Vol 100, No 3 (2023)

The problem of the gravitational collapse of the core of a massive star is considered, taking into account the neutrino transport in the flux-limited diffusion approximation. To reduce the computational domain of a multidimensional problem on a fixed computational grid, the core of a star, which is already at the stage of collapse, is considered. Since the collapse stage is delayed in time compared to the gas-dynamic time scale for an emerging proto-neutron star, we consider the mathematical problem for the initial configuration in equilibrium and neglected the initial radial velocity. Pressure for a long time at the collapse stage is provided by relativistic degenerate electrons, so the relationship between pressure and density in the initial configuration is described by a polytropic equation with the polytropic index n=3. The purpose of this paper is to test the hypothesis that large-scale convection is independent of the 2D and 3D geometry of the mathematical problem and computational grid parameters, as well as the choice of the initial stage of gravitational collapse. The scale of convection is determined by the size of the region of decreasing entropy with neutrino losses, i.e., nonequilibrium neutronization, and the presence of a weak initial rotation.

We present results of the study of maser emission variability in the 1665 MHz OH line in the G43.8–0.1 star formation region based on observations (monitoring) in 2008–2022 at the Large Radio Telescope in Nancy (France). Variability of all polarization parameters of the majority of spectral features, which has a monotonic regular character, has been found. Spatial identification of the main spectral features of the OH 1665 MHz line with maser spots (condensations) on the VLA map has been carried out. For the Zeeman pair VLSR=44.15 km/s, a monotonic change of the splitting with time during 2008–2022 was found and, consequently, a change of the magnitude of the longitudinal magnetic field. According to our calculations, at the end of 2012, the direction of the magnetic field changed to the opposite. Сorrelated with H∥, there were changes in the angle χ and, as a consequence, changes in the direction of the vector of the transverse magnetic field H⊥0. For the maser feature at 44.5 km/s, a change of H⊥ by 180° was found. In 2016–2022, some reorientation of the global magnetic field (H⊥) in G43.8–0.1 occurred. The field became less chaotic: in the eastern part, the field in maser condensations is perpendicular to the arc, and in the western part, it is parallel to the arc. It is assumed that the global magnetic field in the entire U H II region of the G43.8–0.1 source has the same direction: along the axis (northeast)—(southwest).

Clustering of radio pulsars with observable giant pulses (GPs) has been carried out using the principal component analysis. Five parameters were used (period, its derivative, observed luminosity, kinematic age, and the angle between the rotation axis and the magnetic moment of the central neutron star). It was shown that the set of all known GP pulsars is divided into two clusters in the phase space of the principal components. One of the clusters contains four pulsars with short periods and high luminosity; the second cluster contains nine long-period and fainter sources. A separate object, not included in these two clusters, is the pulsar in the Crab Nebula. Possible models that could explain the observed difference between GP pulsars were considered.

In the development and testing of methods for predicting interplanetary coronal mass ejections (ICMEs), it is important to establish their relationship with sources on the Sun—coronal mass ejections (CMEs) observed by coronagraphs. The often used inverse ballistic calculation of the CME onset time does not consider variations in the CME speed when moving through the heliosphere and can give an uncertainty up to a day. With a good accuracy (on the order of ±10 h), the propagation of CMEs in the heliosphere from the Sun to the Earth is described by the model of the magnetodynamic interaction of CMEs with the background solar wind (drag-based model, DBM). In this paper, we propose to search for possible coronal sources of ICMEs, observed near the Earth, using the reverse model of magnetodynamic interaction (reverse DBM, RDBM), which reconstructs in the reverse course the probable propagation of CMEs in the heliosphere and determines their outflow parameters in the solar corona using the measured ICME parameters. The model uses the speed of the background solar wind, which is calculated from the area of coronal holes in the central part of the Sun and presented on the website of the Space Monitoring Data Center of the Skobeltsyn Institute of Nuclear Physics, Moscow State University (SINP MSU), with correction factors.