Search Publications
Galactic Rotation Parameters Based on Stars from Active Star-Forming Regions with Data from the Gaia DR2 Catalogue
Bobylev, V. V.; Bajkova, A. T.; Krisanova, O. I.
We have studied a sample of more than 25 000 young stars with proper motions and trigonometric parallaxes from the Gaia DR2 catalogue. The relative errors of their parallaxes do not exceed 10$%$. The selection of stars belonging to active star-forming regions was made by Marton et al. based on data from the Gaia DR2 catalogue by invoking infrared …
Influence of Collisions with Hydrogen on Titanium Abundance Determinations in Cool Stars
Sitnova, T. M.; Yakovleva, S. A.; Belyaev, A. K. +1 more
The possibility of solving the problem of a discrepancy in the non-LTE abundances from Ti I and Ti II lines in metal-poor stars is investigated by applying accurate data to take into account the collisions with hydrogen atoms. For this purpose, we have calculated for the first time the rate coefficients for bound-bound transitions in inelastic col…
Study of the Galactic Rotation Based on Masers and Radio Stars with VLBI Measurements of Their Parallaxes
Bobylev, V. V.; Bajkova, A. T.; Krisanova, O. I.
Based on published data, we have produced a sample of 256 radio sources whose trigonometric parallaxes and proper motions were measured by VLBI. This sample contains Galactic masers associated with massive protostars and stars in active star-forming regions. It also includes young low-mass stars from the Gould Belt region whose radio observations …
Analysis of Close Stellar Encounters with the Solar System
Bobylev, V. V.; Bajkova, A. T.
We consider 36 candidates for close (within 1 pc) encounters with the Solar system. These stars have been selected in accordance with the results of an analysis of their motion obtained by various authors. For most stars from this list the kinematic characteristics have been taken from the Gaia DR2 catalogue. The parameters of the encounters of th…
A Model of the Dust Envelope of the Carbon Mira Star V CrB from Photometry, Infrared Spectroscopy, and Speckle Polarimetry
Safonov, B. S.; Tatarnikov, A. M.; Shenavrin, V. I. +2 more
$UBVJHKLM$ photometry for the carbon Mira star V CrB are presented. The infrared observations were carried out in the time interval 1989-2018, while the $U$, $B$, and $V$ data were obtained in 2001-2014. The light and color curves are analyzed. The pulsation period of V CrB has been found to be $355\overset{\textrm{d}}{.}2$ in the infrared $JHKLM$…
Evolutionary Status of the Ap Stars HD 110066 and HD 153882
Romanovskaya, A. M.; Ryabchikova, T. A.; Shulyak, D. V.
We present the results of our determination of the fundamental atmospheric parameters for the magnetic chemically peculiar Ap stars HD 110066 (AX CVn) and HD 153882 (V451 Her). The determination of the atmospheric parameters ($T_{\textrm{eff}}$, $\textrm{log}{g}$, $R/R_{\odot}$, and $L/L_{\odot}$) is based on a self-consistent analysis of high-res…
Kinematics of T Tauri Stars Close to the Sun from the Gaia DR2 Catalogue
Bobylev, V. V.
The spatial and kinematic properties of a large sample of young T Tauri stars from the solar neighborhood 500 pc in radius have been studied. The following parameters of the position ellipsoid have been determined from the most probable members of the Gould Belt: its sizes are $350× 270× 87$ pc and it is oriented at an angle of $14^{\circ}± 1^{\ci…
The First Orbits of Six Wide Double Stars in the Solar Neighborhood Based on Gaia DR2 Observations
Romanenko, L. G.; Kiyaeva, O. V.
The apparent motion parameter (AMP) method is designed to determine the orbits of wide pairs of double stars with orbital periods of hundreds and thousands of years. This is a dynamical method using all that is known about the star at one moment to reconstruct its complete orbit within the two-body problem. The Gaia DR2 catalog contains all of the…
Search for Evolutionary Changes in the Period the Cepheid ET Vul
Berdnikov, L. N.; Pastukhova, E. N.
The reduction of all the available photometry for the Cepheid ET Vul has allowed its $O-C$ diagram spanning a time interval of 130 years to be constructed. This has made it possible to calculate for the first time the rate of evolutionary decrease in the period, $dP/dt=-426.5(±{29.7})$ s yr${}^{-1}$, in agreement with the results of model calculat…
Optical Identification of Four Hard X-ray Sources from the INTEGRAL Sky Surveys
Medvedev, P. S.; Sazonov, S. Yu.; Eselevich, M. V. +8 more
We continue the study begun in Karasev et al. (2018) and present the results of our optical identifications of four hard X-ray sources from the INTEGRAL sky surveys. Having first improved the positions of these objects in the sky with the X-ray telescope (XRT) of the Swift observatory, we have identified their counterparts using optical and infrar…