Subjects -> ASTRONOMY (Total: 94 journals)
Showing 1 - 46 of 46 Journals sorted alphabetically
Advances in Astronomy     Open Access   (Followers: 49)
Annual Review of Astronomy and Astrophysics     Full-text available via subscription   (Followers: 50)
Annual Review of Earth and Planetary Sciences     Full-text available via subscription   (Followers: 67)
Artificial Satellites     Open Access   (Followers: 21)
Astrobiology     Hybrid Journal   (Followers: 11)
Astronomical & Astrophysical Transactions: The Journal of the Eurasian Astronomical Society     Hybrid Journal   (Followers: 7)
Astronomical Review     Open Access   (Followers: 5)
Astronomische Nachrichten     Hybrid Journal   (Followers: 4)
Astronomy & Geophysics     Hybrid Journal   (Followers: 49)
Astronomy and Astrophysics     Full-text available via subscription   (Followers: 67)
Astronomy and Computing     Hybrid Journal   (Followers: 6)
Astronomy Letters     Hybrid Journal   (Followers: 22)
Astronomy Reports     Hybrid Journal   (Followers: 22)
Astronomy Studies Development     Open Access   (Followers: 15)
Astroparticle Physics     Hybrid Journal   (Followers: 10)
Astrophysical Bulletin     Hybrid Journal   (Followers: 4)
Astrophysics     Hybrid Journal   (Followers: 35)
Astrophysics and Space Science     Hybrid Journal   (Followers: 49)
Astrophysics and Space Sciences Transactions (ASTRA)     Open Access   (Followers: 60)
Astropolitics: The International Journal of Space Politics & Policy     Hybrid Journal   (Followers: 13)
Celestial Mechanics and Dynamical Astronomy     Hybrid Journal   (Followers: 15)
Chinese Astronomy and Astrophysics     Full-text available via subscription   (Followers: 25)
Colloid Journal     Hybrid Journal   (Followers: 2)
Comptes Rendus : Physique     Open Access   (Followers: 2)
Computational Astrophysics and Cosmology     Open Access   (Followers: 6)
Earth and Planetary Science Letters     Hybrid Journal   (Followers: 142)
Earth, Moon, and Planets     Hybrid Journal   (Followers: 47)
Earth, Planets and Space     Open Access   (Followers: 77)
EAS Publications Series     Full-text available via subscription   (Followers: 8)
EPL Europhysics Letters     Partially Free   (Followers: 8)
Experimental Astronomy     Hybrid Journal   (Followers: 38)
Expert Opinion on Astronomy and Astrophysics     Open Access   (Followers: 8)
Extreme Life, Biospeology & Astrobiology - International Journal of the Bioflux Society     Full-text available via subscription   (Followers: 4)
Few-Body Systems     Hybrid Journal   (Followers: 1)
Foundations of Physics     Hybrid Journal   (Followers: 40)
Frontiers in Astronomy and Space Sciences     Open Access   (Followers: 15)
Galaxies     Open Access   (Followers: 6)
Globe, The     Full-text available via subscription   (Followers: 3)
Gravitation and Cosmology     Hybrid Journal   (Followers: 6)
Icarus     Hybrid Journal   (Followers: 71)
International Journal of Advanced Astronomy     Open Access   (Followers: 21)
International Journal of Astrobiology     Hybrid Journal   (Followers: 4)
International Journal of Astronomy     Open Access   (Followers: 22)
International Journal of Astronomy and Astrophysics     Open Access   (Followers: 36)
International Journal of Satellite Communications Policy and Management     Hybrid Journal   (Followers: 15)
International Letters of Chemistry, Physics and Astronomy     Open Access   (Followers: 8)
ISRN Astronomy and Astrophysics     Open Access   (Followers: 14)
Journal for the History of Astronomy     Full-text available via subscription   (Followers: 20)
Journal of Astrobiology & Outreach     Open Access   (Followers: 5)
Journal of Astronomical Instrumentation     Open Access   (Followers: 3)
Journal of Astrophysics     Open Access   (Followers: 33)
Journal of Astrophysics and Astronomy     Open Access   (Followers: 58)
Journal of Atmospheric and Solar-Terrestrial Physics     Hybrid Journal   (Followers: 133)
Journal of Geophysical Research : Planets     Full-text available via subscription   (Followers: 115)
Journal of Geophysical Research : Space Physics     Full-text available via subscription   (Followers: 134)
Journal of High Energy Astrophysics     Full-text available via subscription   (Followers: 25)
Kinematics and Physics of Celestial Bodies     Hybrid Journal   (Followers: 11)
KronoScope     Hybrid Journal   (Followers: 1)
Macalester Journal of Physics and Astronomy     Open Access   (Followers: 5)
Monthly Notices of the Royal Astronomical Society     Hybrid Journal   (Followers: 13)
Monthly Notices of the Royal Astronomical Society : Letters     Hybrid Journal   (Followers: 2)
Nature Astronomy     Hybrid Journal   (Followers: 14)
New Astronomy     Hybrid Journal   (Followers: 26)
New Astronomy Reviews     Full-text available via subscription   (Followers: 19)
Nonlinear Dynamics     Hybrid Journal   (Followers: 19)
NRIAG Journal of Astronomy and Geophysics     Open Access   (Followers: 4)
Physics of the Dark Universe     Open Access   (Followers: 4)
Planetary and Space Science     Hybrid Journal   (Followers: 106)
Planetary Science     Open Access   (Followers: 52)
Proceedings of the International Astronomical Union     Full-text available via subscription   (Followers: 2)
Publications of the Astronomical Society of Australia     Hybrid Journal   (Followers: 3)
Publications of the Astronomical Society of Japan     Hybrid Journal   (Followers: 4)
Research & Reviews : Journal of Space Science & Technology     Full-text available via subscription   (Followers: 20)
Research in Astronomy and Astrophysics     Full-text available via subscription   (Followers: 38)
Revista Mexicana de AstronomĂ­a y AstrofĂ­sica     Open Access   (Followers: 3)
Science China : Physics, Mechanics & Astronomy     Full-text available via subscription   (Followers: 4)
Science China Physics, Mechanics & Astronomy     Hybrid Journal   (Followers: 4)
Solar Physics     Hybrid Journal   (Followers: 29)
Solar System Research     Hybrid Journal   (Followers: 15)
Space Science International     Open Access   (Followers: 117)
Space Science Reviews     Hybrid Journal   (Followers: 92)
Space Weather     Full-text available via subscription   (Followers: 27)
Transport and Aerospace Engineering     Open Access   (Followers: 13)
Universe     Open Access   (Followers: 6)
Similar Journals
Journal Cover
Astrophysics
Journal Prestige (SJR): 0.225
Number of Followers: 35  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1573-8191 - ISSN (Online) 0571-7256
Published by Springer-Verlag Homepage  [2469 journals]
  • Spottedness Activity of the Young Star TOI 1227 with a Planetary System
           from Lower Centaurus Crux OB Association (Musca)

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      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.
      PubDate: 2022-05-13
       
  • Transition 212-303 May Help for Detection of Methylene in a Cool Cosmic
           Object

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      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.
      PubDate: 2022-05-13
       
  • Circumstellar Properties of the Herbig Be Star HD 259431. I. Signatures of
           Magnetospheric Accretion

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      Abstract: Results are presented from a spectroscopic study of the Ae/Be Herbig star HD 259431 conducted from 2010 to 2019 using high-resolution spectrographs at: (a) the Crimean Astrophysical Observatory, (b) European Southern Observatory ESO (Chile), (c) the OAN SPM Observatory in Mexico, and (d) the Kourovskaya Astronomical Observatory at the Urals Federal University. 245 spectra of the object were obtained in the neighborhood of circumstellar lines (mainly, Hα, Hβ, HeI 5876, FeII 4923, and DNaI), as well as some lines from its atmosphere (HeI 4009, 4026). This article is concerned only with analyzing the cyclical variability of the parameters of some circumstellar lines on a time scale of the order of one day. Antiphase variations in the bisector velocity of the emission profile of Hβ and the velocity of the boundary of the red wing of the HeI 5876 absorption line is observed. A period P = 2.839 days is found in these variations. Assuming that this value may be the period of rotation of the star, an angle of inclination of the axis of rotation to the line of sight of i = 48° ± 7° is estimated. Since at different phases of this period the profiles of Hβ and Hγ looked like either a PCyg-profile or a double emission with a depression on the red side, it was suggested that the observed variability is associated with the existence of a magnetosphere around HD 259431, which has an inclination of the magnetic axis relative to the axis of rotation. In this case over one rotation of the star, along the line of sight an accretion and then an outflow flux of matter occurs, since the regions with these two types of kinematics according to the model lie at different magnetic latitudes. The existence of the magnetosphere is supported by the very high velocities of the boundary of the red wing of the HeI 5876 absorption line (up to +400 km/s), observed at the phases when an accretion flow is on the line of sight. It was found that similar variations are also manifested by the Hδ, HeI 6678, and OI 7773 lines. At the same time, in a number of lines formed in the circumstellar medium, far from the region of the disk/star interaction region, this kind of cyclical variability was not observed. We note that this is the first case of detecting a magnetosphere in a Be Herbig star of such an early class (B6). Earlier it was assumed that magnetospheres cannot be observed in Be Herbig stars. Keywords: Ae/Be Herbig stars: circumstellar shells: disk accretion: wind: HD 259431
      PubDate: 2022-05-13
       
  • Conservation Laws in Time-Dependent Radiative Transfer Problems

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      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.
      PubDate: 2022-05-13
       
  • 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

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      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.
      PubDate: 2022-05-13
       
  • Properties of Hot Quark Matter with Neutrino Confinement in the NJL Model

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      Abstract: The thermodynamic characteristics of hot β-equilibrium three-flavor quark matter with neutrino confinement are studied in terms of the local SU(3) Nambu-Jona-Lasinio (NJL) model, which also accounts for the ‘t Hooft interaction which leads to mixing of quark flavors. For different temperatures T ∈ [20 ÷100] MeV and baryon number densities nB ∈ [0 ÷ 1.8] fm-3 the constituent quark masses, quark condensates, and relative contributions of individual types of particles to the pressure and chemical potentials of the constituent particles are determined. In order to determine the role of neutrinos in the hot quark matter, the pressures and energies in states with and without neutrinos are compared.
      PubDate: 2022-05-13
       
  • The Red Giants EK Eri and OU And as Probable Descendents of Ap-stars: A
           Search for Abundance Anomalies

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      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.
      PubDate: 2022-05-13
       
  • Compton Scattering in Plane Media: Polarization of Radiation and Azimuth
           Independence. I. Theory

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      Abstract: Compton scattering of polarized radiation by a nondegenerate and unpolarized electron gas is examined. Two polarization bases are introduced for pulses of photons: external, connected with the geometry of the medium and internal, connected with a scattering event. Starting with a general relativistic kinetic equation describing the multiple effect of the mechanism taking induced processes into account, it is shown that for describing a stationary, azimuthally independent radiation field in a plane layer, two Stokes parameters for linear polarization are sufficient. The features of the redistribution functions (RF) in frequency and direction are clarified, as well as the rotation angles from internal bases to external ones, and back which arise with forward and backward scattering. An algorithm is proposed for eliminating singularities during azimuthal averaging. The azimuthal averages from the most singular term of the RF are expressed in terms of elliptical integrals of the first kind.
      PubDate: 2022-05-13
       
  • Asynchronous Rotation of a Massive Star in Close Binary Systems

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      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.
      PubDate: 2022-05-13
       
  • Study of the Rapid Variability of the BL Lac Object MRK 421 in the Optical
           Range

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      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.
      PubDate: 2022-05-13
       
  • Several Star-Formation Regions in the Southern Hemisphere

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      Abstract: Three new star-formation regions in the Southern Hemisphere, SFR 1, SFR 2, and SNO 28 are presented. SFR 1 is located in a dark globule with a rim, which lies in a radial system of dark globules of the first kind and represents a group of mainly IR stars, many of which are related to dust disks or envelopes. Two of the stars are related to cometary nebulae. They include Herbig-Haro objects. SFR 2 is in a dark cloud. There are stars with cometary nebulae, dust envelopes, or disks. From a star with a conical nebula a jet with a condensation is observed. SNO 28 is a star that has a dust disk with two opposite jets. One of the jets and part of the second are embedded in a dark cloud and are visible only in the IR. The outer part of the second jet emerges from the cloud and can be seen only in the visible. The second jet contains a condensation which may be a Herbig-Haro object. This object is related to the point source IRAS 08196-4931 which has IR colors typical of sources associated with water masers.
      PubDate: 2021-12-01
      DOI: 10.1007/s10511-021-09708-w
       
  • White Dwarfs in a Uniform Sphere Approximation, with General Relativity
           Effects Taken into Account

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      Abstract: The limiting mass of cold white dwarfs was first calculated by E. Stoner in an approximate model of a uniform star and was soon reduced by ~20% in papers by S. Chandrasekhar and L. D. Landau based on an exact solution of the equations for the stellar equilibrium. Here we examine uniform models of white dwarfs taking general relativity effects and the influence of finite temperature into account. Solutions are obtained in the form of finite analytic formulas and, for masses differing by no more than ~20% from the exact solutions, found by numerical integration of the differential equations for the stellar equilibrium.
      PubDate: 2021-12-01
      DOI: 10.1007/s10511-021-09711-1
       
  • Time Dependent Radiative Transfer Problems in a One-Dimensional Medium

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      Abstract: The solution of several one-dimensional problems in nonstationary radiative transfer at frequencies in a spectral line is given. An approach based on searching for the unknowns in the form of Neumann series expansions is applied. The evolution of the line profile formed during reflection from a semi-infinite atmosphere is studied both with coherent and with fully incoherent scattering in the medium. The time dependence of the profiles formed at the boundaries of a finite atmosphere is also examined. In the two problems it is assumed that the atmosphere is illuminated by radiation either in the form of a δ(t) –pulse or by radiation with a unit intensity pulse. The solution takes into account both possible causes of time loss by photons during diffusion in the medium: the time spent by an atom in an excited state and the time lost by photons in passing between two successive scattering events. It is shown that with this general statement of the problem, the resultant probability density distribution function of the emerging radiation is given by a convolution of the distributions corresponding to the two components of the photon time expenditure.
      PubDate: 2021-12-01
      DOI: 10.1007/s10511-021-09710-2
       
  • Environmental Dependence of All the Five Band Luminosities of Active
           Galactic Nucleus (AGN) Host Galaxies

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      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 u-, g-, r-, i- and z -band luminosities of AGN host galaxies. We divide the whole apparent-magnitude limited AGN sample into many subsamples with redshift binning size ∆z = 0.01, and analyse the environmental dependence of all the five band luminosities of subsamples in each redshift bin. It turns out that overall, all the five band luminosities of AGN host galaxies are weakly correlated with the local environment.
      PubDate: 2021-12-01
      DOI: 10.1007/s10511-021-09706-y
       
  • Fermionic Condensate in de Sitter Spacetime

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      Abstract: Fermionic condensate is investigated in (D + 1)-dimensional de Sitter spacetime by using the cutoff function regularization. In order to fix the renormalization ambiguity for massive fields an additional condition is imposed, requiring the condensate to vanish in the infinite mass limit. For large values of the field mass the condensate decays exponentially in odd dimensional spacetimes and follows a power law decay in even dimensional spacetimes. For a massless field the fermionic condensate vanishes for odd values of the spatial dimension D and is nonzero for even D. Depending on the spatial dimension the fermionic condensate can be either positive or negative. The change in the sign of the condensate may lead to instabilities in interacting field theories.
      PubDate: 2021-12-01
      DOI: 10.1007/s10511-021-09713-z
       
  • Dust Luminescence and Gas Fluorescence in the CED 201 Nebula

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      Abstract: Physical and chemical properties of the dust in the nebula CED 201 are studied. Luminescence emissions of frozen hydrocarbon particles and diamond dust are revealed in the spectrum of this nebula. A brief catalog of the fluorescence emissions of atoms and ions of the gaseous component of matter in this nebula is presented. Several other aspects of the problem are discussed.
      PubDate: 2021-12-01
      DOI: 10.1007/s10511-021-09709-9
       
  • Multicolor Photometry of the WZ Sge-Type Cataclysmic Variable AY Lac

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      Abstract: During the outburst of the dwarf nova AY Lac in October 2020, the authors obtained more 2200 CCD-frames in UBVRcIc-bands of the variable. An analysis of the observed photometric series showed that superhumps were observed on this type SUWZ star both before early on and in the “B” stage, with periods of 0d.058074 and 0d.059418, respectively. The change in the shape of the superhumps during the outburst was studied, values of Pdot = P / P = 6.6 ∙10-5 and a period excess of ε = 0.024 were found, and a most probable ratio q = 0.11 of the masses of the components was estimated, as well as color temperatures and a number of other quantities. It is shown that AY Lac is a typical WZ Sge-type star in terms of all the characteristics that were studied.
      PubDate: 2021-12-01
      DOI: 10.1007/s10511-021-09707-x
       
  • Modified Renyi Holographic Dark Energy (MRHDE) in f(R, T) Theory of
           Gravity

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      Abstract: In this work, we investigate the dynamics of Bianchi type VI0 space-time in the framework of f(R, T) theory of gravity where R stands for Ricci scalar and T stands for the trace of the stress energy-momentum tensor with Modified Renyi Holographic Dark Energy (MRHDE). With the specific choice of the functional f(R, T) = f1(R) + f2 (T) = μ1 R+ μ2 T where f1(R) and f2 (T) are arbitrary functions of R and T respectively and μ1 and μ2 are two parameters, we have obtained the exact solutions of the model by considering the energy density of MRHDE and by using a law of variation for the Hubble parameter H. It is found that our model leads to the accelerated expansion of the Universe. The EOS parameter ωDE > -1 DE indicates that our cosmological model behaves like a quintessence dark energy model which is consistent with the recent observations. A correspondence between MRHDE and quintessence dark energy is established. The quintessence dynamics of the potential and scalar field are reconstructed, which illustrates the late-time cosmic acceleration. All physical parameters are calculated and discussed graphically.
      PubDate: 2021-12-01
      DOI: 10.1007/s10511-021-09712-0
       
  • Discrepancy between Values of the Hubble Constant Obtained by Different
           Methods

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      Abstract: The discrepancy in the values of the Hubble constant determined for the “early” and “late” universe is examined. It is noted that in determining the first value the physical properties of baryonic matter do not appear explicitly, while in the second case the velocities of cosmic objects based on redshift measurements are used for determination of the same coefficient. The hypothesis is advanced that the discrepancy may be related to the evolution of baryonic matter. An analysis shows that a change in the masses of atomic nuclei and elementary particles by a fraction of 6.67·10-12 per year may lead to the observed discrepancy. This result is consistent with our previous conclusion regarding the increase in the Sun’s mass owing to the evolution of baryonic matter.
      PubDate: 2021-12-01
      DOI: 10.1007/s10511-021-09705-z
       
  • Correction to: Light Curve Analysis of some Eclipsing Binary Systems

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      PubDate: 2021-09-01
      DOI: 10.1007/s10511-021-09699-8
       
 
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