Astronomičeskij žurnal

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

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. Analysis of the conditions of the evolution of planetary systems in star clusters shows 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, taking into account 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 (part of 65 systems) obtained by the Apparent Motion parameters (AMP) method. Problem statement: the possibility of determining the AMP orbits of these pairs using Gaia DR3 data at the moment 2016.0 is considered. Results: 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 average motion from all available observations. A possible reason is the presence of internal subsystems. 3) We also give AMP orbits for 3 bright stars (ADS 2080, ADS 7724, and ADS 9173) and 3 close pairs (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 are 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 a semi-major axis of the orbit greater than 100 AU. Among them, for 17 pairs, families of orbits with minimum periods from 5 thousand to 730 thousand years and minimum semi-major axes of more than 400 AU were obtained. The only possible 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 1520%. The orientation of the resulting orbits in the galactic coordinate system is also determined.