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Interactions of particles accelerated in solar flares with matter in the solar atmosphere give rise to neutrons, which are efficiently captured on hydrogen nuclei as they are slowed to thermal velocities. This capture is accompanied by the emission of a gamma-ray with energy 2.223 MeV. Observational data for the temporal profiles of the gamma-ray fluxes in this line are used to study the plasma-density distribution in the solar atmosphere during the flares of December 16, 1988, March 22, 1991, and November 6, 1997. This analysis is based on comparisons between the observations and profiles computed taking into account a number of parameters describing the generation and transport of the flare neutrons in atmospheric layers of various densities. In three cases studied, the density of the material in the photosphere below the flare region is enhanced compared to the density in an unperturbed part of the solar atmosphere at the same height. In the case of the December 16, 1988 flare, we are able for the first time to relate the profile of the 2.223 MeV line with the shape of the accelerated particle (proton) spectrum. This opens new possibilities for studies of particle acceleration on the Sun based on observations of flare gamma-ray emission. 相似文献
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Based on 21 spectra with resolutions from 12 000 to 42 000 taken in 1997–2016 for the yellow supergiant α Aqr (which is believed to be nonvariable in the Cepheid instability strip), we have determined its effective temperature Teff and radial velocities from metal and hydrogen absorption lines. Blue and red components that account for 20–25% of the total number of lines used have been detected in the profiles of these lines. The effective temperature and radial velocities estimated from metal lines and their components do not show any noticeable variations, while the radial velocities determined from hydrogen lines show variations that are largest for the Hα line, with an amplitude of more than 10 km s?1. These variations resemble periodic (～100 days) and sporadic ones. The presence of variable red components in the hydrogen line cores confirms that there is a circumstellar envelope around the supergiant. The radial velocities of these components exhibit a behavior similar to that of the hydrogen lines but with larger amplitudes (it is twice that for the R component of the Hα line). Such an unusual variability as well as the presence of blue components in metal lines and the star’s position at the red edge of the Cepheid instability strip can be explained by a possible residual pulsational activity in the upper atmospheric layers of the star, which “swings” the envelope with a larger amplitude when passing into a less dense medium. The multicomponent structure of the Na I D doublet lines and their variations over long time intervals may be indicative of a chromospheric activity and a change in the stellar wind intensity. These processes can affect the sporadic variations of the radial velocities in the upper atmospheric layers of the star and its envelope. We raise the question about a revision of the classification of α Aqr as a yellow nonvariable supergiant. 相似文献
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L. I. Miroshnichenko J. A. Pérez-Peraza V. M. Velasco-Herrera J. Zapotitla E. V. Vashenyuk 《Geomagnetism and Aeronomy》2012,52(5):547-560
Using modern wavelet analysis techniques, we have made an attempt to search for oscillations of intensity of galactic cosmic rays (GCR), sunspot numbers (SS) and magnitudes of coronal index (CI) implying that the time evolution of those oscillations may serve as a precursor of Ground Level Enhancements (GLEs) of solar cosmic rays (SCR). From total number of 70 GLEs registered in 1942–2006, the four large events — 23 February 1956, 14 July 2000, 28 October 2003, and 20 January 2005 — have been chosen for our study. By the results of our analysis, it was shown that a frequency of oscillations of GCR decreases as time approaches to the event day. We have also studied a behaviour of common periodicities of GCR and SCR within the time interval of individual GLE. The oscillations of GLE occurrence rate (OR) at different stages of the solar activity (SA) cycle is of special interest. We have found some common periodicities of SS and CI in the range of short (2.8, 5.2, 27 and 60 days), medium (0.3, 0.5, 0.7, 1.3, 1.8 and 3.2 years) and long (4.6 and 11.0 years) periods. Short and medium periodicities, in general, are rather concentrated around the maxima of solar cycles and display the complex phase relations. When comparing these results with the behaviour of OR oscillations we found that the period of 11 years is dominating (controlling); it is continuous over the entire time interval of 1942–2006, and during all this time it displays high synchronization and clear linear ratios between the phases of oscillations of η, SS and CI. It implies that SCR generation is not isolated stochastic phenomena characteristic exclusively for chromospheric and/or coronal structures. In fact, this process may have global features and involve large regions in the Sun’s atmosphere. 相似文献
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V. A. San’kov A. V. Parfeevets A. V. Lukhnev A. I. Miroshnichenko S. V. Ashurkov 《Geotectonics》2011,45(5):378-393
Comprehensive analysis of the parameters characterizing contemporary and neotectonic deformations of the Earth’s crust and
upper mantle developed in the Mongolia-Siberia area is presented. The orientation of the axes of horizontal deformation in
the geodetic network from the data of GPS geodesy is accepted as an indicator of current deformations at the Earth’s surface.
At the level of the middle crust, this is the orientation of the principal axes of the stress-tensors calculated from the
mechanisms of earthquake sources. The orientation of the axes of stress-tensors reconstructed on the basis of structural data
is accepted as an indicator of Late Cenozoic deformations in the upper crust. Data on seismic anisotropy of the upper mantle
derived from published sources on the results of splitting of shear waves from remote earthquakes serve as indicators of deformation
in the mantle. It is shown that the direction of extension (minimum compression) in the studied region coincides with the
direction of anisotropy of the upper mantle, the median value of which is 310–320° NW. Seismic anisotropy is interpreted as
the ordered orientation of olivine crystals induced by strong deformation owing to the flow of mantle matter. The observed
mechanical coupling of the crust and upper mantle of the Mongolia-Siberia mobile area shows that the lithospheric mantle participated
in the formation of neotectonic structural elements and makes it possible to ascertain the main processes determining the
Late Cenozoic tectogenesis in this territory. One of the main mechanisms driving neotectonic and contemporary deformations
in the eastern part of the Mongolia-Siberia area is the long-living and large-scale flow of the upper mantle matter from the
northwest to the southeast, which induces both the movement of the northern part of the continent as a whole and the divergence
of North Eurasia and the Amur Plate with the formation of the Baikal Rift System. In the western part of the region, deformation
of the lithosphere is related to collisional compression, while in the central part, it is due to the dynamic interaction
of these two large-scale processes. 相似文献
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The advent of new and better instruments in space has resulted in a considerable increase in the number of solar gamma-ray events (GRE) detected. In this paper, we analyze available SMM/GRS and GRANAT/PHEBUS data on the hard X-ray and gamma-ray events, and their associations with solar proton events (SPE) at the Earth's orbit, for the observation period of 1980–1995. About 58% of the GREs under study were found to be SPE-related ones. Size (frequency) distributions have been obtained, for the first time, for the events with different types of emissions (bremsstrahlung, narrow GR lines, positron annihilation line, neutron capture line, SPEs, etc.). We discuss the possible relationships between size distributions implied by the parameter correlation. The distribution for GR events turns out to be generally harder than that for X-ray bursts. The GREs involving energetic particles in space are shown to have a harder frequency distribution in comparison with that for GREs without detectable SPEs. There is also a tendency for the GREs with highest fluences to be related with SPEs. Finally, no correlation seems to exist between the GRL fluence and maximum flux of >10 MeV protons near the Earth. 相似文献
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A. I. Miroshnichenko A. P. Sorokin V. A. San’kov A. V. Lukhnev S. V. Ashurkov A. T. Sorokina N. I. Panfilov M. A. Serov S. I. Sherman 《Russian Journal of Pacific Geology》2008,2(1):64-71
The Amur-Zeya geodynamic test ground was set up in 2000 to study recent intracontinental crustal deformations. The velocity field calculations for the period of 2000 to 2003 describe three movements scales. The general level is characterized by the vectors of IGS sites in the eastern part of Asia, the BLAG (Blagoveshchensk) site included. The southeast movement of the IRKT (Irkutsk) site of the stable Siberian Platform is indicative of deformations in the northeastern part of the Amur Plate. Measurement data on the regional near-latitudinal profile Blagoveshchensk-Sutara, which crosses the Nizhnyaya Zeya Basin, demonstrate a southwestward displacement of the Badzhal-Bureya-Lesser Khingan block relative to the North China block. The dynamic effect of the convergent boundary between the Amur and Okhotsk Sea plates is assumed to extend inland also involving the Zeya-Bureya Basin area. The measurements on the local geodynamic test site relate the deformations of buildings and constructions in the Settlement of Konstantinovka to the mobility of basement faults in the southern part of the Nizhnyaya Zeya Basin. Aseismic deformations are determined by slow horizontal tectonic movements in the junction zone of NNE-trending structures of the latter basin and near-latitudinal faults of the Khailar-Xunhei Belt. 相似文献