Search Publications
Searching for new cataclysmic variables in different X-ray and optical catalogs
Galiullin, I. I.
Cataclysmic variables (CVs) are binary systems in which a white dwarf accretes matter from a Roche-lobe-filling companion star. Numerous CVs can be seen in optical light curves as periodic sources. Moreover, accretion can result in outbursts, which are visible in their optical light curves, especially in non-magnetic CVs. I review a modern multiwa…
Variability of optical and X-ray spectra of Gamma Cassiopeia stars
Yakunin, I. A.; Kholtygin, A. F.; Ryspaeva, E. B. +1 more
Stars of the γ Cas type (γ Cas analogs) belong to a small group of Be stars with a high X-ray luminosity of 10 31 ‑ 10 33 erg/s and an anomalously high temperature of the plasma emitting in the X-ray range of 10–20 keV or more, assuming a completely thermal X-ray emission. The results of the analysis of the optical spectra of γ Cas under the progr…
Variable stars in the field of open cluster NGC 6819
Karimov, R. G.; Gaysin, R. A.
Here we present preliminary results of searching and study of variable stars based on space observation data of the TESS mission in the field of the open star cluster NGC 6819. The light curves of variable stars of various types located in the field of an open cluster are studied. Based on the data from the GAIA DR3 mission, the probable members o…
Cometocentric coordinates of the tail axis of comet 67P/Churyumov-Gerasimenko
Ibragimov, A. A.
In this paper, we consider errors in the measurement of cometocentric coordinates. The sequence of actions for determining the cometocentric coordinates by perspective projection of the image points of the comet onto the orbital plane is given on the example of comet 67P. Conditions are shown that increase the accuracy of determining the angle of …
Method of evaluation of the most probable mean radial velocities of open star clusters
Kovaleva, D. A.; Kalinkin, A. D.; Kondratev, N. E. +1 more
In this article the method of self-consistent estimate of star clusters' average radial velocity by kinematic parameters was proposed. The method is based on convergent point method of probable cluster members determination. By modelling the method validation was held and properties of received estimate depending on a number of cluster parameters …
Fundamental parameters of Ap-star HD 108662
Romanovskaya, A. M.; Ryabchikova, T. A.; Shulyak, D. V.
We present the results of self-consistent spectroscopic analysis of the atmosphere of Ap-star HD 108662 based on high resolution spectrum and spectrophotometric observations in a wide wavelength range. Magnetic field effects were taking into account. Abundances of 24 chemical elements were derived, and stratification of Fe which lines make the mai…
Observational signs of wide binary stars dissolution in Gaia DR2 data
Kovaleva, D. A.; Sapozhnikov, S. A.
Binary and common proper motion stars within 100 pc of the Sun are being investigated using Gaia DR2 data. An artificial random pairs sample is constructed to exclude possible random pairing contamination. Numerical estimation of this contamination shows that the chosen method to select the common proper motion stars yields little contamination ev…
The kinematics of OB-stars and Cepheids based on Gaia DR2 catalogue
Pakhomova, P. V.
The purpose of the work was to study the kinematics and refine the distance scale of young objects of the galactic disk: OB stars and high-luminosity stars of late spectral classes, as well as Cepheids. We used the observational data obtained during the Gaia mission and published in the Gaia DR2 catalog. The statistical parallax method was used to…
On possibility using photometry of Landolt fields for determination of stellar parameters and interstellar reddening
Pakhomov, Yu. V.; Stepina, Yu. A.
The paper analyzes the possibility of determination of stellar parameters and interstellar reddening based on UBVRIJHK photometry of secondary standards of the Landolt field S98. It is shown that the accuracy of photometric measurements should be 0.010 - 0.015 m or better and, at least 0.02 m , if a measured parallax is available.
Objects of the Catalog of Orbits of Visual Binary Stars in Gaia DR2
Chulkov, D. A.
Cross-identification is made for the Catalog of Orbits of Visual Binary Stars and Gaia DR2. At least one component has been matched for 88% systems, for 15% identification is available for both stars. Systems with substantially different parallaxes of components are found, which are the candidates to be the optical pairs. It's shown that published…