Electric Current Systems in Active Regions at a Late Stage of Evolution and Their Role in the Processes of Stabilization/Destabilization of Sunspots

Abstract: Data from the Helioseismic and Magnetic Imager (HMI) instrument on board the Solar Dynamic Observatory (SDO) on the components of the magnetic field vector in the sun’s photosphere are obtained for 46 active regions (AR) in the final stage of evolution to calculate the magnitudes of the horizontal, vertical, and large-scale electric current at the solar photosphere level. In each case the dynamics of the parameters of the electric current over the time the regions are within ±35° from the central solar meridian was studied. The parameters of the electric current with the decay rate of the magnetic flux in a sunspot was compared. The following results are obtained: (1) a direct relationship between the value of the average unsigned density of the local vertical electric currents and the decay rate of the magnetic flux in a spot with a correlation coefficient of k = 0.56 was found. (2) A nonzero large-scale electric current only in ARs with a relatively low decay rate of the magnetic flux in a sunspot (not exceeding the value 6.0∙1019 Mx h-1) was detected. Thus, a large-scale electric current can have a stabilizing effect on a sunspot without being the only mechanism for stabilizing sunspots, since only for the 37

active regions;electric currents;magnetic field;sun


N-S Asymmetry and Periodicity of Daily Sunspot Number During Solar Cycles 22-24

Abstract: In this paper, a broad examination of the N-S asymmetry of daily sunspot numbers during the period January 1992 to March 2020 has been performed, examining its statistical significance and looking for the short term periodicity of daily sunspot numbers using the Fast Fourier Transform (FFT) during solar cycle 22 (1 January 1986 to 27 August 1996), cycle 23 (28 August 1996 to 10 December 2008) and cycle 24 (11 December 2008 to 31 March 2020). The present study indicates that sunspot number activity dominates in the southern hemisphere during the solar cycles 22 and 23, while during the solar cycle 24, the sunspot number becomes dominant in the northern hemisphere. It is also revealed that the magnitude of sunspot number activity for solar cycle 23 is more prominent in both the northern and southern hemispheres than in solar cycles 22 and 24. The power spectrum of daily sunspot numbers shows several significant periodicities in a wide range between 26 days and 83 days. We discuss the possible explanations of the observed periodicities and north-south asymmetry of the daily sunspot number in light of previous results and existing techniques.

daily sunspot number;n-s asymmetry;periodicity


ASASSN-19fy: Features of a Dwarf Nova in the “Period Gap”

Abstract: Photometric studies of the dwarf nova ASASSN-19fy in the “period gap” were carried out in 2020-2021 over 24 nights at the Crimean Astrophysical Observatory of the Russian Academy of Sciences and 3 nights at the Sanglokh International Astronomical Observatory of the Institute of Astrophysics, National Academy of Sciences of Tajikistan. The observations covered a superoutburst, two successive rebrightenings, and a slow return to the pre-outburst (quiescent) state. During this time, superhumps were observed, in the evolution of which the stages of developed superhumps “B,” their damping “C,” and a transition between them were identified. The average period of the superhumps in stage “B” was 0.09278(13) days and it was found its increase during this stage at a rate of (dP / dT) / P = 10·10–5. In stage “C” the period of the superhumps was equal to 0.092289(15) days. It is shown that ASASSN-19fy is the twelfth object to join the group of long-period dwarf novae similar to WZ Sge-type stars.


Photometric Activity of CQ Tau over a Time Interval of 125 Years

Abstract: The star CQ Tau belongs to the family of UX Ori type stars and is characterized by very complicated photometric behavior and a complex structure of its circumstellar environment. Based on published photometric data, in this article we construct a light curve for this star covering 125 years. It implies that besides a random component characteristic of UX Ori type stars, the changes in brightness also include a large amplitude periodic component with a period of 10 years. It existence was suspected previously and new observations confirm its reality. This indicates the existence of a second component in the neighborhood of the star. Matter flows and density waves caused by the motion of the companion lead to periodic changes in the circumstellar extinction and brightness of the star. This result is discussed in the context of recent observations of CQ Tau with high angular resolution.

periodic changes;photometric activity;ux ori type star


Quark Matter in the NJL Model with a Vector Interaction and the Structure of Hybrid Stars

Abstract: The properties of hadron-quark hybrid stars are studied when the quark phase is described in terms of a local SU(3) Nambu-Jona-Lasinio (NJL) model taking into account the contribution of the vector and axial-vector interaction between the quarks, and the hadronic phase, in the relativistic mean field (RMF) model. For different values of the vector coupling constant GV, the equations of state of the quark matter are calculated and the parameters of the hadron-quark phase transition are determined under the assumption that the phase transition takes place in accordance with Maxwell’s construction. It is shown that for a larger vector coupling constant, the equation of state of the quark matter will be “stiffer” and the coexistence pressure P0 of the phases will be greater. Using the resulting hybrid equations of state, the TOV equations are integrated numerically and the mass and radius of the compact star are determined for different values of the central pressure Pc. It is shown that when GV is larger, the maximum mass of the compact star will be larger and thereby, the radius of the configuration with maximum mass will be smaller. Questions of the stability of hybrid stars are also discussed. It is shown that in terms of the model examined here, for all values of the vector coupling constant, a hybrid star with an infinitely small quark core is stable. These results are compared with recent measurements of the mass and radius of the pulsars PSR J0030+0451 and PSR J0740+6620, carried out at the International Space Station with the NICER X-ray telescope. A comparison of the theoretical results with observational data does not exclude the possibility of quark deconfinement in the interiors of compact stars.

delta meson;hadronic matter;hybrid stars;njl model;quark matter;quark phase transition;relativistic mean field (rmf) theory;vector interaction


Asynchronous Rotation of a Massive Star in Close Binary Systems

Abstract: The problem of asynchronous rotation of massive stars in close binary systems is investigated in this paper. A massive star with twice the sun’s mass, a convective core, and an external radiative transfer zone (envelope) is examined. The model takes into account the influence of the companion on the star. It is assumed that the tidal flow is dissipated through radiative viscosity. The asynchrony of massive stars is explained by pseudosynchronization and differential rotation of the star.

asynchronous stars;close binary systems;massive stars;tidal interactions


Theory of Classical Gaseous Polytropes in an Integral Representation. II. Analytic Approximations to the Emden Functions and Density Profiles in a Closed Form

Abstract: Analytic approximations are presented for the exact solutions of the Volterra type nonlinear integral equation of the second kind for classical gaseous polytropes in closed form. This equation is considered as the integral equivalent of the Lane-Emden differential equation with boundary conditions which describes the standard polytropic models in terms of a Cauchy problem. With the aid of a linear approximation of this equation and general heuristic considerations of a physical character, as well as with the aid of a graphical model and variation of the parameters of the approximating functions, approximate expressions for the Emden functions and the dimensionless density are obtained in closed form with a mean square accuracy from  10-4 to a few percent for a series of values of the polytropic index n of practical interest (n = 0.5, 3, 4, 6, ∞). Our previous approximation for the spatial density of the isothermal model is compared with a pseudo-isothermal law describing the distribution of the density of dark matter surrounding spiral galaxies and used by various authors for studying their rotation curves.

emden function;lane-emden equation;polytropes;volterra type nonlinear integral equation of the second kind


Abstract: In this work we propose Modified Tsallis Holographic Dark Energy (MTHDE) in General Relativity (GR) in the framework of Bianchi type III space-time. Einstein's field equations are solved by using a special law of variation of Hubble parameter H proposed by Berman which yields constant deceleration parameter (DP). Interestingly, for the two different constant values of deceleration parameter, we have obtained two different cosmological models. The model 1 behaves like a quintessence dark energy model whereas model 2 behaves like a cosmological constant model. A correspondence between model 1 and quintessence scalar field is established. The quintessence dynamics of the potential and scalar field are reconstructed which illustrates the accelerating phase of the Universe. Various parameters like deceleration parameter, Hubble parameter, anisotropy parameter, equation of state (EOS) parameter, etc. for both the cosmological models are thoroughly discussed. The results obtained are found to be consistent with the recent observations on the present-day Universe.

deceleration parameter dp;gr;hubble parameter;mthde


Accelerating Kaluza-Klein Universe in Modified Theory of Gravitation

Abstract: The purpose of this paper is to study the Kaluza-Klein universe in the context of the f (R, T) gravity theory using magnetized strange quark matter (MSQM). To obtain exact solutions of field equations, we assume two types of volumetric expansion: power law and exponential law volumetric expansions. The violation of energy conditions has been studied. The physical and geometrical properties of the examined model have also been investigated thoroughly.

f(r;t) gravity;kaluza-klein metric;magnetized strange quark matter;power and exponential law


Bulk Viscous String Cosmological Model with Power Law Volumetric Expansion in Teleparallel Gravity

Abstract: In this paper, we have investigated the Bianchi-type V cosmological model which is spatially homogeneous and anisotropic in presence of bulk viscous fluid containing one-dimensional cosmic string. We have obtained the exact solutions of highly non-linear differential field equations considering the power-law volumetric expansion of the universe and f (T) = T formalism. Some physical and kinematical properties of the constructed model have been discussed and presented graphically and it is interesting to note that the resultant model resembles the recent observational data.

bulk viscous fluid;cosmic string;teleparallel gravity


Swampland Criteria and Neutrino Generation in a Non-Cold Dark Matter Universe

Abstract: In this paper, the implications of string Swampland criteria for a dark energy-dominated universe, where we have a deviation from the cold dark matter model, will be discussed. In particular, we have considered two models. One of them is one parameter model, while the second one has been crafted to reveal the dynamics in the deviation. The analysis has been obtained through the use of Gaussian processes (GPs) and H(z) expansion rate data (a 30-point sample deduced from a differential age method and a 10- point sample obtained from the radial BAO method). We learned that the tension with the Swampland criteria still will survive as in the cases of the models where dark matter is cold. In the analysis besides mentioned 40-point H(z) data, we used the latest values of H 0 reported by the Planck and Hubble missions to reveal possible solutions for the H 0 tension problem. Finally, the constraints on the neutrino generation number have been obtained revealing interesting results to be discussed yet. This and various related questions have been left to be discussed in forthcoming papers.

gaussian processes;non-cold dark matter model;swampland criteria


Multiwavelength Monitoring of Blazars PKS 2155-304 and S5 0716+71

Abstract: The study of multiwavelength emission properties of blazar jets has the potential to shed light on the particle acceleration and emission mechanisms taking place in them. The emission of PKS 2155-304 (z = 0.116) and S5 0716+71 (z = 0.31) bright blazars in the optical/UV, X-ray and γ -ray bands is investigated by analyzing data from Fermi-LAT, Swift XRT and Swift UVOT telescopes. The multiwavelength light curves of both sources in these bands show multiple peaks when the flux increased substantially. In the optical/UV bands, the flux of both sources increased above 2∙10-10 erg cm-2 s-1. The X-ray emission from PKS 2155-304 was characterized by a harder-when-brighter trend, whereas the γ-ray emission from S5 0716+71 showed a moderated trend of softer-when-brighter. The correlation analysis shows a strong correlation between the UV and γ-ray emission of PKS 2155-304, while there is a correlation between the optical/UV and X-ray emission of S5 0716+71. The observed broadband spectral energy distribution of both sources as well as the observed variability and correlations can be accounted for within one-zone synchrotron/synchrotron-self-Compton models.

blazars;pks 2155-304;s5 0716+71;x-rays;γ –rays


WASP-18b Secondary Eclipses Revisited Using TESS Observation

Abstract: We report the characterization of a transiting hot Jupiter WASP-18b at optical wavelengths measured by the transiting exoplanet survey satellite (TESS). We analyze the publicly available data collected by the TESS in sector 2. Here, we model the systematic noise using Gaussian processes (GPs) and fit it to the data using the Markov Chain Monte Carlo (MCMC) method. Modelling the TESS light curve returns a planet-to-star radius ratio, p=0.098010−0.000346+0.000368 and secondary eclipse depth of 354−10+11 part-per-million (ppm). The transit ephemeris of WASP-18b is updated using the MCMC method. Finally, we use updated ephemeris to look for transit time variations (TTVs) for WASP-18b to complement our study. We find a quite small deviation of transit timings from a linear ephemeris, which is statistically insignificant.


The Revisited BPT Diagram from the Self-Consistent Analysis

Abstract: Galaxies' spectral energy distribution has been explored through the use of spectral synthesis codes, and these techniques have been essential in identifying many aspects of the current galaxy evolution model. Most of the spectral synthesis codes that have been developed so far are solely stellar and assume a negligible nebular contribution to the overall continuum. FADO (Fitting Analysis using Differential Evolution Optimisation) is the first spectral synthesis code to fit self-consistently stellar and nebular components. Diagnostic diagrams are powerful tools for classifying galaxies based on the emission line ratio of collisionally excited lines such as [OIII] λ 5007, [NII] λ 6584, [SII] λ 6716, 6731, [OI] λ 6300, and the Balmer recombination lines such as Hα, Hβ. This paper explores the impact of including nebular components on diagnostic diagrams. We investigated the results of the application of FADO to the Sloan Digital Sky Survey Data Release 8 using the data analysed by MPA-JHU, the Max Planck Institute for Astrophysics, and Johns Hopkins University. We found that in all diagnostic diagrams, the fluxes for FADO are higher than those for MPA-JHU; the difference is significant compared to the error in the flux measurement. FADO overestimates the flux ratio of all three diagnostic diagrams over MPA-JHU, but the overestimation is comparable with the line flux ratio errors. The results indicate that the inclusion of a nebular continuum is very important when fitting the spectral energy distribution as it increases the fluxes of all galaxies. However, there is a mild impact from the inclusion of nebular component analysis in the diagnostic diagrams used to classify the ionisation state of galaxies’ interstellar medium.


The Environmental Dependence of the Stellar Velocity Dispersion of Active Galactic Nucleus (AGN) Host Galaxies and Dependence of the Clustering Properties of AGN Host Galaxies on the Stellar Velocity Dispersion

Abstract: We use two volume-limited active galactic nucleus (AGN) host galaxy samples constructed by Deng     Wen [47], and explore the environmental dependence of the stellar velocity dispersion in these two volume-limited AGN host galaxy samples. In the luminous volume-limited AGN host galaxy sample, the stellar velocity dispersion of AGN host galaxies apparently depends on local environments: AGN host galaxies with large stellar velocity dispersion exist preferentially in high density regime, while AGN host galaxies with small stellar velocity dispersion are located preferentially in low density regions. But in the faint volume-limited AGN host galaxy sample, this dependence is fairly weak. We also examine the dependence of the clustering properties of AGN host galaxies on the stellar velocity dispersion by cluster analysis, and find that in the luminous volume-limited AGN host galaxy sample, AGN host galaxies with small stellar velocity dispersion preferentially form isolated galaxies, close pairs and small groups, while AGN host galaxies with large stellar velocity dispersion preferentially inhabit the dense groups and clusters. In the faint volume-limited AGN host galaxy sample, although the fraction of isolated galaxies with small stellar velocity dispersion is apparently higher than the one with large stellar velocity dispersion, the trend in the luminous volume-limited sample is very difficultly observed. This likely is due to the galaxy number of the faint volume-limited AGN host galaxy sample being too small to ensure an ideal statistical analysis.

cosmology;fundamental parameters;large-scale structure of universe – galaxies


Activity of the Star Gl 414A with Two Planets and its Effect on the Loss of Mass of the Atmosphere of the Planet Gl 414A b

Abstract: Results are presented from a study of manifestations of the activity of the dwarf Gl 414A of spectral class K7 with two planets, one of which (the planet Gl 414A b) with an eccentricity e=0.45 was found to be within the habitable zone over a large part of its orbit. Our analysis showed that the most reliable determination of the rotation period of Gl 414A was obtained from an analysis of photometric observations of the star in the KELT (Kilodegree Extremely Little Telescope) survey which yield a rotation period of P=42 days. However, the existence of this period is not confirmed by periodograms constructed from other observations of Gl 414A. The long-term activity cycle of the star is on the order of 3800 days (10.4 years). The obtained data on the activity of the star were used to estimate the loss of matter from the atmosphere of the planet Gl 414A b using an approximation formula for a model of atmospheric loss with a limit on energy. Based on 486 estimates of the parameter SHK, the loss of matter by the atmosphere of Gl 414A b over an interval of 5805 days (15.9 years) was calculated. The magnitude of these losses mainly lies within a range of log(Mloss) from 7.15 to 7.50 with a median of 7.30. For an eccentricity of 0.45 the distance from the central star to Gl 414A b ranges from 0.13 to 0.34 a.u., and for these distances the estimated losses of matter by the atmosphere are 16.21·1017 and 2.37·1017 g/s, respectively.

activity;atmospheres of exoplanets;photometry;planetary systems;spots;stars;variability


Evolution of Spectrum Lines in an Inhomogeneous Atmosphere Illuminated by Nonstationary Energy Sources

Abstract: The effect of the inhomogeneity of a scattering and absorbing medium of finite thickness on the evolution of spectrum lines which appear when it is illuminated by nonstationary energy sources is examined. Special attention is devoted to the role of scattering in the continuum spectrum. It is assumed that the inhomogeneity arises from the variation in the scattering coefficient with depth, which may be increasing or decreasing on approaching the illuminated boundary. Two types of nonstationarity of the external energy source are studied with a shape corresponding to δ(t), the Dirac function, and H(t), the unit step function of Heaviside. The question of using observed time changes in the profiles of spectrum lines for determining their optical characteristics, the frequency dependence of the external energy sources, and the physical properties of the illuminated medium itself, is studied.

cumulative distribution function;evolution of spectrum line profiles;inhomogeneous atmosphere;probability density distribution


UX OrI Type Stars in the Cluster IC 348: Results of Long-Term Photometric Monitoring

Abstract: Results of a long-term (17 years) photometric monitoring of five T Tau stars in the VRI bands are presented. All the studied objects are members of the young cluster IC 348 and show the UX Ori type variability caused by changes in the circumstellar extinction. Three of them (V712 Per, V716 Per, and V909 Per) are classical T Tau type stars (CTTS) and the other two (V695 Per, V715 Per) are weak-line T Tauri stars (WTTS). Their light curves demonstrate the large diversity. Three of the objects have a combination of two different types of activity: stochastic UX Ori type variability and periodic brightness variations similar to those observed in AA Tau stars. Two of the stars demonstrate only the stochastic brightness variations owing to fluctuations in circumstellar extinction at different characteristic times. The features of the photometric activity of the stars investigated are discussed in detail in this article.

ic 348;photometry;t tau type star;ux ori


Photometric Study and Orbital Solution for Some Newly Discovered Eclipsing Binary Systems

Abstract: We present an orbital solution and light curve analysis for the three newly discovered W UMa systems: V0757 And, IK Lyn, and V0996 Per by means of first CCD observations. New times of minima were estimated and the observed light curves were analyzed using the most recent version of Wilson-Devinney modeling code (WD code) based on model atmospheres by Kurucz. The accepted models revealed some parameters describing the orbit of each system which showed that the primary components in all systems are massive and hotter than the secondary components. The spectral types of the systems’ components were adopted and the locations of the systems on the theoretical mass-luminosity and mass-radius relations revealed a good fit for all the systems components except the secondary components of the systems V0996 Per and V0757 And are located above the TAMS track.

eclipsing binaries;evolutionary state;orbital solution


Renyi Holographic Dark Energy and Its Behaviour in f(G) Gravity

Abstract: In this work, the Renyi holographic dark energy (RHDE) and its behaviour has been explored with the anisotropic and spatially homogeneous Bianchi type-I Universe in the framework of f (G) gravity. We use IR cutoff as the Hubble and Granda-Oliveros (GO) horizons. To find a consistent solutions of the field equations of the models, it is assumed that the deceleration parameter is defined in terms of function of Hubble parameter H. With reference to current cosmological data, the behaviors of the cosmological parameters relating to the dark energy model are evaluated and their physical significance is examined. It is observed that for both the models, the equation of state parameter approaches to -1 at late times. However, the RHDE model with the Hubble horizon exhibits stability from the squared sound speed, but the RHDE model with the GO horizon exhibits instability. In both the models, deceleration parameter and statefinder diagnostic confirm the accelerated expansion of the Universe and also correspond to the ΛCDM model at late times.

bianchi type-i metric;cosmology;f(g) gravity;renyi holographic dark energy


On the Unified Scheme of γ-Ray Emitting Jetted Active Galactic Nuclei

Abstract: The discovery of γ - ray emitting Seyfert galaxies has opened a new unified scheme of active galactic nuclei (AGN) in which jetted Seyfert galaxies are viewed as young counterparts of radio loud AGN. In this paper, we investigate the relationship between gamma-ray (γ - ray) properties of jetted Seyfert galaxies and those of traditionally radio galaxies, radio quasars and BL Lac objects. Results show that jetted Seyfert galaxies appear as low luminosity tail of the radio loud AGNs on the luminosity redshift (Lγ – z) plane, indicating an evolutionary link between them. Nevertheless, narrow-line Seyfert galaxies (NLS1s) do not share similar characteristics with Seyfert galaxies as they possess higher luminosities and redshift than Seyfert galaxies, suggestive that NLS1s are more evolved sources. Analyses of γ – ray and radio core-dominance show that for each subclass of jetted AGN, the beaming angle is wider for radio than for γ - ray emissions. While Seyferts and radio galaxies, on average, have similar low inclination to the line of sight, NLS1 objects have orientations similar to quasars and BL Lacs. There is a significant correlation (r   0.7) between the γ - ray core dominance and γ - ray luminosity. The results are consistent with the revised unification scheme and suggests that NLS1s are highly beamed sources whose parent populations can be found among the regular Seyferts and/or radio galaxies


Activity of Stars with Planets in the Habitable Zone

Abstract: Based on data on stars with planets located in the habitable zone, a study is made of manifestations of their activity. Light curves obtained during observations in the Q3 set with the Kepler Space Telescope for them were studied and the amplitudes of the brightness variability were studied in order to determine the presence and properties of spots on their surface. Estimates of the rotation periods of the objects were also obtained. Diagrams of the dependence of the area of the spots A on the surface of stars with exoplanets according to published data (including in those in the Habitable Zone) on the effective temperature and rotation period are examined. Indications are obtained that the distributions of the stars with exoplanets located in the habitability zone are shifted toward the region of lower spot areas and rotation periods compared to the data for all the stars with exoplanets. Data from the archive of the Kepler Space Telescope for a star with pronounced rotational modulation, KOI-3497 (Kepler-1512, KIC 8424002) are analyzed. It is noted that it should be characterized by a a star of spectral class K, rather than M. KOI-3497 has flare activity (47 flashes with energy E in the range from 2·1031 to 2·1032 erg have been recorded for it.)


Study of the Rapid Variability of the BL Lac Object MRK 421 in the Optical Range

Abstract: MRK 421 is a giant elliptical galaxy in the Ursa Major constellation whose core has all the properties of a BL Lac object. It manifests a high activity and variability from the radio to gamma-ray ranges on time scales from a few hours to more than 10 years. MRK 421 has a large companion— a spiral, probably, also active galaxy (MRK 421-5). This paper presents the results of an analysis of observations (in the V, R, and I bands) as part of a joint Latvian-Ukrainian project for study of the variability of bright AGN. In addition, the light curves of MRK 421 from the AAVSO data base (American Association of Variable Star Observers) are analyzed to confirm the results of periodogram analysis. Ultimately, over the time interval studied here, MRK 421 is suspected of having a cyclical variability with a characteristic time in the range of 9.3-13.4 days determined by two different methods (approximation of the data by sinusoids and the CLEANest method), which is confirmed by an analysis of longer observations of MRK 421 in the V band (with AAVSO data). The longer variability of MRK 421 was also analyzed. It was found that in the V, R, and I light curves from AAVSO the maxima of the LS-periodograms correspond to periods of 1.6-1.7 years. This is close to earlier results from an analysis of historical light curves of MRK 421 obtained by other authors. The AAVSO data also indicate the presence in MRK 421 of a longer cycle of brightness variation with a characteristic time of 20-30 years.

active galactic nuclei;intra-day and extra-day variability;mrk 421;optical photometry;radio galaxy


Instabilities of a Nonstationary Model of a Self-Gravitating Disk. V. New Annular Perturbation Modes

Abstract: The problem of gravitational instabilities of annular perturbation modes against the background of a self-gravitating disk model nonlinearly oscillating in its plane, which is a nonstationary generalization of the well-known equilibrium Bisnovaty-Kogan-Zel’dovich model is examined. The corresponding nonstationary analogs of the dispersion equation for the new annular perturbations are found. The results of the calculations are given in the form of critical dependences of the initial virial ratio on the degree of rotation of the disk. A comparative analysis is also made of the increments of the gravitational instability of these perturbation modes. It turns out that with an increasing degree of rotation of the nonstationary disk the range of the initial virial ratio for which annular structures can be formed increases.

annular galaxies;gravitational instability;nonstationary model;self-gravitating disk


Variation of Doppler Velocities and D3 Spicule Half-Widths

Abstract: This paper analyzes spectral observations of spicules in the helium D3 line obtained at the Abastumani Observatory (Georgia).with a 53-cm eclipse-free coronagraph. It is concluded that the changes in the Doppler (radial) velocities and half-widths of the D-3 lines are in antiphase. The maxima of the periods of the oscillations of the Doppler velocities coincide with the minima of the oscillations of the half-width of D3.

d3 line;doppler velocities;line half-half width


Plane Symmetric String Cosmological Model with Zero Mass Scalar Field in f (R) Gravity

Abstract: In this article, an anisotropic Locally Rotationally Symmetric (LRS) Bianchi type I metric in the presence of cloud string fluid and zero mass scalar field in reference to f (R) gravity have been investigated. To obtain the deterministic solutions we assumed the weak field limit for a point-like source f (R) = R 3/2 and the very well-known expansion-shear scalar proportionality relation. Furthermore, some physical and kinematical parameters have been calculated to study the astrophysical consequences of obtained model, which shows a good resemblance to the recent observational data.

bianchi type i metric;cosmic string;f (r) gravity;scalar field


First Light Curve Modelling of Eclipsing Binary Systems V1264 Cas, V0664 Lac and GSC 0199-2035

Abstract: Photometric analysis for the newly discovered systems V1264 Cas, V0664 Lac and GSC 0199-2035 were carried out using the most recent version of the Wilson-Devinney binary star modeling code (WD) based on model atmospheres by Kurucz. Accepted models revealed physical parameters use to adopt the spectral type of the components of the studied systems. Locations of the systems on the theoretical massluminosity and mass-radius relations revealed good fit for all the systems components except for the secondary components of the systems; V1264 Cas and GSC 0199-2035 where they lie above the TAMS track.

eclipsing binaries;evolutionary state;light curve modelling


Emission Spectra of Galaxies with Supermassive Black Holes at z > 6

Abstract: The masses of supermassive black holes and the (parent) galaxies containing them are related approximately by MBH   0.002 M*. This indicates their close interaction during the process of their joint evolution. However, the large spread in the observed masses around this relation and, in particular, the considerably larger value, by an order of magnitude, of this mass ratio in the early universe (z > 6) observed in recent years indicates that the character of their interaction may vary significantly as they evolve. This circumstance requires a reliable observational determination of the ratios of the masses of the black holes, stellar populations, and interstellar gas in galaxies at large redshifts when these cannot be measured directly. In this paper a simple description illustrating this possibility is proposed. The features of the spectra of galaxies containing growing black holes and a forming stellar population are examined. A set of models with variations in the masses of the black hole, stellar population, and interstellar gas is used to illustrate the feasibility of finding the ratio of their masses using multiwavelength spectra: far infrared, submillimeter, and X-ray.

extinction;galaxies;interstellar dust;interstellar medium;supermassive black holes


Transition 212-303 May Help for Detection of Methylene in a Cool Cosmic Object

Abstract: Methylene is an important astrochemical compound. Though its laboratory spectrum was analyzed in 1982, its first unambiguous detection could be feasible after more than one decade in the hot core of Orion-KL nebula and the approximate molecular cloud of the continuum source W51M through its emission line 404-313. Since then waiting of its further detection has now broken as it has been detected in W51 E, W51 M, W51 N, W49 N, W43, W75 N, DR21, and S140 star forming regions, and in W3 IRS5 through the same transition 404-313. To find potential lines of methylene, we have performed Sobolev LVG analysis of each of the ortho and para species of methylene, considering 10 rotational levels having energy up to 324 cm-1. We have found only three lines, 404-313, 505-414 and 212-303 of methylene, which may help for its detection in a cosmic object. The line 212-303 lying at the lowest energy may be more helpful in a cosmic object having low kinetic temperature.

ism;methylene;molecules;radiative transition;sobolev lvg analysis


Conservation Laws in Time-Dependent Radiative Transfer Problems

Abstract: The classical problem of radiative transfer with the escape of a photon from a semi-infinite scattering and absorbing atmosphere is generalized by the author to the case where the time expended by photons in multiple scattering in it is taken into account. The possibility of a variational formulation of the problem and the generalization of quadratic and bilinear conservation laws obtained in the stationary problem is raised. It is shown that the general statement of the problem does not allow this formulation owing to the nonpotentiality of the resulting differential operator; however, it is possible in the special case of conservative scattering. The resulting two conservation laws reflect the fact that the medium is homogeneous and time is isotropic.

canonical equations;conservation laws;hamilton’s principle;time-dependent radiative transfer;variational problem


New Entropies, Black Holes, and Holographic Dark Energy

Abstract: The Bekenstein-Hawking entropy is a cornerstone of horizon thermodynamics but quantum effects correct it, while inequivalent entropies arise also in non-extensive thermodynamics. Reviewing our previous work, we advocate for a new entropy construct that comprises recent and older proposals and satisfies four minimal key properties. The new proposal is then applied to black holes and to holographic dark energy and shown to have the potential to cause early universe inflation or to alleviate the current Hubble tension. We then analyze black hole temperatures and masses consistent with alternative entropies.


Optical Classification of BZG Objects from the BZCAT Blazar Catalog

Abstract: In the blazar catalog BZCAT the objects are divided into 4 types: BZB, BZQ, BZG, and BZU. In this paper BZG objects are studied in order to determine their physical nature. Of the 274 BZG objects, 150 have optical spectra in the SDSS spectroscopic catalog, for which a detailed spectral classification has been carried out. A radio study showed that these objects mostly (69

blazar;optical spectral classification;quasar;radio spectral index


HH 1216: The Extended Bipolar Flow Associated with IRAS 06212-1049

Abstract: A narrow-band survey of star-formation regions is under way with the 1-m Schmidt telescope at the Byurakan Observatory (the Byurakan Narrow Band Imaging Survey, BNBIS). One of the goals of the survey is a search for Herbig-Haro (HH) type outflows in the neighborhoods of bright infrared sources in dark clouds. One of the first discoveries in this program was an extended bipolar outflow from the optically invisible IRAS 06212-1049 source associated with a previously unknown biconical reflecting nebula. This bipolar outflow (HH 1216) consist of several optically bright HH-knots and a small emission jet along the axis of the nebula. The overall length of the observable part of the HH 1216 outflow is estimated at about 1 pc and its distance at  950 pc. The bolometric luminosity of the source IRAS 06212-1049 is at least 13 L⨀. Yet another HH-knot, HH 1217, has been observed near the source IRAS 06216-1044 with a luminosity of at least 13 L⨀ and located in the same dark cloud. Yet another isolated emission object has been found in this region; it is probably a distant planetary nebula.

dark clouds;herbig-haro outflows and objects;ir sources;pms-stars


Theory of Classical Gaseous Polytropes in an Integral Representation. I. Some General Results

Abstract: The well known results of the theory of classical gaseous polytropes are presented in the framework of an integral approach where the standard Lane-Emden differential equation for a spherically symmetric gravitating mass is examined via its equivalent in the form of a nonlinear integral Volterra equation of the 2nd kind. It is shown that the inverse Laplace transform of the Lane-Emden equation for polytropes with an index of n=5 (Schuster model) is a recurrence relation for Bessel functions of the first kind. The invariance of the nonlinear integral Volterra equation with respect to homological transformations is shown, as well as the possibility of obtaining singular solutions under certain conditions. It is also shown that for whole integral and half integral polytrope indices, this equation is equivalent to a multidimensional integral equation, and finding the expansion of the Emden function in a power series of the dimensionless distance ξ from the center of the polytrope is equivalent to finding the Neumann series and the iterated nuclei in the Fredholm theory. Approximations of the Emden functions in closed form and their applicability to various astrophysical objects will be presented and discussed in the second part of this paper. Polytropes of other geometries and dimensionalities are not considered here.

emden function;lane-emden equation;nonlinear volterra-type integral equation of the second kind;polytropes


Features of the Magnetic Field Behavior of the Ae/Be Star HD190073

Abstract: An attempt is made to explain the sudden change in the surface structure of the magnetic field of the type HAe/Be star HD190073 assuming a variable nonstationarity of the upper layers of the star which takes place owing to accretion and burning of deuterium. At the same time, data are presented which contradict the assumption of magnetic field generation within the convective core.


Spottedness Activity of the Young Star TOI 1227 with a Planetary System from Lower Centaurus Crux OB Association (Musca)

Abstract: Based on high-precision data from the archive of the TESS space mission, a study of the photometric variability of the brightness of TOI 1227, a young member of the Musca group with an age of 11 million years. is carried out. The obtained results are compared with data on another young star with an exoplanet that we studied previously, EPIC 205117205 (K2-33) from the Upper Scorpius subgroup of the Sco-Cen association. TOI 1227 and K2-33 are among the youngest of the stars with planetary systems studied using data from the Kepler and TESS missions. Estimates of its rotation period and the amplitude of its brightness amplitude are made from all the accessible observations, and the standard method is used to estimate the absolute measure of the spottedness parameter A. The area of the spots on the surface of TOI 1227 is 14600 MSH and significantly exceeds the area of the spots on the sun. It is found that for TOI 1227 over the observation interval in three sectors from the TESS space mission, there were no manifestations of flare activity. Besides its youth, the TOI 1277 system is of special interest owing to the substantially larger radius of the planet found compared to other planets with low-mass stars. New observations and further studies will be required in order to refine the properties of TOI 1227b and the reliability of its detection.


Herbig-Haro Flows and Young Stars in the Dobashi 5006 Dark Cloud

Abstract: Two new Herbig-Haro flows were found in a study of the isolated Dobashi 5006 dark cloud (l = 216°.7, b = –13°.9): one certain (HH 1179) and one presumable, associated with the infrared sources 2MASS 06082284-0936139 and 2MASS 06081525-0933490, correspondingly. Judging from their spectral energy distributions, these sources may be Class 1 objects with luminosities of order 23 L⨀ and 3.6 L⨀, respectively. They are part of the poor star cluster MWSC 0739, study of which based on data from the Gaia DR3 survey has made it possible to detect 17 stars which are probably members of it. A list of them and their main parameters is given. The distance of the cluster is estimated to be 820 pc and the color excess on the path to the cluster is E(BP - RP) ≈ 1.05 mag. All of these stars are PMS-objects and most of them are optically variable. It is concluded that the newly discovered compact star-formation zone in the Dobashi 5006 cloud has an age of no more than a few million years and this process continues up to the present time.

dobashi 5006;herbig-haro objects;young stars


Effect of the Interaction Between Hyperons on the Moment of Inertia of the Proto Neutron Stars

Abstract: Effect of the interaction between hyperons on the moment of inertia of proto neutron stars (PNSs) PSR J0740+6620, PSR J0348+0432, PSR J1614-2230 and PSR J0737-3039A is examined by means of relativistic mean field theory. Taking into account the interaction between hyperons, the mass M of the PNS decreases with respect to the same radius R, the energy density ε increases with respect to the same pressure p, and the moment of inertia I of the PNS decreases with respect to the same central energy density εc. Under the constraint of the mass of the PNS, considering the interaction between hyperons, the larger the mass of the PNS, the more the radius and moment of inertia of the PNS decrease, while the more energy density and pressure increase. For smaller PNSs, the effect can be negligible.

hyperon;neutron star;relativistic mean field theory


Photometric and Spectroscopic Analysis of the SX Phe Star BL Cam

Abstract: In the present paper, we report the photometric and spectroscopic observations of the pulsating star BL Cam obtained by the 1.88 m telescope at the Kottamia astronomical observatory (KAO). Fourier analysis of the light curves indicates one frequency, 25.14427 c/d, with harmonics 51.112 c/d, 33.388 c/d, and 17.72464 c/d. The frequency of 31-32 c/d reported in the literature is not detected in our data except for one close to 33.3882934 c/d. A total of 55 new times of maximum light have been presented. A new value of (1/P) dP/dt is estimated using the O-C diagram based on all newly obtained times of maximum light combined with those taken from the literature, assuming the periods are decreasing and changing smoothly. Using model atmosphere analysis, we computed the effective temperature and surface gravity as Teff = 7625 ± 300 K and logg = 4.30 ± 0.37. The bolometric magnitude Mbol = 2.335, radius R = 1.69 R⨀, luminosity L = 0.957 L⨀, the mass M = 1.68M⨀, and pulsation constant Q = 0.025 days. Locations of the star on the M-R and M-L diagrams indicate that it is close to the ZAMS track and is an unevolved star.

frequency and pulsation analysis;model atmosphere analysis;stars;sx phe stars;variables


The Red Giants EK Eri and OU And as Probable Descendents of Ap-stars: A Search for Abundance Anomalies

Abstract: The red giants EK Eri and OU And, with magnetic fields Bmax=99 and 41 G, respectively, which presumably are descendents of magnetic Ap-stars, are studied. Their fundamental parameters are found and their chemical composition is analyzed. The abundances of 17 elements from lithium (Z=3) to hafnium (Z=72) are found for these giants, as well as for the comparison star βGem (Pollux). The abundance of nitrogen and the carbon isotope ratio 12C/13C are found using CN molecular lines. The low ratios 12C/13C=17.3 for EK Eri and 17.2 for βGem prove that these giants have passed through deep convective mixing in the First Dredge-Up (FDU) phase. For OU And, it was not possible to determine 12C/13C because of the relatively fast rotation and higher effective temperature of this star. but a high ratio N/C (higher than the sun by 1.1 dex) may serve to confirm that even this giant has also passed through an FDU phase. An analysis of the chemical composition led to an important conclusion: none of the three giants have any kinds of anomalies in the abundances of the heavy elements; in particular there are no excesses of any kind in the abundances of the rare-earth elements, which reach 4 dex in magnetic Ap-stars. The absence of such excesses may be a consequence of deep mixing during the FDU phase. In all three cases the abundances of carbon and nitrogen revealed the expected anomalies for stars of this type: a deficit of C from -0.3 to -0.6 dex and an excess of N from +0.3 to +0.6 dex. The theoretical prediction of a constant sum of C+N+O in the evolution process is confirmed: the combined abundance logε(C+N+O)=8.96-8.98 essentially coincides with the initial value of this quantity, specifically with the value of logε(C+N+O)=8.94 obtained for the sun and for early B-type MS stars. The Li 6707.76 Å line was detected in the spectra of all three stars, revealing a lithium abundance of logε(Li)=0.7-1.5; however, the presence of lithium in the atmospheres of giants that have passed through an FDU phase conflicts with the standard theory. Two of the observed phenomena that were unexpected for post-FDU giants, i.e., the existence of a magnetic field and the presence of lithium in the atmosphere, can be explained in terms of a single hypothesis: engulfment by a red giant of a planet with a mass several times that of Jupiter.


Environmental Dependence of Different Colors of Active Galactic Nucleus (AGN) Host Galaxies

Abstract: Using the apparent-magnitude limited active galactic nucleus (AGN) host galaxy sample of the Sloan Digital Sky Survey Data Release 12 (SDSS DR12), we investigate the environmental dependence of the u-r, u-g, g-r, r-i and i-z colors of AGN host galaxies. We divide the whole apparent-magnitude limited AGN sample into many subsamples with a redshift binning size of ∆z = 0.01, and analyze the environmental dependence of all five galaxy colors of subsamples in each redshift bin. It turns out that overall, all five galaxy colors of AGN host galaxies are weakly correlated with the local environment.

fundamental parameters - galaxies;galaxies;statistics


Results of Spectral Observations of 15 Seyfert Galaxies

Abstract: Results of spectral studies of fifteen Seyfert galaxies at red wavelengths based on long-term observations are presented. In this range there are lines of hydrogen Hα, [NII], [OI], and [SII]. Data on the absolute emission fluxes in the emission lines and in the continuum at the wavelength of λ = 6400 Å are presented. In order to objectively compare the examined galaxies with one another, the values of their luminosities were calculated in absolute units with the distances to these objects taken into account.

emission fluxes;emission lines;galaxies with active nuclei;seyfert galaxies


Nine Nearby K-Giants with Planets: A Detailed Analysis of their Chemical Composition

Abstract: The chemical composition of 9 K-giants with planets located within 100 pc of the sun is studied. Here fundamental parameters of the stars which we have found previously are used; for the giant μ Leo the metallicity index [Fe/H] = +0.26 is redetermined along with the microturbulence parameter Vt=1.3 km/s from the lines of FeI. The abundances of 17 chemical elements from lithium (Z = 3) to hafnium (Z = 72) are found. Some elements are analyzed without assuming LTE (local thermodynamic equilibrium). Infrared CN molecular lines are used to determine the nitrogen abundance and the carbon isotope ratio 12C/13C. Low values of 12C/13C=8-18 show that the program giants have passed through deep convective mixing in the FDU (First Dredge-Up) phase. When analyzing the abundances obtained we added our recent data for the magnetic giants EK Eri and OU And found by the same technique. Lithium was not found for 7 of the 11 giants in question. An absence of lithium in atmospheres of stars that have passed through deep mixing in the FDU phase agrees with theoretical predictions. However for 4 of the giants, we found lithium; earlier for 3 of these 4 stars a magnetic field has been detected. These two phenomena, i.e., the presence of lithium in its atmosphere and the existence of a magnetic field, are unexpected for post-FDU giants in terms of the standard theory, can be be explained in the framework of a single hypothesis: an engulfment by a star of the planet with a mass several times that of Jupiter. For the 11 giants examined here we found a distinct correlation between the [N/C] and [N/O] values. A comparison of the observed relation with the theoretical model computed with rotation included showed that the theory cannot explain the high values of [N/C]=1.0 – 1.4 obtained for the most of the giants. Apparently, the known hypothesis of extra mixing is needed here. The combined abundance of C+N+O, which, according to the theory, should remain constant from the star’s formation, showed a correlation with the metallicity index [Fe/H]. In this regard, for the stars with the normal metallicity [Fe/H] = ±0.1 a value of logε(C + N + O) = 8.97 was found that agrees perfectly with the solar value logε(C + N + O) = 8.94. For the giant m Leo with a high metallicity [Fe/H]=+0.26 the highest value of logε(C + N + O) = 9.31 was obtained. An anticorrelation was found between [RE/Fe], the mean abundance of rare earth (RE) elements (relative to Fe) and the index [Fe/H]. It is in good agreement with data for F- and G-dwarfs in the sun’s neighborhood and reflects the initial chemical composition of the giants studied here.


Large-Scale Electric Currents in Coronal Heating Processes above Active Regions on the Sun

Abstract: This paper poses the problem of studying the role of large-scale electric currents propagating in the upper layers of the solar atmosphere in processes of coronal heating of the sun. For detecting and calculating the magnitude of the large-scale electric current, data on the distribution of the components of the magnetic field vector in the photosphere provided by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) were used. Photoheliograms of the sun’s corona in the ultraviolet radiation channels at 131, 171, 193, and 211 Å provided by the Atmospheric Imaging Assembly (AIA/SDO) were used to estimate the temperature in the corona above active regions (ARs). The dynamics of the large-scale current and the average temperature in 9 regions with different levels of flare activity of the corona above the ARs have been studied and charts of the spatial distribution of the temperature in the corona above the ARs have been constructed. The following results have been obtained: 1. Heating of the coronal matter owing to ohmic dissipation of large-scale electric currents proceeds in a stationary regime. 2. The increase in the average temperature in the corona above an AR during solar flares to < log T¯ > = 6.3 - 6.5 (2.0-3.2 MK) is caused, not only by heating of coronal structures by large-scale electric currents, but also by other processes at coronal elevations. 3. For the NOAA 11899 and 12494 regions a reduction in the average temperature of the corona to < log T¯ > = 5.7 (0.5-0.6 MK) was observed with a simultaneous drop in the values of the large-scale electric current to zero. These observations indicate that the mechanism for heating of the corona by ohmic dissipation of electric currents is shut off at zero values (within the computational errors) of the large-scale electric current. 4. In the NOAA regions 12192 and 12371, when constructing charts of the temperature distribution in the corona outside flare events, hot structures with temperatures ≥ 10 MK were observed outside the flare events which appear to mark the location of the channel of a large-scale electric current at coronal elevations. For the NOAA region 12192 this assumption is confirmed by a numerical simulation carried out in 2016.

active regions;coronal heating;electric currents;magnetic field;sun;ultraviolet radiation


Motion of a Particle in the Field of an Infinite Flat Slab

Abstract: This paper studies the motion of a light signal and a test particle in the field of an infinite flat slab in terms of the general theory of relativity. The two cases of an external solution for a gravitational field in a vacuum corresponding to Rindler and Taub metrics are examined. The time of the motion and the path traveled by a particle before it stops are determined. It is shown that in the Taub geometry, as opposed to a light signal, a material particle does not reach a singularity. The minimum distance from the singularity is determined as a function of the particle energy. Results in terms of the special theory of relativity are given for comparison.

plane-symmetric gravitational field;rindler metric;taub metric


Multiwavelength Properties of Selected High Redshift Blazars

Abstract: High-redshift blazars detected in the γ -ray band are the most powerful steady objects in the universe. Multiwavelength observations of these distant objects are of particular interest as they can help to understand the γ -ray evolution of blazars as well as the formation and propagation of relativistic jets in the early epochs of the Universe. In this study, we investigate the origin of broadband emission from 7 blazars with redshifts greater than 2.5 by analyzing the data accumulated with Swift UVOT/XRT and Fermi-LAT. We observe several flaring periods with significant increases in flux and hardening of the photon index in the high-energy γ -ray band for PKS 1830-211 (z = 2.507), LQAC 247-061 (z = 2.578), TXS 0536+145 (z = 2.690), and 4C+41.32 (z = 2.550). PKS 1830-211 was in an extraordinarily bright state on MJD 58596.49 when the 3-day averaged flux increased up to (1.74 ± 0.04)·10–5 photon cm-2 s-1. The X-ray emission of PKS 1830-211 is also strongly variable and is characterized by a hard photon index in the range of 0.34-0.94. To model the time-averaged broadband spectral energy distribution of the considered sources, we used a one-zone leptonic emission mechanism for the inverse Compton scattering, considering both synchrotron and external photons. We estimated the corresponding parameters of the emitting particles as well as the energetics of the jet.


Halo Effect on Bar Rotation in Galaxies

Abstract: The effect of a massive gravitating halo on the rotation of an ellipsoidal bar in disk galaxies is studied. The method is based on calculating the moment of forces between a bar and a halo using a function of their mutual gravitational energy. Two models are examined to test the new method: a simple variant with uniform components and a more complex variant in which the halo is represented by a layered-heterogeneous ellipsoid with a parabolic density law. For both models expressions are obtained for the mutual gravitational energy of the bar and the halo, the Lagrangian is constructed, and differential equations for the nonlinear rotational oscillations of the bar are derived. These equations describe the rotation of a bar with a variable angular velocity. The frequencies and periods of the librations of the angular velocity of the bar are found both in the general nonlinear case and in the approximation of harmonic oscillations. It is found that taking the inhomogeneity of the halo into account can significantly (by roughly a factor of 2) increase the period of these oscillations.

bars and halos;frequencies and periods of oscillations;linear and nonlinear equations of rotational oscillations of bars;mutual energy of ellipsoids;structure of disk galaxies


Surface Photometry of 50 Dwarf Galaxies in the Local Volume

Abstract: Results of surface photometry of 50 galaxies in the Local Volume based on archived images obtained with the Hubble Space Telescope are presented. Integrated magnitudes in the V and I bands are introduced for the chosen galaxies, along with brightness and color profiles. The obtained photometric parameters are compared with the measurements of other authors.

dwarf galaxies;galaxies;photometric parameters- galaxies


Spottedness Activity of the Young Star HIP 94235 from the Moving Group AB Doradus

Abstract: Based on high-precision data from the archive of the TESS space mission, a study is made of the photometric variability of the brightness of HIP 94235, a bright star belonging to the 120 million years old moving group AB Doradus. We obtained an estimate for the rotation period of the star and the amplitude of the brightness variability, as well as an estimate of 31750 m.s.h. for the spottedness parameter A in an absolute measure, substantially greater than the density of spots on the Sun. During the interval of the observations with the TESS space mission there were no manifestations of flare activity on HIP 94235, For each sector of the observations which sequentially cover one period of the star’s rotation, the inverse problem of recovering maps of the surface temperature inhomogeneities of the star from the light curve was solved for the position of the active regions and to study their time evolution. The differential rotation parameter of the star ∆Ω =0.038 ± 0.07 rad/d is estimated from the relative differences in the displacements of the active regions. The results are compared with data on another young solar-type star with an exoplanet which we have studied, TOI 837, a member of the southern cluster IC 2602 with an age of 35 million years.


Ultrafast Variability of Line Profiles in Spectra of γ Ori

Abstract: High time-resolution (∆T 2 min) observations of the B2V star γ Ori on the 2-m telescope at the Terskol Peak Observatory are presented. Regular components of line profile variations with periods from  57 min to  130 min are recorded. The nature of these variations is discussed.

individual;spectra — line profiles— variability;stars;γ ori


On a Possible Mechanism for the Start or Resumption of Activity of Radio Galaxies in Clusters of Galaxies

Abstract: We study the close proximity of the well-known and well-studied 3C31 class FRI radio galaxy in order to reveal the influence of the environment on an extragalactic radio source. It was shown that about 110 million years ago the galaxies NGC 380 and NGC 386 were located near the galaxy NGC 383 (the parent galaxy of 3C31). On the other hand, the modeling of the spectral characteristics of the radio emission of the central part of the radio galaxy 3C31 gives an estimate of the age of the central jet of about 100 million years. Therefore, it can be assumed that one of the possible reasons for the appearance or resumption of the radioactivity of the galaxy NGC 383 may be a triple close passage of galaxies.

clusters of galaxies;environment of galaxies;galaxies;radio galaxies