Abstract The variations in the orbital period of the eclipsing binary system Z Per 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 1.61 × 10–6 days/year and its three cyclic variations with periods of 22.6, 37.9, and 62.4 years. Z Per is most likely a quadruple system with periods of additional

Abstract—For the case of the sub-Alfvén regime of the stellar wind flyby around the planet, the flow structure in the vicinity of a hot Jupiter have been studied by three-dimensional numerical simulation. As an example, the hot Jupiter HD 209458b was considered. The planet’s magnetic moment was set equal to 10% of the magnetic moment of Jupiter. The average magnetic field at the parent star’s surface

Abstract—The distribution of young pulsars in the log(dP/dt)–log(tc) diagram that have a characteristic age tc < ~5 × 106 yr and a period derivative dP/dt > ~10–16 is analyzed. Six clusters-stripes are revealed for the first time, along which the long-term evolution tracks of individual pulsars pass. The mean track in a stripe corresponds to the long-term regular evolution for a typical pulsar of this

Abstract The interpretation of high-precision transit light curves of binary systems with exoplanets Kepler-5b, Kepler-6b, and Kepler-7b is performed for three different epochs. It has been demonstrated that the values of the stellar limb-darkening coefficients differ significantly for each epoch, while the geometric parameters for each epoch agree well with each other within the error margin. It is

Abstract The study explores black hole (BH) shadow images which can be restored by data processing and image recovery procedures during space Very Large Baseline Interferometry (VLBI) missions in the future. For Kerr BHs with masses and coordinates of SgrA*, M87*, and M31*, all illuminated by a light source behind them, three kinds of observation are considered: the ground-based interferometer (similar

Abstract We present the observation results of the star forming region NGC 2071 in the 1.35-cm H2O line and 18-cm OH lines obtained with the 22-m radio telescope in Pushchino (Russia) and the large radio telescope in Nançay (France), respectively. The catalog of H2O maser emission spectra from December 2010 to January 2020 is given. The total flux variability for the entire monitoring period (1979–2020)

Abstract We present the model calculation results of the atomic oxygen loss rate from the Martian atmosphere induced by precipitation of high-energy protons and hydrogen atoms (H/H+) from the solar wind plasma. Penetration of energetic protons and hydrogen atoms from the solar wind plasma to the upper atmosphere of Mars at altitudes of 100−250 km is accompanied by the momentum and energy transfer in

Abstract In this paper, we check the claim of dependence of the halo density profile on the ratio between stellar and halo mass. Namely, we want to continue the work done in a previous paper by Del Popolo (2015), to see to what extent the SN feedback scenario is able to describe the inner structure of galaxies, employing more sophisticated statistical tools than those indicated in the quoted paper

Abstract The paper considers the principles of space navigation using pulsars observed in the radio range. The requirements for receiving equipment are outlined, a recommended pulsar list is given, and an algorithm for determining the position of a spacecraft in barycentric coordinates and calculating corrections to the onboard time scale is described.

The flow structure in the asynchronous polar CD Ind was investigated in the approximation of an offset dipole. Computation results made it possible to identify such system features as the drift of hot spots over the white dwarf surface, the flow structure dependence on the phase of the beat period, and the magnetic pole switching. To study the flow structure, a three-dimensional numerical MHD model

Abstract— The results of polarimetric observations of blazar S5 0716+714, carried out with the 6-meter BTA telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences, are presented. The polarized emission microvariability of blazar S5 0716+714 was observed in the R band with an initial time resolution of 3–5 seconds. Exposures were integrated at 1-minute intervals with a

Abstract The development of the solar magnetic activity in cycle 24 has been analyzed. It has been shown that the significant north–south asymmetry of magnetic activity was accompanied by the asynchronous reorganization of solar magnetic fields in the northern and southern hemispheres. The formation of unipolar magnetic regions after the decay of activity centers has been studied. The meridional transport

Abstract During five years of daily observations, the search for new pulsars using the BSA LPI radio telescope in 96 spatial beams covering 17 000 square degrees was conducted. Five new pulsars were identified. Candidate pulsars were selected in summed power spectra. A noise generator was used to renormalize data and total the power spectra for individual directions correctly. As a result, the sensitivity

Abstract A new approach to the study of long-period and secular perturbations in celestial mechanics is developed. In contrast to the traditional use of the apparatus of the perturbing Lagrange function, we rely on the mutual potential energy of elliptic Gaussian rings. This approach is important due to the fact that instead of averaging the expression for the perturbing Lagrange function obtained

Abstract— The theory of relativistic reductions for future challenges of space gravimetry with target accuracy of up to 1 picometer is developed in this paper.

Abstract— We report observations of molecular line emission toward dense clumps of the WB 673 interstellar filament: WB 668, WB 673, S233–IR, and G173.57+2.43. The observations were done with the 20-m telescope at the Onsala Space Observatory (Sweden). Maps of emission, column densities, and relative abundances of CO, N2H\(^{ + }\), CS, HCN, and HNC molecules are presented. It was found that the molecular

Abstract We analyze all the available X-ray data in order to monitor the narrow-line Seyfert 1 galaxy NGC 4748, namely XMM-Newton (EPIC and OM), INTEGRAL (ISGRI and JEM-X), and SWIFT (BAT and XRT) data to study both the wide-band 0.5–195 keV spectrum and light curves in details. To this aim, we use the autocorrelation analysis of the light curves, modeling the spectra with several physically-conditioned

Abstract The results of the search for Apollo, Amor, and Aten asteroids with the orbits close to those of meteoroids of the δ-Cancrids meteor complex (code DCA), which consists of the northern (code NCC) and southern (code SCC) branches, are presented. The search for small bodies in close orbits was performed on the basis of a multifactorial method of combining several criteria: Drummond orbital similarity

The variation of the orbital periods found in high-mass X-ray binaries occurring over time can be explained by two models. According to the first model, orbital decay occurs due to dynamic tidal forces. The second model shows that the change occurs due to the inertia moments of a massive star during its evolution. These models are applied to LMC X-4 and Cen X-3.

Abstract The search for compact components of strong (\({{S}_{{{\text{int}}}}} \geqslant 5\) Jy at 102.5 MHz) discrete radio sources from the Pushchino catalogue was carried out using the method of interplanetary scintillation. A total of 3620 sources were examined, and 812 of them were found to harbor compact (scintillating) components. Estimates of fluctuations of the flux density of these compact

We present results of the analysis of photometric and spectroscopic observations of the young stellar complexes in the late giant spiral galaxy UGC 11973. Photometric analysis in the \(UBVRI\) bands have been carried out for the 13 largest complexes. For one of them, metallicity of the surrounding gas \(Z = 0.013 \pm 0.005\), the mass \(M = (4.6 \pm 1.6) \times {{10}^{6}}{\kern 1pt} {{M}_{ \odot }}\)

Abstract For the first time, BVIc observations of the Cepheid V811 Oph were obtained by using a new 60‑cm telescope at the Caucasus Mountain Observatory, Sternberg Astronomical Institute, Moscow State University (SAI MSU). An \(O{-}C\) diagram covering a time span of 124 years was plotted using photometry from old photographic and modern sky surveys. The diagram has a parabola shape, which made it

Abstract The kinematic properties of the Scorpius–Centaurus association were studied using spatial velocities of approximately 700 young T Tauri stars. Their proper motions and trigonometric parallaxes were selected by Zari et al. from the Gaia DR2 catalog, and radial velocities were taken from various sources. The linear expansion coefficient’s new estimate of the association \(K = 39 \pm 2\) km/s/kpc

Abstract— We applied a new approach to measure the time delays of magnetohydrodynamic waves propagating in the solar atmosphere. A small flare in the flare region of the chromosphere served as a modulator of 3‑ and 5-minute oscillations. The oscillation amplitude increased several times, which made it possible to easily fix the wave train formed as it spread upward through the solar atmosphere layers

Abstract— The averaging method is widely used in celestial mechanics, in which a mean orbit is introduced and slightly deviates from an osculating one, as long as disturbing forces are small. The difference \(\delta {\mathbf{r}}\) in the celestial body positions in the mean and osculating orbits is a quasi-periodic function of time. Estimating the norm \(\left\| {\delta {\mathbf{r}}} \right\|\) for

Abstract This paper constraints dynamic dark energy equation of state (EoS) parameters using the type Ia supernovae from Union 2.1 dataset. The paper also discusses the dependency of dynamic dark energy EoS parameters on the chosen or assumed value of the Hubble Constant. To understand the correlation between the Hubble Constant values and measured dynamic dark energy EoS parameters, we used recent

Abstract— Astronomical observations indicate a high abundance of methanol molecules in the gas phase of molecular-cloud dense cores, which cannot be explained by gas-phase chemical reactions only. A significant contribution to the methanol abundance should be provided by chemical reactions on the dust particle surface with subsequent desorption of the produced molecules into the gas phase. For the

Abstract A sample of 22 spiral galaxies compiled from published data is studied. The galaxy rotation curves pass through a maximum distance of more than ~1 kpc from the center with a subsequent decrease in the rotation velocity. The galaxy position in the Tully–Fisher (TF) and baryonic Tully–Fisher (BTF) diagrams show that the maximum rotation velocities are located on the same sequence with other

Abstract Modeling of hydrogen emission lines is a powerful tool to study physical processes in the nearest vicinity of young stars because spectral lines carry information on the kinematics and physical conditions of the gas. One of the lines that probe emitting regions closest to the star is the Br\(\gamma \) line. We consider different types of hybrid models to reproduce both interferometric VLTI-AMBER

Abstract The presented observation results of the blazar J0238+1636 were obtained in: 2014–2019 with the RATAN-600 radio telescope from the Special Astrophysical Observatory of the Russian Academy of Sciences at 2.3, 4.8, 8.2, 11.2, and 21.7 GHz; and 2015–2017 with the 32-m Zelenchuk and Badary radio telescopes of the Institute of Applied Astronomy of the Russian Academy of Sciences at 4.84 and 8.57

Abstract— The results of three-dimensional numerical simulation of heat transfer in the outer layers of magnetized neutron stars are presented. Determining the structure of the magnetic field on a neutron star surface is an important task of modern astrophysics. In the presence of strong magnetic fields, the medium becomes anisotropic, and the laws of heat conduction change. The tensor coefficient

Abstract We present the first high accuracy UBVRI(RI)c CCD light curves of the newly discovered eclipsing system PS UMa = GSC 4375 1733 (\(P = 9_{·}^{d}27\), \(V = 12_{·}^{m}42\)). The photometric solutions are found, the physical parameters of the components are derived. The eccentricity of the orbit was found to be negligible e = 0.074, which made it difficult to measure the rate of the apsidal rotation

Abstract Solar filaments (prominences), which suddenly and swiftly ascend, i.e., become eruptive, sometimes decelerate and stop at comparatively low altitudes. Causes of failed eruptions generally remain uncertain. The present study analyzes two eruptive phenomena with very similar initial geometries and configurations of external magnetic fields; one of these eruptions evolves in a coronal mass ejection

Abstract At the present time, the induction of several microgauss in large-scale fields of the Galaxy has been repeatedly confirmed. There are numerous arguments in favor of the fact that the magnetic field exhibits so-called reversals associated with a direction change from one region to another. Such configurations are allowed in the nonlinear equations context of the dynamo theory, which describes

Abstract The orientation parameter effect of a hot Jupiter’s intrinsic dipole magnetic field on the flow structure in an extended gaseous (ionospheric) envelope of the planet is studied with a three-dimensional numerical simulation. For example, the hot Jupiter HD 209458b is considered. The magnitude of the planet’s magnetic momentum was set equal to 0.1 of the magnetic momentum of Jupiter. The parameters

Abstract A survey of massive star forming regions in the lines of the lowest transitions of deuterated molecules DCN, DNC, DCO+, N2D+ in the 4 mm wavelength range was performed using the 20 m radio telescope of the Onsala Space Observatory. A total of about 60 sources was observed. Lines of the DCN, DNC, and DCO+ molecules are registered in about a third of them, lines of the N2D+ molecule only in

Abstract Based on space velocity components UVW and using a recent dataset for Castor and Ursa Major moving groups, we compute the apex position with two methods. Classical convergent procedures give (Acp, Dcp) = (80\(_{.}^{\circ}\)7830, –17\(_{.}^{\circ}\)2598; Castor, 298\(_{.}^{\circ}\)334, –34\(_{.}^{\circ}\)6405; UMa) for Castor and Ursa Major groups. According to the AD-map method we deduce the

Abstract—In circumstellar disks, the size of dust particles varies from submicron to several centimeters, while planetesimals have sizes of hundreds of kilometers. Therefore, various regimes for the aerodynamic drag between solid bodies and gas can be realized in these disks, depending on the grain sizes and velocities: Epstein, Stokes, and Newton, as well as transitional regimes between them. This

Abstract As of 2019, the International VLBI Service for Geodesy and Astrometry (IVS) has existed for 20 years. This service is the largest and most prominent organization that coordinates international activities in its field, which currently includes approximately 60 radio telescopes located in many countries from all continents. The IVS data center has accumulated more than 18 million observations

Abstract—Currently, hot Jupiters have extended gaseous (ionospheric) envelopes extending far beyond the Roche lobe. The envelopes are loosely bound to the planet and are subject to a strong influence by stellar wind fluctuations. Since hot Jupiters are close to the parent star, the magnetic field of the stellar wind is an important factor which defines the structure of their magnetospheres. For a typical

Abstract— We present the results of early observations for 130 error-boxes of gamma-ray bursts performed with the Mobile Astronomical System of TElescope-Robots (MASTER) global network of robotic telescopes from Moscow State University in fully automatic mode (2011–2017). Among them, GRB 130907A, GRB 120811C, GRB 110801A, GRB 120404A, GRB 140129B, GRB140311B, and GRB 160227A are considered in details