CME) related
to this flare reflects the primary energy release. In the strong limb
flare of July 14, 2005, the CME observed in the external layers of the
corona seems to be a consequence of repeated energy releases and plasma
emissions. Apparently, this is indicated by the additional emission
in the decimeter range, which is typical of posteruptive processes. An
example of a weak flare during the decay phase of the strong event of
April 15, 2001, was also accompanied by a decimeter burst.
Title: Magnetic field dynamics based on SOHO/MDI data in the region
of flares related to halo coronal mass ejections
Authors: Fainshtein, V. G.; Popova, T. E.; Kashapova, L. K.
Bibcode: 2012Ge&Ae..52.1075F
Altcode:
Variations in the photospheric magnetic field in the region of
solar flares, related to halo coronal mass ejections (HCMEs) with
velocities V > 1500, 1000 < V < 1500, and V < 650 km/s,
have been studied based on SOHO/MDI data. Using data with a time
resolution of 96 min, it has been indicated that on average the <
B L> and <| B L|> field characteristics
increase nonmonotonically during 1-1.5 days before a flare and decrease
during 0.5-1 days after a flare for groups of ejections with V >
1000 km/s for all considered HCME groups. Angle brackets designate
averaging of the measured B L magnetic field component and
its magnitude | B L| within an area with specified dimensions
and the center coincident with the projection onto the region where the
flare center field is measured. It has been established that a solar
flare related to an HCME originates when the < B L>
and <| B L|> values are larger than the boundary
values in the flare region. Based on 1-min data, it has been found
for several HCMEs with V > 1500 km/s that the beginning of powerful
flares related to ejections is accompanied by rapid impulsive or stepped
variations in < B L> and <| B L|>
near the center of a flare with a size of approximately 4.5°. It has
been established that the HCME velocity positively correlates with
the |< B L>| value at the flare onset.
Title: Detection of Acceleration Processes During the Initial Phase
of the 12 June 2010 Flare
Authors: Kashapova, L. K.; Meshalkina, N. S.; Kisil, M. S.
Bibcode: 2012SoPh..280..525K
Altcode: 2012SoPh..tmp..189K; 2012arXiv1207.5896K
We present an analysis of the plasma parameters during the initial
phase of the 12 June 2010 flare (SOL2010-06-12T00:57). A peculiarity
of the flare was the detection of γ-ray emission that is unusual for
such weak and short event. The analysis revealed the presence of a
flare precursor detected about five minutes before the flare onset
in 94 Å images which spatially coincided with the non-polarized
microwave (MW) source at 17 GHz (the Nobeyama Radio Heliograph)
that is the Neutral Line associated Source (NLS). A comparison of the
results obtained from MW data by the Nobeyama Radio Polarimeters and
the multi-frequency Siberian Radioheliograph (the new 10-antenna
radio heliograph prototype at 4.6 and 6.4 GHz) and hard X-ray
(HXR) observations by the Fermi Gamma-ray Space Telescope reveal the
presence of accelerated electrons during the flare's initial phase. The
analysis of MW and HXR spectra also confirms the presence of accelerated
particles. Moreover, a good temporal correlation between several light
curves in different HXR energy bands and at MW frequencies indicates
the generation of both HXR and MW emission by a common population of
accelerated electrons. Detection of accelerated particles during the
initial phase of the flare and soft-hard-harder (SHH) behavior of the
spectra indicate several episodes of particle acceleration and confirm
the non-impulsive type of the flare evolution.
Title: Observation of the powerful solar flare of October 27, 2002
on the far side of the sun
Authors: Vybornov, V. I.; Livshits, M. A.; Kashapova, L. K.;
Mitrofanov, I. G.; Golovin, D. V.; Kozyrev, A. S.; Litvak, M. L.;
Sanin, A. B.; Tret'yakov, V. I.; Boynton, W.; Shinohara, K.; Hamara, D.
Bibcode: 2012ARep...56..805V
Altcode: 2012AZh....89..888V
Observations of the hard X-ray and radio event of October 27, 2002
are analyzed. This flare was observed from near-Martian orbit by
the HEND instrument developed at the Space Research Institute of
the Russian Academy of Sciences and installed on the Mars Odyssey
satellite. Although this powerful flare was observed far over the
eastern solar limb, the extended source associated with the flare
was detected by RHESSI at energies up to about 60 keV. The eruptive
event was observed in the radio at the Nobeyama Radio Observatory. The
properties of the X-ray radiation are used to calculate the spectrum
of the accelerated electrons responsible for the observed radiation,
assuming that the target is thick for a Martian observer and thin for
a terrestrial observer. The results are compared with the results of
radio observations. The conditions for electron propagation in the
corona are discussed.
Title: On Detection of Balmer-Series Lines Response to Accelerated
Particles in Solar Flares
Authors: Kotrč, P.; Kashapova, L. K.; Kupryakov, Y. A.
Bibcode: 2012ASPC..454..337K
Altcode:
Comparison of the Balmer series lines with HXR and microwave emissions
are used as tools for study of the chromospheric response to effects
of accelerated particle beams in solar flares. We studied the Hα
and Hβ lines and the ratio of the line profiles for several solar
flares observed with a high cadence to find and to analyze variations
predicted from the theoretical simulations of Kašparová & Heinzel
(2002). The profiles extracted at individual kernels during different
flare phases were analyzed with respect to the radio and X-ray data
patterns. We found that the theoretical predictions of the Hα/Hβ
line profile ratios and the observations were in a good qualitative
agreement. However, as concerns quantitative correspondence, we found
some difference in position of the predicted profile ratio maxima,
moment of arising and the duration of the effect, influence of energy
cutoff of electron beam. We try to find some explanations for those
discrepancies and discuss perspectives of simultaneous observations
of Balmer series lines.
Title: Particle transport effects in solar flares for interpretation
of HXR and MW emission: theory versus observations
Authors: Zharkova, V. V.; Taras, S.; Kashapova, L.; Kuznetsov, A.
Bibcode: 2011AGUFMSH41A1893Z
Altcode:
In this paper we discuss the effects of different energy loss mechanisms
on resulting hard X-ray and MW emission of beam electrons injected in
the loop top in the corona and precipitating into loop footpoints. For
this purpose we use numeric solutions of Fokker-Planck equation
considering collisional and Ohmic energy losses and anisotropic
scattering in converging magnetic field for different scenarios
of particle injections with respect to pitch angle anisotropy and
different flaring atmosphere models. Electron beam distributions
obtained in collisional, collisional plus Ohmic losses, collisional
plus Ohmic plus turbulent losses for the models with different magnetic
convergence factors are compared. The resulting HXR and MW emission
and polarisation for each models are compared and implications for
the interpretation of observations are also discussed.
Title: Effect of a self-induced electric field on the electron beam
kinetics and resulting hard X-ray and microwave emissions in flares
Authors: Zharkova, V. V.; Meshalkina, N. S.; Kashapova, L. K.;
Altyntsev, A. T.; Kuznetsov, A. A.
Bibcode: 2011Ge&Ae..51.1029Z
Altcode:
The kinetics of beam electron precipitation from the top of a loop
into the solar atmosphere with density gradients and an increasing
magnetic field have been generally described. The Fokker-Planck
equations are solved with regard to Coulomb collisions and the effect
of the electric field induced by this beam. The photon spectra and
polarization degree in hard X-ray (10-300 keV) and microwave (1-80
GHz) emissions are simulated under different assumptions regarding
the beam electron distribution function. The simulation results are
compared with the flare observations on March 10, 2001, and July 23,
2002, visible at different position angles. It has been indicated that
the coincidence of the theoretical photon spectra with simultaneous
observations of the hard X-ray and microwave emissions of these flares
is the best for models that not only take into account collisions,
but also the electric field induced by electron fluxes propagating in
flare loops with very weakly or moderately converging magnetic fields.
Title: Physics of post-eruptive solar arcades: Interpretation of
RATAN-600 and STEREO spacecraft observations
Authors: Livshits, M. A.; Urnov, A. M.; Goryaev, F. F.; Kashapova,
L. K.; Grigor'eva, I. Yu.; Kal'Tman, T. I.
Bibcode: 2011ARep...55..918L
Altcode: 2011AZh....88..997L
Results of simultaneous measurements of radiation fluxes from
post-eruption arcades on the Sun at 171, 195, 284, and 304 Å (from
STEREO spacecraft data) and at radio wavelengths (from the RATAN-600
radio telescope) are presented. An original probabilistic approach
developed earlier by Urnov was used to determine the differential
emission measure. This method requires no regularization, and the
obtained results do not depend on the choice of the temperature
grid. This approach has yielded the differential measure of emission at
temperatures approximately from 0.3 to 15 MK. The subsequent calculation
of thermal magnetobremsstrahlung in a multi-temperature model with
the magnetic field decreasing with height produces a spectrum similar
to that observed on RATAN-600. Thus, in many non-stationary events
with modest powers, a thermal multi-temperature model is quite able
to explain the emission of post-eruption arcade systems, and it is not
necessary to invoke the emission of accelerated particles. The proposed
model enables direct estimation of the ratio of the magnetic and gas
pressures at the tops of post-eruption arcades, and determination
of the conditions required for the origin of secondary nonstationary
processes in the decay stage of the main flare.
Title: Erratum to: "Culmination of the flare activity of group 10786
in July 2005: X-ray observations from near-Mars and near-Earth orbits"
Authors: Livshits, M. A.; Golovin, D. V.; Kashapova, L. K.; Mitrofanov,
I. G.; Kozyrev, A. S.; Litvak, M. L.; Sanin, A. B.; Tret'yakov, V. I.;
Boynton, W.; Shinohara, K.; Hamara, D.
Bibcode: 2011ARep...55..943L
Altcode:
No abstract at ADS
Title: Diagnostics of electron beam properties from the simultaneous
hard X-ray and microwave emission in the 2001 March 10 flare
Authors: Zharkova, V. V.; Meshalkina, N. S.; Kashapova, L. K.;
Kuznetsov, A. A.; Altyntsev, A. T.
Bibcode: 2011A&A...532A..17Z
Altcode: 2011arXiv1105.3508Z; 2010A&A...532A..17Z
Context. Microwave (MW) and hard X-ray (HXR) data are thought to be
powerful means of investigating the mechanisms of particle acceleration
and precipitation in solar flares, reflecting different aspects
of electron interaction with ambient particles in the presence of a
magnetic field. Simultaneous simulation of HXR and MW emission with the
same populations of electrons is still a big challenge for interpreting
observations of real events. Recent progress in simulations of particle
kinetics with the time-dependent Fokker-Planck (FP) approach offers an
opportunity to produce this interpretation.
Aims: In this paper
we apply the FP kinetic model of precipitation of electron beam with
energy range from 12 keV to 1.2 MeV to the interpretation of X-ray and
MW emissions observed in the flare of 2001 March 10.
Methods:
The theoretical HXR and MW emissions were calculated by using the
distribution functions of electron beams found by solving time-dependent
approach in a converging magnetic field for anisotropic scattering
of beam electrons on the ambient particles in Coloumb collisions and
Ohmic losses.
Results: The simultaneously observed HXR photon
spectra and frequency distribution of MW emission and polarization
were fit by those simulated from FP models that include the effects
of electric field induced by beam electrons and precipitation onto a
converging magnetic loop. Magnetic field strengths in the footpoints on
the photosphere were updated with newly calibrated SOHO/MDI data. The
observed HXR energy spectrum above 10 keV is shown to be a double power
law that was precisely fit by the photon HXR spectrum simulated for the
model including the self-induced electric field but without magnetic
convergence. The MW emission simulated for different models of electron
precipitation revealed a better fit (above 90% confidence level) to the
observed distribution at higher frequencies for the models combining
collisions and electric field effects with a moderate magnetic field
convergence of two. The MW simulations were able to reproduce closely
the main features of the MW emission observed at higher frequencies:
the spectral index, the frequency of peak intensity and the frequency of
the MW polarization reversal, while at lower frequencies the simulated
MW intensities are lower than the observed ones.
Title: Culmination of the flare activity of Group 10786 in July 2005:
X-Ray observations from near-mars and near-earth orbits
Authors: Livshits, M. A.; Golovin, D. V.; Kashapova, L. K.; Mitrofanov,
I. G.; Kozyrev, A. S.; Litvak, M. L.; Sanin, A. B.; Tret'yakov, V. I.;
Boynton, W.; Shinohara, K.; Hamara, D.
Bibcode: 2011ARep...55..551L
Altcode: 2011AZh....88..598L
A detailed study of two major solar flares that occurred in Group
10786 at the time of its disappearance behind the western limb
is presented. The flares of July 14, 2005 were previously studied
fairly poorly, as no RHESSI hard X-ray observations were available
for themaxima of the twomost powerful of these flares. Observations
carried out using the HEND equipment (on the Mars Odyssey spacecraft)
developed at the Institute for Space Research in Moscow are used
here to fill this gap. In the first flare, an intense, impulsive
burst occurred at 07:23 UT, about 1.5 h after the onset of a weak,
prolonged event. While processes in the neighborhood of the northern
spot dominated in the flares of July 5-9, a powerful impulsive energy
release on July 14 emerged when the flare process that originated
in the North reached the southern spot. Our analysis of the flare
activity of this medium-sized group reveals a gradual enhancement of
the flare activity and a strong interaction between the acceleration
above the magnetic-field neutral line and in the immediate vicinity
of the spots. At the time of the culmination of the flare activity in
the group on July 13 and 14, the pattern of nonstationary processes
changes: fast coronal mass ejections form after a series of impulsive
energy-release events. Spacecraft observations of the burst of July
14 after 11 UT at points separated in longitude (on RHESSI and Mars
Odyssey) revealed clear anisotropy of the flare emission at energies
exceeding 80 keV.
Title: The effect of energetic particle beams on the chromospheric
emission of the 2004 July 25 flare
Authors: Zharkova, V. V.; Kashapova, L. K.; Chornogor, S. N.;
Andrienko, O. V.
Bibcode: 2011MNRAS.411.1562Z
Altcode:
In this paper the role of particle beams in the generation of a
close spatial and temporal correlation between hard X-ray (HXR)
energy and Hα line emission bursts in the solar flare of 2004 July
25 is discussed. The light curves in the HXR emission and Hα line
reveal that the pre-flare and main flare events are correlated with the
variations of line-of-sight (LOS) magnetic flux. The HXR emission shows
three main bursts during the main flare phase, which are accompanied by
Hα intensity increases. The latter appear in 10 locations (kernels) at
different times in succession; the kernel locations are associated with
strong magnetic sources situated on the opposite side from the magnetic
neutral line (MNL). The appearance of Hα kernels in the pre-flare
event and those at the start of the main event ia correlated very
closely (within a few seconds) with the HXR emission observed by the
Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) (HXR+Hα
kernels), while the appearance of some others, not associated with HXR
emission, was delayed by tens of seconds. Electron-beam parameters were
derived from the RHESSI spectra in which the observed HXR photon flux
was corrected for the self-induced electric field effect. Possible
implications of this electric field on the production of transient
magnetic fields observed during the flare are discussed. The Hα
emission observed during the first burst was simulated in a hydrodynamic
atmosphere for 5 levels plus a continuum hydrogen atom with the full
non-local thermodynamic equilibrium (non-LTE) approach combining
radiative, thermal and non-thermal excitation and ionization by an
electron beam with the derived parameters. The simulated temporal
profiles of Hα emission produced by non-thermal hydrogen excitation
revealed a very good fit to the observed ones in the HXR+Hα kernels
and 10-20 s delays in the other kernels. This allows us to speculate
that Hα emission is caused mainly by electrons in the HXR+Hα kernels
and mainly by protons in the others.
Title: On the Chromospheric Response At The Pre-CME Phase Of The 18
March 2003 Solar Flare
Authors: Kashapova, L. K.; Kotrč, P.; Kupryakov, Yu. A.
Bibcode: 2011CEAB...35..125K
Altcode:
We present a study of the X1.5 solar flare that occurred in the AR
10314 and was followed by a partial halo CME. Our main target was
to find characteristic parameters associated with the pre-CME and
CME phase. Special attention is devoted to parameters obtained from
chromospheric observations. We analysed Hα spectra and Hα slit-jaw
images from the Ondřejov Multichannel Flare Spectrograph observed with
a high temporal resolution. Comparison of the Hα shift and the HXR
data revealed that before the CME onset each injection of accelerated
particles to the chromosphere was followed by upward mass motions with
a delay of about 45 seconds. We did not find a significant value of the
Hα shift that could be associated with Moreton wave velocities during
the ejection phase. All values of the Hα blue shift corresponded to
the evaporation process. Thus the role of the chromosphere in the CME
preparatory phase was to increase the amount of the mass above the
flare region which was then released by the CME.
Title: Study of energy release and transport processes of the 14th
July 2005 flares in AR~10786
Authors: Sizykh, T. S.; Kashapova, L. K.
Bibcode: 2011CEAB...35...93S
Altcode:
We studied acceleration processes in two large flares (M1.0 and X1.2)
that originated in the active region 10786 on 14 July 2005 when the
region was partially occulted at the west limb of the Sun. The M1.0
flare had a thermal spectrum while the X1.2 flare had a significant
non-thermal component. A comparison of temperature (T) vs. emission
measure (EM) diagrams and spectral index vs. flux diagrams for the
X1.2 flare shows that the impulsive phase corresponded to the period of
rising T and EM. The T vs. EM diagrams of both flares had small turns,
near the time of flare impulsive phase, which could be associated with
CME events.
Title: The post-eruptive arcade formation in the limb event on July
31, 2004 from microwave solar observations with the RATAN-600 radio
telescope
Authors: Grigoryeva, I. Yu.; Kashapova, L. K.; Borovik, V. N.;
Livshits, M. A.
Bibcode: 2010SunGe...5...58G
Altcode:
A CME/flare event occurred at the western limb on 31 July 2004. Five
successive multi-wavelength scans in centimeter range were obtained
with the RATAN-600 radio telescope starting at the early stage of
post-eruptive arcade formation (24 min after a C8.3 flare peak)
and lasting for 4 hours. Microwave radio emission of the arcade was
rather intense at initial stage indicating a predominant contribution
of thermal emission and then considerably decreased during the decay
phase. Its maximum was co-spatial with the 195 Å Fe XII loop tops. At
the end of microwave observations the contribution of the emission from
accelerated particles became significant. The similarity of microwave
characteristics of two eruptive events (on 31 July 2004 at the western
limb and on 25 January 2007 at the eastern limb) is shown.
Title: Catalogue of solar flare spectra observed at Ondrejov in
1998-2007
Authors: Kupryakov, Yu. A.; Kotrc, P.; Kashapova, L. K.
Bibcode: 2010SunGe...5...61K
Altcode:
We present a catalogue of solar flare data observed with two Ondřejov
optical spectrographs during 1998-2007 years. This database was
created to enable the data processing more convenient for users
interested in the study of the energy release and transport in solar
flares. The spectra and Hα filtergrams were obtained both at the
Multichannel Flare Spectrograph (MFS) and at the Large Horizontal
Spectrograph (HSFA2). The catalogue contains basic information
about time of observation of solar flares, their location in
AR, importance, availability of related data at the selected
X-ray, EUV and radio instruments. The catalogue is available at
www.asu.cas.cz/~sos/flare_archive.html.
Title: Latitudinal and Solar-Cycle Variations of the White-Light
Corona from SOHO/LASCO Observations
Authors: Fainshtein, V. G.; Tsivileva, D. M.; Kashapova, L. K.
Bibcode: 2010SoPh..267..203F
Altcode: 2010SoPh..tmp..182F
SOHO/LASCO data were used to obtain the latitudinal and radial
distributions of the brightness of the K- and F-corona in the period
of 1996 - 2007, and their solar-cycle variations were studied. Then
an inversion method was employed to obtain the radial distributions
of the electron density Ne(R,θ) for various latitude
values on the coronal images. Our values of Ne(R,θ) are
in good agreement with the findings of other authors. We found that
in an edge-on streamer belt the electron density, like the K-corona
brightness, varies with distance more slowly in the near-equatorial rays
than in near-polar regions. We have developed a method for assessing
the maximum values of the electron density at the center of the face-on
streamer belt in its bright rays and depressions between them. Not
all bright rays observed in the face-on streamer belt are found to be
associated with an increased electron density in them. Mechanisms for
forming such rays have been suggested.
Title: Properties of the magnetic fields of coronal holes with
active regions
Authors: Fainshtein, V. G.; Stepanian, N. N.; Rudenko, G. V.;
Malashchuk, V. M.; Kashapova, L. K.
Bibcode: 2010BCrAO.106....1F
Altcode:
We determine the structure of the magnetic fields of coronal holes (CHs)
and investigate its change in connection with the emergence of active
regions (ARs) in CHs. Based on our observations in the HeI 1083 nm line
performed with the CrAO TST-2 telescope, we have selected CHs of two
types: without (15 CHs) and with (28 CHs) ARs. Magnetograms obtained at
the Kitt Peak National Solar Observatory have been used to calculate the
magnetic fields of the same objects. We have calculated magnetic field
characteristics by Rudenko’s method in the potential approximation at
several heights in the corona, namely, the average (over the CH area)
radial field component < B r > and its magnitude <|
B r |/ B> and the maximum and minimum (over the CH area)
values of B r . The distributions of the isolines of these
parameters superimposed on the CH images and the field lines of the
calculated magnetic field have been constructed with resolutions of
33.4″ and 100.2″ on the solar surface. Analysis of these data has
yielded the following results: The field lines originating in
CHs without ARs are open or very high loops that are closed outside
CHs. The latter occurs in completely or partially closed CHs.
Title: Determination of Geometric and Kinematical Parameters of
Coronal Mass Ejections Using STEREO Data
Authors: Fainshtein, V. G.; Tsivileva, D. M.; Kashapova, L. K.
Bibcode: 2010AIPC.1216..416F
Altcode:
We present a new, relatively simple and fast method to determine true
geometric and kinematical CME parameters from simultaneous STEREO A,
B observations of CMEs. These parameters are the three-dimensional
direction of CME propagation, velocity and acceleration of CME front,
CME angular sizes and front position depending on time. The method
is based on the assumption that CME shape may be described by a
modification of so-called ice-cream cone models. The method has been
tested for several CMEs.
Title: Investigation of acceleration processes of the 14th july 2005
flare series occurred in ar 10786
Authors: Sizykh, Tatyana; Kashapova, Larisa
Bibcode: 2010cosp...38.1975S
Altcode: 2010cosp.meet.1975S
We present the results of acceleration process study in the flare
series occurred 14th July 2005 on the western limb of the Sun. Our
investigation is based on HXR data obtained by RHESSI. It was observed
increasing of solar flare activity with X1.2 class flare at its
culmination. The presence of accelerated electrons (the power-law
component of HXR spectrum for energies more than 25 keV) was clearly
signified only in the first (C3.8) and the last of studied flares. We
applied lgT-1/2lgEM diagrams ( Jakimiec et al,1986) for quantitative
study of HXR spectrums for all flares. For analysis of the flares
showed presence of significant flux of accelerated electrons we also
used diagrams made on base of parameters obtained from non-thermal
part of the spectrum (flux, spectral index, spectral curvature, Grigis
Benz 2009). The possible scenario of evolution of this active region
is discussed.
Title: Directivity of HXR Solar Flare Emission Obtained from
Stereoscopic Observations by Mars Odyssey (HEND), RHESSI and CORONAS-F
(SONG)
Authors: Livshits, Moisey; Golovin, Dmitry; Mitrofanov, Igor; Kozyrev,
S. Alexander; Litvak, Maxim; Tretyakov, Vladislav; Sanin, Anton;
Boynton, William V.; Kashapova, Larisa; Myagkova, Irina; Bogomolov,
Andrey
Bibcode: 2010cosp...38.2984L
Altcode: 2010cosp.meet.2984L
Two powerful X-Ray flares were observed on 2005, July 14 by three
spacecrafts whose heliolon-gitudes were spaced on 39 degrees. The flares
were observed, as projected on the solar disc by Mars Odyssey (HEND)
and seeing almost directly on the limb by RHESSI and CORONAS-F. The most
intensive hard X-ray and gamma-ray flare (up to 2 MeV) was observed by
HEND and SONG on 07:23 UT, and measured time profiles were similar,
but the spectra were quite rather different. Particular pulses of
flares were studied by data from different instruments with dif-ferent
heliolongitudes, and conclusion was drawn that difference between fluxes
at these flares is more likely due to a directivity of radiation. The
emission directivity was more clearly seen for the source at the top
of flare loop for burst observed near 11:00 UT.
Title: Diagnostics of the beam anisotropy from the HXR and MW emission
data in the flare of 10 March 2001.
Authors: Meshalkina, Natalia; Zharkova, Valentina; Kashapova, Larisa;
Altyntsev, Alexander; Kuznetsov, Alexey
Bibcode: 2010cosp...38.1963M
Altcode: 2010cosp.meet.1963M
Microwave and hard X-ray data are thought to be powerful mean
for investigating the mech-anisms of particle acceleration and
precipitation in solar flares. In this paper X-ray and mi-crowave
emission is investigated for the flare of 10 March 2010 previously
studied by Altyntsev et al. (2008), who concluded there was a beamlike
anisotropy in the particle distribution in the event. The simulations
of HXR and MW emissions produced by beam electrons with en-ergies from
12keV to 1.2 MeV are carried out by taking into account anisotropic
scattering in converging magnetic field of beam electrons in Coloumb
collisions and Ohmic losses by using time-dependent Fokker-Planck
approach (Zharkova at al, AA, 2010; Kuznetsov and Zharkova, AA,
2010). The simulated HXR photons spectra, MW emission spectra (1-80
GHz) and polar-ization are compared with the observed ones using
the magnetic field values updated with new calibrated MDI. Similar
to the previous simulations (Altyntsev et al, 2008), we conclude the
absence of a detectable magnetic field convergence in both HXR and MW
emission. However, the simulated HXR photon spectra, MW emission and
polarization reveal the best fit for the models including the effect
of electric field induced by beam electrons show the both emission
emitted from a slightly tilted loop in the flare location and not in
the perpendicular direction deduced in earlier simulations.
Title: Some properties of the continuous latitude distributions of
the brightness of the K and F coronas as deduced from the LASCO data
Authors: Fainshtein, V. G.; Kashapova, L. K.; Tsivileva, D. M.
Bibcode: 2009Ge&Ae..49.1106F
Altcode:
Using two new methods for separating the K and F coronas and the LASCO
C2 and C3 coronagraph data, continuous latitude distributions of the
brightness of the K and F coronas have been obtained and examined as
a function of the distance for different solar activity phases.
Title: High-Energy Emission from a Solar Flare in Hard X-rays and
Microwaves
Authors: Kundu, M. R.; Grechnev, V. V.; White, S. M.; Schmahl, E. J.;
Meshalkina, N. S.; Kashapova, L. K.
Bibcode: 2009SoPh..260..135K
Altcode: 2009arXiv0908.0385K
We investigate accelerated electron energy spectra for different sources
in a large flare using simultaneous observations obtained with two
instruments, the Nobeyama Radio Heliograph (NoRH) at 17 and 34 GHz,
and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI)
at hard X-rays. This flare is one of the few in which emission up to
energies exceeding 200 keV can be imaged in hard X-rays. Furthermore,
we can investigate the spectra of individual sources up to this
energy. We discuss and compare the HXR and microwave spectra and
morphology. Although the event overall appears to correspond to the
standard scenario with magnetic reconnection under an eruptive filament,
several of its features do not seem to be consistent with popular flare
models. In particular we find that (1) microwave emissions might be
optically thick at high frequencies despite a low peak frequency in
the total flux radio spectrum, presumably due to the inhomogeneity
of the emitting source; (2) magnetic fields in high-frequency radio
sources might be stronger than sometimes assumed; (3) sources spread
over a very large volume can show matching evolution in their hard
X-ray spectra that may provide a challenge to acceleration models. Our
results emphasize the importance of studies of sunspot-associated flares
and total flux measurements of radio bursts in the millimeter range.
Title: Eruptions of Magnetic Ropes in Two Homologous Solar Events
of 2002 June 1 and 2: a Key to Understanding an Enigmatic Flare
Authors: Meshalkina, Nataliya S.; Uralov, Arkadiy M.; Grechnev,
Victor V.; Altyntsev, Alexander T.; Kashapova, Larisa K.
Bibcode: 2009PASJ...61..791M
Altcode: 2009arXiv0908.0384M
The goal of this paper is to understand the drivers, configurations,
and scenarios of two similar eruptive events, which occurred in
the same solar active region 9973 on 2002 June 1 and 2. The June 2
event was previously studied by Sui, Holman, and Dennis (2006, ApJ,
646, 605; 2008, Adv. Space Res., 41, 976), who concluded that it was
challenging for popular flare models. Using multi-spectral data, we
analyzed a combination of the two events. Each of the events exhibited
an evolving cusp-like feature. We have revealed that these apparent
``cusps'' were most likely mimicked by twisted magnetic flux ropes,
but unlikely to be related to the inverted Y-like magnetic configuration
in the standard flare model. The ropes originated inside a funnel-like
magnetic domain whose base was bounded by an EUV ring structure, and
the top was associated with a coronal null point. The ropes appear to
be the major drivers for the events, but their rise was not triggered
by reconnection in the coronal null point. We propose a scenario and
a three-dimensional scheme for these events in which the filament
eruptions and flares were caused by interaction of the ropes.
Title: High-Energy Emission from a Solar Flare in Hard X-Rays and
Microwaves
Authors: Kundu, Mukul R.; Grechnev, V. V.; White, S. M.; Schmahl,
E. J.; Meshalkina, N. S.; Kashapova, L. K.
Bibcode: 2009SPD....40.1920K
Altcode:
We investigate accelerated electron energy spectra for different sources
in a large flare using simultaneous observations obtained with two
instruments, the Nobeyama Radio Heliograph (NoRH) at 17 and 34 GHz,
and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI)
at hard X-rays. This flare is one of the few in which emission up to
energies exceeding 200 keV can be imaged in hard X-rays. Furthermore,
we can investigate the spectra of individual sources up to this
energy. We discuss and compare the HXR and microwave spectra and
morphology. Although the event overall appears to correspond to the
standard scenario with magnetic reconnection under an eruptive filament,
several of its features do not seem to be consistent with popular flare
models. In particular we find that (1) microwave emissions might be
optically thick at high frequencies despite a low peak frequency in
the total flux radio spectrum, presumably due to the inhomogeneity
of the emitting source; (2) magnetic fields in high-frequency radio
sources might be stronger than sometimes assumed; (3) sources spread
over a very large volume can show matching evolution in their hard
X-ray spectra that may provide a challenge to acceleration models. Our
results emphasize the importance of studies of sunspot-associated flares
and total flux measurements of radio bursts in the millimeter range.
Title: Forecasting the velocity of quasi-stationary solar wind and
the intensity of geomagnetic disturbances produced by it
Authors: Eselevich, V. G.; Fainshtein, V. G.; Rudenko, G. V.;
Eselevich, M. V.; Kashapova, L. K.
Bibcode: 2009CosRe..47...95E
Altcode:
A brief review is given of contemporary approaches to solving the
problem of medium-term forecast of the velocity of quasi-stationary
solar wind (SW) and of the intensity of geomagnetic disturbances caused
by it. At the present time, two promising models of calculating
the velocity of quasi-stationary SW at the Earth’s orbit are
realized. One model is the semi-empirical model of Wang-Sheeley-Arge
(WSA) which allows one to calculate the dependence V( t) of SW velocity
at the Earth’s orbit using measured values of the photospheric
magnetic field. This model is based on calculation of the local
divergence f S of magnetic field lines. The second model
is semi-empirical model by Eselevich-Fainshtein-Rudenko (EFR). It
is based on calculation in a potential approximation of the area
of foot points on the solar surface of open magnetic tubes (sources
of fast quasistationary SW). The new Bd-technology is used in these
calculations, allowing one to calculate instantaneous distributions of
the magnetic field above the entire visible surface of the Sun. Using
predicted V( t) profiles, one can in EFR model calculate also the
intensity of geomagnetic disturbances caused by quasi-stationary
SW. This intensity is expressed through the K p index. In
this paper the EFR model is discussed in detail. Some examples of
epignosis and real forecast of V( t) and K p ( t) are
discussed. A comparison of the results of applying these two models
for the SW velocity forecasting is presented.
Title: Microwave observations with the RATAN-600 radio telescope:
detection of the thermal emission sources
Authors: Grigoryeva, Irina Yu.; Kashapova, Larisa K.; Livshits,
Moisey A.; Borovik, Valery N.
Bibcode: 2009IAUS..257..177G
Altcode:
We report on two off-limb radio sources of microwave emission
which were detected in one-dimensional RATAN-600 solar scans of the
post-eruptive loops: on December 2, 2003 (off west limb) and January
25, 2007 (east limb). The microwave spectra showed that the thermal
emission was predominant at the early stage of the arcade formation
with a small contribution of non-thermal emission. There were no
high-energy particles in these events. The microwave spectra of the
radio sources associated with the tops of postflare loops show the
predominant thermal emission during one hour after the eruption. In case
of a small contribution from accelerated particles to the microwave
emission, there is a large amount of hot plasma in the region of the
loop tops after the eruption.
Title: A Possible Scenario of Energy Transport in the 17th
May 2002 Flare
Authors: Kotrč, P.; Kashapova, L. K.; Frolova, A. S.; Kuprjakov,
Yu. A.
Bibcode: 2009CEAB...33..207K
Altcode:
We deduce the energy transport scenario from simultaneous observations
in a wide range of the electromagnetic spectrum. High-temporal
resolution optical and radio spectra from the Ondřejov observatory,
and data obtained by RHESSI, Nobeyama Radio Observatory, Radio Solar
Telescope Network (RSTN) and by SOHO (MDI and EIT) were analysed to
get a complex view on the event. As follows from the microwave data the
maximum of emission at 17 GHz evolved from the eastern part of the flare
to the western one. Chromospheric emission of the flare originated from
two eruptive centres -- eastern and western ones. While the eastern
centre consisted of a single Hα kernel, the western one was rather
a complex structure. These centres were associated with different
HXR sources. The western centre was connected with a more mighty HXR
source of 25-100 keV. We studied a correlation of the hard X-rays,
radio emission and the Balmer series lines for the western centre
in detail. Probable agents and scenarios of the energy transport
are discussed.
Title: Eruptive processes at the beginning of development of powerful
flare-active regions on the sun
Authors: Kashapova, L. K.; Livshits, M. A.
Bibcode: 2008ARep...52.1015K
Altcode: 2008AZh....85.1129K
The evolution of large solar activity centers is studied, and
the conditions resulting in powerful nonstationary processes are
clarified. In addition to the factors that are usually considered
(changes in sunspot area, the structure of magnetic fields, the
character of motions), we examine to what extent observations of
nonstationary processes (flares and associated coronal mass ejections)
can be used to predict the development of such processes in the
subsequent evolution of the activity center. We considered the example
of a powerful group in October 2003, which could be observed before
its appearance at the eastern limb using a spacecraft in near-Mars
orbit. We plotted for events occurring in 2003 images of flares in
various spectral ranges and analyzed high-energy processes in group
486, which was isolated at the beginning of its development, and then
in the interrelated groups 486 and 484. The analysis of the peculiar
early development of group 486 suggested that an intensification of the
activity could be expected due to the emergence of new magnetic flux
(and satellite groups), as well as the interaction and synchronization
of two and then three large groups of the end of October 2003. In
other words, in this case, extremely powerful nonstationary processes
are associated with a relatively higher contribution of large-scale
magnetic fields. We compare our results to analyses of motions and
magnetic fields in this activity center throughout its transit across
the disk from October 23 to November 5, 2003.
Title: Non-thermal particle effects on the Hα and Hβ line profiles
in the 18 August 2002 solar flare
Authors: Kashapova, L. K.; Kotrč, P.; Kupryakov, Yu. A.
Bibcode: 2008AnGeo..26.2975K
Altcode:
We present results of the 18 August 2002 flare analysis as an example
for developing a diagnostic tool for thermal and non-thermal processes
in chromospheric lines. Taking into account the hard X-ray (HXR)
emission, we attempted to derive the Hα and Hβ line properties which
were caused by the non-thermal electron contribution and could be useful
for diagnostic purposes. The flare itself was a sequence of harder and
softer bursts in HXR and we investigated three flare kernels associated
with them. Two of the kernels appeared simultaneously. This phase of
the flare could be observed in a broad band of wavelengths (HXR, UV,
optical and microwaves). Kernel 1 did not clearly coincide with any
HXR source but its intensity increased with the HXR flux rise. The
flare kernel~3 did not show any significant response in microwaves,
however, the related HXR flux was comparable with the flux of the
previous kernels. We carried out an analysis of the difference between
the Hα/Hβ profile rate in the line center at the distance of 0.5 Å
from the line center. Only kernel 2 showed parameter fluctuations that
were related to HXR flux evolution. The supposition of the non-thermal
electron effect on the Hα/Hβ profile ratio was confirmed only at
the kernel connected with the 25 50 keV HXR source. We found further
confirmation that the Hα/Hβ line intensity ratio could be used as
a diagnostic tool for non-thermal electron presence.
Title: An Extreme Solar Event of 20 January 2005: Properties of the
Flare and the Origin of Energetic Particles
Authors: Grechnev, V. V.; Kurt, V. G.; Chertok, I. M.; Uralov,
A. M.; Nakajima, H.; Altyntsev, A. T.; Belov, A. V.; Yushkov, B. Yu.;
Kuznetsov, S. N.; Kashapova, L. K.; Meshalkina, N. S.; Prestage, N. P.
Bibcode: 2008SoPh..252..149G
Altcode: 2008arXiv0806.4424G; 2008SoPh..tmp..145G
The famous extreme solar and particle event of 20 January 2005 is
analyzed from two perspectives. Firstly, using multi-spectral data,
we study temporal, spectral, and spatial features of the main phase
of the flare, when the strongest emissions from microwaves up to 200
MeV gamma-rays were observed. Secondly, we relate our results to a
long-standing controversy on the origin of solar energetic particles
(SEP) arriving at Earth, i.e., acceleration in flares, or shocks
ahead of coronal mass ejections (CMEs). Our analysis shows that
all electromagnetic emissions from microwaves up to 2.22 MeV line
gamma-rays during the main flare phase originated within a compact
structure located just above sunspot umbrae. In particular, a huge
(≈ 105 sfu) radio burst with a high frequency maximum
at 30 GHz was observed, indicating the presence of a large number of
energetic electrons in very strong magnetic fields. Thus, protons and
electrons responsible for various flare emissions during its main phase
were accelerated within the magnetic field of the active region. The
leading, impulsive parts of the ground-level enhancement (GLE),
and highest-energy gamma-rays identified with π0-decay
emission, are similar and closely correspond in time. The origin of
the π0-decay gamma-rays is argued to be the same as that
of lower-energy emissions, although this is not proven. On the other
hand, we estimate the sky-plane speed of the CME to be 2 000 - 2 600
km s−1, i.e., high, but of the same order as preceding
non-GLE-related CMEs from the same active region. Hence, the flare
itself rather than the CME appears to determine the extreme nature of
this event. We therefore conclude that the acceleration, at least, to
sub-relativistic energies, of electrons and protons, responsible for
both the major flare emissions and the leading spike of SEP/GLE by 07
UT, are likely to have occurred nearly simultaneously within the flare
region. However, our analysis does not rule out a probable contribution
from particles accelerated in the CME-driven shock for the leading
GLE spike, which seemed to dominate at later stages of the SEP event.
Title: On Fast Chromospheric Responses to Microwave Subsecond Bursts
Authors: Kashapova, L. K.; Kotrc, P.; Meshalkina, N. S.
Bibcode: 2008ESPM...12.2.47K
Altcode:
We present a multi-wavelength analysis of chromosphere responses
produced during the subsecond bursts detected by Siberian Solar Radio
Telescope (SSRT, 5.7 GHz) on April 26, 2003 at 08:05:30 UT. The data
obtained by Nobeyama Radioheliograph (NoRH, 17 and 34 GHz), Ondrejov
observatory and RHESSI were also used. A correlation of multi-wavelength
observations (microwave emission, hard X-rays and the video-cadence
chromospheric line spectra from the Ondrejov observatory obtained with
0.04 second resolution) was performed to study fluxes on various levels
of solar atmosphere before, during and after the event. The temporal
resolution was high enough to resolve responses to subsecond pulses in
the individual correlated fluxes and their possible interrelations. The
results and possible scenario are briefly discussed from point of view
of the energy transport mechanisms.
Title: On Dynamics of H-alpha/H-beta Line Ratio and Non-thermal
Particle Effects in Solar Flares
Authors: Kotrc, P.; Kashapova, L. K.; Kuprjakov, Yu. A.
Bibcode: 2008ESPM...12.2.61K
Altcode:
The ratio of the H-alpha?/H-beta line profiles was analyzed as
a diagnostic indicator of non-thermal particle effects in solar
flares. Differences between the H-alpha/H-beta profile ratio in the line
center and at the distance of 0.5 Angstroms from the line center were
studied in various phases of flares as concerns presence of responses
to non-thermal effects. Variations of this parameter were compared
with the HXR flux evolution for the 26 June 1999 and the 18 August
2002 solar flares. The sign of the parameter changed from negative
to positive value only for these flare kernels where coincidence with
the HXR sources indicated presence of accelerated particles. However,
no such a change was found for the other kernels. The revealed
effect was compared with information obtained from correlation between
the temporal fluctuations of the H? and H? line and the HXR flux. The obtained results are discussed from point of view of their
possible diagnostical applications.
Title: On the Total Emissivity in Chromospheric Lines in the 17th
May 2002 Flare
Authors: Prosecky, T.; Kotrc, P.; Kashapova, L. K.
Bibcode: 2008ESPM...12.2.63P
Altcode:
Energy balance in the 17th May 2002 flare was studied. Chromospheric
lines observed by the Ondrejov spectrograph were analysed taking into
account the HXR data from RHESSI. Positions of the HXR sources were
identified at the H-alpha slit-jaw images and the corresponding flare
spectra were processed. Total emissivity in H-alpha and H-beta lines was
derived and the net energy emitted in these lines during various phases
of the flare was estimated. The results were compared with evolution
of HXR flux and plasma parameters obtained from the HXR spectra.
Title: On Energy Transport Scenarios in the 17th May 2002 Near-limb
Flare
Authors: Kotrc, P.; Kashapova, L. K.; Frolova, A. S.; Kuprjakov, A. Yu.
Bibcode: 2008ESPM...12.2.62K
Altcode:
We present a reconstruction of the energy transport scenario based
on the simultaneous observations in a wide range of electromagnetic
spectrum. Particularly, the high-temporal resolution optical and radio
spectra from the Ondrejov observatory, data obtained by RHESSI, Nobeyama
Radio Observatory, Radio Solar Telescope Network (RSTN), Siberian
Solar Radio Telescope (SSRT) and SOHO (MDI and EIT) were analysed to
obtain a complex view on the event. Especial attention was payed to
the role of accelerated particles in the energy transport and to the
excitation mechanisms in different kernels of the flare. As follows from
the microwave data the maximum of emission at 17 GHz evolved from the
eastern part of the flare to the western one. On chromospheric level
the flare consisted of two eruptive centers - eastern and western
ones. While the eastern center consisted from a single H? kernel,
the western one was rather a complex structure. These centers were
associated with different HXR sources. It is worth to note that the
western center was connected with a more mighty HXR source of 25-100
keV. We studied a correlation of the hard X-rays, radio emission
and the Balmer series lines for the western center. Probable agents
and scenarios of the energy transport as well as possible diagnostic
aspects of the results are briefly discussed.
Title: Multi-wavelength investigation of energy release and transport
in the 16 August 2004 flare
Authors: Kashapova, L. K.; Zharkova, V. V.; Grechnev, V. V.; Ipson,
S. S.
Bibcode: 2008IAUS..247..222K
Altcode: 2007IAUS..247..222K
The current contribution investigates the solar flare of 16th August
2004 with the multi-wavelength observations with high temporal
resolution from RHESSI, Large Solar Vacuum Telescope (LSVT), Hiraiso
Solar observatory, Nobeyama Radioheliograph (NoRH, 17 and 34 GHz) and
Siberian Solar Radio Telescope (SSRT, 5.7 GHz), TRACE. The main flare
was preceded by a pre-flare event with a very short energy release
time. The observations of the main flare reveal a close temporal
correlation between the Hα intensity observed with LSVT and those in
hard and soft X-ray emissions observed with RHESSI, and in microwave
fluxes observed with NoRH and SSRT. This close temporal correlation can
be only associated with high-energy particles. The role of energetic
particles in energy transport and non-thermal excitation and ionisation
on Hα emission during the pre-flare and pre-flare event is investigated
with full non-LTE approach and possible agents and scenarios of energy
transport are discussed.
Title: Balmer-Line Diagnostics of Accelerated Particles
Authors: Kashapova, L. K.; Kotrč, P.; Kupryakov, Yu. A.
Bibcode: 2007ASPC..368..431K
Altcode:
Preliminary results of empirical study of a non-thermal electron effect
on Hα/Hβ line intensity ratio in solar flares are presented. Analysis
of spectral observations of the 26 June 1999 flare revealed some
peculiarities of the Hα/Hβ line intensity ratio (the ``sidelobes'')
in the emission kernels associated with radio bursts and HXR emission
that could be considered as an indirect evidence of accelerated
non-thermal particle beams. According to our conclusions they appeared
due to non-thermal electron beam effects. Consequently, the obtained
results confirmed the theoretical predictions and bore a first witness
for a detection of the spatial and temporal presence or absence of
the non-thermal electron beams in optical spectra. However, as a more
statistically probative evidence was needed, we extended our analysis
on two flares where presence of non-thermal mechanisms of excitation
was verified by HXR data. The obtained results are quite promising as
concerns of diagnostics of the energy release and transfer mechanisms
during the flare.
Title: Signatures of High-Energy Particles in Hα Emission Before
the Solar Flare of August 16, 2004
Authors: Kashapova, L. K.; Zharkova, V. V.; Grechnev, V. V.
Bibcode: 2007ASPC..368..437K
Altcode:
We study multi-spectral chromospheric and coronal emissions that
appeared during the impulsive event occurring before the flare on
16 August 2004 observed by RHESSI, Large Solar Vacuum Telescope
(Irkutsk), and Nobeyama Radioheliograph (NoRH, 17 and 34 GHz). There
are three separate sources detected: 1 in hard X-rays (RHESSI), two
in microwaves (NoRH) (1 of which coincides with HXR) and one in Hα
emission (3). The emission in all sources reveals a close (within 1 s)
temporal correlation that can be only associated with precipitation
of high-energy particles. Possible scenarios of particle precipitation
and its effect on the observed signatures are discussed.
Title: The multi-wavelength study of the effect of energetic particle
beams on the chromospheric emission in the 25th July 2004 solar flare
Authors: Zharkova, V. V.; Kashapova, L. K.; Chornogor, S. N.;
Andriyenko, O. V.
Bibcode: 2007AdSpR..39.1483Z
Altcode:
We present the multi-wavelength study of short-term variations of
Hα line emission located in multiple kernels on the both sides from
magnetic neutral line in the 25th July 2004 solar flare observed by VTT
(Tenerife). The HXR and Hα emission in the kernels 1 and 3 is close
spatially and temporally while in kernels 4 and 7 there is only delayed
Hα emission observed tens seconds after HXR in the kernels 1 and 3. The
locations of Hα kernels 1, 3, 4 and 7 are on the opposite sides from
the magnetic neutral line. The temporal variations of Hα emission in
kernels 1 and 3 coincide within 5 s with the HXR photon emission. The
latter is found to have double power law photon spectra, which were
corrected to a single power law with the turning point technique
accounting for Ohmic losses and collisions. The Hα emission is fit by
full non-LTE simulations in an atmosphere heated by an electron beam
with the parameters derived from the HXR emission. The combination
of radiative, thermal and non-thermal mechanisms of excitation and
ionization of hydrogen atoms is considered. The temporal evolution of
simulated Hα emission in the kernel 3 fits rather well the two observed
intensity increases: the first at the flare onset (13:38:39-13:39:30 UT)
caused by pure non-thermal excitation by beam electrons and the second
one appearing after 13:40:00 UT because of a hydrodynamic heating. The
observed close temporal correlation or delay of Hα emission with HXR
emission points out to the precipitation either of electron (kernels
1 and 3) or protons (4 and 7).
Title: On the thermal and non-thermal excitation effects as studied in
the H[alpha], H[beta] and Ca II 8542 Å line profiles in a solar flare
Authors: Kotrč, P.; Kashapova, L. K.
Bibcode: 2007msfa.conf..277K
Altcode:
Spectral observations of the 26 June 1999 flare (Kotrč et al. 2004)
presented a unique opportunity to compare effects of thermal and
non-thermal mechanisms of excitation on profiles of Balmer series and Ca
II 8542 A lines. The radio spectra and HXR flux demonstrated indirect
evidence of the non-thermal beam effect on the chromosphere during
the flare (Kashapova et al. 2005). We compared the line profiles in
the flare kernel associated with the influence of non-thermal electron
beams with the "only thermal" kernels. Results are discussed both from
their observational and theoretical aspects.
Title: Signatures of High Energy Particle Beams in the Chromospheric
Events Before the 25 July 2004 Flare Onset
Authors: Kashapova, L. K.; Zharkova, V. V.; Chornogo, S. N.; Kotrc, P.
Bibcode: 2006IAUJD...1E..47K
Altcode:
A role of particle beams is studied in the origin and evolution
of small-scale chromospheric events appeared before the main phase
onset at 13:37 UT of the July 25, 2004 flare. The main goal of our
investigation was to detect possible locations of energy release and to
trace the processes of energy transport by high-energy particles to the
chromosphere. Based on the plasma and beam parameters deduced from hard
X-ray flux and UV data, 1D hydrodynamic responses of the atmosphere
is calculated and used for a full non-LTE simulation of hydrogen
H-alpha line emission taking into account thermal and non-thermal
processes. Theoretical line profiles are compared with the observed
dynamics of H-alpha intensity. A comparison is carried out of the
high energy particle parameters deduced from chromospheric emission,
hard X-ray flux and UV data that allows us to find a possible scenario
of the event evolution.
Title: On Possible Manifestation of Non-Thermal Electrons in the
Hα/Hβ Line Profile Ratio in the June 26, 1999 Flare
Authors: Kotrc, P.; Kashapova, L. K.
Bibcode: 2006IAUJD...1E..46K
Altcode:
We analyzed the solar flare on 26 June 1999 which consisted of three
subsequent phases. All of them were followed by events of quite
different types (Kotrc et al., IAU Symp 223, 2004). Just the second
phase of the flare was accompanied by radio bursts and HXR emission
that could be considered as an indirect evidence of accelerated
non-thermal particle beams. Theoretical calculations of thermal
mechanisms coupled with accelerated electron beams in flares showed
that the ratio of the Hα/Hβ line profiles could be a possible
indicator whether a mechanism of non-thermal radiation excitation
was present or absent (Kasparova & Heinzel, A&A, 2002). This
effect should follow the occurrence of the particle beams in time
and then decay. In the flare kernel associated thus possibly with
the influence of non-thermal electron beams we found that the ratio
of the Hα/Hβ line profiles demonstrated a very specific form which
substantially differs from those ones obtained in "thermal" kernels
(occurring in the first and in the another flare phases). This effect
can be characterized by presence of specific "sidelobes" occurring in
the ratio of the line profiles. The effect was observed in the region
nearby the HXR sourcelocation where it appeared just after the end of
the radio-spectrum spike and therefore it corresponds most probably to
the occurrence of non-thermal processes in the flare. The associated
HXR effect was rather short lasting, i.e. the effect of "sidelobes"
disappeared earlier then the emission. We try to trace the evolution and
the possible decay of this effect. On one hand the obtained results will
be an additional evidence of the theoretical predictions, on the other
hand they could be useful for development of technique for detecting
the presence or absence of the non-thermal electron beams. Conclusions
are discussed both from their observational and theoretical aspects.
Title: The evolution of Hα and CaII K emission before and during
the solar M-class flare on 25th July 2004
Authors: Chornogor, S. N.; Kashapova, L. K.; Andriyenko, O. V.
Bibcode: 2006IAUS..233..122C
Altcode:
The last decade observations revealed the essential variations of energy
balance take place in the pre-flare active regions at all atmospheric
levels and they are caused by both evolution of AR and processes
associated with flare activity. We present the multi-wavelength study
of the solar flare jointly with the preceding event. The combined
investigation is perspective for the mechanism understanding of the
energy storage, trigger and release during the solar flares. A special
attention was given to signatures of energetic particle beam effect on
chromosphere according to Hα and CaII K intensity changes. Combination
of data from ground based instruments and space observatories (TRACE,
MDI, RHESSI) will allow us to track processes taking place in a wide
range of solar atmosphere layers - from the temperature minimum region
to the corona. The obtained results are discussed.
Title: Investigation of pre-flare role of Ellerman bombs in solar
active regions
Authors: Papernaya, Yu. V.; Kashapova, L. K.
Bibcode: 2006IAUS..233..181P
Altcode:
Ellerman bombs or moustache are known as short-living fine
emission structures associated with a local energy release in solar
atmosphere. The relation between the moustaches and flare has been
discussed since the moment of the moustaches discovery. The resent
results of the Flare Genesis Experiment demonstrated that this problem
is still actual and attractive. We took into account the possibility
of different mechanisms of their origin (thermal and non-thermal) by
using spectro polarimetric data obtained in summer 1999 and carried
out analysis of Ellerman bomb's role in flare activity of the Sun by
the example of the several active regions.
Title: The multi-wavelength study of the effect of energetic particle
beams on the chromospheric emission in the 20th and 25th July 2004
solar flares
Authors: Zharkova, V. V.; Andriyenko, O. V.; Chornogor, S. N.;
Kashapova, L. K.; Sych, R. A.
Bibcode: 2006cosp...36.2256Z
Altcode: 2006cosp.meet.2256Z
We present the results of a multi-wavelength study of short-term
variations of H-alpha and CaII K line emission in the 20th and 25th July
2004 solar flares In both flares the fast changes of H-alpha and CaII
K intensity observed from VTT correlated very closely seconds with the
HXR emission observed by RHESSI that is considered as the signatures
of energetic particle beams in the chromosphere For interpretation
of the observed emission the full non-LTE radiative simulations were
carried out for a combination of radiative thermal and non-thermal
mechanisms of excitation and ionization of the hydrogen and Ca emission
in flaring atmospheres Various theoretical models are compared with the
observational results in order to define the best fits and to clarify
the processes of energy transport within a short timescale of seconds
from upper to lower atmospheric levels in the solar flares
Title: On AN Effect of Particle Beams on Correlation Between Balmer
Series Lines
Authors: Kashapova, L. K.; Kotrč, P.; Kupryakov, Yu. A.; Kašparová,
J.
Bibcode: 2005ESASP.600E.126K
Altcode: 2005dysu.confE.126K; 2005ESPM...11..126K
No abstract at ADS
Title: Preflare HXR and Chromospheric Line Emission in NOAA 0652 ON
25TH July 2004
Authors: Chornogor, S. N.; Kashapova, L. K.; Sych, R. A.; Andriyenko,
O. V.
Bibcode: 2005ESASP.600E.115C
Altcode: 2005dysu.confE.115C; 2005ESPM...11..115C
No abstract at ADS
Title: The viewing angle effect on Hα-line impact polarisation in
impulsive solar events
Authors: Zharkova, V. V.; Kashapova, L. K.
Bibcode: 2005A&A...431.1075Z
Altcode:
The effect of a viewing angle on the hydroden Hα-line impact
polarisation is investigated in a plane vertical atmosphere arbitrary
located on the solar disk. The impact polarisation is assumed
to be caused by precipitating beam electrons with pitch-angular
anisotropy steadily injected into the flaring atmosphere from its
top. The polarisation is calculated for a 3 level plus continuum
hydrogen atom affected by Zeeman splitting in a moderate magnetic
field taking into account depolarising effects of diffusive radiation
and collisions with thermal electrons. The Hα polarisation profiles
are affected by electron beams only in the line cores whereas the
wings are fully depolarized by the collisions with thermal electrons
despite the extended wing emission, or “moustaches”, caused by
beam electrons. The full (integrated in wavelength) Hα-line linear
polarisation, caused by moderate electron beams, is shown to be 2{-}20%
and either negative or positive depending on the position of a flaring
loop on the solar disk and the direction of an emitted photon from
the local magnetic field. The polarisation plane is projected onto
a viewing angle psi, being a superposition of the flare location
on a solar disk and the magnetic field deviation from vertical on
the solar surface. For viewing angles less then 50^circ the Hα-line
impact polarisation is negative increasing up to -10% towards smaller
angles, meaning that the polarisation is mostly perpendicular to the
plane {B}× {K} where B is the magnetic field induction and K is the
photon momentum vector. For viewing angles greater than 60^circ the
measured impact polarisation becomes positive, sharply increasing up
to 20% towards the limb. In the range of 50{-}60^circ the observed
impact polarisation goes through a zero point despite the actual
presence of beam electrons in the flaring atmosphere. The theoretical
predictions of the dependence of polarisation degree on viewing angle
fit remarkably well the observations of Hα-line linear polarisation
in small-scale flaring events such as moustaches or Ellerman bombs,
located in different positions on a solar disk.
Title: Transfer of energy within coronal bright points according to
the observation in optical spectra and microwave
Authors: Prosovetsky, D. V.; Kashapova, L. K.
Bibcode: 2004IAUS..223..479P
Altcode: 2005IAUS..223..479P
The paper is devoted to the coronal bright points. We carried out
the analysis of the simultaneous observations in IR He λ10830 Å and
microwaves at 5.2 and 1.76 cm. It was obtained that microwave sources
correspond to the dark points in IR He λ10830 Å with line-of-sight
velocities directed from a observer. The possible mechanism of the
energy transport within the bright points are suggested.
Title: On the presence of linear polarization in the flare on 26
June, 1999
Authors: Kotrc, P.; Kashapova, L. K.; Kupryakov, J. A.
Bibcode: 2004IAUS..223..463K
Altcode: 2005IAUS..223..463K
Solar flare on 26 June 1999 was accompanied by radio bursts giving
an indirect evidence of accelerated superthermal particle beams. It
is generally believed that this effect can stimulate an impact linear
polarization in Balmer series spectral lines. The flare was observed
simultaneously by the Ondrejov Multichannel Flare Spectrograph (MFS)
and by the Large Solar Vacuum Telescope (LSVT) using the polarization
optics in the Halpha line. Spectropolarimetric data obtained by the two
instruments are analyzed, however no substantial linear polarization
was detected. Both spectral and auxiliary data, including radio and
X-ray observations are analyzed to discuss possible reasons of the
lack of linear polarization.
Title: Polarization of Ellerman bombs and the arch structure of
active region: some results of investigation
Authors: Kashapova, L. K.
Bibcode: 2004IAUS..223..459K
Altcode: 2005IAUS..223..459K
The comparison of the polarization presence in Ellerman bombs or
moustaches and the active region arch structure was carried out. In the
most cases of the polarization, interpreted as impact polarization, were
detected in that regions where the bright small loops were observed. On
the contrary, when a significant polarization wasn't detected the
scanning during observation was carried out nearby the large loops.
Title: Spectropolarimetric Investigation of Hα Line Profiles in
Moustaches
Authors: Kashapova, L. K.
Bibcode: 2003ASPC..307..474K
Altcode:
No abstract at ADS
Title: Some results of the spectropolarimetric investigation of
Ellerman bombs
Authors: Kashapova, L. K.
Bibcode: 2002ESASP.506..661K
Altcode: 2002svco.conf..661K; 2002ESPM...10..661K
Ellerman bombs (EB) or moustaches are enigmatic phenomena of solar
atmosphere and mechanisms of their excitation are still unclear. There
are two main models of their explanation. Thermal model implies the
compression and heating of small regions of solar atmosphere. According
to the non-thermal model the beams of energetic particles are considered
as the source of EB origin. If the EB have thermal origin, then there
is a large possibility that they will show a prominent center-to limb
variation of the Hα line profiles. The Hα line polarization would
be about 2-3% both in the line core and in the wings. The moustaches
arisen as the result of bombardment by energetic particle beams will
show a polarization observed in the Hα line core only. The form of
these Hα line profiles would correlate with their life time. The
contribution presents an investigation of the Hα line profiles in
EB which showed the polarization of different types. We also make
an attempt to analyse correlation between the life time and the form
of the Hα line profiles obtained for three long-living moustaches,
which showed significant linear polarization in the line core.
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.
Bibcode: 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: On the possible manifestation of the solar G-mode in the
Earth atmosphere
Authors: Klochek, N. V.; Nikonova, M. V.; Kashapova, L. K.; Sotnikova,
R. T.
Bibcode: 2002ESASP.506..153K
Altcode: 2002ESPM...10..153K; 2002svco.conf..153K
The Sun influences the processes occurred in the Earth's atmosphere
and interplanetary space by means of not only electromagnetic but
presumably gravitational forces. As it was reported by a group of
researches (Thomson, D. et al.) charged particles in the interplanetary
medium reveal variations with periods approaching theoretically expected
periods of solar g-modes. It is believed that the detected periodicities
are an indirect manifestation of these modes. Special attention was paid
to the quasi-two-day periodicity of 2.2 days. To investigate its origin
these authors carried out an analysis of atmospheric pressure variations
which reveals the 2.2 day periodicity. We are justified in anticipating
a manifestation of characteristic properties of this periodicity in
space and in time. The wave process in the Earth's atmosphere with a
typical quasi-two-day period reveals the quadrupole structure which
seems to be the response to the effect of the low-frequency g-mode of
the Sun.
Title: A Spectropolarimetric Study of Ellerman Bombs
Authors: Kashapova, L. K.
Bibcode: 2002ARep...46..918K
Altcode:
We have studied four 10 to 40 minute sets of Hα spectropolarimetric
observations of five Ellerman bombs (a total of 241 spectropolarimetric
recordings) selected from data for more than 200 Ellerman bombs obtained
with the Large Solar Vacuum Telescope at the Ba kal Astrophysical
Observatory. The degree of polarization P and azimuth of the plane
of polarization were derived from quasi-simultaneous observations of
the Stokes parameters Q/I and U/I. We interpret the observed linear
polarization as impact polarization. A method for comparing the
polarization parameters of Ellerman bombs observed at different times
and distances from the center of the solar disk is suggested, which can
be used to relate variations of the polarimetric parameters with the
lifetimes of Ellerman bombs. A comparison between the observations and
theoretical calculations indicates that the observed Ellerman bombs
were due to electron beams with energies of several hundred keV.
Title: Observation of the linear polarization in the flare with a
powerful surge
Authors: Firstova, N. M.; Kashapova, L. K.
Bibcode: 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.
Bibcode: 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.
Bibcode: 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.
Bibcode: 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: Program for the 1999 August 11 eclipse
Authors: Grigoriev, V. M.; Eselevich, V. G.; Kashapova, L. K.;
Salakhutdinov, R. T.; Skomorovsky, V. I.
Bibcode: 1999CoSka..28..256G
Altcode:
A study of the solar coronal fine structure up to 5--6 solar radii
as an indicator of the global and local processes on the Sun. The
experimental detection of fast changes in coronal structures. An
investigation of the minimal and maximal coronal structure (streamer
form) as a result of the plasma layer projection on the picture plane
along the neutral line. Obtaining 8--10 images of the white-light corona
with the radial neutral filter. The special telescope was developed
and manufactured. The telescope tube is directed to (or from) the
polar star. The Sun's tracking is carried out by the whole telescope
tube with the heliostat mirror around the polar axis. The lens of the
telescope is a two-component Petzval type, the diameter is 120 mm,
and the focal length is 1200 mm. The assumed angular resolution at the
region +/-2.5 degree is near 5 arcsec. Data will be recorded either
via an automatic 8-cm aerial camera or using a CCD-detector.
Title: The linear polarization in moustaches
Authors: Firstova, N. M.; Boulatov, A. V.; Kashapova, L. K.
Bibcode: 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.
Bibcode: 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 alpha 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.
Bibcode: 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: A program of Observations for the August 11, 1999 Total
Solar Eclipse
Authors: Grigoriev, V. M.; Eselevich, V. G.; Kashapova, L. K.;
Salakhutdinov, R. T.; Skomorovsky, V. I.
Bibcode: 1998jena.conf...12G
Altcode:
A study of the solar coronal fine structure up to 5--6 solar radii
as an indicator of the global and local processes on the Sun. The
experimental detection of fast changes in coronal structures. An
investigation of the minimal and maximal coronal structure (streamer
form) as a result of the plasma layer projection on the picture plane
along the neutral line. Obtaining 8--10 images of the white-light corona
with the radial neutral filter. The special telescope was developed
and manufactured. The telescope tube is directed to (or from) the
polar star. The Sun's tracking is carried out by the whole telescope
tube with the heliostat mirror around the polar axis. The lens of the
telescope is a two-component Petzval type, the diameter is 120 mm,
and the focal length is 1200 mm. The assumed angular resolution at the
region ±2.5 degree is near 5 arcsec. Data will be recorded either
via an automatic 8-cm aerial camera or using a CCD-detector.
Title: Image Processing of Digitized Spectral Data
Authors: Boulatov, A. V.; Kashapova, L. K.
Bibcode: 1998ASPC..145...63B
Altcode: 1998adass...7...63B
Every observatory has a library of old pictures taken by photographic
cameras. These measurements are not as such high quality as those
from modern CCD systems, but could contain important data about
rare phenomena or source data for long-period investigations (e.g.,
concerning the solar cycle). This paper presents methods for converting
photographic images, collected at the Large Solar Vacuum Telescope
(Baikal Astrophysical Observatory) to digital images, similar to CCD
pictures. Special algorithms were used for this task and have been
implemented in the IDL environment. The results of processing real
spectral data and a comparison of processed photographic images and
images taken with a TEK CCD are presented.