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Parameters of the Radcliffe Wave from Masers, Radio Stars, and T Tauri Stars
Bobylev, V. V.; Bajkova, A. T.; Mishurov, Yu. N.
The Radcliffe wave is shown to be present in both positions and vertical velocities of masers and radio stars belonging to the Local Arm. At the same time, it appears that the Radcliffe structure is not a wave in the true sense of the word. It more closely resembles a local high-amplitude spike that rapidly tails off. This structure has the larges…
Scandium Abundance in F-G-K Stars in a Wide Metallicity Range
Mashonkina, L. I.; Romanovskaya, A. M.
A new Sc II model atom has been constructed using up-to-date atomic data. To test it, we have carried out nonlocal thermodynamic equilibrium (non-LTE) calculations for three stars with reliably determined atmospheric parameters: the Sun, HD 61421 (Procyon), and HD 84937. Allowance for the departures from LTE leads to a decrease in the root-mean-sq…
Parameters of the Galactic Spiral Density Wave from Masers with Parallax Errors Less Than 10\boldsymbol{%}
Bobylev, V. V.; Bajkova, A. T.
We have studied the kinematics of Galactic masers and radio stars with measured VLBI trigonometric parallaxes and proper motions. We have considered masers with relative trigonometric parallax errors less than 10${%}$ and determined the Galactic rotation parameters from them. In particular, the linear rotation velocity of the Galaxy at the solar d…
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…