Abstract A mean-element differential equation system is solved analytically in the first approximation in a small parameter to investigate the orbital evolution of an asteroid moving under the attraction of the Sun and additional perturbing acceleration \({\mathbf{P}} = {\mathbf{P}}{\kern 1pt}' {\text{/}}{{r}^{2}}\), which arises due to the Yarkovsky effect. Here, \(r\) is the heliocentric distance;

Abstract In this paper, the orbital evolution of exoplanets at the late stages of stellar evolution was studied using the population synthesis method. Stellar evolution was traced from the main sequence stage to the white dwarf stage. The evolutionary tracks were calculated using the MESA package. The statistics of planets that were absorbed, ejected from the system, and surviving by the time of the

Abstract We presented the analysis results of the possibilities for increasing the spatial and temporal resolution of the existing models of the Earth’s gravitational field (EGF) by optimizing the orbital parameters (semi-major axis and inclination) of a constellation of spacecraft (SC) in a near-Earth orbit. As a result of numerical modeling, the spacecraft orbit elements were found. They cover 100%

Abstract This paper presents an original analytical calculation of the linear polarization degree of Hα lines caused by anisotropic protons during solar flares, when the temperature of thermal protons in the solar chromosphere is higher than the temperature of thermal electrons. The dependences of the linear polarization degree on the parameters of the distribution function of thermal and nonthermal

Recent studies have shown that among the population of radio-loud active galactic nuclei in the local U-niverse, they numerically dominate compact radio sources of the FR0 class. In this paper, we present ob-servation results of a sample of 33 FR0 radio galaxies with RATAN-600 in the first half of 2020. For the first time, quasi-simultaneous spectra of this class objects have been measured in the frequency

Abstract An overview is presented of the main results of the study of the polar coronal hole over the North pole of the Sun based on observations of the solar eclipse on March 29, 2006, using the RATAN-600 radio telescope in a wide cm-range of wavelengths (1.03, 1.38, 2.7, 6.2, 13.0, 30.7 cm) along with observational and theoretical data about the properties of Solar coronal holes published by various

Abstract The Earth’s N2-dominated atmosphere is a very special feature. Firstly, N2 as main gas is unique on terrestrial planets in the inner Solar System and gives a hint for tectonic activity. Studying the origins of atmospheric nitrogen and its stability provides insights into the uniqueness of the Earth’s habitat. Secondly, the coexistence of N2 and O2 within an atmosphere is unequaled in the entire

Abstract Some asteroids, comets, and planets (ACPs) are accelerated by giant planets and ejected from parent planetary systems with velocities of several kilometers per second. When leaving a disintegrating stellar cluster rather than only a parent star, ACPs form a spear-shaped cloud in space. Thereby, ACP spears are formed at the Sun, stars, and stellar clusters. Consequently, due to ACP spears,

Abstract TUS (Tracking Ultraviolet Set-up), the first orbital telescope of ultra-high energy cosmic rays (UHECRs), has demonstrated that instruments of this kind have much broader capabilities and can also detect various transient luminous events, meteors, anthropogenic glow and other processes taking place in Earth atmosphere in the UV frequency range. In this short paper, we address the question

Abstract— The topic of the present study is combining a dynamic model of a protoplanetary disk with the computations of radiation transfer for obtaining synthetic spectra and disk images suitable for immediate comparison of the model with observations. Evolution of the disk was computed using the FEOSAD hydrodynamic model, which includes a self-consistent calculation of the dynamics of dust and gas

Abstract The review considers the contribution of the results of measuring fluctuations of relic cosmic microwave background (CMB) radiation to cosmological model and the latest results of observational cosmology. We discussed the basics of the modern cosmological model, the stages of obtaining information from observational data of the Planck space observatory, namely, analysis of time series of observations

Abstract We use a modified method of the apparent motion parameters (AMP), in which the initial data from the Gaia DR2 catalog are not only high-precision coordinates, parallaxes, and radial velocities of the components of the studied wide binary stars, but are also their proper motions. The coincidence of the AMP orbits obtained both from the Gaia DR2 data and from the Pulkovo series from 1960–2019

Abstract We present the first high accuracy UBVRI(RI)c CCD light curves of the poorly investigated eclipsing system V680 Mon = GSC 7428 218 (P = 8.54d, V = 10.02m). They were used to find the photometric solutions and to derive the physical characteristics of the components. The highest known eccentricity e = 0.613 was found in the class of systems with eccentric orbits. The orientation of the orbital

Abstract This paper presents the results of calculating the efficiency of solar wind proton charge exchange as a function of variations in the column density of hydrogen atoms in the extended corona of Mars. The presence of regular density variations has been known for a long time and has been associated with the change of seasons on Mars. However, sporadic density variations in the upper Martian atmosphere

Abstract— This study is focused on the analysis of data of the long-term latitude observations and the Global Navigation Satellite System (GNSS). The latitude observations include small-amplitude periodic and random harmonics as noise components of different nature and duration. These harmonics are a source of valuable information on seismology, geodynamic processes, and Earth structure in the telescope

Abstract Variations in the orbital period of eclipsing binaries RY Aqr, AK Vir, and AX Vul are studied. It is shown these variations can be represented with equal accuracy in two ways: either in the form of a superposition of secular decrease and cyclic variations or only in the form of cyclic fluctuations. Cyclic variations in the periods of AK Vir and AX Vul can be fully explained by the light-time

Abstract We estimated the contribution of binary systems to the velocity dispersion inside OB-associations derived from Gaia DR2 proper motions. The maximum contribution to the velocity dispersion is given by the systems with the period of revolution of \(P = 5.9\) yr whose components shift by a distance of about the diameter of the system during the base-line time of Gaia DR2 observations. We employed

Abstract An algorithm has been developed for finding the global minimum of a multidimensional error function by fitting model spectral maps into observed ones. Principal component analysis is applied to reduce the dimensionality of the model and the coupling degree between the parameters, and to determine the region of the minimum. The k-nearest neighbors method is used to calculate the optimal parameter

Abstract A near-Earth gravity experiment is considered in which a pair of satellites exchange laser signals. As a concrete example, numerical estimates were made using the satellite configuration in the GRACE-FO mission. An expression for the signal phase is obtained, which provides an accuracy of 1 picometer (pm) when calculating the distance between satellites. The influence of all significant gravitational

Abstract Estimates for the parameters of accretion plasma flows and the central black hole by comparing the MHD model numerical calculations with observations for the center of our Galaxy Sagittarius A* in the radio range are obtained. The accretion flow was modeled in terms of the distribution of a toroidal two-temperature electron-proton plasma. It is assumed that protons are heated due to viscous

Abstract Stars located closely to supermassive black holes (SMBHs) can, under certain conditions, form close binary systems with the SMBHs, in which the star may fill the Roche lobe and intensive accretion of stellar matter onto the SMBH is possible. In this paper, the evolution of star + SMBH binary systems is studied under the assumption that the black hole mainly accretes the matter from the companion

Abstract The paper presents the results of experiments for studying the dynamics and internal structure of an axial plasma jet at the PF-3 facility. Measurements of the azimuthal distribution of the toroidal magnetic field \({{B}_{\varphi }}(\varphi )\) were carried out. A joint analysis of the experimental base of the obtained distributions \({{B}_{\varphi }}(\varphi )\) and the optical detection

Abstract The spatial properties of the entrances to spherically symmetric black holes and wormholes with zero and positive masses are compared. The properties were studied in terms of bulk and brane. The explicit expressions for the entrances are found and it is shown that in both representations the spatial funnels of the entrances to the wormholes are the steepest for the Schwarzschild black holes

Abstract Simulation results are presented for the Lyα flux impact from the parent star on the Hα absorption spectrum in the atmospheres of the hot Jupiters HD189733b and HD 209458b. The atmosphere is simulated using a three-dimensional hydrodynamic code. Several options are considered for the upper atmospheric composition, including variations in the XUV parameter. The Lyα photon transfer in the atmosphere

Abstract— The studies of close-orbit gaseous exoplanets—hot Jupiters and warm Neptunes—are reviewed. Transit spectral observations of the Hubble Space Telescope stimulated the numerical modeling of these objects. The supersonic outflow of the upper atmosphere of hot exoplanets and its interaction with the stellar plasma flow is a newly-discovered phenomenon in plasma physics and astrophysics that pools

Abstract The monitoring results of the OH maser source in W75 N in the main line at 1665 MHz performed in 2007–2020 using the Nançay Radio Telescope (France) are presented. Generally, the maser in 2007–2009 is characterized by a high activity. During the monitoring, time variations of the Stokes parameters were found for all spectral features in the radial velocity range from –1 to 14 km/s. We found

Abstract The change of pulsar period and inclination angle under the braking of magnetic radiation and magnetic decay is studied. The system of equations for evolution of period and inclination angle with time is given and solved. The solution shows that the period increases, and the inclination angle decreases with time under the braking of magnetic radiation and decay. The numerical results for the

Abstract The work is devoted to the study of the physical libration of the Moon. Interest in the traditional topic related to the rotation of the Moon is stirred up by the activity of many countries regarding the development of circumlunar space. Scientifically, the main agenda is to consider the viscosity of the core. At this stage of the theory development, such effects as indirect and direct perturbations

Abstract Being generated, the relic neutrino background contained equal fractions of electron \({{\nu }_{e}}\), muon \({{\nu }_{\mu }}\), and taon \({{\nu }_{\tau }}\) neutrinos. We show that the gravitational field of our Galaxy and other nearby cosmic objects changes this composition near the Solar System. As a result, the relic background becomes enriched with taon and particularly muon neutrinos

Abstract In this paper we extended the spherical collapse model to take account of angular momentum and dynamical friction and studied how the accreted mass, the threshold of collapse, the virial overdensity, and the mass function change. Solving the equation of motion we got the relationships between mass, M, and the turn-around radius, \({{R}_{0}}\). This relation is important because knowing \({{R}_{0}}\)

Abstract It is shown that it is possible to extend the application of \(\delta \mathcal{N}\) formalism to some special separable non-canonic cases. In this work, we extended the multi-brid idea to the multi-field separable model with a non-canonical kinetic term, mainly DBI (Dirac–Born–Infeld) action. Multi-brid stands for multi-component hybrid inflation which is based on δN formalism. To be more

Abstract TianQin is a project of a space-based gravitational wave detector for detecting GW events in the millihertz frequency range. The space-based detector must be implemented on three identical drag-free spacecraft orbiting around the Earth. The key technologies that form the principles of operation of the space-based GW detector are, first, an ultrastable transponder laser interferometer and,

Abstract We have studied the kinematic properties of young pre-main-sequence stars. We have selected these stars based on data from the Gaia DR2 catalogue by invoking a number of photometric infrared surveys. Using 4564 stars with parallax errors less than 20%, we have found the following parameters of the angular velocity of Galactic rotation: \({{\Omega }_{0}} = 28.84 \pm 0.10\) km s–1 kpc–1, \(\Omega

Abstract— An algorithm for the numerical solution of Kepler’s equation with machine precision is presented. The convergence of the iterative sequence of Newton’s method is proved for the indicated initial approximation. The problem of finding a numerical solution to Kepler’s equation as a floating point number is formulated. Aspects related to computations near machine zero are taken into account.

Abstract The results of spectral observations of NGC 3516 with the 2-m telescope of the Shamakhy Astrophysical Observatory during 2016–2019 are presented. In the first half of 2016, the intensive broad component H\(\beta \) was found, which indicates a spectral type change compared to 2014, when the broad component was almost invisible. In the second half of 2016, the broad component H\(\beta \) again

Abstract— This study is focused on the relationships between the κ-Cygnid meteor shower and different groups of asteroids crossing the Earth’s orbit (the so-called near-Earth objects (NEOs)). The analysis is based on the visible structure of the meteor shower and a comprehensive strategy for estimating the proximity of orbits of two bodies. The κ-Cygnid meteor shower (abbreviated as KCG) is observed

Abstract Computer simulation results are reported for planned lunar-based observations to be conducted using an automated zenith telescope that can be placed at any lunar latitude. Benefits of lunar-based observations are shown, in comparison with lunar laser ranging. It is investigated whether, and how effectively, these observations can be used to determine the lunar rotation parameters (physical

Abstract Propagation of a strong shock wave in the expanding universe is studied using approximate analytic and exact numerical solution of self-similar equations. Both solutions have similar properties, which change qualitatively, depending on the adiabatic powers γ. In the interval \(1 < \gamma < {{\gamma }_{{{\text{cr}}}}} \sim 1.16\) analytic and numeric solutions fill all the space without any

Abstract The origin of several rings in lenticular galaxies with no signs of ongoing or recent star formation (without emission lines and a signal in the ultraviolet spectral range) is investigated. Stellar population parameters—the average age and the magnesium–iron ratio—are measured; structural features are analyzed. It is concluded that the rings in all the galaxies have a different history of

Abstract— As is known, the influence of the ionizing radiation and the gravity of a star on a hot Jupiter results in the outflow of its atmosphere. Due to the gravity of the planet, the outflowing matter acquires angular momentum, after which it is accumulated on a higher circular orbit around the star and forms a disk or a torus. The angular momentum interexchange between the torus and the planet

Abstract— The hydrogen spectrum of the UX Ori-type star is modeled in a bright state and during an eclipse by an opaque dusty fragment of its own protoplanetary disk. The disk wind is considered as the main source of the emission spectrum. The radiation generated in the stellar magnetosphere is also taken into account. We showed that variations in the Hα line profile during eclipses depend sensitively

Abstract For the interpretation of X-ray radiation from kiloparsec jets of quasars, the inverse Compton scattering of the cosmic microwave background has been widely used for almost 20 years. A recent analysis of the Fermi-LAT observational data showed that this assumption is inapplicable for jets of several quasars. In this paper, we consider the inverse Compton scattering of photons from a central

Abstract The results of 14-year photometric monitoring of the contact close binary system (CBS) W UMa-type AM Leo are presented. Low-amplitude cyclic variations in brightness with a period of \(7.6 \pm 0.3\) years, not associated with the phenomena of eclipses and tidal deformations of the components, as well as low-amplitude cyclic variations of the CBS period with practically the same value of the

Abstract A comparison of the virial parameters of galaxies and galaxy clusters (radius, density, and entropy function) in a wide range of masses, \({{10}^{6}} \leqslant {{M}_{{{\text{vir}}}}}{\text{/}}{{M}_{ \odot }} \leqslant {{10}^{{14}}}\), shows that these parameters are correlated and depend on the virial mass of an object in a regular way. For the observed galaxies and galaxy clusters the available

Abstract The variations in the orbital period of the eclipsing binary system V505 Sgr, which is a part of the visual binary system CHR 90, have been analyzed. It has been shown that the variations in the period can be represented as a superposition of the secular decrease in the period at a rate of 2.97 × 10–7 days/year and the light-time effect with a period of 72.8 years. The secular decrease in

Abstract— A new algorithm for autonomous long-term predictions realized in ground navigation receivers for ephemerides of GLONASS and GPS spacecraft is developed and analyzed. The algorithm can be applied to determinations of user’s coordinates, when it is impossible or difficult to receive the spacecraft ephemerides (for example, in conditions of a bad radio-visibility of the satellites). It is shown

Abstract We present a three-dimensional model of the evolution of the asteroid–cometary–planetary (ACP) component of the Solar System under the gravitational influence of Jupiter. We demonstrate the origin of the Kuiper belt of the Sun, the Oort cloud of the Sun and Jupiter, as well as the ACP “spear,” which becomes elongated with time and transforms into a “ring” of ACP objects along the trajectory

Abstract The paper presents the component measurement results of plumb-line deviations (PLDs) with a digital astrometer at the Moscow gravitational anomaly (attraction). The anomaly was first discovered in the 1850s by B. Ya. Schweitzer, Professor of Astronomy of the Moscow University. The paper is based on the conference talk made at “Astronomy yesterday, today, tomorrow” (Sternberg Astronomical Institute

Abstract In this article, we proceed to study convection as a possible factor of episodic accretion in protoplanetary disks. Within the model presented in Article I, the accretion history is analyzed at different rates and areas of matter inflow from the envelope onto the disk. It is shown that the burst-like regime occurs in a wide range of parameters. The long-term evolution of the disk is also modeled

Abstract We present the results of our observations of the star-forming region located in the Perseus arm and associated with the Sharpless nebula S231 in the lines of H2O at a wavelength of 1.35 cm and OH at a wavelength of 18 cm obtained with the Pushchino 22-m radio telescope (Russia) and the Nançay Large Radio Telescope (France), respectively. We provide a catalog of H2O maser spectra in the period

Abstract The differences in the relationships between the physical parameters and the chemical-element abundances in accreted globular star clusters and those formed inside the Galaxy have been investigated. The information on the supposed formation sites of the clusters based on the Gaia DR2 data is borrowed from the literature. Those sources estimate the probability of belonging to the Galactic bulge

Abstract This paper presents a scenario of the evolution of OB associations and star clusters from formation to decay, in the process of which they turn into stellar streams moving in the disk and stellar “rings” around the galactic center. The scenario also includes the formation of stellar streams by galaxies absorbing their dwarf satellite galaxies. The simplest spatial kinematic models of evolution

Abstract— Model calculations of the charge exchange efficiency for solar wind protons colliding with hydrogen atoms of the extensive Martian corona are presented. It is shown that the energy spectrum of hydrogen atoms penetrating in the Martian atmosphere is identical to the spectrum of protons of the unperturbed solar wind. The charge exchange efficiency varies from 2 to 4% depending on the boundary

Abstract The cyclic variations in the quadrupole component of the solar magnetic field is studied in tensor description. The results are consistent with the classical description of the quadrupole using spherical functions, and the mathematical apparatus of tensor algebra allows one to compare the observed changes in the magnetic quadrupole and the changes predicted by the dynamo theories. In conclusion

Abstract The problem of the secular evolution of a thin ring around a rapidly rotating triaxial celestial body is formulated and solved. The technology for calculating secular perturbations is based on two formulas: the azimuthally averaged force field of the central body and the mutual energy \({{W}_{{{\text{mut}}}}}\) of this body and a Gaussian ring. With \({{W}_{{{\text{mut}}}}}\) instead of the

Abstract— We have carried out a comparative analysis of the parameters of two samples of radio pulsars. The first of them is characterized by periods \(P > 2\) s, the second one—by the surface magnetic fields \({{B}_{s}} > 4.4 \times \) 1013 G. The purpose for selecting these values is for the understanding the origin of the difference between normal pulsars and anomalous X-ray pulsars (AXP) and gamma-repeaters

Abstract The problem of the motion of two gravitating bodies in the presence of dark energy (DE), considered as a perturbing factor, is investigated. In addition to the orbit precession frequency obtained in previous studies, the correction to the orbital motion frequency was calculated, and the oscillations of the semi-major axis and the eccentricity of the orbit caused by the influence of DE were

Abstract The initial form of present-day space optical observations contain considerable geometrical and brightness distortions. This problem can be solved based on geometrical correction and transformation of reference object coordinates into commonly accepted cartographic projections. In this work, the method of coordinate transformation to the reference selenocentric dynamic system by using a base

Abstract The motion of a point with zero mass under the action of attraction to the central body \(\mathcal{S}\) and perturbing acceleration \({\mathbf{P}}{\kern 1pt} ' = {\mathbf{P}}{\text{/}}{{r}^{2}}\), inversely proportional to the square of the distance to \(\mathcal{S}\), is considered. It is assumed that \({\mathbf{P}}{\kern 1pt} '\) is small in absolute value compared to the main acceleration

Abstract In order to solve the problem of deflecting a dangerous asteroid from a collision orbit with the Earth, using a low-thrust engine directed tangentially to the trajectory is considered. The engine can be mounted on the asteroid or on a “gravity tractor.” The purpose of this study is to establish the fundamental possibility of steering away an asteroid to a safe distance over times of approximately