When and where are solar cosmic rays accelerated most efficiently?     

M. A. Livshits  A. V. Belov 《Astronomy Reports》2004,48(8):665-677

The acceleration of particles by solar flares with extremely large proton fluxes whose energies exceed 100 MeV is considered. Most importantly, the location of the source of such acceleration in the flare of July 14, 2000, is determined assuming that the acceleration time coincides with the observed burst of hard line and continuous gamma-ray emission. The onset of this event corresponds to 10:19 UT, when data taken by the TRACE space observatory show that one of the flare ribbons reached a large sunspot in a group. The time interval for the development of the flare, 10:20–10:28 UT, is associated with the beginning of an increasing proton flux at the Earth. The region of efficient acceleration is estimated to be approximately two to three times higher than the height where the hard X-ray pulse usually originates (about 7000 km). The results are generalized for 28 powerful flares with extremely efficient acceleration of relativistic particles—in particular, for the well-studied events of June 15, 1991, and May 24, 1990—and are compared with the results of a statistical analysis of over 1100 increasing-proton-flux events. Efficient particle acceleration seems to be associated with the powerful impulsive episodes of the large flares analyzed. The results suggest that, along with sources of local (as in impulsive flares) and post-eruptive acceleration, there is an additional, very efficient, moderate-scale “accelerator” in tenuous regions with fairly strong magnetic fields and magnetic-field gradients.  相似文献   

A space-based decametric wavelength radio telescope concept     

K. Belov  A. Branch  S. Broschart  J. Castillo-Rogez  S. Chien  L. Clare  R. Dengler  J. Gao  D. Garza  A. Hegedus  S. Hernandez  S. Herzig  T. Imken  H. Kim  S. Mandutianu  A. Romero-Wolf  S. Schaffer  M. Troesch  E. J. Wyatt  J. Lazio 《Experimental Astronomy》2018,46(2):241-284

This paper reports a design study for a space-based decametric wavelength telescope. While not a new concept, this design study focused on many of the operational aspects that would be required for an actual mission. This design optimized the number of spacecraft to insure good visibility of approx. 80% of the radio galaxies– the primary science target for the mission. A 5,000 km lunar orbit was selected to guarantee minimal gravitational perturbations from Earth and lower radio interference. Optimal schemes for data downlink, spacecraft ranging, and power consumption were identified. An optimal mission duration of 1 year was chosen based on science goals, payload complexity, and other factors. Finally, preliminary simulations showing image reconstruction were conducted to confirm viability of the mission. This work is intended to show the viability and science benefits of conducting multi-spacecraft networked radio astronomy missions in the next few years.  相似文献   

Peak-Size Distributions of Proton Fluxes and Associated Soft X-Ray Flares     

A. Belov  V. Kurt  H. Mavromichalaki  M. Gerontidou 《Solar physics》2007,246(2):457-470

A database combining information about solar proton enhancements (SPEs) near the Earth and soft X-ray flares (GOES measurements) has been used for the study of different correlations through the period from 1975 to May 2006. The emphasis of this work is on the treatment of peak-size distributions of SXR flares and SPEs. The frequency of SXR flares and solar proton events (>10 and >100 MeV, respectively) for the past three solar cycles has been found to follow mainly a power-law distribution over three to five orders of magnitude of fluxes, which is physically correct beyond the “sensitivity” problem with the smallest peak values. The absence of significant spectral steepening in the domain of the highest peak values demonstrates that during the period considered, lasting 30 years, the limit of the highest flare’s energy release has not yet been achieved. The power-law exponents were found to be −2.19±0.04, −1.34±0.02, and −1.46±0.04, for the total SXR flare distribution and the total SPE distributions (for both E _P>10 MeV and E _P>100 MeV), respectively. For SPEs associated with flares located to the West of 20° W, the exponents are −1.22±0.05 (E _P>10 MeV) and −1.26±0.03 (E _P>100 MeV). The size distribution for corresponding flares follows a power law with a slope of −1.29±0.12. Thus, X-ray and proton fluxes produced in the same solar events have very similar distribution shapes. Moreover, the derived slopes are not incompatible with a linear dependence between X-ray flare power and proton fluxes near the Earth. A similar statistical relation is obtained independently from the direct comparison of the X-ray and proton fluxes. These all argue for a statistically significant relationship between X-ray and proton emissions.  相似文献   

Regularities of C<Subscript>org</Subscript> distribution in bottom sediments of the Russian part of the Sea of Azov     

Yu. A. Fedorov  I. V. Dotsenko  A. N. Kuznetsov  A. A. Belov  E. A. Loginov 《Oceanology》2009,49(2):211-217

The principal regularities were ascertained for the spatiotemporal distribution of organic carbon in the water and bottom sediments of the Russian part of the Sea of Azov. The relationships between allo- and autochthonous organic matter in water and bottom sediments from different parts of the sea aquatic area were found. The behavior of organic carbon in the water-bottom sediments system was characterized as the effect of the variability of hydrochemical, biological, and hydrological factors ad processes.  相似文献   

Solar Activity Parameters and Associated Forbush Decreases During the Minimum Between Cycles 23 and 24 and the Ascending Phase of Cycle 24     

D. Lingri  H. Mavromichalaki  A. Belov  E. Eroshenko  V. Yanke  A. Abunin  M. Abunina 《Solar physics》2016,291(3):1025-1041

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Plasma flow in vicinity of the heliopause stagnation point in the presence of hydrogen neutral atoms     

N. A. Belov 《Astronomy Letters》2010,36(2):144-149

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On the Analysis of the Complex Forbush Decreases of January 2005     

A. Papaioannou  O. Malandraki  A. Belov  R. Skoug  H. Mavromichalaki  E. Eroshenko  A. Abunin  S. Lepri 《Solar physics》2010,266(1):181-193

In this work an analysis of a series of complex cosmic ray events that occurred between 17 January 2005 and 23 January 2005 using solar, interplanetary and ground based cosmic ray data is being performed. The investigated period was characterized both by significant galactic cosmic ray (GCR) and solar cosmic ray (SCR) variations with highlighted cases such as the noticeable series of Forbush effects (FEs) from 17 January 2005 to 20 January 2005, the Forbush decrease (FD) on 21 January 2005 and the ground level enhancement (GLE) of the cosmic ray counter measurements on 20 January 2005. The analysis is focusing on the aforementioned FE cases, with special attention drawn on the 21 January 2005, FD event, which demonstrated several exceptional features testifying its uniqueness. Data from the ACE spacecraft, together with GOES X-ray recordings and LASCO CME coronagraph images were used in conjunction to the ground based recordings of the Worldwide Neutron Monitor Network, the interplanetary data of OMNI database and the geomagnetic activity manifestations denoted by K _p and D _st indices. More than that, cosmic ray characteristics as density, anisotropy and density gradients were also calculated. The results illustrate the state of the interplanetary space that cosmic rays crossed and their corresponding modulation with respect to the multiple extreme solar events of this period. In addition, the western location of the 21 January 2005 solar source indicates a new cosmic ray feature, which connects the position of the solar source to the cosmic ray anisotropy variations. In the future, this feature could serve as an indicator of the solar source and can prove to be a valuable asset, especially when satellite data are unavailable.  相似文献   

Characteristics of Low-Frequency Radiation Excited by the Impact of an Oscillating,High-Frequency Beam on the Ionosphere According to In Situ Measurements     

Belov  A. S. 《Geomagnetism and Aeronomy》2022,62(1-2):116-124

Geomagnetism and Aeronomy - The results of experimental studies of the characteristics of low-frequency (LF) radiation excited by the impact of two frequency-shifted, unmodulated pump waves emitted...  相似文献   

Solar Activity,Galactic Cosmic Ray Variations,and the Global Seismicity of the Earth     

Khegai  V. V.  Legen&#;ka  A. D.  Abunin  A. A.  Abunina  M. A.  Belov  A. V.  Gaidash  S. P. 《Geomagnetism and Aeronomy》2022,61(1):S36-S47

Geomagnetism and Aeronomy - A comparative analysis of the correlation between the number of strong (magnitude M ≥ 5.0), crustal (hypocenter depth 0 ≤ h ≤ 60 km) earthquakes per...  相似文献   

A Challenging Solar Eruptive Event of 18 November 2003 and the Causes of the 20 November Geomagnetic Superstorm. IV. Unusual Magnetic Cloud and Overall Scenario     

V. V. Grechnev  A. M. Uralov  I. M. Chertok  A. V. Belov  B. P. Filippov  V. A. Slemzin  B. V. Jackson 《Solar physics》2014,289(12):4653-4673

The geomagnetic superstorm of 20 November 2003 with Dst=?422 nT, one of the most intense in history, is not well understood. The superstorm was caused by a moderate solar eruptive event on 18 November, comprehensively studied in our preceding Papers I?–?III. The analysis has shown a number of unusual and extremely complex features, which presumably led to the formation of an isolated right-handed magnetic-field configuration. Here we analyze the interplanetary disturbance responsible for the 20 November superstorm, compare some of its properties with the extreme 28?–?29 October event, and reveal a compact size of the magnetic cloud (MC) and its disconnection from the Sun. Most likely, the MC had a spheromak configuration and expanded in a narrow angle of ≤?14^°. A very strong magnetic field in the MC up to 56 nT was due to the unusually weak expansion of the disconnected spheromak in an enhanced-density environment constituted by the tails of the preceding ICMEs. Additional circumstances favoring the superstorm were i) the exact impact of the spheromak on the Earth’s magnetosphere and ii) the almost exact southward orientation of the magnetic field, corresponding to the original orientation in its probable source region near the solar disk center.  相似文献