Astronomy Reports最新文献

In the article, we have studied the impact linear polarization of the helium D₃ line that takes place in the solar chromosphere under the action of protons accelerated in solar flares. The dependence of the energy distribution of protons on the distance traveled inside the chromosphere is calculated. The ratio of the concentrations of nonthermal protons and thermal electrons at different depths is theoretically determined. From the calculation of the degree of linear polarization of the helium line D₃ for different layers of the chromosphere, the region of probable formation of the line is determined.

It is known that so-called solar flares systematically occur in the area of sunspots. They are accompanied by radiation in almost all frequency ranges and sometimes by the emission of hot plasma. Observations on the RATAN-600 radio telescope have shown that the radio emission spectrum of plasma clouds heated to values of the order of 10⁶ K erupted from the solar flare region turned out to be adiabatic. The high correlation of the inhomogeneities of the radio emission spectra of active formation over a group of sunspots indicates the stable presence of recombination radio lines in the radiation of active formation. However, the radio emission spectra of hot plasma clouds ejected from the region of solar flares occurring in this group of spots do not show any correlation.

Several new models of a layered inhomogeneous elliptical galaxy (EG) having the shape either a triaxial ellipsoid or an oblate or prolate spheroid and consisting of baryonic mass and dark matter with different laws of density distribution—profiles. Based on these models, some key dynamic parameters of the EG were determined: gravitational (potential) energy and rotational kinetic energy, total surface brightness, total luminosity, and velocity dispersion depending on the distance to the EG center. The relationships between the important dynamic parameters of the galaxy have been established: “mass–dimensions”, “mass–velocity dispersion”, “size–dispersion speeds–luminosity” (surface brightness). Evolutionary scenarios for the formation of EG were studied according to these models. The results obtained were applied to sixty model EGs with parameters exactly matching those that actually exist and are presented in the form of tables.

An analysis of photometric observations of the star V647 Her (M3.5V) obtained at the 1.25-m telescope of the Crimean Astrophysical Observatory in 2022 is presented. The presence of a low-amplitude variability in brightness of the star with a period of 20.69 d, found from observations in 2019 was confirmed. It is shown that as the brightness decreases, the star becomes redder. The observed kind of photometric variability is due to the presence of cool spots on the surface of the star and rotational modulation of brightness with a full amplitude of no more than 0(^{{text{m}}}_{.})05. We perform a comparison of the photometric results obtained in 2019, 2022, and 2004. The locations of starspots at different epochs were determined from the analysis of phase curves. The distribution of starspots has been maintained for 40–100 days. Starspot parameters were estimated in the framework of the zonal model. The temperature of starspots is 2700–2800 K. The area they occupied in 2004 is 15% of the total surface area of the star. According to the 2019 and 2022 data, it increases up to 30%. The seasonal redistribution of starspots leads to the difference between the spottedness of hemispheres, which is less than 2%.

The short biography of one of the founders of stellar astronomy as a science, Pavel Petrovich Parenago, is presented. Considered the question of which scientific phenomena and objects in astronomy bear his name.

Observations of the dwarf nova SS Cyg were made in 2019–2021 at different brightness levels ((V sim 10{-} {{12}^{m}})) both at the brightness decay stage after the outburst maximum, and in the quite state between outbursts. Data were obtained in ({{R}_{c}}) (( sim {kern 1pt} 8650) observations, 3 sets) and V (( sim {kern 1pt} 50,000) points, 22 sets) bands. The value of the system’s orbital period obtained in 2019–2021 (({{P}_{{{text{orb}}}}}{{ = 0.27408(2)}^{d}})) used in this study is 0.4% less than the value obtained more than a quarter of a century ago (1983–1996). The time resolution between two successive measurements is 6–14 s depending on the equipment used. An extensive database of new observational data allowed us to perform a quantitative analysis of observations. Analysis of the data after taking into account orbital variability and other trends associated with changes in the system’s emission flux during the night showed the presence of cyclic fluctuations in brightness, usually 4–10 events per orbital cycle – flickering. For most series of observations, the Lafleur-Kinman method determined such a value of the oscillation period at which convolution of observations with it showed a single wave. The obtained values of the characteristic flickering times and their amplitudes show their dependence on the average brightness level of the system. With increasing luminosity of the system, both of these quantities decreased linearly. From the size ratios of the binary system components of SS Cyg, it was shown that the source of flickering is located in the interaction region of the gas flow with the near-disk halo: only this region in the SS Cyg system with parameters ((q), (i), ({{R}_{d}})), defined by the authors earlier, can be eclipsed at large radii disk, and is clearly visible in all other orbital phases of the system.

One of the most important tasks of studying seeing conditions of possible locations for the Eurasian Submillimeter Telescopes is to research the statistics of precipitated water vapor, optical depth and cloudiness. In this paper, the statistics of precipitated water vapor and total cloudiness in northern Eurasia are studied using ERA-5 reanalysis. Optical depth statistics at a wavelength of 3 mm were obtained using the Liebe model from the ERA-5 reanalysis for the region where the Large Altazimuth Telescope BTA is located. The most favorable astroclimatic zones of Eurasia, along with Tibet and the eastern Pamirs, are certain areas of the Sayan Mountains, mountainous Altai and mountainous Dagestan. The work verifies the ERA-5 reanalysis data using radiosounding, GNSS measurement data and radiometric measurements for 2021.

UBVR polarimetric observations of 12 main-belt mostly primitive asteroids located near perihelion heliocentric distances were carried out from December 2022 to April 2023 with Zeiss-2000 telescope at the Terskol Peak observatory. The purpose of the monitoring program was to search for changes in the polarimetric parameters of the asteroids caused by possible sublimation-dust activity, as a result of which the formation of rarefied dust exospheres of asteroids is possible. The objects of the program were asteroids: (1) Ceres, (53) Kalypso, (117) Lomia, (164) Eva, (214) Ashera, (324) Bamberga, (419) Aurelia, (505) Cava, (554) Peraga, (654) Zelinda, (704) Interamnia, (1021) Flammario. Polarimetric observations of asteroids (117) Lomia, (164) Eva and (505) Kava were made for the first time, the remaining asteroids were observed earlier. Only for two asteroids (1) Ceres and (704) Interamnia, according to spectrophotometric observations, temporal spectrophotometric variability was noted earlier. Analysis of temporal changes in the degree of polarization of asteroids and comparison of the results of observations with the data available in the literature showed that the stability of the observed degree of polarization is comparable with measurement errors of ( sim {kern 1pt} (0.02{-} 0.1))% for asteroids of different brightness. Thus, during the observation period, no noticeable polarization signs of temporary sublimation-dust activity of the observed asteroids were detected. Additionally, it is shown that the currently existing variants of the spectral taxonomy of asteroids, based on spectrophotometric data and albedo, demonstrate a significant scattering of the selected classes when compared with their polarimetric phase dependencies. The asteroid (554) Peraga has been confirmed to have a negative degree of polarization at angles less than the inversion angle. Measurements of the polarization of the asteroid (1) Ceres in a wide range of wavelengths did not confirm the previously suspected change in the angle of the polarization plane with the wavelength.

We study the effect of modifying the equation of state parameter ((w)) of dark energy on the results of the previous study [1] (hereafter Paper II), in which dark energy was assumed to be a cosmological constant. As a first step, solving the equation of motion, we found a relation between mass, (M), and the turn-around radius, ({{R}_{0}}). Then, we obtained a relationship between the velocity, ({v}), and radius, (R). The relation was fitted to data of the groups used in Paper II to obtain the Hubble parameter, and the mass, (M) of the groups. We observe a significant reduction of the mass, (M), comparing Paper II results (for which (w = - 1)) and the case (w = - 1{text{/}}3), while the Hubble constant increases going from (w = - 1) to (w = - 1{text{/}}3).

Our objective is to construct models of the velocity ellipsoid and the retrieved Solar motion for program stars with 4924 points within the Solar neighborhood (∼2 kpc). In which 1374 early types (B5, A0, A5, F0, and F5) and about 3550 late types (G0, G5, K0, and K5) with more recent data source with Gaia DR3. Based on space velocity vectors ((bar {U},bar {V},bar {W};;{text{km }}{{{text{s}}}^{{ - 1}}})), we have determined a velocity ellipsoid parameter for our program stars. We have derived the Solar velocity (({{S}_{ odot }})), which ranged from 13.39 ± 3.66 to 25.06 ± 5.06 km s^–1, and other Solar elements (({text{i}}.{text{e}}.,;{{l}_{{text{A}}}},;{{b}_{{text{A}}}},;{{{{alpha }}}_{{text{A}}}},;{{{{delta }}}_{{text{A}}}})), the velocity dispersion (left( sigma right)), ranging from 26.65 ± 5.16 to 57.29 ± 7.57 km s^–1 for considered program stars, the projected distances (({{X}_{ odot }},{{Y}_{ odot }},{{Z}_{ odot }};;{text{kpc}})), ratio of (left( {{{sigma }_{2}}{text{/}}{{sigma }_{1}}} right)), ranging from 0.52 to 0.92, which relates to Oort’s constants ((A,B;;{text{km}};{{{text{s}}}^{{ - 1}}}{text{ kp}}{{{text{c}}}^{{ - 1}}}),) and finally the ratio of (({{sigma }_{3}}{text{/}}{{sigma }_{1}})), ranging from 0.41 to 0.61.