arXiv subjects

A. V. Halevin

Publications and source records attributed to A. V. Halevin.

6 recordsLinked to original sources

arXiv2009

On the accretion disc properties in eclipsing dwarf nova EM Cyg

In this paper we analyzed the behavior of the unusual dwarf nova EM Cyg using the data obtained in April-October, 2007 in Vyhorlat observatory (Slovak Republic) and in September, 2006 in Crimean Astrophysical Observatory (Ukraine). During our observations EM Cyg has shown outbursts in every 15-40 days. Because on the light curves of EM Cyg the partial eclipse of an accretion disc is observed we applied the eclipse mapping technique to reconstruct the temperature distribution in eclipsed parts of the disc. Calculations of the accretion rate in the system were made for the quiescent and the outburst states of activity for different distances.

astro-ph.SR↗

arXiv2008

Eclipse mapping of RW Tri in the low luminosity state

We analyzed the eclipse light curve of the nova-like star RW Tri in its low luminosity state. During approximately 150 days, RW Tri was about one magnitude fainter than in its usual state. Our eclipse map shows that the brightness temperature in the disc ranges from 19000 K near the white dwarf to 8700 at the disc edge. For the inner parts of accretion disc, the radial temperature distribution is flatter than that predicted from the steady state models, and for the outer parts, it is close to the R^(-3/4) law. Fitting of the temperature distribution with one for the steady state disc model gives a mean accretion rate of (3.85+-0.19) 10^{-9} M year^(-1). The hotspot in the disc is placed at a distance of 0.17a from the white dwarf, where a is the orbital separation.

astro-ph↗

arXiv2008

Genetic algorithm eclipse mapping

In this paper we analyse capabilities of eclipse mapping technique, based on genetic algorithm optimization. To model of accretion disk we used the "fire-flies" conception. This model allows us to reconstruct the distribution of radiating medium in the disk using less number of free parameters than in other methods. Test models show that we can achieve good approximation without optimizing techniques.

astro-ph↗

arXiv2004

Dynamic X-ray spectra of Chandra cataclysmic variables

In this work we have tested conception of energy dependent power spectra which can be applied for analysis of X-ray dynamic spectra of cataclysmic variables. Using this technique we can study properties of variability in different energy ranges.

astro-ph↗

arXiv2004

Multidimensional analysis of X-ray variability of AGN

In this work we analyzed X-ray light curves of active galactic nucleus NGC 4051 obtained using Advanced CCD Imaging Spectrometer of Chandra satellite. Taking into account mainly flaring behaviour of AGNs we have used wavelet analysis for searching of short time lived events on light curves.

astro-ph↗

arXiv2003

Blobby accretion in magnetic cataclysmic variables

The processes of accretion of the gaseous blobs with different masses and densities onto strongly magnetized white dwarfs in the systems of polars have been modeled. We have proved that shot noise in blue wavelengths represents accretion of the smaller and denser blobs than in redder wavelengths. Using combined "smooth particle hydrodynamics - drag force" model, we have predicted a shape of the accretion stream and active regions on the white dwarf surface.

astro-ph↗