Peculiarities of giant pulses from the crab pulsar at frequencies of 594 and 2228 MHz     

S. V. Kostyuk  V. I. Kondratiev  A. D. Kuzmin  M. V. Popov  V. A. Soglasnov 《Astronomy Letters》2003,29(6):387-393

We present the results of our simultaneous observations of giant pulses from the Crab pulsar B0531+21 at frequencies of 594 and 2228 MHz with a high (62.5 ns) time resolution. The pulse broadening by scattering was found to be 25 and 0.4 µs at 594 and 2228 MHz, respectively. We obtained the original giant-pulse profiles compensated for interstellar scattering. The measured profile widths at the two frequencies are approximately equal, ≈0.5 µs; i.e., the giant pulses are narrower than the integrated profile by a factor of about 1000. We detected an extremely high brightness temperature of radio emission, T_b≥10³⁶ K radio emission, which is higher than the previous estimates of this parameter by five orders of magnitude. The decorrelation bandwidth of the radio-spectrum diffraction distortions has been determined for this pulsar for the first time: 10 kHz at 594 MHz and 300 kHz at 2228 MHz.  相似文献   

Emission line features in the spectra of four type 1 Seyfert galaxies     

V. N. Popov  É. E. Khachikyan 《Astrophysics》1980,16(2):127-132

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Spectrophotometric investigation of the nucleus of the seyfert galaxy markaryan 308     

V. N. Popov  É. E. Khachikyan 《Astrophysics》1980,16(1):33-36

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Boundary conditions for simulations of the thermal outburst of a type Ia supernova     

M. V. Popov  S. D. Ustyugov  V. M. Chechetkin 《Astronomy Reports》2005,49(6):450-458

We present a technique to calculate the boundary conditions for simulations of the development of large-scale convective instability in the cores of rotating white-dwarf progenitors of type Ia supernovae. The hydrodynamical equations describing this situation are analyzed. We also study the impact of the boundary conditions on the development of the thermal outburst.  相似文献   

The development of large-scale instability in stellar accretion disks and its influence on the redistribution of angular momentum     

A. Yu. Lugovskii  S. I. Mukhin  Yu. P. Popov  V. M. Chechetkin 《Astronomy Reports》2008,52(10):811-814

The paper continues our studies of large-scale instability arising during shearmotions in stellar accretion disks due to the development of small perturbations. The evolution of a local perturbation introduced into the outer part of a stationary accretion disk is modeled mathematically. The possible formation of large-scale structures that propagate throughout the disk, leading to an appreciable redistribution of angular momentum, is demonstrated.  相似文献   

Results of three-frequency monitoring of giant pulses from the crab pulsar     

M. V. Popov  V. A. Soglasnov  V. I. Kondrat’ev  A. V. Bilous  S. V. Sazankov  A. I. Smirnov  B. Z. Kanevskiĭ  V. V. Oreshko  Yu. P. Ilyasov 《Astronomy Reports》2008,52(11):900-909

We present the results of long-term, three-frequency monitoring of giant pulses from the Crab pulsar on the 64-m radio telescope in Kalyazin. The total monitoring time was 160 hours. The signal power was recorded simultaneously at 600, 1650, and 4850 MHz via direct sampling of the received signals in the total receiver bandwidth without any compensation for interstellar dispersion. In total, 1117 and 352 giant pulses were detected at 600 and 4850 MHz, respectively. The frequency band centered at 1650 MHz was contaminated by interference, and was used only to identify events found in other frequency bands. The cumulative energy distribution of the giant pulses follows a power law at 600 and 4850 MHz up to the highest energies. A deep modulation in the radio spectra of individual giant pulses was observed on both large (Δv/v ≈ 0.5) and small (Δv/v ≈ (2?4) × 10^?3) frequency scales. The simultaneous appearance of giant pulses at the interpulse longitudes at high (4850 MHz) and low (1650 and/or 600 MHz) frequencies testifies to their common origin, in spite of the observed differences in other parameters.  相似文献   

Assessment of Variations in the Annual Sum of Active Temperatures and Total Precipitation during the Vegetation Period in Russia and Neighboring Countries     

E.?N.?PopovaEmail author  I.?O.?Popov  S.?M.?Semenov 《Russian Meteorology and Hydrology》2018,43(6):412-417

The long–term values are calculated for the annual sum ofactive temperatures in the surface air layer and for total precipitation during the vegetation period (May–September) in Russia and neighboring countries for two time periods: 1951–1970 and 1991–2010. The statistical procedures are used to demonstrate the reliability of differences in the values of these parameters for the analyzed time periods. The sum of active temperatures significantly increased almost on the whole territory of Russia except for some Arctic and Far East regions. The spatial variations in total precipitation during the vegetation period are obviously inhomogeneous.  相似文献   

The estimate of the Venus magnetotail length     

I. Yu. Vasko  L. M. Zelenyi  V. Yu. Popov 《Solar System Research》2014,48(2):91-104

We consider the process of flux tubes straightening in the Venus magnetotail on the basis of MHD model. We estimate the distance x _t, where flux tubes are fully straightened due to the magnetic tension and the magnetotail with the characteristic geometry of field lines (“slingshot” geometry) ends. We investigate the influence of the transversal current sheet scale on the process of flux tubes straightening. The assumption of a thin current sheet allows to obtain a lower estimate of the magnetotail length, x _t > 31R _V (R _V is the Venus radius), while the assumption of a broad current sheet allows to obtain an upper estimate, x _t < 44R _V. We show that kinetic effects associated with the losses of particles with small pitch angles from the flux tube and the influx of magnetosheath plasma into the flux tube do not significantly affect the estimate of the magnetotail length. The model predicts the existence of energetic fluxes of protons H⁺ (2–5 keV) and oxygen ions O⁺ (35–80 keV) in the distant tail. We discuss the magnetotail structure at x > x _t.  相似文献   

Geochemistry of obsidian from Krasnoe Lake on the Chukchi Peninsula (Northeastern Siberia)     

Popov  V. K.  Grebennikov  A. V.  Kuzmin  Ya. V.  Glascock  M. D.  Nozdrachev  E. A.  Budnitsky  S. Yu.  Vorobey  I. E. 《Doklady Earth Sciences》2017,476(1):1099-1104

Doklady Earth Sciences - This report considers features of the geochemical composition of obsidian from beach sediments of Krasnoe Lake along the lower course of the Anadyr River, as well as from...  相似文献   

Distribution of interstellar plasma in the direction of PSR B0525+21 from data obtained on a ground–space interferometer     

A. S. Andrianov  T. V. Smirnova  V. I. Shishov  C. Gwinn  M. V. Popov 《Astronomy Reports》2017,61(6):513-520

Observations on the RadioAstron ground–space interferometer with the participation of the Green Bank and Arecibo ground telescopes at 1668 MHz have enabled studies of the characteristics of the interstellar plasma in the direction of the pulsar PSR B0525+21. The maximum projected baseline for the ground–space interferometer was 233 600 km. The scintillations in these observations were strong, and the spectrum of inhomogeneties in the interstellar plasma was a power law with index n = 3.74, corresponding to a Kolmogorov spectrum. A new method for estimating the size of the scattering disk was applied to estimate the scattering angle (scattering disk radius) in the direction toward PSR B0525+21, θ _scat = 0.028 ± 0.002 milliarcsecond. The scattering in this direction occurs in a plasma layer located at a distance of 0.1Z from the pulsar, where Z is the distance from the pulsar to the observer. For the adopted distance Z = 1.6 kpc, the screen is located at a distance of 1.44 kpc from the observer.  相似文献