Astronomy Reports最新文献

Our photoelectric measurements over the past 30 years and a new solution of the radial velocity curve of the eclipsing star with an elliptical orbit V501 Mon (A8 + F2) allowed us to determine with high accuracy all the main parameters of the system: ({{T}_{1}} = 7380 pm 60) K, ({{M}_{1}} = 1.66 pm 0.03{kern 1pt} {{M}_{ odot }}), ({{R}_{1}} = 1.90 pm 0.02{kern 1pt} {{R}_{ odot }}), ({{T}_{2}} = 6920 pm 30) K, ({{M}_{2}} = 1.47 pm 0.02{kern 1pt} {{M}_{ odot }}), ({{R}_{2}} = 1.58 pm 0.01{kern 1pt} {{R}_{ odot }}). The photometric parallax determined in the study coincides with the Gaia value (pi =0.00103{''} ) within the error limits. For the first time, the apsidal motion rate ({{dot {omega }}_{{{text{obs}}}}} = 0.022^circ )/year was accurately measured, which, within the error limits, matches the theoretical value: ({{dot {omega }}_{{{text{theor}}}}} = 0.024^circ )/year; 70% of this value is a relativistic contribution. The system possibly satisfies the condition of synchronism between rotational and orbital angular momenta. The age of the stars was determined to be 0.95 billion years. The main component is probably a pulsating variable star of the (delta ) Scuti type (DSCT).

In this study, we investigated the radial variation of the azimuthal propagation of star formation across the spiral arms in the nearby galaxy NGC 5194 (M51a) by analysing the spatial separation between young star clusters and their nearest H II regions. The significant differences in the radial profiles of the mean azimuthal offsets in the M51a arms were found when the southern and northern arms were studied separately. The northern arm analysis showed that its radial profile is consistent with the predictions of stationary density wave theory for trailing spirals, while the explanation of the radial profile for the southern arm required its pattern speed to be higher than the rotation velocity of disc matter within the corotation circle, and lower than that outside of it. At the same time, these different radial profiles of the mean azimuthal offset in the two arms are joined by a common localization of corotation resonances, confirmed by independent studies using different methods.

The motion of stars whose spatial velocities have radial directions of motion in the galactic disk has been studied using numerical modeling. For this purpose, stars located within 100 pc from the Sun with spatial velocities directed approximately to the galactic Center (or anticenter) have been selected from the Gaia DR3 catalog. The sample included 13 stars with characteristics of halo stars: the eccentricities of their spatial orbits are close to unity and metallicity is significantly less than zero. An axisymmetric model of the Galaxy, including the bulge, disk, and halo, has been used. It has been found that the orbital apsides of the stars in our sample show a retrogradely directed precession with a velocity of 15–20 pc/million years in the interval from 10 to 20 kpc from the CG.

It has been previously demonstrated by Panov et al. (2021) that the TAIGA-HiSCORE Cherenkov array, originally built for cosmic ray physics and ultrahigh-energy gamma-ray astronomy studies using the extensive air shower method, can be used in conventional optical astronomy for wide-field searches for rare nanosecond optical transients of astrophysical origin. The field of view of the facility is on the scale of 1 ster, and it is capable of detecting very rare transients in the visible light range with fluxes greater than approximately 3000 quanta/m²/10 ns (10 ns is the apparatus integration time) and pulse durations of 10 ns. Among the potential sources of distant nanosecond optical transients are the evaporation of primary black holes, magnetic reconnection in the accretion disks of black holes, and signals from distant lasers of extraterrestrial civilizations. The paper describes the methods and results of the search for optical transients using the TAIGA-HiSCORE Cherenkov array from 2018 to 2022 (four winter seasons of data collection). No reliable astrophysical candidates for optical transients were found. We set an upper bound on the flux of the searched events as ( sim {kern 1pt} 1 times {{10}^{{ - 3}}}) events/ster/h.

About a third of stars in open star clusters of the Galaxy may have planetary systems. The increased density of stars in clusters introduces its own peculiarities into the evolution of their planetary systems. An analysis of the evolution conditions of planetary systems in star clusters has shown that close passages of cluster stars during its lifetime of ~3 × 10⁸ years destroy the peripheral structures of planetary systems: asteroid–comet–planetary (ACP) spears, Kuiper belts. At the same time, the parts of planetary systems close to the star are not affected. As a result of the ACP, objects with major semi-axes of orbits exceeding ~17 AU are lost by planetary systems, forming the ACP of the cluster spear. The result of the cluster evolution after its disintegration is the formation of the ACP flow, coinciding with the stellar flow. The observed displacement of massive clusters of the Galaxy relative to the center of their stellar copies is a consequence of the gravitational braking of the clusters. It can be used to estimate the rotation parameters of the dark halo of the Galaxy with allowance for the asymmetry of the stellar copies of massive clusters caused by the gravitational braking of the nuclei.

The paper presents orbits of 69 wide pairs of visual binary and multiple stars (belonging to 65 systems) obtained by the Apparent Motion Parameters (AMP) method. The possibility of determining the AMP orbits of these pairs using Gaia DR3 data at the time point 2016.0 is considered. (1) Orbits according to Gaia DR3 were obtained for 45 pairs. (2) For another 20 pairs, the quasi-instantaneous motion according to Gaia data contradicts the mean motion from all available observations. A possible reason is the presence of inner subsystems. (3) AMP orbits were also determined for 3 bright stars (ADS 2080, ADS 7724, and ADS 9173) and 3 close pairs (angular separation less than (2'' ): ADS 2416, ADS 5570, and T Tau NS) that do not have the Gaia DR3 positional observations. The basis for the study in cases 2 and 3 is the Pulkovo series of observations on the 26-inch refractor and/or data from the literature. Of the 69 pairs of stars studied, 59 have semi-major axes of the orbit greater than 100 AU. Among them, families of orbits with minimum periods from 5000 to 730 000 years and minimum semi-major axes of more than 400 AU were obtained for 17 pairs. Unique solutions were obtained for the orbits of 28 pairs. Of these, 20 pairs have a semi-major axis of the orbit greater than 100 AU and periods from 600 to 6000 years. Relative errors in determining the elements are generally about 15–20%. The orientation of the resulting orbits in the Galactic coordinate system is also determined.

The observed power-law spectra of relativistic jets from active galactic nuclei clearly indicate a synchrotron mechanism of radiation by particles that similarly possess a power-law energy spectrum. However, the issue of their angular anisotropy has not been given sufficient attention until recently, although the example of the solar wind (where a strongly magnetized wind is realized in a similar way) shows the importance of taking this circumstance into account. In this paper, we study the evolution of an initially isotropic power-law spectrum of radiating particles as they propagate along expanding relativistic jets. It is shown that for relativistic flows in which the electric field plays a crucial role, the preservation of the first adiabatic invariant does not lead to a decrease in the pitch angles of radiating particles as they enter the region of weak magnetic fields. This is due to the drift nature of the particle motion.

The values of proper motions and distances for 21 radio pulsars with age of τ < 10⁵ years and distances to the known supernova remnants (SNRs) to search for the possible genetic relation between these objects have been used. It has been shown that the distributions of pulsar velocities V_trans for pulsars with τ < 10⁵ years and τ > 10⁵ years and mean values of V_trans in these samples do not differ significantly. This means that the gravitational potential of Galaxy and the interstellar medium do not affect significantly the movement of pulsars. Angular distances of pulsars from their expected parent SNRs have been estimated. For 20 pulsars with age of τ < 10⁵ years, the possible native SNRs have been found. The associations with SNRs have been indicated already for 13 of them in the ATNF catalog. For seven radio pulsars, such associations have been found for the first time.

The slope of the late-giant branch in some two-color diagrams differs considerably from the slope of other sequences as well as from the slope of reddening lines. This fact makes red giants an indispensable sourse of data on stellar parameters as well as on interstellar extinction. This study aims at finding two-color diagrams suitable for parameterization of M giants and developing techniques of parameterisation based on observed photometric data. As a result, we obtained an instrument for determination of intrinsic color indices, spectral types, and interstellar extinction for the (WBVR) and (ugriz) photometric systems. This paper is based, in part, on the talk presented at the “Modern Stellar Astronomy—2024” conference.

Based on lists of objects from the archives of the LAMOST survey telescope and the TESS, Kepler, and K2 space missions, the manifestations of the spot activity of solar-type stars with exoplanets with pronounced flare activity have been studied. Diagrams (spottedness parameter S-flare energy) and (spottedness parameter S-rotation period ({{P}_{{{text{rot}}}}})) have been considered. As in the case of solar-type stars with superflares and other active stars, among the considered objects, the most active ones rotate faster, they are younger and the area of spots on their surface is bigger. The difference is that the spottedness of most stars with planetary systems does not reach the maximal values of the spottedness parameter for stars with superflares. Of the six objects with the light curves available in the TESS mission archive, the TIC 410214986 (DS Tuc) solar-type star with pronounced photospheric and chromospheric activity, which is a member of the Tucana–Horologium group with an age of ~45 mln years, attracts special attention.