Abstract— One of the varieties of firehose instability, whose cause is not the temperature anisotropy of plasma particles but the dynamic pressure of the beam, is considered. It is shown that such a generation mechanism can lead to an effective increase in low-frequency perturbations not only of the Alfven type but also of the magnetosonic type and also lead to instability not only in the finite and

Abstract— Evolution and morphological properties of the active region NOAA 9087 are analyzed based on space and ground observational data. Data on hard X-ray (HXR) and soft X-ray (SXR) were obtained from Yohkoh Telescopes (HXT and SXT) and the Geostationary Operational Environmental Satellite. Magnetograms and images in far ultraviolet were obtained from the Michelson Doppler Imager (MDI) and Extreme

Abstract The propagation of solar cosmic rays in the interplanetary medium is considered on the basis of the kinetic equation describing the small-angle multiple scattering of charged particles. Energetic particles are assumed to be injected into the interplanetary medium by an instantaneous point-like source. The spatial-temporal distribution of the density and anisotropy of high-velocity particles

Abstract One of the unsolved problems of cosmic ray physics is determining the nature and sources of ultrahigh energy cosmic rays (UHECRs, E > 1018 eV). The high degree of isotropy of the observed UHECR intensity caused mainly by the deviations of the UHECR trajectories in extragalactic and Galactic magnetic fields, as well as the significant uncertainty in their chemical composition (atomic mass)

Abstract A chain of events accompanying the occurrence of a substorm in the Earth’s ionosphere and magnetosphere is considered. Features of geomagnetic pulsations and mechanisms of their generation are indicated. Measurements of magnetic field fluctuations from fluxgate magnetometers, as well as the data on temperature, velocity, and concentration of electrons, and different types of ions from the

Abstract A theory on the emergence of global hydrodynamic flows of matter and the generation of global magnetic fields in the solar convective zone is proposed. The unstable profile of differential rotation plays a crucial role in it: all hydrodynamic flows on the Sun (poloidal circulation, torsion oscillations, and spatiotemporal variations of the poloidal flow) are generated due to the loss of stability

Abstract As is known from multiyear theoretical and experimental studies, acoustic−gravity waves (AGW) determine the dynamics and energy balance of the atmospheres of planets and the Sun to a considerable extent. Linear wave perturbations in the atmosphere can be described with a system of second-order equations for the vertical and horizontal components of the perturbed velocity. It follows from this

Abstract Integrated characteristics of a sample of 66 star-forming galaxies with extremely low oxygen abundances from the SDSS Data Release 14 are studied. The oxygen abundances were determined by the direct Te method for 42 galaxies with detected [O III] 436.3 nm emission lines and by the strong-line method for the remaining galaxies. Derived abundances 12 + log (O/H) fall within the 6.97–7.52 range

Abstract The magnetic effect of meteors was first observed and theoretically explained back in the middle of the 20th century. The mechanisms for the magnetic effect of large celestial bodies (1–10 m and more) fundamentally differ from the mechanisms of geomagnetic field disturbances caused by meteors at ionospheric heights. The passage of a large meteoroid through the atmosphere and its explosion

Abstract In the case of astronomical observations from the surface of the Earth, it is difficult to obtain high resolution images due to the distorting influence of the atmosphere. There are two groups of methods for mitigating this influence. The first group does not interfere with the process of image formation and is related to the processing of already recorded images. The methods from the second

Abstract The high-resolution fiber echelle Cassegrain spectrograph for the 2-m telescope at the Shamakhy Astrophysical Observatory (ShaFES) is described. The optical circuit and the schematic of the suspended part of the spectrograph are presented. The spectrograph operates in two modes with a spectral resolution of 27 500 and 55 000 in the 370–850 nm wavelength range. The results of its testing are

Abstract—The paper deals with the distribution of discovery dates of comets through phases of the 11‑year cycle of solar activity (SA). Four groups of comets are considered: long-period comets (LPCs) with an orbital period exceeding 200 yr, periodic comets (PCs) of Jupiter’s family, LPCs with a weak absolute brightness, and a group of LPC with perihelia near the plane perpendicular to the ecliptic

Abstract The validity of the lambda-meter method for determining the quiet Sun velocity field using the Si I 1082.7 nm line is investigated. To this end, the intensity profiles of this line were calculated for the solar disk center by means of NLTE simulations in a three-dimensional model atmosphere describing the small-scale magnetic activity in the quiet solar photosphere. The velocity field recovered

Abstract The subsolar point on Jupiter’s magnetosphere changes its position by an angle of approximately 26° over the orbital period of Jupiter, which induces seasonal variations in physical and optical characteristics of the planetary atmosphere. At the time close to the summer solstice for the northern hemisphere, Jupiter is in perihelion. Consequently, due to the significant orbital eccentricity

Abstract We present the results of computations of the trajectories (the asymptotic latitude and asymptotic longitude) and the magnetic cutoff rigidity of galactic cosmic ray (GCR) particles for the airport Deblin, Poland (geographical latitude 51°33′32′′ N, geographical longitude 21°50′53′′ E) based on the numerical integration of equations of motion of charged particles of cosmic rays in the Earth’s

Abstract Comprehensive modeling studies of the processes induced in all geospheres by the passage and explosion of the meteoroid near the city of Lipetsk (Russia) on June 21, 2018, have been conducted. Magnetic, electric, electromagnetic, ionospheric, and seismic effects, as well as the effects of acoustic-gravity waves have been estimated. The magnetic effect of turbulence has been shown to be insignificant

Abstract We study the mid-infrared photometric properties of a sample of compact star-forming galaxies from the SDSS Data Release 14. The sample includes about 30 000 galaxies. The Hβ emission lines with equivalent widths EW(Hβ) > 1 nm are observed in the spectra of all selected galaxies. The selected galaxies are compact objects with angular diameters less than 6 arcsec. About 10 000 galaxies were

Abstract The problem of anomalous meteors with diffuse view and increased size of their comas at the beginning of radiation is considered. Results from processing some meteors detected with high-sensitive observational TV systems of the Super-Isocon type during Leonid storm observations in 2002 are given. As opposed to similar cases described in literature previously, the given meteors had an increased

Abstract According to the data of complex 2D observations on the VTT telescope of the solar facula, a 3D model of the solar atmosphere in the facular region was obtained by solving the inverse radiative transfer problem in the Ba II 4554 A line. The magnetic field was estimated using the Stokes V profiles of the Fe I 15648 A line. The influence of magnetic field on photospheric convection was investigated:

Abstract—Comprehensive modeling studies of the processes induced in all geospheres by the passage and explosion of the meteoroid near the city of Lipetsk (Russia) on June 21, 2018, have been performed. Thermodynamic and plasma effects and the effects of the plume and turbulence accompanying the passage of the Lipetsk meteoroid have been estimated. It has been shown that the passage of the celestial

Abstract—The propagation of solar cosmic rays (SCR) in the interplanetary medium is considered on the basis of the Fokker–Planck kinetic equation. It is known that the SCR distribution function averaged over a solar proton event contains valuable data on the scattering process for energetic charged particles by interplanetary magnetic fields. A steady-state solution for the kinetic equation in the

Abstract—From 2D-spectral observation data of a quiet region of the solar disk center in the Fe I λ 557.609 nm line, 3D hydrodynamic models of photospheric jets are built by solving the inverse radiative transfer problem. The obtained models describe thermodynamic parameters and the complete velocity field (vertical and horizontal). It is shown that the photospheric jets under consideration arise from

Abstract—The importance of taking the SiO absorption in the infrared spectrum into account for spectral analysis of late-type stars is demonstrated. The lists of absorption lines of the fundamental SiO system calculated by the group of J. Tennison in the ExoMol project were used. The bands of isotopic molecules 28SiO, 29SiO, and 30SiO were identified in the spectrum of red giant HD 196610 (V*EU Del

Abstract—Additional arguments for the existence of a specific nongravitational effect (NGE) in the asteroid belt, which was discovered more than 10 years ago, are presented. Under the influence of this NGE, the semimajor axes of orbits of low-albedo asteroids increase gradually relative to the semimajor axes of orbits of asteroids with higher albedos. This is confirmed by the albedo–semimajor axis