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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. 相似文献
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M. R. Kundu V. V. Grechnev S. M. White E. J. Schmahl N. S. Meshalkina L. K. Kashapova 《Solar physics》2009,260(1):135-156
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. 相似文献
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V. V. Zharkova N. S. Meshalkina L. K. Kashapova A. T. Altyntsev A. A. Kuznetsov 《Geomagnetism and Aeronomy》2011,51(8):1029-1040
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. 相似文献
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M. A. Livshits D. V. Golovin L. K. Kashapova I. G. Mitrofanov A. S. Kozyrev M. L. Litvak A. B. Sanin V. I. Tret’yakov W. Boynton K. Shinohara D. Hamara 《Astronomy Reports》2011,55(6):551-560
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. 相似文献
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Astronomy Reports - 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... 相似文献
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V. I. Vybornov M. A. Livshits L. K. Kashapova I. G. Mitrofanov D. V. Golovin A. S. Kozyrev M. L. Litvak A. B. Sanin V. I. Tret’yakov W. Boynton K. Shinohara D. Hamara 《Astronomy Reports》2012,56(10):805-812
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. 相似文献
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R. V. Vasil’ev D. S. Kushnarev L. K. Kashapova V. P. Lebedev A. V. Medvedev N. I. Nevedimov K. G. Ratovskii 《Astronomy Reports》2013,57(11):872-881
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. 相似文献