Astrophysical Bulletin最新文献

We report the results of a study of the distribution of galaxies in the projection along the radius ((R leqslant 3{{R}_{{200{text{c}}}}})) for 157 groups and clusters of galaxies in the local Universe (0.01 < (z) < 0.10) with line-of-sight velocity dispersions 200 < (sigma ) < 1100 km s^–1. We introduce a new observed boundary for the halos of clusters of galaxies, which we identify with the splashback radius ({{R}_{{{text{sp}}}}}). We also identified the core of groups/clusters of galaxies with the radius ({{R}_{{text{c}}}}). These radii are determined by the observed integrated distribution of the number of galaxies as a function of squared angular radius from the center of the group/cluster, which (usually) coincides with the brightest galaxy. We found for the entire sample that the boundary of dark matter ({{R}_{{{text{sp}}}}}) for groups/clusters of galaxies is proportional to the radius ({{R}_{{{text{200}}}}}) of the virialized region. We measured the mean radius (langle {{R}_{{{text{sp}}}}}rangle = 1.14 pm 0.02) Mpc for groups of galaxies ((sigma leqslant 400) km s^–1) and (langle {{R}_{{{text{sp}}}}}rangle = 2.00 pm 0.07) Mpc for clusters of galaxies ((sigma > 400) km s^–1). The mean ratio of radii is (langle {{{{R}_{{{text{sp}}}}}} mathord{left/ {vphantom {{{{R}_{{{text{sp}}}}}} {{{R}_{{{text{200c}}}}}}}} right. kern-0em} {{{R}_{{{text{200c}}}}}}}rangle = 1.40 pm 0.02), or (langle {{{{R}_{{{text{sp}}}}}} mathord{left/ {vphantom {{{{R}_{{{text{sp}}}}}} {{{R}_{{{text{200m}}}}}}}} right. kern-0em} {{{R}_{{{text{200m}}}}}}}rangle = 0.88 pm 0.02).

Abstract—The article provides a brief description of the software package DECH for processing and analysis of astronomical spectra. DECH supports all stages of processing and analysis of spectral data, including image preprocessing, spectra extraction (including those with a variable tilted slit), wavelength calibration by a two-dimensional polynomial, continuum normalization (manual or automatic), measurement of equivalent widths and radial velocities in various ways, cross-correlation analysis, etc. The DECH software package is actively used by astronomers from different countries and continues to be improved. In particular, utilities for processing and analysis of data from the high-resolution fiber-feed echelle spectrograph installed at 6-m telescope of Special Astrophysical Observatory of Russian Academy of Sciences were added in the latest version. Software provides high-precision measurements of radial velocities, including those for detection of extraterrestrial planets.

Abstract—We present a review of the papers written in the research field of stellar magnetism in 2021. The instruments, observation, and data analysis methods, photometry, spectroscopy, and spectropolarimetry results are considered. We present new data on magnetic fields of chemically peculiar stars and other objects of various types.

Abstract—The new observational data concerning distribution, excitation, and kinematics of the ionized gas in the giant early-type galaxy NGC 2655 obtained at the 6m telescope of the Special Astrophysical Observatory (SAO RAS) and at the 2.5 m telescope of the Caucasian Mountain Observatory (CMO SAI MSU) are presented in this work. The joint analysis of these and earlier spectral observations has allowed us to make a conclusion about multiple nature of the gas in NGC 2655. Together with a proper large gaseous disk experiencing regular circular rotation in the equatorial plane of the stellar potential of the galaxy for billions years, we observe also remnants of a merged small satellite having striked the central part of NGC 2655 almost vertically for some 10 million years ago.

Abstract—The paper studies the magnetic field structures of chemically peculiar magnetic stars. There is a great variety of structures and parameters of magnetic configurations associated with the similar variety of initial conditions in protostellar clouds. It is thought that destruction of a magnetic field does not occur in the non-stationary phase of evolution, and the conditions allow the initial large-scale configurations to be preserved. No matter how tangled a magnetic field in a protostar is, the common vector always corresponds to a poloidal field which is weak relative to local values. By the time a star arrives at the ZAMS, small-scale configurations are destroyed mainly as a result of ohmic dissipation in a time proportional to l², where (l) is the characteristic size of the magnetic field inhomogeneity. Due to ohmic dissipation and field-line tension, magnetic configurations become simpler up to the structure of a poloidal field which, with enough approximation, can be described by a magnetic dipole. Owing to high conductivity of the stellar matter, magnetic configurations practically do not change during the entire stay on the Main Sequence; theoretically, due to the enormous size of a star and the high conductivity of plasma, a magnetic field can persist until an age of ({{10}^{{10}}})–({{10}^{{11}}}) years. The magnetic star rotates solidly.

Abstract—We present the magnetic field measurements results for 74 stars observed in 2014. The sample of objects consists of chemically peculiar and standard stars. Observations were carried out with the 6-m BTA telescope of SAO RAS using the Main Stellar Spectrograph (MSS). Magnetic field for HD 168481, HD 184961, HD 187128 and HD 214923 were discovered for the first time by analyzing the circularly polarized spectra.