Abstract Interstellar dust (ISD) penetrates into the heliosphere due to the relative motion of the Sun and the local interstellar medium (LISM). Inside the heliosphere and at the boundaries, where solar wind interacts with the LISM, distribution of ISD is modified due to the action of the electromagnetic forces, the solar gravitation and the radiation pressure. These forces make the distribution of

Abstract A method of correcting the statistical data of the exoplanets discovered through radial velocity measurements is proposed. The statistical regularities of the mass and orbital period distributions of exoplanets have been analyzed.

Abstract We have studied the light curves of type Ia supernovae (SNe Ia) and the physical parameters inferred from them. We have constructed both analytical and numerical light curves of SNe Ia. Using an empirical relation between the SN luminosity and light-curve parameters, we have managed to impose constraints on the hydrodynamic solutions obtained by the STELLA code and to produce a sample of models

Abstract For two classical Cepheids, CEa Cas and CEb Cas, members of the open cluster NGC 7790, we have constructed \(O-C\) diagrams spanning a time interval of 125 years. The \(O-C\) diagrams have the shape of parabolas, which has allowed us for the first time to determine the quadratic light elements and to calculate the rates of evolutionary changes in their periods: \(dP/dt={-}0.038({\pm}{0.017})\)

Abstract Several years ago a series of powerful millisecond radio bursts with close dispersion measures was detected toward the galaxy M31. Taking the hypothesis about the possible association of these radio bursts with a magnetar in M31 as a starting point, we have searched for periodic X-ray signal sources using data from the XMM-Newton X-ray telescope. As a result of our data analysis, we have identified

Abstract Variable circumstellar extinction models as applied to T Tauri stars are considered. In contrast to hotter UX Ori stars, for which simplified eclipse models are applicable, the star is deemed a point source of light, while the circumstellar dust clouds obscuring the star are assumed to be homogeneous. In the case considered here, both these simplifications may not work. Hot accretion spots

Abstract The technique of coronal mass ejection (CME) mass estimates from the energy of stellar flares has been applied to the data on the flare activity of late-type stars. In this study we use the data from catalogs on stellar flares obtained from the results of observations with the Kepler Space Telescope and present the relations between CME mass and effective temperature for objects from these

Abstract Multicolor photometric observations in the optical band and a comprehensive study in the X-ray, gamma-ray, and radio bands are presented for GRB 181201A and its afterglow. The optical observations began \({\sim}0.5\) day after the burst and lasted almost continuously for \({\sim}24\) days. They were resumed after eight months, which allowed us to determine the contribution of the host galaxy

Abstract Two algorithms for reconstructing the distribution of accretion spots over the surface of white dwarfs in AM Her variables are described. Both algorithms suggest the use of photopolarimetric observations. In the first case, the assumption that the spots are geometrically thin is used, while the white dwarf magnetic dipole orientation and the accretion spot position are found by fitting the

Abstract The Transient Double-beam Spectrograph (TDS) is designed for low-spectral-resolution optical observations of nonstationary and extragalactic sources at the 2.5-m telescope of the Caucasus Mountain Observatory (CMO) of SAI MSU. The spectra are recorded simultaneously in two channels, short-wavelength (360–577 nm, reciprocal dispersion 1.21 Å/pixel, resolution \(R=1300\) with a \(1^{\prime\prime}\)-wide

Abstract Observations of individual pulses from the pulsar PSR B1530+27 have been carried out. The dispersion measure (DM) toward this pulsar has been found from 11 084 pulses to be \(DM=14.6904\pm 0.0009\) pc cm\({}^{-3}\). The (\(3\sigma\)) upper limit on the DM derivative is \(|dDM/dt|<0.001\) pc cm\({}^{-3}\) yr\({}^{-1}\). The seasonal DM variations related to the passage of radiation through

Abstract The linear increase of the cosmic microwave background (CMB) temperature with cosmological redshift, \(T_{\textrm{CMB}}=T_{{0}}(1+z)\), is a prediction of the standard cosmological \(\Lambda\)CDM model. There are currently two methods to measure this dependence at redshift \(z>0\) and, what is equally important, to estimate of the CMB temperature \(T_{0}\) at the present epoch. The first method

Abstract The possibility of the existence of radiation belts near a planet possessing an intrinsic magnetic field and located in a stellar plasma flow is considered using Mercury as an example. An analysis is performed both using Størmer’s theory of charged particle motion, in which not the specific trajectories of individual particles, but the regions of allowed motion in an axisymmetric field are

Abstract Stellar evolution calculations for population II stars with initial composition \(Y_{0}=0.25\), \(Z_{0}=10^{-3}\) and the initial stellar mass \(M_{0}=0.82M_{\odot}\) were carried out from the main sequence to the white dwarf stage. Twelve AGB and post-AGB evolutionary sequences were computed with different values of the parameter in the Blöcker mass loss rate formula (\(0.01\leq\eta_{\textrm{B}}\leq

Abstract We present the results of long-term photometric monitoring of two active galactic nuclei, 2MASX J08535955+7700543 (\(z\sim 0.106\)) and VII Zw 244 (\(z\sim 0.131\)), being investigated by the reverberation mapping method in medium-band filters. To estimate the size of the broad line region, we have analyzed the light curves with the JAVELIN code. The emission line widths have been measured

Abstract The SDO/AIA 193 Å and ACE/SWEPAM data acquired in 2019 are used to compare the effects of polar and equatorial coronal holes (CHs) on solar wind (SW) characteristics under conditions of low solar activity. As expected, most geomagnetic storms in this period were caused by high-speed SW streams (\({>}500{-}600\) km s\({}^{-1}\)) originating from equatorial CHs. At the same time, it has been

Abstract Extensive numerical experiments on the long-term dynamics of planetesimals near the orbits of planets around single stars with debris disks have been carried out. The radial sizes of planetesimal clusters and the planetary chaotic zone as a function of mass parameter \(\mu\) (planet–star mass ratio) have been determined numerically with a high accuracy separately for the outer and inner parts

Abstract Based on the previously proposed steady-state 3D model of a solar facular knot, we have developed its modified version in which the solitary nature of the facular object is reflected: its magnetic field is sharply bounded in the radial direction. The facula temperature profile calculated for the steady state of such a magnetic structure is compared with the high-resolution filtergram taken

Abstract We analyze the minimum orbital intersection distances (MOIDs) for a sample of long-period comets (1360) and the giant planets of the Solar System. Our calculations have revealed a considerable number of long-period comets that may have had close encounters with the giant planets: Jupiter (268), Saturn (176), Uranus (81), and Neptune (75). Among them there are 107 cases where the comet approaches

Abstract The spatial distribution of the north–south (N–S) asymmetry over 1977–2001 is studied. A comparison of the distributions and time variations of the asymmetry index \(A\) in the green coronal Fe XIV 530.3 nm line, in the total coronal magnetic field, and in small- and large-scale fields has shown that at low latitudes the distribution of \(A\) for small-scale fields bears the greatest similarity

Abstract In 2012–2014 we obtained 3296 CCD frames in the \(BVI_{c}\) photometric system for the RR Lyrae star T Men with the 76-cm telescope of the South African Astronomical Observatory (SAAO, SAR) and the 1-m telescopes of the Las Cumbres Observatory Global Telescope (LCOGT). Our observations showed a slightly increased scatter of data points on the light curve, which allowed the Blazhko effect with

Abstract A model of a population of ultraluminous X-ray sources with magnetized neutron stars (NULXs) in a spiral galaxy with a star formation history as in the thin disk of the Milky Way is constructed by the hybrid population synthesis method. First, based on analytical approximations (BSE code), we compute a set of close binary systems (CBSs), potential precursors of NULXs, and, then, the evolution

Abstract Results of the first spectroscopic observations at the 1.5-m Russian–Turkish telescope for the X-ray sources discovered by the eROSITA telescope onboard the SRG space observatory and identified by the SRGz machine learning system as candidates for distant X-ray quasars are presented. Seven objects have been confirmed as quasars at redshifts \(z=2.7{-}4.2\) and two sources, which were included

Abstract Results of the first multicolor photometric observations of the unusual dwarf nova V2466 Cygni during its 2003 and 2019 superoutbursts are presented. The total amplitude of the 2019 superoutburst in the \(R_{c}\) band is 7.4 magnitudes. A single rebrightening was observed at the end of the 2019 superoutburst. While analyzing the \(O-C\) diagram for the superhumps, we identified pronounced

Abstract A detailed analysis of the GBM/Fermi experiment data is carried out to classify GRB 200415A. It is shown that, on the one hand, this event exhibits typical for type I (short) gamma-ray bursts (GRBs) properties, such as duration, variability, and the character of spectral evolution (lag). On the other hand, the localization of the event source on the celestial plane, obtained by the triangulation

Abstract We have constructed a new K I model atom using currently available atomic data. We have performed calculations for K I by abandoning the assumption of local thermodynamic equilibrium (non-LTE) for the Sun and three moderately metal-poor dwarf stars. To take into account the inelastic processes in collisions with hydrogen atoms, for the first time we have used the rate constants calculated

Abstract H 3-75 is a medium-excitation planetary nebula with a binary central star consisting of a hot subdwarf with \(T_{\textrm{hot}}\sim 10^{5}\) K and a cool giant. We present the results of our photometric and spectroscopic observations obtained in 2020 and analyze data from the literature. The brightness of the cool component of the binary system has been measured in the \(VR_{C}I_{C}JHK\) bands

Abstract Based on archival Hubble Space Telescope images, we have performed stellar photometry for the spiral Seyfert galaxy NGC 1672 located in the Dorado (Goldfish) galaxy group. The distance to this galaxy measured by the TRGB method (\(D=15.8\pm 0.8\) Mpc) has shown that NGC 1672 does enter into the Dorado group. We have identified stars of various ages and luminosities on the Hertzsprung–Russell

Abstract The reduction of all the available photometry for the Cepheid CC Lyr has allowed its \(O-C\) diagram spanning a time interval of 124 years to be constructed. The data obtained provide evidence for the existence of large random fluctuations in the period (\(\varepsilon/P\approx 0.046\)). A formal fitting of the \(O-C\) residuals has made it possible to estimate the rate of secular increase

Abstract Only a handful of quadruple systems with two accurate inner visual orbits are known. The architecture of two such systems is studied here to determine the period ratios, mutual orbit orientation, and other parameters; updated orbital elements and their errors are derived. Gliese 225.1 (HIP 28442) is composed of three K-type and one M-type dwarfs and has inner orbital periods of 67.2 \(\pm\)

Abstract A novel method is proposed for the reconstruction of the early bolometric light curve for supernovae IIP with the available set of H\(\alpha\) emission spectra on the first day after the shock breakout. The method uses the effect of radiative acceleration of the preshock circumstellar gas that is manifested in broad H\(\alpha\) wings. The efficiency of the method is demonstrated in the case

Abstract 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 data for epoch 2015.5 that are needed to use

Abstract The nucleosynthesis of heavy elements in the scenario for the evolution of a close binary of neutron stars differing greatly in mass is considered. In contrast to the scenario for the merger of two neutron stars of comparable masses considered repeatedly in the literature, the evolution of such a binary at the final stage consists in a rapid mass transfer to the more massive star and an explosive

Abstract Based on SDSS data, we consider the fraction of active galactic nuclei among polar-ring galaxies. We have found evidence for an excess of Seyfert galaxies and LINERS among polar-ring galaxies compared to ordinary objects. The observed nuclear activity of polar-ring galaxies may be associated with the accretion of gas from the region of the polar structures onto the central galaxies.

Abstract The technique of spherical harmonics, both scalar and vector ones, has long been applied to analyze the astronomical data on a sphere, for example, in the representation of systematic errors, in stellar kinematics. Up to now, spherical harmonics have been used exclusively in heliocentric coordinate systems: the equatorial or Galactic one. To study the kinematics of the entire Galaxy (and not

Abstract Evidence of wind variability and velocity stratification in the extended atmosphere has been found in the spectra of the supergiant V340 Ser (\({=}\)IRAS 17279\(-\)1119) taken at the 6-m BTA telescope with a resolution \(R\geq 60\,000\). The H\(\alpha\) line has a P Cyg profile whose absorption component (\(V_{\odot}={+}34\) km s\({}^{-1}\)) is formed in the upper layers of the expanding atmosphere

Abstract On the basis of consistent stellar evolution and nonlinear stellar pulsation calculations, the Cepheid V1033 Cyg is shown to be the post-main sequence star at the first crossing of the instability strip during the gravitational contraction of the helium core. The observed light variability of V1033 Cyg is due to the radial oscillations in the fundamental mode. The best agreement (within one

Abstract The formation of the rubidium resonance lines is considered by taking into account the effects of departures from local thermodynamic equilibrium (LTE). A rubidium model atom has been constructed using 29 Rb I levels and the Rb II ground level. Non-LTE calculations have been performed for a grid of model atmospheres with \(T_{\textrm{eff}}\) from 3500 to 6500 K, \(\log g\) from 1.0 to 5.0

Abstract The laboratory simulations of jets from young stars that have been carried out for many years at plasma focus facilities allow the internal structure of the active regions emerging during the interaction of the jet with the surrounding plasma to be studied in detail. We have found a new wide class of solutions for the equations of ideal magnetohydrodynamics describing the closed axisymmetric

Abstract Based on observations with the new transient double-beam spectrograph (TDS) at the 2.5-m telescope of the Caucasus Mountain Observatory of SAI MSU, we have determined the types and found the redshifts for six new X-ray sources (four quasars and two galaxy clusters) detected by the SRG space observatory during the Lockman Hole observations at the eROSITA performance verification phase. We show

Abstract The collisional pumping of OH masers in non-dissociative C-type shocks near supernova remnants is considered. The emergence of maser emission in OH lines is investigated for various shock parameters—the shock speed, the preshock gas density, the cosmic-ray ionization rate, and the magnetic field strength. The largest optical depth in the 1720 MHz line is reached at high gas ionization rates

Abstract 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 were performed in continuum. Based on this

Abstract Based on moderate-resolution spectra in the range 4200–5200 Å, we have studied B and Be stars in the young open star cluster NGC 581. The temperatures of the program stars have been derived by the differential method with the choice of simple spectroscopic parameters for a number of lines and their comparison with the analogous parameters of a large sample of B stars for which accurate estimates

Abstract We present the results of the first year of searching for polar candidates within the 3BS (3-Band Survey) program using medium-band filters. Observational data for 84 selected objects from the catalog of cataclysmic variables of the CRTS DR1 sky survey were obtained while implementing the program. A dwarf nova during its outburst and a polar were detected. The available archival data are analyzed

Abstract We discuss the model for the evolution of an active region (AR) in which the graph constructed from the singular points of the magnetic field codes the AR magnetic patterns. The AR dynamic scenarios are mapped by the discrete structure of the network formed from the maxima, minima, and saddle points of the magnetic field. The AR dynamics leads to a rearrangement of the graph, graph dynamics

Abstract 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 measurements from the WISE and Planck catalogues

Abstract We present the first results of Mars neutron sounding by FREND instrument onboard ESA’s Trace Gas Orbiter data analysis. Neutron flux mapping is performed with high spatial resolution, which allows to match epithermal neutron flux variation with relief’s geomorphological structures. Local regions with suppressed neutron flux indicate the presence of considerable amount of hydrogen atoms in

Abstract We present the results of our numerical simulations of the general circulation in the atmosphere of a hypothetical super-Earth within a model based on the solution of the complete system of hydrodynamic equations. The MIPT/PGI GCM model used for our computations has already been successfully adopted to describe the general circulation of the atmosphere of Venus. The model features high resolution

Abstract We have solved the problem of the acceleration of ions (protons) incident on the front of a nonlinear whistler for which the structure of its electromagnetic fields is assumed to be known and defined by the relations derived by us previously. We have established the dependence of the energy to which the protons are accelerated on the angle between the whistler propagation direction and the

Abstract We propose a method of analyzing the absorption spectra of quasars that allows the physical parameters of absorbing clouds, absorbers, to be roughly estimated: their masses, sizes, and mean densities. An analysis of three representative catalogs of the Lyman-alpha (\(Ly_{\alpha}\)) forest and metal absorption line systems confirms that these observations refer to two types of objects with

Abstract We consider the evolution of the abundance of singly and doubly deuterated isotopologues of water and methanol in a typical protostellar cloud. The main processes determining their abundance in various regions of the cloud have been revealed. We show that the abundances of the deuterated isotopologues can exceed the abundance of the main molecules in a number of cases.

Abstract The reduction of all the available photometry for the Cepheid EV Aql has allowed its \(O-C\) diagram spanning a time interval of 130 years to be constructed. This has made it possible to calculate the rate of evolutionary decrease in the period, \(dP/dt=-33.2({\pm}{6.9})\) s yr\({}^{-1}\), in agreement with the results of model calculations for the second crossing of the instability strip

Abstract We consider the dynamical evolution of planetary systems whose structure is nearly circular and coplanar. The analysis is performed by the Hori–Deprit averaging method within the theory of the first order in planetary masses. A convenient set of canonical elements and a rarely employed variety of astrocentric coordinates are used to derive the equations of motion. Owing to the use of the chosen

Abstract I explore the origin of an asymmetry of the H\(\alpha\) emission from a circumstellar (CS) shell around type IIP supernova SN 2013fs in the spectrum taken 10.3 h after the shock breakout. A spherical model of the H\(\alpha\) emission from the CS shell that takes into account a preshock gas acceleration by a supernova radiation permits us to successfully reproduce the H\(\alpha\) profile. Principal

Abstract 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-resolution spectra (ESPaDOnS with \(R=65\

Abstract The sensitivity of future far-infrared telescopes, such as Millimetron, will be limited by the confusion noise produced by distant galaxies. We have constructed a model of the cosmic infrared background whose main goal is to investigate the confusion noise parameters. The model is based on the publicly accessible eGALICS simulation. For each galaxy from the simulation we construct a model

Abstract We present the results of our spectroscopic study of the lenticular galaxy NGC 4143—a peripheral member of the Ursa Major cluster. Using the observations at the 6-m SAO RAS telescope with the SCORPIO-2 instrument and the archival data of panoramic spectroscopy with the SAURON instrument at the WHT, we have detected an extended inclined gaseous disk in this lenticular galaxy with a spin approximately

Abstract The evolutionary calculations for population I stars with masses on the main sequence \(5M_{\odot}\leq M_{0}\leq 6.1M_{\odot}\) and initial fractional abundances of helium \(Y_{0}=0.28\) and heavier elements \(Z_{0}=0.02\) were carried out to the stage of central helium exhaustion. Selected core helium–burning models were used as initial conditions for solution of the equations of hydrodynamics

Abstract We consider the effect of a change in the rate of flux decline in the \(U\) band for type II-P supernovae (SNe IIP) as a function of metallicity \(Z\). Based on this effect, we propose a new method to determine the photometric redshift from the SN IIP light curve in the \(U\) band. Using the STELLA code, we have constructed model light curves in different bands for different redshifts \(z=0

AbstractThe Spectrum–Röntgen–Gamma (SRG) space observatory was launched from Baikonur on July 13, 2019, and is currently on a flight trajectory in the vicinity of the collinear Sun–Earth libration point L2. The planned service life of the observatory is 7 years and includes an all-sky survey and in-depth studies of individual objects in the X-ray range 0.3–15 keV. We consider the technical limitations