Search Publications
SRGz: Building an Optical Cross-Match Model for the X-ray SRG/eROSITA Sources Using the Lockman Hole Data
Gilfanov, M. R.; Medvedev, P. S.; Meshcheryakov, A. V. +1 more
We present a probabilistic model built for the optical cross-match between the SRG/eROSITA X-ray sources and photometric data from the DESI Legacy Imaging Surveys. The model relies both on positional and photometric information on optical objects nearby X-ray sources and allows performing selection with precision and recall ${≈}94%$ (for $F_{\text…
Detection of AGNs and Quasars with Significant Proper Motions Based on Gaia Data in the SRG/eROSITA Catalog of X-ray Sources
Irtuganov, E. N.; Bikmaev, I. F.; Gilfanov, M. R. +4 more
Based on a comparison of the SRG/eROSITA catalog of X-ray active stars and the Gaia catalog, we have obtained a sample of 502 peculiar objects for which Gaia, on the one hand, detects statistically significant parallaxes or proper motions and, on the other hand, records signs of a nonzero optical extent. On the $FX/F_{\textrm{opt}}$-col…
Estimation of the Parameters of the Spiral Pattern in the Galaxy Based on a Sample of Classical Cepheids
Bobylev, V. V.
We consider a sample of Galactic classical Cepheids with highly accurate estimates of their distances taken from Skowron et al., where they were determined based on the period-luminosity relation. We have refined the geometric characteristics of two spiral arm segments—the Carina-Sagittarius and Outer ones. For this purpose, we have selected 269 C…
Search for Close Stellar Encounters with the Solar System Based on Data from the Gaia DR3 Catalogue
Bobylev, V. V.; Bajkova, A. T.
We have searched for close stellar encounters with the Solar System using data from the Gaia DR3 catalogue. We have considered 31 stars with an encounter parameter $d_min<1$ pc. Among them 15 stars act as candidates for close encounters for the first time. The status of the stars GJ 710 and HD 7977 as candidates for deep penetration into the in…
Optical Cross-Match of SRG/eROSITA X-ray Sources Using the Deep Lockman Hole Survey as an Example
Gilfanov, M. R.; Belvedersky, M. I.; Bykov, S. D.
We present a method for the optical cross-match of sources detected in wide-field X-ray sky surveys. For this purpose, we have constructed and trained a neural network model to characterize the photometric attributes of the populations of optical counterparts of X-ray sources and optical field objects. The photometric information processing result…
Estimation of Galactic Spiral Density Wave Parameters Based on the Velocities of OB2 Stars from the Gaia EDR3 Catalogue
Bobylev, V. V.; Bajkova, A. T.
We have analyzed the kinematics of 9750 OB2 stars with proper motions and parallaxes selected by Xu et al. from the Gaia EDR3 catalogue. The relative parallax errors for these stars do not exceed 10${%}$. Based on the entire sample of stars, we have found the velocities $(U,V)_{\odot}=(7.17,7.37)±(0.16,0.24)$ km s${}^{-1}$ and the components of th…
Symbiotic Nature of the Zirconium Star CSS 1102
Ikonnikova, N. P.; Tatarnikov, A. M.; Dodin, A. V. +2 more
Based on the spectroscopic observations carried out with the 2.5-m telescope at the Caucasus Mountain Observatory (CMO) of the Sternberg Astronomical Institute (SAI), we have established the symbiotic nature of the poorly studied S star CSS 1102. The Balmer jump in emission is observed in the object's spectrum, and there are lines typical for gase…
Activity of the Young Star with an Exoplanet Kepler-1627
Savanov, I. S.
Based on data from the Kepler Space Telescope archive, we have studied the photometric variability of the young solar analog Kepler-1627, a G8V-type star with a planet of 3.777 Earth radii in size and an orbital period ${∼}$7.2 days. Kepler-1627 is a member of the $δ$ Lyr cluster with an age of 38 Myr and is currently the system with the youngest …
Kinematics of the Galaxy from Young Open Star Clusters with Data from the Gaia EDR3 Catalogue
Bobylev, V. V.; Bajkova, A. T.
We have analyzed the kinematics of open star clusters (OSCs) with the proper motions and distances calculated by Hao et al. based on Gaia EDR3 data. The mean line-of-sight velocities are known for a number of clusters from this list. We show that the Galactic rotation parameters determined from samples of OSCs with various ages are in good agreeme…
Estimation of the Mass of the Very Massive Galaxy Cluster SRGe CL2305.2-2248 from Strong Lensing
Bikmaev, I. F.; Gilfanov, M. R.; Khamitov, I. M. +10 more
SRGe CL2305.2-2248 (SPT-CL J2305-2248, ACT-CL J2305.1-2248) is one of the most massive galaxy clusters at high redshifts ($z∼eq 0.76$) and is of great interest for cosmology. Deep images have been obtained at the Russian-Turkish 1.5-m telescope (RTT-150) for an optical identification of this cluster. In combination with the open Hubble Space Teles…