Subjects -> ASTRONOMY (Total: 94 journals)
 Showing 1 - 46 of 46 Journals sorted alphabetically Advances in Astronomy       (Followers: 49) Annual Review of Astronomy and Astrophysics       (Followers: 50) Annual Review of Earth and Planetary Sciences       (Followers: 67) Artificial Satellites       (Followers: 21) Astrobiology       (Followers: 11) Astronomical & Astrophysical Transactions: The Journal of the Eurasian Astronomical Society       (Followers: 7) Astronomical Review       (Followers: 5) Astronomische Nachrichten       (Followers: 4) Astronomy & Geophysics       (Followers: 49) Astronomy and Astrophysics       (Followers: 67) Astronomy and Computing       (Followers: 6) Astronomy Letters       (Followers: 22) Astronomy Reports       (Followers: 22) Astronomy Studies Development       (Followers: 15) Astroparticle Physics       (Followers: 10) Astrophysical Bulletin       (Followers: 4) Astrophysics       (Followers: 35) Astrophysics and Space Science       (Followers: 49) Astrophysics and Space Sciences Transactions (ASTRA)       (Followers: 60) Astropolitics: The International Journal of Space Politics & Policy       (Followers: 13) Celestial Mechanics and Dynamical Astronomy       (Followers: 15) Chinese Astronomy and Astrophysics       (Followers: 25) Colloid Journal       (Followers: 2) Comptes Rendus : Physique       (Followers: 2) Computational Astrophysics and Cosmology       (Followers: 6) Earth and Planetary Science Letters       (Followers: 143) Earth, Moon, and Planets       (Followers: 47) Earth, Planets and Space       (Followers: 77) EAS Publications Series       (Followers: 8) EPL Europhysics Letters       (Followers: 8) Experimental Astronomy       (Followers: 38) Expert Opinion on Astronomy and Astrophysics       (Followers: 8) Extreme Life, Biospeology & Astrobiology - International Journal of the Bioflux Society       (Followers: 4) Few-Body Systems       (Followers: 1) Foundations of Physics       (Followers: 40) Frontiers in Astronomy and Space Sciences       (Followers: 15) Galaxies       (Followers: 6) Globe, The       (Followers: 3) Gravitation and Cosmology       (Followers: 6) Icarus       (Followers: 71) International Journal of Advanced Astronomy       (Followers: 21) International Journal of Astrobiology       (Followers: 4) International Journal of Astronomy       (Followers: 22) International Journal of Astronomy and Astrophysics       (Followers: 36) International Journal of Satellite Communications Policy and Management       (Followers: 15) International Letters of Chemistry, Physics and Astronomy       (Followers: 8) ISRN Astronomy and Astrophysics       (Followers: 14) Journal for the History of Astronomy       (Followers: 20) Journal of Astrobiology & Outreach       (Followers: 5) Journal of Astronomical Instrumentation       (Followers: 3) Journal of Astrophysics       (Followers: 33) Journal of Astrophysics and Astronomy       (Followers: 58) Journal of Atmospheric and Solar-Terrestrial Physics       (Followers: 133) Journal of Geophysical Research : Planets       (Followers: 116) Journal of Geophysical Research : Space Physics       (Followers: 136) Journal of High Energy Astrophysics       (Followers: 25) Kinematics and Physics of Celestial Bodies       (Followers: 11) KronoScope       (Followers: 1) Macalester Journal of Physics and Astronomy       (Followers: 5) Monthly Notices of the Royal Astronomical Society       (Followers: 13) Monthly Notices of the Royal Astronomical Society : Letters       (Followers: 2) Nature Astronomy       (Followers: 14) New Astronomy       (Followers: 26) New Astronomy Reviews       (Followers: 19) Nonlinear Dynamics       (Followers: 19) NRIAG Journal of Astronomy and Geophysics       (Followers: 4) Physics of the Dark Universe       (Followers: 4) Planetary and Space Science       (Followers: 106) Planetary Science       (Followers: 52) Proceedings of the International Astronomical Union       (Followers: 2) Publications of the Astronomical Society of Australia       (Followers: 3) Publications of the Astronomical Society of Japan       (Followers: 4) Research & Reviews : Journal of Space Science & Technology       (Followers: 20) Research in Astronomy and Astrophysics       (Followers: 38) Revista Mexicana de Astronomía y Astrofísica       (Followers: 3) Science China : Physics, Mechanics & Astronomy       (Followers: 4) Science China Physics, Mechanics & Astronomy       (Followers: 4) Solar Physics       (Followers: 29) Solar System Research       (Followers: 15) Space Science International       (Followers: 118) Space Science Reviews       (Followers: 92) Space Weather       (Followers: 27) Transport and Aerospace Engineering       (Followers: 13) Universe       (Followers: 6)
Similar Journals
 Astrophysical BulletinJournal Prestige (SJR): 0.447 Citation Impact (citeScore): 1Number of Followers: 4      Hybrid journal (It can contain Open Access articles) ISSN (Print) 1990-3421 - ISSN (Online) 1990-3413 Published by Springer-Verlag  [2469 journals]
• Mass of the Asteroid (7348) 1993FJ22 as Determined by the Dynamic Method

Abstract: Abstract—The mass of the asteroid ( $$7348$$ ) is determined by the dynamic method based on the analysis of gravitational perturbations in the motion of the asteroid (7562) Kagiroino–Oka caused by asteroid (7348). The choice of these asteroids is due to the fact that on March $$26$$ , $$1993,$$ they approached each other at a distance of about 1060 km. The diameter of the asteroid ( $$7348$$ ) is estimated at $$10$$ km. The coordinates of the major planets were calculated according to the DE440 ephemeris. Perturbations from dwarf planets and $$340$$  minor bodies included in the ephemeris model were also taken into account with the masses adopted in this ephemeris. Additionally, perturbations from asteroids ( $$656$$ ) and ( $$1027$$ ) that had close encounters with ( $$7562$$ ) during the considered time interval were also taken into account. In the analysis of the orbit of ( $$7562$$ ), $$2864$$ Minor Planet Center catalog optical observations from the $$1986$$ – $$2021$$ interval were used. These observations were supplemented with $$90$$ observations from Gaia (DR2) space observatory obtained in $$2014$$ – $$2016$$ . As a result of solving the normal system with respect to the orbital parameter corrections for asteroid (7562) Kagiroino–Oka and the mass correction of ( $$7348$$ ), the mass of ( $$7348$$ ) was derived as $$(0.867 \pm {{0.243)10}^{{ - 14}}}{{M}_{ \odot }}$$ . Currently, it is the smallest asteroid the mass of which was determined by the dynamic method.
PubDate: 2022-03-01

• Star Formation in the Elliptical (') Galaxy NGC 5173

Abstract: Abstract—Using the MaNGaL tunable-filter photometer at the 2.5-m telescope of the Caucasian Mountain Observatory of the Sternberg Astronomical Institute of Lomonosov Moscow State University, we studied star formation in an early-type gas-rich galaxy, which was until now considered to be elliptical,—NGC 5173. The gas has probably been accreted in the recent past by the galaxy from a direction inclined to its disk. Star formation that we observe now has led in the past 400 Myr to the formation of compact massive clusters with shock excitation of gas around them—a star formation behavior corresponding to what is usually observed in the interacting Antennae-like galaxies. In combination with the almost solar metallicity of the gas, this allows us to conclude that NGC 5173 has assimilate a very gas-rich companion with a mass of at least 10–20% of its own stellar mass.
PubDate: 2022-03-01

• Peculiar Objects in the Birthplaces of Radio Pulsars—Stellar-Mass
Black Hole Candidates

Abstract: Abstract—We perform a search for stellar-mass black hole candidates in the spatial regions with increased probability of their occurrence, isolated based on the evolutionary scenarios for compact objects originating in disrupted binaries. We analyze the sources located in these regions with available spectral or photometric data, as well as measured proper motions and distances. Nine objects whose characteristics correspond to the theoretical predictions for the observational manifestations of an isolated black hole are marked for further study as black hole candidates.
PubDate: 2022-03-01

• Energy Budget in Supernovae-Driven H I Shells

Abstract: Abstract—Giant H I shells of several hundred parsecs and larger observed in nearby galaxies with a moderate inclination ( $$i \lesssim$$ 50°) are formed by multiple supernova explosions in stellar clusters. To estimate the total energy of these supernovae the relation obtained for the evolution of a single supernova in a homogeneous medium is commonly used. Here we study uncertainties encountered in estimating the total energy using the quantities measured in observations, i.e. radius and velocity of a shell, gas density before shock front of a shell. We analyze these quantities gained from the “synthetic observations” of the data obtained in the 3D simulations of the shell driven by multiple supernovae in a stratified interstellar medium. We show that the value of the total energy can be overestimated as well as underestimated in several times and more using the relation for a single supernova. We discuss how the estimate of the total energy depends on the properties of a gas (density, metallicity), scale height of a disk, number of supernovae and when this estimate is applicable for interpreting observations of H I shell in nearby galaxies.
PubDate: 2022-03-01

• Comparison of Spectral Properties of Microwave Background Inhomogeneities
on Planck Multi-Frequency Maps Near RCR Catalog Sources with Spectral
Properties of NVSS and Planck Catalog Sources

Abstract: Abstract—The study of the relationship of positive fluctuations on Planck frequency maps with the nearest radio sources of the RCR catalog (RATAN Cold Refined) was continued. A linear correlation was found between the spectral indices of radio sources at frequencies of 1.4 and 3.94 GHz and the spectral indices of the nearest spots in the frequency range of 30–217 GHz. The spectral indices of NVSS sources in the range of 150 MHz–3.94 GHz were compared with the spectral indices of the nearest objects of the Planck catalog in the range of 30–217 GHz, between which a linear correlation was also found. The dependences between the spectral indices of RCR sources and the spectral indices of spots and the dependences between the spectral indices of NVSS sources and the objects of the Planck catalog turned out to be identical. The differences in the tangents of the angles of inclination of the approximating lines of these dependencies ranged from 8 to 21%. Combined spectra are constructed for RCR sources and the nearest positive spots, as well as for NVSS sources and the nearest objects of the Planck catalog. It is shown that some of the spots detected near RCR objects are most likely their manifestation in the submillimeter range. In a larger group of spots whose flux densities exceed the flux densities of radio sources extrapolated to the microwave region of the spectrum, these discrepancies may be due to inaccuracy of calibrations or a random coincidence of their coordinates. However, a more detailed study of the combined spectra of NVSS and Planck sources in the range of 70 MHz–857 GHz showed that the shape of the spectra of RCR objects and nearby spots can be explained by the variability of radio sources. The spectrum of averaged temperatures of hot spots detected near RCR sources was constructed, which showed a quantitative excess over those obtained earlier by modeling, which can be explained by the influence of synchrotron background or the contribution of radio sources or their host galaxies to radiation in the submillimeter range. The appearance of the obtained spectrum indicates that most of the spots have an extragalactic nature. The obtained statistics of spectral indices confirm the connection of radio sources with the nearest positive spots on Planck frequency maps. We believe that the contribution of unaccounted radio sources to the foreground may affect the resulting map of the cosmological microwave background.
PubDate: 2022-03-01

• Results of Selected Stellar Spectroscopy Programs at the 6-m Telescope of
the Special Astrophysical Observatory of the Russian Academy of Sciences
Performed with the NES Echelle Spectrograph

Abstract: Abstract—Over the past two decades NES spectrograph attached to the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences was used to perform spectroscopy of stars at advanced stages of evolution spanning a wide range of masses. The studies cover a variety of star types with high mass-loss rates during the preceding and current stages of evolution. All these stars have extended atmospheres and structured circumstellar envelopes produced by strong stellar winds. We have studied luminous blue variables (LBVs) near the Eddington limit; hot supergiants exhibiting B[e] phenomenon, which are very likely intermediate-mass binary systems soon after the fast mass exchange stage; a group of yellow hypergiants, as well as an extensive sample of low-mass post-AGB supergiants. The diverse nature of the types of these stars whose common feature is the presence of a envelope makes the spectroscopy of such objects a comprehensive task. Such studies consist of many etapes, which include not only determining the specifics of the chemical composition and understanding the role of supergiants in the enrichment of the interstellar medium with freshly synthesized elements, but also the determination of the evolutionary stage of the objects considered, as well as search for and analysis of spectroscopic manifestations of kinematic processes in their extended and unstable atmospheres and gas-dust envelopes. We spectroscopically monitored selected objects to study in detail the instability of the kinematic state of the atmospheres of the stars considered. Studies of stars at neighboring evolutionary stages have been initiated. This review reports the most significant observational obtained within the framework of the $$1998$$ – $$2021$$ programs.
PubDate: 2022-03-01

• Photometric Study of the Open Cluster NGC 225

Abstract: Abstract—NGC 225 is a young moderately populated cluster with discrepant age, distance, and color excess estimates reported by different authors. We combine our photometry with the data from large surveys (2MASS, WISE, Pan-STARRS) to derive the parameters of NGC 225 and study the extinction law in the near infrared in the direction of the cluster. We use theoretical isochrones to infer the color excess $$E(B - V) = 0.29 \pm 0.01$$ , distance $$D = 667 \pm 18$$ pc, and Age = $$100$$ – $$160$$ Myr. We fit extinction in the infrared by a power-law relation, $${{\lambda }^{{ - \alpha }}}$$ , and find $$\alpha = 2.16 \pm 0.34$$ .
PubDate: 2022-03-01

• Results of Magnetic-Field Measurements with the 6-m BTA Telescope. VII.
Observations in 2013

Abstract: Abstract—The paper provides complete measurement results of the effective longitudinal magnetic field $${{B}_{e}}$$ and the radial velocity $${{V}_{R}}$$ for 107 targets that are mainly Main-Sequence chemically peculiar stars and standard stars. The spectropolarmetric data were obtained in 2013 with the Main Stellar Spectrograph (MSS) at the 6-m BTA telescope of SAO RAS. Seven new magnetic stars were discovered during the year: HD 16545, HD 34736, HD 36997, HD 37633, HD 128220, HD 220846, and BD +37°431. During 11 observation nights, 296 circularly polarized spectra were obtained. Radial velocities were measured for all the objects, for sixty-four of them—for the first time. Observations of standard magnetic and non-magnetic stars confirm the absence of any significant systematic errors capable of distorting the $${{B}_{e}}$$ measurement results. The paper presents comments for measurement results for all the observed stars.
PubDate: 2022-03-01

• Galaxy Cluster A 2142: Halo Boundary, “Red Sequence”, Properties of
Galaxies Based on SDSS

Abstract: Abstract—Here we present results of studying the dynamics of galaxies, properties of early-type galaxies, properties of galaxies with the quenched star formation (QGs) in the A 2142 cluster based on the archival data from the Sloan Digital Sky Survey Data (SDSS DR10). We found the observed halo boundary, the “splashback” radius $${{R}_{{{\text{sp}}}}}$$ , which is equal to 4.12 Mpc ( $${{M}_{r}} < - {{20.}^{{\text{m}}}}3$$ ) and 4.06 Mpc ( $${{M}_{r}} < - {{21.}^{{\text{m}}}}5$$ ) over the integral distribution of the number of galaxies as a function of the squared distance from the center. We have studied how early-type galaxies are distributed in the center and in the outskirts of the cluster ( $${R \mathord{\left/ {\vphantom {R {{{R}_{{200}}}}}} \right. \kern-0em} {{{R}_{{200}}}}}$$ < 3, $${{M}_{r}} < - {{20.}^{{\text{m}}}}3$$ ) and plotted the “red sequence” in the form of $$(g - r) = ( - 0.024 \pm 0.001){{M}_{r}} + (0.441 \pm 0.005)$$ . Among all the cluster galaxies, the galaxies with the quenched star formation ( $$- 12$$ yr $$^{{ - 1}} < \log sSFR < 10.75$$ yr $$^{{ - 1}}$$ ) make up about one third. We have found that the fraction of QGs beyond the “splashback” radius $${{R}_{{{\text{s}}p}}}$$ is the same as in the field at the same $$z$$ with coordinates of the center of $${\text{16}}{{{\text{.}}}^{{\text{h}}}}{\text{5,}}\,\,31$$ ° and a size of 300′. For galaxies with the stellar masses $$\log {{{{M}_{*}}} \mathord{\left/ {\vphantom {{{{M}_{*}}} {{{M}_{ \odot }}}}} \right. \kern-0em} {{{M}_{ \odot }}}} = [10.5;11.0]$$ (this is the main mass range of QGs), when entering the cluster, there is a decrease in the radii $${{R}_{{90,r}}}$$ by about $$30\%$$ when moving towards the center.
PubDate: 2022-03-01

• Two Modifications of Fabry–Perot Interferometer

Abstract: Abstract—Two modifications of the Fabry–Perot interferometer were developed that use oblique incidence planar fronts from the source: Fabry–Perot interferometer with an open beam input and Fabry–Perot interferometer with an open beam output. The modifications differ only in the direction of the rays. The first modification has already been used as a basic element of the solar interference spectrograph layout (Kulagin, 1980) and the stellar interference spectrograph layout (Kulagin and Panchuk, 2017). The second modification has no analogues. Estimates of the increase in the illumination of interference patterns in the modifications are given. The same formula describes the dependence of the intensity of the outgoing radiation on the interference phase in both devices. However, the properties of the modifications differ dramatically. Possible applications of the two modifications combined with a diffraction grating are described.
PubDate: 2022-03-01

• BLAZAR S5 0716+714: Variation of Linear Polarization

Abstract: Abstract—From January 2019 to February 2021, observations of the linear polarization of the object S5 0716+714 were carried out with the Zeiss-600 telescope of SAO RAS. A Felix Savart plate was used as a polaroid. The result is a Fourier power spectrum of the linear polarization variation in the frequency range of $$f = 10$$ – $$150$$  days $$^{{ - 1}}$$ without any harmonic component evidence; the spectrum is proportional to the power law $$F \sim {{f}^{{ - 0.55}}}$$ . The distribution of polarization values over the entire observation period is subject to the Relay distribution which does not demonstrate any signs of a periodic component. There is a harmonic dependence of the polarization on the brightness of an object with a period of 10 mJy.
PubDate: 2022-03-01

• The Brightest Stars of Irregular and Low-Mass Spiral Galaxies

Abstract: A search for a correlation between the luminosities of the brightest stars and luminosities of their host galaxies was carried out on archival Hubble Space Telescope (HST) $$F606W$$ or $$F555W$$ (V) and $$F814W$$ (I) images of 150 nearby galaxies. The sample contains only galaxies with ongoing star formation and with known distances we derived with the TRGB-method. We correlated the average absolute luminosities of the three brightest blue and the three brightest red stars with the luminosity of a host. We find a linear relation for both the blue and the red stars in irregular and low-mass spiral galaxies. Their scatters are sufficiently small ( $${{0.}^{{\text{m}}}}4$$ ) to make these relations useful for distance determination for low-mass galaxies. We found that all 31 dwarf galaxies $$({{M}_{B}} > - {{13}^{{\text{m}}}})$$ in our sample lack bright massive stars $$({{M}_{V}}{\text{(BS)}} < - {{7.}^{{\text{m}}}}0)$$ , probably due to the physical conditions that prevent their birth. For galaxies with higher an average luminosity in the range $$- {{18}^{{\text{m}}}} < {{M}_{B}} < - {{13}^{{\text{m}}}}$$ , there is an asymmetry in the distribution of the number of galaxies relative to the linear dependence, indicating an increase in the fraction of galaxies with bright stars.
PubDate: 2021-10-01
DOI: 10.1134/S1990341321040143

• High Temporal Resolution Multi-Mode Panoramic Photospectropolarimeter

Abstract: The paper describes a new stage in the development of the hardware-software complex of the MANIA experiment to search for and study the brightness variability of astrophysical objects with a temporal resolution of $${{10}^{{ - 6}}}$$ s. The panoramic photospectropolarimeter uses the remotely mounted optical units—the color separation modules which allow one to carry out observations in five modes: the most transparent, multi-band, photo-polarimetric, spectroscopic, and spectro-polarimetric. Two photodetectors (PDs) based on position sensitive detectors (PSDs) with the S-20 and GaAs cathodes, the multiplication of photocurrents with microchannel plates (MCPs), and detection using collectors with the number of elements from 4 up to 16 and an EMCCD camera allow one to detect light fluxes from objects and reference stars in a field of view of up to $$1$$ in several color bands in the low resolution spectroscopic mode, and at the same time to measure the linear polarization in three Stokes parameters. The detection system accumulates the observed data: the digitized photocount fluxes from both PDs with a temporal resolution of $$1\, \mu {\text{s;}}$$ while the EMCCD camera accumulates video sequences with a subsecond resolution simultaneously with the reception of ultraviolet quanta with a microsecond resolution on a single PD. We present some research results obtained in observations with the 6-m SAO RAS telescope.
PubDate: 2021-10-01
DOI: 10.1134/S1990341321040106

• The Activity of Stars with Planetary Systems and Its Impact on the Loss of
Atmosphere by Hot Exoplanets

Abstract: The review presents the results of a wide range of studies on modeling the atmospheres and shells of exoplanets and studying the processes associated with the activity of the parent star, performed at the Institute of Astronomy of the Russian Academy of Sciences in recent years. The developed methods of analyzing superflares in solar-type stars are applied to stars with planetary systems and the obtained estimates are used to detail the conditions of extreme stellar activity in the study of atmospheric losses for Earth-type planets in low orbits—super-Earths and sub-Neptunes. The results of calculations of the rate of atmospheric loss for exoplanets in orbits close to the parent star (close-in exoplanets) are presented and it is shown that under conditions of a high level of stellar radiation rigidity, and even more so under conditions of a stellar flare, the contribution of exothermic photochemistry processes to the formation of a flow of supra-thermal hydrogen atoms escaping from the atmosphere becomes significant and comparable to the flow of hydrodynamic outflow. Accordingly, this source of supra-thermalhydrogen atoms should be included in modern aeronomic models of physical and chemical processes in the upper atmospheres of hot exoplanets. Taking into account the contribution of supra-thermal particles in the aeronomic model made it possible to clarify the heating rates of atmospheric gas due to the absorption of hard radiation from the parent star. This, in turn, made it possible to more accurately calculate the values of the rate of mass loss by atmospheres and, accordingly, to study the evolutionary properties of the atmospheres of hot exoplanets. It is also important to note that the kinetic and aeronomic models presented in the review, developed in recent years at the Institute of Astronomy of the Russian Academy of Sciences, will be used to analyze and interpret existing and expected observations of the atmospheres of Earth-type exoplanets. Such work will allow to impose additional restrictions on the models and thereby make them more reliable.
PubDate: 2021-10-01
DOI: 10.1134/S199034132104012X

• Masses of Isolated Spiral KIG Galaxies, Determined by the Motions of Their
Faint Companions

Abstract: We have updated the classification of late-type galaxies presented in the Catalog of Isolated Galaxies (KIG) using the advanced digital sky surveys. Our search for companions around 959 KIG galaxies revealed 141 neighbors associated with 111 KIG galaxies within the mutual projection separation of less than 330 kpc and the radial velocity difference not exceeding 500 km s–1. Typical luminosity of the companions turned out to be weaker than the luminosity of the main galaxies by more than an order of magnitude. Considering these small companions as test particles that move around the KIG galaxies along the Keplerian orbits with eccentricity of $$e \simeq 0.7,$$ we estimated the total (orbital) masses of spiral KIG galaxies. Their average orbital mass-to-K-band luminosity ratio, $$(20.9 \pm 3.1){{M}_{ \odot }}{\text{/}}{{L}_{ \odot }},$$ is in a good agreement with the corresponding value for the nearby Milky Way, M 31 and M 81-type massive spirals. Isolated disk-shaped galaxies have an on the average 2–3 times smaller total-mass-to-stellar-mass ratio than those of isolated bulge-shaped galaxies.
PubDate: 2021-10-01
DOI: 10.1134/S1990341321040076

• Infrared Speckle Observations of Binary Stars at the 6-m Telescope

Abstract: Speckle observations of binary stars were performed in the 900–1600 nm infrared range at the 6‒m telescope using the commercially available CCD camera SWIR Snake-640 with InGaAs 640 × 512 pixels sensitive area. Peltier cooling of the sensor allows reaching –30°C temperature of the CCD. The thermal noise of the CCD remains significantly high under such temperature. That limits the speckle interferometric application of the camera to approximately 9th magnitude under moderate seeing conditions. To estimate other characteristics of the camera for interferometric application in the near-IR, we used it to measure separations, position angles and magnitude differences of some well-studied binary stars. Diffraction-limited angular resolution was achieved for each of the reconstructed images.
PubDate: 2021-10-01
DOI: 10.1134/S1990341321040039

• Study of Integrated Spectra of Four Globular Clusters in M 31

Abstract: The results of determining the metallicity, age, helium mass fraction (Y) and abundances of the elements C, N, Mg, Ca, Mn, Ti and Cr by moderate resolution spectra for four globular clusters in the galaxy M 31: Bol 6, Bol 20, Bol 45 and Bol 50 are presented. The chemical composition for Bol 20 and Bol 50, and Y for four clusters are determined for the first time. The spectra of the studied objects were obtained with the 6-meter telescope of the SAO RAS in 2020. All the clusters under study turned out to be older than 11 Gyrs. The determined metallicities [Fe/H] are in the range from $$- 1.1$$ to $$- 0.75$$ dex. They are lower than the metallicity of stars of the M 31 halo at a given distance from the galactic center ( $${{R}_{{{\text{M}}{\kern 1pt} 31}}} < 10$$ kpc). The abundances of the elements of the α-process $$[\alpha {\text{/Fe}}] = ([{\text{O/Fe}}] + [{\text{Mg/Fe}}] + [{\text{Ca/Fe}}]){\text{/}}3$$ of the four clusters correspond to those of the stars of the inner halo of M 31.
PubDate: 2021-10-01
DOI: 10.1134/S199034132104009X

• Magnetic Fields of Chemically Peculiar and Related Stars. VII. Main
Results of 2020 and Near-Future Prospects

Abstract: We present a review of the papers written in the field of stellar magnetism studies in 2020. More than 70 original papers related to different areas of the specified scientific topics have been analyzed. Instruments, methods of analysis, and software are considered, as well as: chemically peculiar stars and their identification; magnetic fields, chemical abundance, and photometry of chemically peculiar stars; magnetic white dwarfs, active cool stars and other objects. In the field of stellar magnetism research, 6–7 scientific groups continue to work actively using the world’s largest telescopes, which fact indicates the relevance and importance of the problem under study.
PubDate: 2021-10-01
DOI: 10.1134/S1990341321040118

• Pulsations of the AS Cam Eclipsing Binary in TESS Light Curves

Abstract: An analysis of TESS satellite observations of the AS Cam eclipsing binary has shown that the light of this source pulsates at two frequencies: $${{\nu }_{1}} = 0.7556$$ days–1 and $${{\nu }_{2}} = 0.8658$$ days–1 with the amplitudes $${{A}_{1}} = 0_{.}^{{\text{m}}}0110$$ and $${{A}_{2}} = 0_{.}^{{\text{m}}}0087,$$ correspondingly. Such variations are typical for slowly pulsating B-type stars. We modeled the light curves of AS Cam obtained from 1968 to 2019 to confirm the discovery of a gradual increase in the orbit eccentricity of the system by approximately 0.018 over 50 years. A third light, as one of the light curve solution parameters, on average, amounts to approximately 4% of the total luminosity of the system. For AS Cam this would correspond to an F8–F9-type suggested third body—a main sequence star, the presence of which follows from the light equation of the system. If the third light is a result of a random overlapping of a star unrelated to AS Cam, then the third body may turn out to be a degenerate object or a close binary system. The extremely slow apsidal motion in this system (compared to the value predicted by the standard theory) can be explained by the gravitational influence of a third body with a mass of about $$1.2{{M}_{ \odot }}$$ and an orbital inclination of about $$70$$ with respect to the image plane.
PubDate: 2021-10-01
DOI: 10.1134/S1990341321040088

• Polarimetric Studies of Azimuthal Magnetic Inhomogeneities in the
Envelopes of Herbig Ae/Be Stars

Abstract: We discuss a technique for studying local gas inhomogeneities in the envelopes of young stars based on multicolor polarimetric observations. The method considered is based on the comparison of the observed time tracks of the variations in the Stokes parameters in the $$(q,{\kern 1pt} \,\,u)$$ plane with the theoretical tracks computed in terms of a simple inhomogeneity model in the form of a gaseous stream with local magnetic field in the rotating envelope of a young star. The computations take into account the process of single scattering of radiation in the electron gas and the Faraday rotation of the polarization plane during propagation of radiation in a medium with magnetic field. The results of our computations depend strongly on the orbital inclination of the inhomogeneity to the line of sight and on the parameters of its magnetic field, whose influence on the polarization parameters increases with wavelength of radiation. The application of the method to the study of inhomogeneities in the envelopes of Herbig stars AB Aur and HD 163296 is described.
PubDate: 2021-10-01
DOI: 10.1134/S1990341321040040

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