


Vol 100, No 10 (2023)
- Year: 2023
- Articles: 7
- URL: https://ruspoj.com/0004-6299/issue/view/10343
Articles
RADIO EMISSION SPECTRUM OF COMPOSITE SUPERNOVA REMNANT G74.9+1.2
Abstract
Measurements of the flux densities of the supernova remnant (SNR) G74.9+1.2 (CTB 87) at frequencies of 4840 and 8450 MHz were carried out with the RT-32 radio telescope of the Svetloye observatory of the IAA RAS in 2018–2019. The data obtained contain signs of the presence of a source of a variable component in the radio emission on a time scale of a month or more. The flux densities of G74.9+1.2 over the time interval 1959.7–2010 are determined from published data, which makes it possible to compare the intensities of G74.9+1.2 and standard sources. All data are presented in a single system based on the exact scale of “artificial moon” (AM) fluxes. A refined spectrum of SOS G74.9+1.2 was obtained. The totality of available data is approximated by two power-law sections with different spectral indices:


OBSERVATIONS OF THE FAST RADIO BURST FRB 20220912A ON THE BSA FIAN AND FAST RADIO TELESCOPES
Abstract
This paper presents the result of the search for pulses from the fast radio burst FRB 20220912A on the antenna of the BSA FIAN at a frequency of 111 MHz during the period of activity in October-November 2022. As a result of observations, pulses were recorded on October 18, 30 and November 12 with a dispersion measure of


KINETIC MODEL OF THE STELLAR WIND FORCING ON THE EXTENDED HYDROGEN ATMOSPHERE OF THE EXOPLANEt π Men c
Abstract
In this paper, an extension of the kinetic model of the aeronomy of the upper atmosphere of an exoplanet is performed by including the processes of the effect of stellar wind plasma on the extended hydrogen corona of a hot sub-neptune. For this purpose, previously developed kinetic Monte Carlo models were used to study the precipitation of protons and hydrogen atoms with high energies into planetary atmospheres. The kinetic model is adapted to the upper atmospheres of hot sub-neptunes, which made it possible to calculate the rate of absorption of stellar wind plasma energy in the planetary corona and to refine estimates of the non-thermal loss rate of the atmosphere due to the influence of the stellar wind. The calculations carried out for the hot sub-neptune π Men c showed that the energy of a flux of energetic neutral hydrogen atoms (ENA H) penetrating the atmosphere, formed during the charge exchange of stellar wind protons with thermal hydrogen corona atoms, mainly goes to heating the hydrogen corona of a hot exoplanet.


ACTIVITY CYCLES OF SINGLE G5 III-IV GIANT HD 199178
Abstract
A unique series of photometric data has been obtained for a period of more than a hundred years for the rapidly rotating single G5 III–IV giant HD 199178 (V1794 Cyg) belonging to the group of stars of the FK Com type. Our analysis of the long-term periodicity of the activity of this star is based on all available measurements of its brightness in B filter. To assess the brightness of HD 199178 in the era preceding photoelectric and CCD observations measurements were made using photographic plates from the archive of the SAI MSU at the Krasnopresnenskaya Observatory of Moscow State University in Moscow (4 plates taken from 1898 to 1903 and 41 plates obtained from 1935 to 1958). As a result, a total of 2142 estimates of the brightness of the star in the B filter were considered . They have a unique duration of 118.3 years and cover the time interval from 1898 to July 2016. Evidence of the existence of long-term cycles of photometric variability with values of the order of 25–60 years has been found. It is assumed that there are possible activity cycles of 2000, 3165, 5050, 9000 and 21600 days (5.5, 8.7, 16.6, 24.7 and 59.2 years). The results obtained are compared with other estimates of activity cycles of HD 199178. The existence of a cycle of 8.7–9 years should be recognized as the most reliable. It is found that to combine data into a single array the conversion of values B into values V using the average value of the color index (


EVOLUTION OF METEOROID STREAMS ORIGINATING FROM NEA COLLISIONS
Abstract
In this work we study formation and evolution of meteoroid streams originating from the collisions of near Earth asteroids (NEA) with objects of the Main Asteroid belt (MAB). Such a collision scenario is considered more probable compared to collisions between NEAs, since many NEAs, by virtue of their origin, cross the MAB region, where the number density of objects is significant compared to the inner regions of the Solar System. Meteoroid streams originating from collisions have a number of differences from the streams of cometary origin, both in terms of the formation and the evolution. In this paper, estimates are obtained for the meteoroid formation rate as a result of NEA collisions with MAB asteroids. On the basis of high-velocity collisions models and the DART experiment data, possible particle size and velocity distributions are obtained. We made numerical simulation taking into account gravitational perturbations and radiation forces and the influence of the initial velocity on the evolution was studied. An analysis was made of the rate of dust and meteoroids production, taking into account the distribution of the current population of the NEA, and it was concluded that the rates of influx of meteoroids of asteroid and cometary origin (in terms of mass) can be quite comparable.


INFLUENCE OF RADIATION FORCES ON THE OBSERVED POSITION AND EVOLUTION OF THE ORBIT OF SPACE DEBRIS OBJECTS WITH A HIGH AREA-TO-MASS RATIO
Abstract
This study is devoted to assessing the effect of light pressure on the observed position and orbital elements of space debris objects with a large area-to-mass ratio


MODIFIED SHAO SPECTROGRAPH FOR SPECTRA WITH LOW RESOLUTION
Abstract
The paper describes an improved spectrograph of the Cassegrain focus of the 2 m ShAO reflector using a CCD camera. The classic Universal Astro Grid Spectrograph (UAGS) was adapted to use the Andor CCD camera to obtain spectra of objects with low brightness in the range of 3600–8000 Å. A spectrograph with a diffraction grating of 651 line/mm makes it possible to obtain the spectra of stars on the 2 m ShAO telescope up to 18 mag with a resolution of 1200, with a signal-to-noise ratio of about 50 for half an hour of exposure. The maximum allowable resolution is R = 3400 with binning 1 × 1. The complex can be used for observations of various types of transient objects, variable stars, and extragalactic objects.

