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 change of period and inclination angle of PSRB0525+21 are given. The conclusions are drawn. PubDate: 2020-12-01

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 from the planets were considered, the 4th order harmonic was included in the gravitational potential of the Moon, and the mean tidal potential was also considered. The inclusion of the described effects in the equations of the Moon’s rotation led to a significant improvement in the solution when compared with the corresponding data from the DE421 theory, although the residual differences still remain greater than the 1 ms accuracy required by the theory. The influence of the direct effect from the planets was milliseconds. The influence of the 4th harmonic manifested itself as a systematic shift of the order of 0.85 \('' \) in the residual differences in libration in longitude. Considering the tide made it possible to reduce the residual differences in latitude by almost an order of magnitude. In this case, the main factor that reduces the residual differences is changes in the second-order Stokes coefficients. The calculations were carried out using the DE421 ephemeris built at NASA Jet Propulsion Laboratory. PubDate: 2020-12-01

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. The electron relic neutrinos are the rarest for a terrestrial observer. PubDate: 2020-12-01

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 \({{R}_{0}}\) one can obtain the mass accreted by the structure. We see that moving from the simple spherical collapse to that accounting for angular momentum and dynamical friction leads to the increase of acquired mass. Then, we showed how angular momentum, and dynamical friction change the threshold of collapse with mass, and also with redshift for different dark energy models. We repeated the calculation for the virial overdensity, and the mass function, founding noteworthy differences with the case of the simple spherical collapse. PubDate: 2020-12-01

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 explicit, we considered the DBI model for two different limits, viz., speed limit and constant sound speed, as examples. PubDate: 2020-12-01

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, second, a system for compensating nongravitational disturbances. This work discusses the basic principles of operation and the current state of the key technologies developed in the PRC. At the current level of technological readiness, it is expected that TianQin will be launched in the second half of the next decade and will serve as a space observatory for a wide class of astrophysical sources of gravitational waves. PubDate: 2020-12-01

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, \(\Omega _{0}^{'} = - 4.063 \pm 0.029\) km s–1 kpc–2, and \(\Omega _{0}^{{''}} = 0.766 \pm 0.020\) km s–1 kpc–3, where the Oort constants are \(A = 16.25 \pm 0.33\) km s–1 kpc–1 and \(B = - 12.58 \pm 0.34\) km s–1 kpc–1. The circular rotation velocity of the solar neighborhood around the Galactic center is \({{V}_{0}} = 230.7 \pm 4.4\) km s–1 for the adopted Galactocentric distance of the Sun \({{R}_{0}} = 8.0 \pm 0.15\) kpc. The residual velocity dispersion for the stars considered is shown to be low, suggesting that they are extremely young. The residual velocity dispersion averaged over three coordinates is ~11 km s–1 for Herbig Ae/Be stars and ~7 km s–1 for T Tauri stars. PubDate: 2020-12-01

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. We analyzed the accuracy of the possible result. A problem is identified that arises when tending for the highest possible accuracy and a solution is proposed. An estimate is given of the computer time required to solve Kepler’s equation by this method. PubDate: 2020-12-01

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 was weakened and was practically not observed, remaining weak until the end of 2019. At the end of 2019, the broad component H \(\beta \) strengthened again, and in May 2020 reached a typical level for the high state of the object. During 2016–2020 we observed several changing looks of NGC 3516. PubDate: 2020-12-01

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 from August 3 to August 25 every year; it is classified as a minor shower, and the size of its mean orbit is around 3.2 AU, while the geocentric velocity is 20.9 km/s. No parent body (PB) of the shower has been found among comets so far. Relationships between the shower and asteroids, as potential PBs of the shower, are under active examination; some hypotheses on this subject can be found on the website of the Meteor Data Center (MDC) of the International Astronomical Union (IAU). PubDate: 2020-12-01

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 libration). The accuracy requirements for these observations are analyzed in view of the accuracy requirements for determining the lunar rotation parameters. The necessary number of telescopes, as well as their optimal locations, is assessed. PubDate: 2020-12-01

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 voids and they are rather close to each other. At larger \(\gamma > {{\gamma }_{{{\text{cr}}}}}\) a pressure becomes zero at finite radius, and a spherical void appears around the origin in both solutions. All matter is collected in thin layer behind the shock wave front. The structure of this layer qualitatively depends on γ. At the inner edge of the layer the pressure is always zero, but the density at this edge is jumping from zero to infinity at \(\gamma \approx 1.4\) in both solutions. PubDate: 2020-12-01

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 formation and a different nature; i.e., for only two of the four rings does the resonance origin associated with the dynamics of the central triaxial structure (bar) seem preferable. PubDate: 2020-12-01

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 induces the migration of the planet to the star. In this paper, we consider the effectiveness of this migration mechanism by the example of the HD 209458 system. It turns out that, after 4.5 × 109 years since the evaporation of the protoplanetary disk, the planet might migrate from an orbit at ≳0.67 AU to its current orbit at 0.045 AU. PubDate: 2020-12-01

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 on the wind opening angle. In models with a large opening angle, the emission line at the minimum brightness becomes single, asymmetric, and shifts towards the red end, which contradicts the observations made in 1992 during the deep minimum of UX Ori, when the asymmetric two-peak emission line turned into an asymmetric single and practically unbiased line. This indicates that one more source contributes to the emission spectrum, which is not occulted by an opaque screen at the moments of eclipses. As possible options, we considered (a) scattered radiation of a hypothetical dust halo in the polar region of the disk and (b) peripheral layers of the gas atmosphere of the disk, which are the source of the photoevaporation wind. To clarify the situation, new high-quality observations of the spectra of this type of star in deep minima are needed. PubDate: 2020-12-01

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 source as a possible mechanism for the formation of X-ray radiation from kiloparsec jets of the quasars PKS 0637–752, 3C 273, PKS 1510–089, and PKS 1045–188. Estimates of the angle between the line of sight and the velocity of kiloparsec jets are obtained. The predicted gamma-ray flux for all objects turned out to be below the upper limit on the flux from a kiloparsec jet obtained from the Fermi-LAT data. It is shown that our assumption about the mechanism of X-ray radiation from kiloparsec jets is consistent with all data of multiwavelength observations available to date. PubDate: 2020-11-01

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 oscillation period, were found. It is concluded that the mechanism generating such oscillations may be the process of changing the magnetic field of the convective shells of the components. Based on the detected decrease in the depths of both minima of the light curves and the change in their relative values, it was concluded that the system is currently transiting from the W-subtype class to the A-subtype class. The values of seven new values of the moments of minima are given. PubDate: 2020-11-01

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 estimates of virial parameters are quite close to each other and the values of reduced virial density Gρ are concentrated in a shallow interval \(0.5 \leqslant {{G}_{\rho }}{\text{/}}\langle {{G}_{\rho }}\rangle \leqslant 2\) around its mean value. This “virial” paradox sharpen when compared with simulations, in which the number of such objects is very small, and for the majority of dark matter halos these densities are ~50–100 times smaller. Our theoretical analysis shows possible reasons for this discrepancy of observations and simulations, pointing out its connection with the spectrum of cosmological perturbations. After some refinement, the considered data can be used to constrain models of cosmological inflation. A number of accompanying questions is discussed. PubDate: 2020-11-01

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 the period can be explained by the loss of angular momentum due to magnetic braking on the secondary component of a late spectral type. The light-time effect is explained by the presence of a third body in the system, which was discovered from both spectral and speckle interferometric observations. PubDate: 2020-11-01

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 that the accuracy of the method exceeds similar characteristics of other known solutions. It is also shown that the coefficients, which take account of the solar pressure and are specific for each satellite, differ for different generations of spacecraft. Simultaneously with parameters of the satellite motion, the Earth’s polar coordinates can be determined with the accuracy of several arc milliseconds. Using the autonomous algorithm for predictions of spacecraft ephemerides significantly advances both the search for visible GLONASS and GPS satellites and the first determination of user’s coordinates after “cold” starts of receivers. This article is based on the report presented at the conference Astrometry Yesterday, Today, and Tomorrow, conducted at Sternberg Astronomical Institute, October 14–16, 2019. PubDate: 2020-11-01