Probing Twisted Magnetic Field Using Microwave Observations in an M Class Solar Flare on 11 February, 2014     

I. N. Sharykin  A. A. Kuznetsov  I. I. Myshyakov 《Solar physics》2018,293(2):34

This work demonstrates the possibility of magnetic-field topology investigations using microwave polarimetric observations. We study a solar flare of GOES M1.7 class that occurred on 11 February, 2014. This flare revealed a clear signature of spatial inversion of the radio-emission polarization sign. We show that the observed polarization pattern can be explained by nonthermal gyrosynchrotron emission from the twisted magnetic structure. Using observations of the Reuven Ramaty High Energy Solar Spectroscopic Imager, Nobeyama Radio Observatory, Radio Solar Telescope Network, and Solar Dynamics Observatory, we have determined the parameters of nonthermal electrons and thermal plasma and identified the magnetic structure where the flare energy release occurred. To reconstruct the coronal magnetic field, we use nonlinear force-free field (NLFFF) and potential magnetic-field approaches. Radio emission of nonthermal electrons is simulated by the GX Simulator code using the extrapolated magnetic field and the parameters of nonthermal electrons and thermal plasma inferred from the observations; the model radio maps and spectra are compared with observations. We have found that the potential-magnetic-field approach fails to explain the observed circular polarization pattern; on the other hand, the Stokes-\(V\) map is successfully explained by assuming nonthermal electrons to be distributed along the twisted magnetic structure determined by the NLFFF extrapolation approach. Thus, we show that the radio-polarization maps can be used for diagnosing the topology of the flare magnetic structures where nonthermal electrons are injected.  相似文献   

General characterization of the seismoelectric effects of the first and second kinds in the Saratov Zavolzh’e region,the Dnieper-Donets basin,and Western Siberia     

A. N. Kuznetsov  I. P. Sokolova  I. P. Moroz  V. M. Kobzova  O. V. Sheremeta 《Izvestiya Physics of the Solid Earth》2007,43(4):309-313

The seismoelectric effects of the first and second kinds of oil and gas reservoir rocks are studied in three geological regions. Rock samples were taken from deep borehole cores of terrigenous and carbonate composition. Measurements were made in the ultrasound range (100–200 kHz) and at a frequency of 300 Hz. It is shown that the relationship between the porosity coefficient and the intensity of the second-kind seismoelectric effect is the same for terrigenous reservoir rocks in the Saratov Zavolzh’e region, an area of Western Siberia, and the Dnieper-Donets basin. An anomalously strong seismoelectric effect of the first kind (a vibration-induced change in the electrical resistance) is discovered for carbonate reservoir rocks of the Zavolzh’e region.  相似文献   

Dynamics of the radiation belt formed by solar protons during magnetic storms     

L. L. Lazutin  S. N. Kuznetsov  A. N. Podorol’skii 《Geomagnetism and Aeronomy》2007,47(2):175-184

Experimental proofs of the existence of the formation and destruction mechanisms of solar proton belts in the inner magnetosphere at a rapid change in the penetration boundary of solar protons are presented. An analysis of the measurements of solar protons and alpha-particles on board the Coronas-F low-altitude polar satellite during the magnetic storms in October–November 2003 is performed. During this period, formation and destruction of the belts of solar cosmic rays was observed several times. The compression of the magnetosphere during a storm makes possible the direct penetration of solar protons deep into the inner magnetosphere. The proton trajectories outside the penetration boundary are open, and the preliminary captured particles can easily leave the magnetosphere. During the recovery of the magnetospheric configuration, when the penetration boundary goes away from the Earth, the solar protons and alpha-particles with relatively low velocity of the magnetic drift remain stably captured, whereas the particles of higher energies follow the motion of the penetration boundary. That is why the energy range of the captured protons is limited from above in contrast to the effect of injection during ineffective SC in the low-energy region.  相似文献   

A possible manifestation of spiral shock waves in the accretion disks of cataclysmic variables     

D. V. Bisikalo  A. A. Boyarchuk  A. A. Kilpio  O. A. Kuznetsov 《Astronomy Reports》2001,45(9):676-685

We present the results of three-dimensional numerical simulations of flow structures in binary systems with spiral shock waves. Variations of the mass-transfer rate perturb the equilibrium state of the accretion disk; consequently, a condensation (blob) behind the shock breaks away from the shock front and moves through the disk with variable speed. Our computations indicate that the blob is a long-lived formation, whose mean parameters do not vary substantially on timescales of several tens of orbital periods of the system. The presence of the spiral shocks maintains the compact blob in the disk: it prevents the blob from spreading due to the differential motion of matter in the disk, and dissipative spreading on this timescale is negligible. A number of cataclysmic variables display periodic or quasi-periodic photometric variations in their light curves with characteristic periods ～0.1–0.2P _orb, where P _orb is the orbital period. The blobs formed in systems with spiral shock waves are examined as a possible origin for these variations. The qualitative (and, in part, quantitative) agreement between our computations and observations of IP Peg and EX Dra provides evidence for the efficacy of the proposed model.  相似文献   

Application of pattern recognition algorithm in the seismic belts of Indian convergent plate margin — CN algorithm     

V K Gagakayt  I V Kuznetsov  I M Rotwain  A M Gabruekiv  V I Keilis-Borok 《Journal of Earth System Science》1992,101(3):227-238

The earthquake catalogue from 1964 to August 1991 is used to identify the times of increased probabilities (TIPs) of the earthquake mainshocks of magnitudes greater than or equal to 6·4 and are associated with the Indian convergent plate margins, in retrospect. In Pakistan and Indo-Burma regions, the analysis was repeated for magnitude threshold 6·2 and 7·0 respectively. All the earthquakes (except one in the Hindukush region and one in Indo-Burmese region) in Pakistan, Hindukush-Pamir, Himalaya and Indo-Burmese regions were preceded by the special activation and hence were predicted. Approximately 23 ± 10% of the total time (1970 to August 1991) is occupied by the TIPs in all the regions. The reasons for failure to predict the two earthquakes in these regions are discussed. Our analysis gives a better picture of the regionalization and the size of the space-time volume for the preparation of an earthquake. The high success ratio of the algorithm proves that it can be applied in this territory for further prediction in the real time, without any significant changes in its parameters.  相似文献   

A catalog of cosmic gamma-ray bursts detected by the PHEBUS instrument on the Granat observatory: October 1994–December 1996     

A. Yu. Tkachenko  O. V. Terekhov  R. A. Sunyaev  A. V. Kuznetsov  C. Barat  J. -P. Dezalay  G. Vedrenne 《Astronomy Letters》2002,28(6):353-365

We present the final part of the catalog of cosmic gamma-ray bursts (GRBs) observed in the PHEBUS experiment on the Granat orbiting astrophysical observatory. The first three parts of the catalog were published by Terekhov et al. (1994, 1995a) and Tkachenko et al. (1998). The fourth part contains information on 32 events recorded from October 1994 until December 1996. We give burst light curves in the energy range 100 keV to 1.6 MeV, integrated energy spectra, and information on the fluence and energy flux at the luminosity peak for energies above 100 keV. Over the entire period of its operation, the PHEBUS instrument detected 206 cosmic GRBs. The mean ?V/V_max? was 0.336±0.007. The mean hardness corresponding to the ratio of count numbers in the energy ranges 400–1000 and 100–400 keV is 0.428±0.018 for events with a duration shorter than 2 s and 0.231±0.004 for events with a duration longer than 2 s.  相似文献   

Planetary statistics of the critical frequency of the ionospheric F 2 region during catastrophic earthquakes     

A. L. Dzvonkovskaya  V. A. Kuznetsov  N. P. Sergeenko 《Geomagnetism and Aeronomy》2006,46(4):522-523

The statistics of the relative variations (δfoF2) in the critical frequency of the ionospheric F ₂ region during catastrophic earthquakes with magnitude M ≥ 6 at 70 vertical sounding (VS) automatic ionospheric stations (AISs) of the global network is considered. Five-day periods including 70 such situations have been selected for 1981 and 1983–1985. Five sets of 24 foF2 measurements from 3 days before to a day after the earthquake instant are formed for each AIS. The number of AISs, for which the fourth statistical invariant is above the significance level (E ≥ 1), has been analyzed. It has been indicated that the histogram deformation at the set of AISs is substantial a day before earthquakes.  相似文献   

The <Superscript>230</Superscript>Th/U dating of sulfide ores in the ocean: Methodical possibilities,measurement results,and perspectives of application     

V. Yu. Kuznetsov  G. A. Cherkashev  V. E. Bel’tenev  A. Yu. Lein  F. E. Maximov  V. V. Shilov  T. V. Stepanova 《Doklady Earth Sciences》2007,417(1):1202-1205

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Strontium isotopic composition of lower Riphean carbonate rocks in the magnesite-bearing Satka Formation,southern Urals     

A. B. Kuznetsov  M. T. Krupenin  I. M. Gorokhov  A. V. Maslov  G. V. Konstantinova  E. P. Kutyavin 《Doklady Earth Sciences》2007,414(1):599-604

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Statistical and probability analysis of frosts in Belarus     

V. F. Loginov  V. S. Mikutskii  G. P. Kuznetsov 《Russian Meteorology and Hydrology》2007,32(10):651-657

Methods of studying May frosts, their time dynamics, and spatial structure in Belarus are considered. The territory of Belarus was divided into western and eastern parts with the help of methods of multivariate statistical analysis, proceeding from the dynamics of a number of frost days in May. Before 1985, the number of frost days prevailed in the western part, while after 1985, in eastern Belarus. A quasi-twelve-year cyclicity is established in the dynamics of a difference between a number of frost days in May in the east and west of the country  相似文献