Astrophysical Bulletin最新文献

Comparison of the properties of magnetic O stars with He-strong objects showed their family connection; the mechanism of their formation and further evolution is obviously the same. The family of magnetic O stars continues the sequence of known magnetic Ap objects towards higher masses. The observed differences in properties are associated with the large mass of O objects.

The results of studying manifestations of activity of the K8V dwarf FR Cnc according to the data from the TESS space telescope archive and other literary sources are presented. The TESS mission archive contains the results of observations of FR Cnc in three sectors: 44, 45, and 46 of a total duration of 78.3 days. The light curves of the star are characterized by the variability due to rotational modulation caused by the presence of cool spots on the surface. Based on the combined data from three observation sectors, the value of the star’s rotation period was estimated as (P_{rm{rot}}=0.8257) days. Features of the amplitude changes of the stellar brightness variability, the shape of the phase light curve, and the position of the minima are highlighted. The fraction of the surface of FR Cnc occupied by spots varied in the range of 8.7–11.4(%) of the visible surface area of the star. The FR Cnc light curves are characterized by a large number of flares of different amplitudes. One of the flares is considered as an example; according to the estimate, its energy is (E_{textrm{TESS}}=1.9times 10^{34}) erg. To determine the long-term activity cycles of the star FR Cnc, the data from the Digital Access to a Sky Century @ Harvard (DASCH) project were used for the observation interval from 1886 to 1989 lasting 103 years in the photographic system close to the photometric one in the (B) filter. An independent estimate of (P_{textrm{cycl}}) was made using the data from the long-term Kamogata Wide-field Survey (KWS) in the (V) filter. Analysis of the data from these surveys showed the long-term brightness variability of FR Cnc with a characteristic time of the order of 4500–4600 days (12.3–12.6 years).

This paper presents a method for estimating precipitable water vapor from radiometric data using machine learning methods. The results of a study of precipitated water vapor for the territory of Chirag (Dagestan), Terskol peak (Elbrus region), Badary observatory (Buryatia) and the Spitsbergen archipelago are presented. A comparative analysis of the assessment of precipitable water vapor for the territory of ‘‘Badary’’ was carried out using GNSS, MERRA-2, water vapor radiometer data and predicting values using machine learning methods based on data from the MIAP-2 microwave radiometer.

The results of photometric, polarimetric, and spectroscopic observations of the young star ZZ Tau IRS in the visible and near-infrared bands are presented. Against the continuum of an M spectral type star about 50 emission lines of allowed (H I, He I, Na I, S II) and forbidden (O I, O II, O III, N I, N II, S II, Ca II, Fe II, Ni II) transitions were identified. It was found that from the autumn of 2020 to the beginning of 2023, the brightness of the star in the visible region decreased ((Delta Iapprox 1overset{textrm{m}}{.}5)) and then began to return to the initial level. As the visible brightness of the star declined, its color indices decreased in the visible region, but increased in the near-IR bands. At light minimum, the degree of polarization in the (I) band reached approx 13(%), and the equivalent widths of, e.g., the H(alpha) and [S II] (lambda) 6731 lines increased to 376 and 79 ({{text{AA}}^{circ}}), respectively. Arguments are given in favor of ZZ Tau IRS being a UX Ori type star, and its variability being due to eclipses by dust clouds, which are inhomogeneities in the dusty disk wind. Forbidden lines are formed both in the disk wind and in the jet, the axis of what is oriented along (PA=61^{circ}pm 3^{circ}). The jet mass-loss rate exceeds (5times 10^{-10}M_{odot}) yr({}^{-1}), what is abnormally large for a star with a mass less than (0.3M_{odot}). Apparently, the disk wind of ZZ Tau IRS is not axially symmetric, probably due to the azimuthal asymmetry of the protoplanetary disk found earlier from ALMA observations.

The flux density spectra of cyclotron sources above the sunspotswere obtained by observations with RATAN-600 in the range of1.7–10 cm with high spectral ((Delta f/fsim 1{-}5%))resolution and their spectral indices were estimated. The spectralindex was then utilized to determine the magnitude of themagnetic field at the base of the transition region on the Sun. Byanalyzing the relationship between theemisson flux density of the sources and the magnetic fieldit was found that the observed characteristics ofsunspot-associated sources did not align with predictions from asimplified radiation model commonly used for data interpretation.Specifically, there was an excess flux density in the spectrum ofordinary mode radiation compared to what was expected.

The article discusses the prospects for developing the observational base at the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS) for astrophysical research in the millimeter-wave range. As a first step, a project is proposed to create a set of sub-terahertz receiving equipment to operate at the optical BTA telescope. Additionally, the possibility of installing a new instrument to operate in the frequency range of up to 230 GHz ((lambda=1.3) mm) at the Upper Research Site of SAO RAS is considered. Technical and operational characteristics of the instrument, site selection for the installation of a fully steerable millimeter-wave antenna, statistics of meteorological data and atmospheric absorption are discussed. A list of potential scientific tasks addressed by instruments of this class is provided.

Based on the fluxes of 1400 nearby galaxies observed in far ultraviolet (FUV) and in the H(alpha) line, we determined the global star formation rate per unit Universe volume, (j_{textrm{SFR}}=(1.34pm 0.16)times 10^{-2}M_{odot}) yr({}^{-1}) Mpc({}^{-3}). With the current star formation rate (({SFR})), ((65pm 4)%) of the observed stellar mass is reproduced in the cosmological time of 13.8 billion years. The neutral gas reserves in the Local Volume with a radius of 11 Mpc will facilitate the current ({SFR}) on a scale of approximately another 5 billion years.

The results of photometric and spectroscopic observations of supernova SN 2022prv carried out with six telescopes including the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences and the 2.5-m telescope of the Caucasus Mountain Observatory of SAI MSU are presented. The dates and magnitudes at the brightness maximum and the parameters of the light curves are determined. The photometric evolution of SN 2022prv is characterized by a constant decrease in brightness after the maximum at a rate quite high for a type II supernovae. Approximately 55 days after the maximum, the rate of the decrease in brightness increased. The maximum luminosity has reached (M_{V}=-18overset{textrm{m}}{.}1) which is higher than average for SN II. In the pre-maximum spectra, high-excitation emission lines were observed characteristic of the ionization of the circumstellar matter by a burst during the shock wave emergence onto the surface of the star. However, approximately 20 days after the maximum, the spectrum did not differ from that typical of SN II. The rate of the envelope expansion at this stage was about 3500 km s({}^{-1}) which is a little smaller than average for SN II values.

In this paper, the phenomenon of lopsidedness associated with the observed effect of displacement of the core of a spiral galaxy from its geometric center is explained by the gravitational instability of individual perturbation modes. The main ones are perturbation modes with radial wave numbers (N=3) and (N=5), where the azimuthal index is (m=1). Unlike other authors, we studied the lopside instability phenomenon against the background of a non-stationary model of a nonlinearly pulsating disk. The mechanisms and criteria for the origin of the phenomenon of displacement of the core in spiral galaxies are revealed. In addition, to determine the dependence of this effect on the geometry of the gravitating system, we also carried out an analysis of lopsided perturbation modes in the framework of a spherical nonstationary model.

A differential image motion monitor (DIMM) has been developed and manufactured to study atmospheric seeing. The monitor is made in a lightweight field version and can operate without a telescope, as has always been the case before. Two apertures are made using 70-mm lenses with a focal distance of 900 mm. The distance between the aperture axes is 300 mm. The images from the apertures are combined in the plane of a single CMOS camera operating at up to 314 frames per second speed with low reading noise of about (3e^{-}). The device also includes a (3^{circ}!times!3^{circ}) field of view viewer for pointing at a star. The monitor proved to work successfully during several astroclimate study expeditions. The monitor data were verified by comparing them with the results of atmospheric seeing measurements at the 2.5 meter telescope of the Caucasian Mountain Observatory.