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Novel Planetary Signatures from the Dark Universe Astrophysics (IF 0.5) Pub Date : 2024-01-16 K. Zioutas, V. Anastassopoulos, A. Argiriou, G. Cantatore, S. Cetin, A. Gardikiotis, H. Haralambous, M. Karuza, A. Kryemadhi, M. Maroudas, A. Mastronikolis, C. Oikonomou, K. Ozbozduman, Y. K. Semertzidis, M. Tsagri, I. Tsagris
“Dunkle Materie” (DM) came from unexpected cosmological observations. Nowadays within our solar system, diverse observations also defy conventional explanations, like the main physical process(es) underlying the heating of the different solar atmospheric layers. Streaming DM offers a viable common scenario following gravitational focusing by the solar system bodies. This fits as the underlying process
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The First Photometric Study of the Binary System CSS J003106.8+313347 Astrophysics (IF 0.5) Pub Date : 2024-01-16
We performed the first photometric study of the CSS J003106.8+313347 W Ursae Majoris (WUMa)-type system based on ground-based observations. We extracted times of minima from our observations and proposed a linear ephemeris based on the increasing incline of the orbital period using a Markov chain Monte Carlo (MCMC) approach. The PHOEBE Python code and the MCMC approach were used for the light curve
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The Digitized First Byurakan Survey Data Base. Late-Type Stars Candidates. New Confirmations. I Astrophysics (IF 0.5) Pub Date : 2024-01-15 K. S. Gigoyan, K. K. Gigoyan, A. Sarkissian, G. R. Kostandyan, M. Meftah, S. Bekki
The Digitized First Byurakan Survey (DFBS) is the digitized version of the First Byurakan Survey (FBS, or Markarian survey). The FBS was the first systematic survey of the extragalactic sky. This objective-prism survey was carried out in 1965-1980 by B.E.Markarian and his colleagues using the 1 m Schmidt telescope of the Byurakan Astrophysical Observatory and resulted in discovery of 1517 UVX-excess
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Periodicity of Flare Frequency of Active Flare Stars Detected by Tess Astrophysics (IF 0.5) Pub Date : 2024-01-15
Data from the TESS orbital observatory are used to study the most active flare stars indicating 100 or more flares during the period from July 2018 through October 2020. The main objectives of this study were: (a) analysis of the light curves, determination of the axial rotation periods, and identification of physical features in individual stars, (b) determination of the parameters of the periodic/cyclical
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Photometric and Spectral Studies of the Group of Galactic Wolf-Rayet Stars. I. WN Sequence Astrophysics (IF 0.5) Pub Date : 2024-01-15 L. N. Kondratyeva, I. V. Reva, E. K. Denissyuk, S. A. Shomshekova, G. K. Aimanova
Photometric and spectral observations of 11 Wolf-Rayet stars of the WN sequence were made at the AFIF during 2021-2022. Estimates of the brightness of objects in BVRc filters and the absolute fluxes of radiation in emission lines in this group are obtained on the basis of these observations. Changes in the brightness over a range of 0m.1-0m.15 are recorded for the stars WR 120, WR 151, and WR 152 in
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Transverse Gradients of Longitudinal Magnetic Field in Active Regions with Different Levels of Flare Productivity. I. Calculation Methods and Dynamics of Selected Parameters Astrophysics (IF 0.5) Pub Date : 2024-01-15 Yu. A. Fursyak
This paper is a study of the dynamics of the parameters describing the transverse component of the gradient of the longitudinal magnetic field ∇⊥ Bz in active regions (AR) with different levels of flare productivity. Data obtained by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) has been used to analyze 75 ARs in the 24-th cycle of solar activity. ∇⊥ Bz has
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Mass Loss from the Atmosphere of the Planet WASP-193 b Astrophysics (IF 0.5) Pub Date : 2024-01-15 I. S. Savanov
Results are presented from an analysis of the manifestations of activity of the star WASP-193 of spectral class F9 with a super-neptune-type planet. The gaseous giant WASP-193 b with a mass 0.13 times Jupiter’s mass and almost one and a half times its radius. The planet has a low density ρ = 0.059±0.014 g/cm3 (Kepler 51 d is an analogous object; there are few other exoplanets of this type). The equilibrium
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Viscous Ricci Dark Energy Cosmological Models in Brans-Dicke Theory Astrophysics (IF 0.5) Pub Date : 2024-01-15 M. Vijaya Santhi, T. Chinnappalanaidu, S. Srivani Madhu
The whole article deals with the analysis of the cosmic model of Ruban’s space-time in the context of a bulk viscosity impact in the form of Ricci dark energy within the framework Brans-Dicke theory. We believe that outer space is filled with dark matter and viscous Ricci dark energy (VRDE) under the pressureless situation. The velocity and rate at which the Universe is expanding are presumed to be
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A Search for New Dwarf Galaxies Outside the Nearby Groups Astrophysics (IF 0.5) Pub Date : 2024-01-15 I. D. Karachentsev, V. E. Karachentseva, S. S. Kaisin, E. I. Kaisina
We undertook a search for new nearby dwarf galaxies outside the known groups in the Local Volume using the data on DESI Legacy Imaging Surveys. In a wide sky area of ~5000 square degrees directed toward the Local Void, we found only 12 candidates to nearby low mass galaxies. Almost all of them are classified as irregular or transition type dwarfs. Additionally, we examined areas of the sky exposed
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Structure of the Magnetic Field of the Star HD133880 (Si) Astrophysics (IF 0.5) Pub Date : 2024-01-15 Yu. V. Glagolevskij
The magnetic field of the star HD133880 is modeled assuming a magnetic field structure that is described by two theoretical magnetic dipoles. A comparison of this result with what was found previously using a representation of the phase dependence Be(Φ) employing a dipole+quadrupole+octupole expansion for the structure shows that this scheme leads only to a formal description of the phase dependence
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The Revisited BPT Diagram from the Self-Consistent Analysis Astrophysics (IF 0.5) Pub Date : 2023-09-29 P. Privatus, C. Pappalardo, P. V. K. Rao, D. T. Mazengo
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
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On a Possible Mechanism for the Start or Resumption of Activity of Radio Galaxies in Clusters of Galaxies Astrophysics (IF 0.5) Pub Date : 2023-09-29 R. R. Andreasyan, H. V. Abrahamyan, G. M. Paronyan, G. A. Mikayelyan, A. M. Mickaelian
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
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Activity of the Young Star EPIC 204376071 from the Upper SCO Association Astrophysics (IF 0.5) Pub Date : 2023-09-29 I. S. Savanov
Based on observations from the K2 mission of the Kepler Space Telescope a study is made of the activity of EPIC 204376071, a young object in the Upper SCO association with an age of 11±3 million years whose light curve has a single darkening lasting one day with a depth of about 80%. EPIC 204376071 is a low-mass M-dwarf with a mass of 0.16 M⨀. Based on observations from the C15 campaign of the K2 mission
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Modified Tsallis Holographic Dark Energy Astrophysics (IF 0.5) Pub Date : 2023-09-29 J. Bharali, K. Das
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
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Motion of a Particle in the Field of an Infinite Flat Slab Astrophysics (IF 0.5) Pub Date : 2023-09-29 R. M. Avagyan, A. A. Saharian, S. S. Jibilyan
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
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Swampland Criteria and Neutrino Generation in a Non-Cold Dark Matter Universe Astrophysics (IF 0.5) Pub Date : 2023-09-29 M. Khurshudyan
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
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Renyi Holographic Dark Energy and Its Behaviour in f(G) Gravity Astrophysics (IF 0.5) Pub Date : 2023-09-29 M. K. Alam, S. S. Singh, L. A. Devi
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
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Plane Symmetric String Cosmological Model with Zero Mass Scalar Field in f (R) Gravity Astrophysics (IF 0.5) Pub Date : 2023-09-28 Kalpana Pawar, A. K. Dabre, Pallavi Makode
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) = R3/2 and the very well-known expansion-shear scalar proportionality relation. Furthermore
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Ephemeris Updates for Seven Selected Hatnet Survey Transiting Exoplanets Astrophysics (IF 0.5) Pub Date : 2023-09-29 A. Poro, F. A. Farahani, E. Jahangiri, A. Sarostad, M. Gozarandi, M. Haghgou, F. Abolhassani, A. Fakhrabadi, Y. Jongen, A. Wünsche, R Naves, P. Guerra, A. Marchini, M. Salisbury, R. Ehrenberger, V-P. Hentunen
We refined the ephemeris of seven transiting exoplanets HAT-P-6b, HAT-P-12b, HAT-P-18b, HAT-P-22b, HAT-P-32b, HAT-P-33b, and HAT-P-52b. We observed 11 transits from eight observatories in different filters for HAT-P-6b and HAT-P-32b. Also, the Exoplanet Transit Database (ETD) observations for each of the seven exoplanets were analyzed, and the light curves of five systems were studied using Transiting
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Surface Photometry of 50 Dwarf Galaxies in the Local Volume Astrophysics (IF 0.5) Pub Date : 2023-09-29 K. A. Kryzhanovsky, M. E. Sharina, I. D. Karachentsev, G. M. Karataeva
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.
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On the Unified Scheme of γ-Ray Emitting Jetted Active Galactic Nuclei Astrophysics (IF 0.5) Pub Date : 2023-07-31 A. I. Audu, F. C. Odo, E. U. Iyida, O. Okike, A. A. Ubachukwu
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
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Environmental Dependence of Different Colors of Active Galactic Nucleus (AGN) Host Galaxies Astrophysics (IF 0.5) Pub Date : 2023-08-03 Xin-Fa Deng, Zhi-Yong Wu
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
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Theory of Classical Gaseous Polytropes in an Integral Representation. II. Analytic Approximations to the Emden Functions and Density Profiles in a Closed Form Astrophysics (IF 0.5) Pub Date : 2023-07-31 G. A. Saiyan
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
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TYC 1417-891-1 and TYC 1478-742-1: Eclipsing Variable Stars. The Gaia EDR3 and TESS Photometric Data Astrophysics (IF 0.5) Pub Date : 2023-07-31 K. K. Gigoyan, K. S. Gigoyan, A. Sarkissian, M. Meftah, G. R. Kostandyan, F. Rahmatullaeva
Based on the TESS (Transiting Exoplanet Survey Satellite) phase dependent light curves, we confirm the eclipsing type variability nature for two G-type dwarfs: TYC 1417-891-1 and TYC 1478-742-1. Both objects show EA (Algol-type) light curves morphology. Orbital period for TYC 1417-891-1 is P ≈ 8.0 day and for TYC 1478-742-1, P ≈ 13.6 day. We present Gaia EDR3 and TESS catalogue important physical parameters
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Multiwavelength Properties of Selected High Redshift Blazars Astrophysics (IF 0.5) Pub Date : 2023-07-31 G. Harutyunyan
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
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Evolution of Spectrum Lines in an Inhomogeneous Atmosphere Illuminated by Nonstationary Energy Sources Astrophysics (IF 0.5) Pub Date : 2023-07-31 A. G. Nikoghossian
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
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Photometric Activity of CQ Tau over a Time Interval of 125 Years Astrophysics (IF 0.5) Pub Date : 2023-07-31 V. P. Grinin, L. V. Tambovtseva, O. Yu. Barsunova, D. N. Shakhovskoy
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
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Large-Scale Electric Currents in Coronal Heating Processes above Active Regions on the Sun Astrophysics (IF 0.5) Pub Date : 2023-07-31 Yu.A. Fursyak
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
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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 Astrophysics (IF 0.5) Pub Date : 2023-07-29 I. S. Savanov
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
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ASASSN-19fy: Features of a Dwarf Nova in the “Period Gap” Astrophysics (IF 0.5) Pub Date : 2023-07-29 O. I. Antonyuk, E. P. Pavlenko, K. A. Antonyuk, N. V. Pit, A. A. Sosnovskij, G. I. Kokhirova, F. D. Rakhmatullaeva
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
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Features of the Magnetic Field Behavior of the Ae/Be Star HD190073 Astrophysics (IF 0.5) Pub Date : 2023-07-29 Yu.V. Glagolevskij
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.
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Bulk Viscous String Cosmological Model with Power Law Volumetric Expansion in Teleparallel Gravity Astrophysics (IF 0.5) Pub Date : 2023-04-14 Kalpana Pawar, A. K. Dabre
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
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Accelerating Kaluza-Klein Universe in Modified Theory of Gravitation Astrophysics (IF 0.5) Pub Date : 2023-04-13 S. D. Katore, S. P. Hatkar, D. P. Tadas
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
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Optical Classification of BZG Objects from the BZCAT Blazar Catalog Astrophysics (IF 0.5) Pub Date : 2023-04-12 H. V. Abrahamyan, A. M. Mickaelian, G. M. Paronyan, G. A. Mikayelyan, A. G. Sukiasyan
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%) have a flat radio spectrum
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Ultrafast Variability of Line Profiles in Spectra of γ Ori Astrophysics (IF 0.5) Pub Date : 2023-04-12 A. F. Kholtygin, V. B. Puzin, I. V. Sokolov, M. S. Kurdoyakova
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.
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Theory of Classical Gaseous Polytropes in an Integral Representation. I. Some General Results Astrophysics (IF 0.5) Pub Date : 2023-04-12 G. A. Saiyan
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
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Distances to 10 Nearby Galaxies Observed with the Hubble Space Telescope Astrophysics (IF 0.5) Pub Date : 2023-04-12 I. D. Karachentsev, N. A. Tikhonov
Images of 10 galaxies in F814W and F606W filters obtained on the Hubble Space Telescope (HST) are used to construct color-magnitude diagrams for the star population of these galaxies. The distances to the galaxies are estimated from the luminosity of the tip of the red giant branch. The galaxies examined here have radial velocities from 250 to 760 km/s relative to the centroid of the Local Group and
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Herbig-Haro Flows and Young Stars in the Dobashi 5006 Dark Cloud Astrophysics (IF 0.5) Pub Date : 2023-04-12 T. A. Movsessian, T. Yu. Magakian, A. S. Rastorguev, H. R. Andreasyan
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
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The Study of Kantowski-Sachs Perfect Fluid Cosmological Model in Modified Gravity Astrophysics (IF 0.5) Pub Date : 2023-04-12 T. Vinutha, K. Niharika, K. S. Kavya
Kantowski-Sachs perfect fluid cosmological model is explored in modified gravity with functional form f (R, T) = f1(R) + f2 (T) where R is Ricci scalar and T is the trace of energymomentum tensor. With this functional form, three different cases have been formulated, namely negative and positive powers of curvature, logarithmic curvature and exponential curvature given by f1 (R) = R + γ R2 – μ4 / R
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Effect of the Interaction Between Hyperons on the Moment of Inertia of the Proto Neutron Stars Astrophysics (IF 0.5) Pub Date : 2023-04-12 Xian-Feng Zhao
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
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Effect of Neutrino Oscillations on the Thermodynamic Properties of Hot Quark Matter Astrophysics (IF 0.5) Pub Date : 2023-04-12 G. B. Alaverdyan, G. S. Hajyan, A. G. Alaverdyan
The effect of neutrino oscillations on the thermodynamic characteristics of three-flavor hot quark matter in β-equilibrium that is opaque for neutrinos is examined in terms of the local SU(3) Nambu-Jona-Lasinio (NJL) model which also accounts for the ‘t Hooft interaction that leads to quark flavor mixing. The thermodynamic characteristics of quark matter are determined for two temperatures, T = 60
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Photometric Study and Orbital Solution for Some Newly Discovered Eclipsing Binary Systems Astrophysics (IF 0.5) Pub Date : 2023-04-12 M. S. Alenazi, M. M. Elkhateeb
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
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Nine Nearby K-Giants with Planets: A Detailed Analysis of their Chemical Composition Astrophysics (IF 0.5) Pub Date : 2023-01-13 L. S. Lyubimkov, D. B. Poklad, S. A. Korotin
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
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Variation of Doppler Velocities and D3 Spicule Half-Widths Astrophysics (IF 0.5) Pub Date : 2023-01-13 D. Khutsishvili, R. Khutsishvili, V. Kakhhiani, M. Sikharulidze
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
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Periodic Variations in the Brightness of the Red Dwarf V647 Her Astrophysics (IF 0.5) Pub Date : 2023-01-13 N. I. Bondar, K. A. Antonyuk, N. V. Pit
Photometric series for the red dwarf V647 Her (M3.5V) obtained from observations in 2019 at the Crimean Astrophysical Observatory and from data in the SuperWASP calalog in 2004-2007 are analyzed. Analysis of the examined light curves reveals the presence of a variability with an amplitude of 0m.04 and a period of 20.69 days. The stability of the characteristics of this variability in different epochs
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Simple Model of a Rotating Star as a Huygens-Roche Figure Astrophysics (IF 0.5) Pub Date : 2023-01-13 G. M. Karelin, M. V. Kostina, P. A. Tarakanov, A. V. Dementyev, Yu.V. Milanova
Simple analytic formulas are obtained for the equatorial radius and relative rotation velocity of a star as functions of its absolute and relative angular momentum as a Huygens-Roche figure. The results are compared with numerical simulations of the structure of rotating stars and it is shown that the analytic model considered here is sufficient for describing the corresponding parameters.
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New Entropies, Black Holes, and Holographic Dark Energy Astrophysics (IF 0.5) Pub Date : 2023-01-13 S. Nojiri, S. D. Odintsov, V. Faraoni
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
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Photometric and Spectroscopic Analysis of the SX Phe Star BL Cam Astrophysics (IF 0.5) Pub Date : 2023-01-13 M. Abdel-Sabour, M. I. Nouh, A. Shokry, G. M. Hamed, H. A. Ismail, A. Takey, S. A. Ata, I. Zead
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
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Results of Spectral Observations of 15 Seyfert Galaxies Astrophysics (IF 0.5) Pub Date : 2023-01-13 E. K. Denissyuk, R. R. Valiullin, S. A. Shomoshekova, L. N. Kondratyeva, I. V. Reva, G. A. Aimanova, M. A. Krugov
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
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The Mysterious Radcliffe Wave Astrophysics (IF 0.5) Pub Date : 2023-01-12 V. V. Bobylev, A. T. Bajkova, Yu.N. Mishurov
This survey is devoted to the Radcliffe Wave discovered recently by Alves et al., from an analysis of the position of molecular clouds. These authors identified a narrow chain of molecular clouds, extended essentially in one line at an angle of about 30° to the galactic axis y. Essentially, the Radcliffe Wave outlines the damped oscillations in the vertical distribution of with a maximum oscillation
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First Light Curve Modelling of Eclipsing Binary Systems V1264 Cas, V0664 Lac and GSC 0199-2035 Astrophysics (IF 0.5) Pub Date : 2023-01-12 M. S. Alenazi, M. M. Elkhateeb
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
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Spottedness Activity of the Young Star HIP 94235 from the Moving Group AB Doradus Astrophysics (IF 0.5) Pub Date : 2023-01-12 I. S. Savanov
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
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Escape Probability and Mean Numbers of Photon Scatterings. I. Exact and Asymptotic Formulas Astrophysics (IF 0.5) Pub Date : 2023-01-12 D. I. Nagirner, Yu.V. Milanova, A. V. Dementyev, E. V. Volkov
The basic formulas of radiative transfer theory are used to obtain more detailed information on the characteristics of photon scattering in a plane layer, specifically, the probabilities of escape of individual photons through the upper and lower boundaries of the layer and the average numbers of scattering events for these photons.
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Halo Effect on Bar Rotation in Galaxies Astrophysics (IF 0.5) Pub Date : 2022-11-03 B. P. Kondratyev, E. N. Kireeva, V. S. Kornoukhov, N. G. Trubitsyna
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
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Multiwavelength Monitoring of Blazars PKS 2155-304 and S5 0716+71 Astrophysics (IF 0.5) Pub Date : 2022-11-03 D. Israelyan
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
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Emission Spectra of Galaxies with Supermassive Black Holes at z > 6 Astrophysics (IF 0.5) Pub Date : 2022-11-04 E. O Vasiliev, Yu. A. Shchekinov, B. B. Nath
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
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N-S Asymmetry and Periodicity of Daily Sunspot Number During Solar Cycles 22-24 Astrophysics (IF 0.5) Pub Date : 2022-11-04 Y. Chandra, B. Pande, M. C. Mathpal, S. Pande
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
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UX OrI Type Stars in the Cluster IC 348: Results of Long-Term Photometric Monitoring Astrophysics (IF 0.5) Pub Date : 2022-11-03 O. Yu. Barsunova, V. P. Grinin, S. G. Sergeev, S. Yu. Shugarov, N. V. Efimova, S. V. Nazarov
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
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Study of Galaxies with Star-Formation Regions. Panoramic Spectroscopy of SBS1001+555 Astrophysics (IF 0.5) Pub Date : 2022-11-03 S. A. Hakopian, S. N. Dodonov, A. V. Moiseev, A. A. Smirnova
The galaxy SBS1001+555 is studied as an object from the base sample in our program for study of evolutionary processes of star formation in galaxies. The work is based on the results of panoramic spectroscopy of the central part, which is the activity zone of the galaxy with its main star formation region, which we denote by A. The observations employ an MPFS (multipupil fiber spectrograph) on the
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Cosmological Evolution with Negative Energy Densities Astrophysics (IF 0.5) Pub Date : 2022-11-03 A. A. Saharian, R. M. Avagyan, E. R. Bezerra de Mello, V. Kh. Kotanjyan, T. A. Petrosyan, H. G. Babujyan
For general number of spatial dimensions we investigate the cosmological dynamics driven by a cosmological constant and by a source with barotropic equation of state. It is assumed that for both those sources the energy density can be either positive or negative. Exact solutions of the cosmological equations are provided for flat models. For models with curved space and with zero cosmological constant