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  • Two Efficient Computational Algorithms to Solve the Nonlinear Singular Lane-Emden Equations
    Astrophysics (IF 0.643) Pub Date : 2020-04-02
    K. Parand, A. Ghaderi-Kangavari, M. Delkosh

    In this paper, two efficient computational algorithms based on Rational and Exponential Bessel (RB and EB) functions are compared to solve several well-known classes of nonlinear Lane-Emden type models. The problems, which are define in some models of non-Newtonian fluid mechanics and mathematical physics, are nonlinear ordinary differential equations of second-order over the semi-infinite interval

    更新日期:2020-04-02
  • Characteristics of Hot Quark Matter with Neutrino Confinement
    Astrophysics (IF 0.643) Pub Date : 2020-04-01
    G. S. Hajyan

    The MIT quark bag model is used to determine the thermodynamic characteristics of hot strange quark matter that is opaque to neutrinos. Three different variants of the lepton content of hot quark matter are considered. The numerical calculations are done for different temperatures and lepton charge densities. It is shown that in hot (kT~100 MeV) quark matter there are roughly as many neutrinos as massive

    更新日期:2020-04-01
  • Oscillations of Ellipsoidal Solar Active Regions
    Astrophysics (IF 0.643) Pub Date : 2020-03-26
    G. Dumbadze, B. Shergelashvili

    Four active regions (AR) of the sun are studied. Observational data were obtained from directly visible (line of sight) sharp_cea_720s SDO/HMI magnetograms. The data for each AR were processed by a least squares method in an ellipse. Using a sequence of images after processing the data in all the AR, oscillations of the major and minor axes of the ellipse, as well as of the angles of inclination of

    更新日期:2020-03-26
  • Coronal Holes during the Period of Maximum Asymmetry in the 24th Solar Activity Cycle
    Astrophysics (IF 0.643) Pub Date : 2020-03-26
    O. A. Andreeva, V. I. Abramenko, V. M. Malaschuk

    The current 24th solar activity cycle differs substantially from previous cycles in a number of parameters, especially in terms of a large asymmetry in the number of sunspots (Sp) during the second peak of its maximum. From March 2013 through December 2015. a significant predominance was observed in the number of sunspots in the southern hemisphere. The main purpose of this paper is to clarify the

    更新日期:2020-03-26
  • On the Origin of Optical Radiation during the Impulsive Phase of Flares on dMe Stars. I. Discussion of Gas Dynamic Models
    Astrophysics (IF 0.643) Pub Date : 2020-03-26
    E. S. Morchenko

    In connection with a published critique, the author justifies the use of a motionless homogeneous plane layer of pure hydrogen plasma that is near local thermodynamic equilibrium (LTE) for analyzing the characteristics of the radiation from a chromospheric condensation of thickness ∆z=10 km in a gas dynamic model of stellar flares. It is shown that the shock-wave model of flares proposed by Belova

    更新日期:2020-03-26
  • The Program Magreg for Determining the Longitudinal Component of Stellar Magnetic Fields from Spectropolarimetric Observations
    Astrophysics (IF 0.643) Pub Date : 2020-03-25
    I. S. Savanov

    The computer program magreg in IDL language has been developed for determining the longitudinal component Bz of the magnetic field of stars. The program has been tested on observations of a number of objects at the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAN) using the main stellar spectrograph of the 6-m telescope. The well studied magnetic star γ Equ is used as an

    更新日期:2020-03-25
  • Photometric Investigation of two W UMa Systems
    Astrophysics (IF 0.643) Pub Date : 2020-03-25
    M. I. Nouh, M. M. Elkhateeb

    In the present paper, we obtained the first orbital solution for the newly discovered W UMa systems: GSC 3983-0544 and GSC 4502-1040. We used the most recent version of the Wilson-Devinney code to model the light curves of the two systems. The spectral type of the components of the two systems was adopted and the accepted solutions revealed some absolute parameters, which enable us to draw a preliminary

    更新日期:2020-03-25
  • Filaments of the Large Scale Structure and Primary Scalar and Vector Gravitational Perturbations
    Astrophysics (IF 0.643) Pub Date : 2020-03-25
    I. K. Rozgacheva, I. B. Kuvshinova

    Published data on the observed properties of the filaments (chains of galaxies and groups of galaxies) which dominate the large-scale structure of the universe are collected. Some of these properties are not described in the standard ΛCDM cosmological model. It is found that the properties of galaxies depend on their position inside or near a filament. The hypothesis is advanced that in the early Universe

    更新日期:2020-03-25
  • Photometric Study of Two Galaxies with X-Structures
    Astrophysics (IF 0.643) Pub Date : 2020-03-25
    V. P. Reshetnikov, P. A. Tarakanov, M. V. Kostina

    Data from the SDSS survey are used to study two galaxies with X-structures (UGC 501 and UGC 12253) visible from the edge. Both objects are spiral galaxies of late morphological types with extended stellar disks. The X-structures in the galaxies have different sizes and shapes. The possibility that the different observational parameters of the X-structures in UGC 501 and UGC 12253 are related to different

    更新日期:2020-03-25
  • Study of Rapid Variability of the Blazar OJ 287 in the Radio and Optical Ranges
    Astrophysics (IF 0.643) Pub Date : 2020-03-25
    A. Sukharev, M. Ryabov, V. Bezrukovs, A. Orbidans, M. Bleiders, S. Udovichenko, L. Keir, I. Eglitits, P. Dubovsky

    The extragalactic radio source OJ 287 is one of the most studied blazars. A huge amount of data has been accumulated on it (for more than 40 years in the radio range and more than 100 in the optical). Studies of the rapid variability in the radio flux and stellar magnitude of this object with characteristic times ranging from a few hours to several days are of interest in connection with the possible

    更新日期:2020-03-25
  • Panoramic Spectroscopy of Galaxies with Star Formation Regions. A Study of SBS0750+603B
    Astrophysics (IF 0.643) Pub Date : 2020-03-25
    S. A. Hakopian, S. N. Dodonov, A. V. Moiseev, A. A. Smirnova

    Details of investigation of SBS0750+603B by providing 3D-spectroscopy are presented as part of a study of a sample of about 350 galaxies of star-formation activity. The observations were made on the 6-m telescope at the Special Astrophysical Observatory (SAO) of the Russian Academy of Sciences using the MPFS multi-pupil spectrograph. An analysis of the surface distributions of the major parameters

    更新日期:2020-03-25
  • A Dozen new Dwarf Galaxy Candidates in the Local Volume
    Astrophysics (IF 0.643) Pub Date : 2020-03-25
    I. D. Karachentsev, P. Riepe, T. Zilch

    We carried out a survey of low-surface-brightness companions around nine luminous Local Volume galaxies using long exposures with small amateur telescopes. We found 12 low- and very low-surfacebrightness objects around the galaxies, NGC 628, NGC 2337, NGC 3368, NGC 3521, NGC 4236, NGC 4258, NGC 4594, NGC 5055, and NGC 6744, situated within 12 Mpc from us. Assuming the dwarf candidates are satellites

    更新日期:2020-03-25
  • On the Size and Mass of Galaxy Clusters
    Astrophysics (IF 0.643) Pub Date : 2020-03-25
    H. M. Tovmassian

    We counted galaxies in the area with 10 Mpc radius around 30 isolated ACO clusters at redshifts z < 0.1. We show that surface densities of galaxies around clusters regularly decrease till 10 Mpc. Separate counts of blue and red galaxies of the cluster environment revealed that at all cluster-centric distances the surface density of red galaxies are higher than that of blue ones. The surface density

    更新日期:2020-03-25
  • Study of Faint Galactic Carbon Stars from the First Byurakan Spectral Sky Survey. IV. GAIA DR2 Data
    Astrophysics (IF 0.643) Pub Date : 2020-03-25
    G. R. Kostandyan

    Data from the second Gaia release (Gaia DR2) are used to analyze and evaluate several important parameters for 127 carbon (C) stars of which 56 are AGB stars of class N and 71 are giants of early CH classes detected in low-dispersion spectral plates from the First Byurakan Survey (FBS). For the FBS C-stars Gaia DR2 G broad – band magnitudes are in the range 9m.4 < G < 18m.2. The radial velocities RV

    更新日期:2020-03-25
  • Activity of the Star bScl Observed by the TESS Space Telescope
    Astrophysics (IF 0.643) Pub Date : 2019-11-28
    I. S. Savanov

    The rotational and flare activity of the chemically peculiar star B9.5IIIpHgMnSi βScl is studied using data from the archive of the TESS space mission. Rotational modulation of the brightness is clearly visible in the light curve of this star, along with two flares that have a structure typical of flares in stars of a later spectral class, with a sharp rise, a peak, and a damping stage. The constructed

    更新日期:2019-11-28
  • Gaseous Components of the Seyfert Galaxy NGC 1275 Nucleus In The Epoch 2012
    Astrophysics (IF 0.643) Pub Date : 2019-11-28
    L. M. Sharipova

    The character of the interaction of two gaseous components which are a structural feature of the nucleus of the Seyfert galaxy NGC 1275 is established during the epoch of a minimum in its activity. A bank of emission line profiles (Hβ and O[III] λ5007Å) obtained from observations on the 1.5-m Russian-Turkish telescope (RTT-150) in January 2012 is used. The physical characteristics (Te, ne) of the emission

    更新日期:2019-11-28
  • Conditions for Formation of the Helium HeI 10830 Å Line in The Disk and Magnetospheric Winds of Young Herbig Ae Stars
    Astrophysics (IF 0.643) Pub Date : 2019-11-28
    T. A. Ermolaeva

    The conditions for formation of helium lines in the disk and magnetospheric winds of Herbig Ae stars are studied. The program package CLOUDY is used to solve this problem. It is shown that the optical thickness of the gas in the HeI 10830 Å line needed to explain the observed P Cyg profiles is reached in the disk or magnetospheric winds of Herbig Ae stars for Te ≥ 10000 K. Here the x-ray emission produced

    更新日期:2019-11-28
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