Astrophysics最新文献

{"title":"Isospin-Asymmetric Cold Nuclear Matter in the Relativistic Mean-Field Theory with a Scalar-Isovector Interaction Channel","authors":"G. B. Alaverdyan,&nbsp;A. G. Alaverdyan","doi":"10.1007/s10511-024-09829-y","DOIUrl":"10.1007/s10511-024-09829-y","url":null,"abstract":"<p>The properties of isospin-asymmetric cold nuclear matter are studied in terms of the relativistic mean-field theory in which, besides the fields of σ, ω, and ρ mesons, and the isovector, Lorentz-scalar field of the δ-meson is also taken into account. The properties of purely nucleonic <i>np</i> matter are studied as a function of the baryon density <i>n</i>_<i>B</i> and the asymmetry parameter α, as well as the properties of electrically neutral β-equilibrium <i>npe</i> μ matter as a function of the baryon density <i>n</i>_<i>B</i><i>.</i> For different values of <i>n</i>_<i>B</i> and a, such characteristics of <i>np</i> matter as the energy per baryon, the specific energy owing to isospin asymmetry, the effective proton and neutron masses, and the specific binding energy, are determined. It is shown that the energy owing to the asymmetry for a fixed value of α is a monotonically increasing function of the baryon density <i>n</i>_<i>B</i>. For <i>npe</i>m matter, the effective proton and neutron masses <span>({M}_{p}^{left(effright)},{M}_{n}^{left(effright)},)</span> the specific binding energy <i>E</i>_<i>bind</i>, the symmetry energy <i>E</i>_<i>sym</i>, the quantitative fraction of protons <i>Y</i>_<i>p</i> = <i>n</i>_<i>p</i>/<i>n</i>_<i>B</i> are studied, as well as the average meson fields <span>(widetilde{upsigma },widetilde{upomega },widetilde{updelta },)</span> and <span>(widetilde{uprho })</span> as functions of the baryon density <i>n</i>_<i>B</i><i>.</i></p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"67 2","pages":"215 - 230"},"PeriodicalIF":0.6,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141869721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reconstruction of the Quintessence Dark Energy Potential from a Gaussian Process","authors":"E. Elizalde,&nbsp;M. Khurshudyan,&nbsp;K. Myrzakulov,&nbsp;S. Bekov","doi":"10.1007/s10511-024-09828-z","DOIUrl":"10.1007/s10511-024-09828-z","url":null,"abstract":"<p>This paper presents the reconstruction of the quintessence dark energy potential in a model- independent way. Reconstruction relies on a Gaussian process and on available expansion rate data. Specifically, 40-point values of H(z) are used, consisting of a 30-point sample deduced from a differential age method and an additional 10-point sample obtained from the radial BAO method. Results are obtained for two kernel functions and for three different values of H₀. This sheds light on the H₀ tension problem indicating that it is not just a numerical problem. The model-independent reconstruction of the potential can serve as a reference to constraint available models and construct new ones. Various possibilities, including V(ϕ) ~ e^-λϕ , are compared with the reconstructions here obtained, which is notably the first truly model-independent reconstruction of the quintessence dark energy potential. This allows the selection of new models that can be interesting for cosmology. The method can be extended to reconstruct the potential of related dark energy models, to be considered in future work.</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"67 2","pages":"192 - 214"},"PeriodicalIF":0.6,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141869716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electromagnetic Properties of Stellar Matter. I. Dielectric Permeability of a Hot Rarefied Plasma with Abundant Production of Electron-Positron Pairs","authors":"G. S. Hajyan,&nbsp;A. S. Harutyunyan","doi":"10.1007/s10511-024-09827-0","DOIUrl":"10.1007/s10511-024-09827-0","url":null,"abstract":"<p>The Vlasov equations are used to determine the transverse and longitudinal dielectric permeabilities of a hot, rarefied ultrarelativistic electron-positron plasma. The Fermi distribution is used as the unperturbed distribution function of the electrons and positrons. It is shown that, owing to the abundant production of electron-positron pairs, the plasma frequency of the ultrarelativistic plasma increases linearly with rising temperature. Here the ratio of the frequency at which the spectral density of the equilibrium emission is maximal to the plasma frequency remains fixed and equals 28. It is shown that in this sort of plasma, in particular in the matter of the early universe in the ultrarelativistic electronpositron epoch, the spectrum of the radiation differs very little from black-body radiation.</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"67 2","pages":"178 - 191"},"PeriodicalIF":0.6,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141869718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photometric Study of the Asynchronous Polar IGR J19552+0044 in 2019-2022","authors":"Ju. V. Babina,&nbsp;E. P. Pavlenko,&nbsp;N. V. Pit,&nbsp;K. A. Antonyuk,&nbsp;A. A. Sosnovskij,&nbsp;V. G. Godunova,&nbsp;I. A. Izviekova,&nbsp;G. I. Kokhirova,&nbsp;F. D. Rakhmatullaeva,&nbsp;A. O. Simon,&nbsp;M. V. Chupira","doi":"10.1007/s10511-024-09825-2","DOIUrl":"10.1007/s10511-024-09825-2","url":null,"abstract":"<p>This paper is an analysis of data from multicolor photometric observations of the asynchronous polar IGR J19552+0044 obtained over 59 nights from 2019-2022 at the Crimean Astrophysical Observatory, as well as at the Terskol Peak, Sanglokh, and Lesniki Observatories, and data from the TESS space telescope obtained on 27 days in 2022. It is shown that the maximum amplitude of the brightness oscillations at the rotation period of the white dwarf (~2^m.5-3^m) is observed in the Ic band and is essentially close to zero in the B band. The rotation period of the white dwarf is refined to 0.05645350(14) days. A dependence of the amplitude of the brightness curve of the rotation period on the phase of the synodic period is detected.</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"67 2","pages":"149 - 160"},"PeriodicalIF":0.6,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141869717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"BSN: First Light Curve Study of the Low Mass Contact Binary V0610 Vir","authors":"A. Alizadehsabegh,&nbsp;F. Lomoz,&nbsp;A. Poro,&nbsp;A. Narimani","doi":"10.1007/s10511-024-09823-4","DOIUrl":"10.1007/s10511-024-09823-4","url":null,"abstract":"<p>Photometric data were used to perform the first light curve analysis of the V0610 Vir binary system. Observations and analysis were done in the form of the Binary Systems of South and North (BSN) Project. We extracted the minima from our observations and compiled the literature, which was few. Therefore, we performed computations using the reference ephemeris and presented a new ephemeris and O-C diagram with a linear fit. Light curve analysis was performed using the PHOEBE Python code and the Markov chain Monte Carlo (MCMC) approach. The assumption of a hot starspot was required due to the asymmetry in the light curve’s maxima. The analysis shows that V0610 Vir is a contact binary system with a fillout factor of 0.085, a mass ratio of 0.998, and an inclination of 70°.65. The absolute parameters of the system were estimated based on the Gaia DR3 parallax method. The results show that the system is a low-mass contact binary with a total mass lower than 0.8 M_⨀. The location of the stars was shown in the M - L and M - R diagrams.</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"67 2","pages":"128 - 139"},"PeriodicalIF":0.6,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141869720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transverse Gradients of Longitudinal Magnetic Field in Active Regions with Different Levels of Flare Productivity. II. Statistical Analysis","authors":"Yu. A. Fursyak","doi":"10.1007/s10511-024-09818-1","DOIUrl":"10.1007/s10511-024-09818-1","url":null,"abstract":"<p>Here, we performed a statistical analysis of the parameters describing the transverse component of the longitudinal magnetic field gradient (∇ _⊥ <b><i>B </i></b>_<i>z</i> ) in the active regions of the AR – the AR-averaged transverse component of the longitudinal magnetic field gradient &lt;∇ _⊥ <b><i>B z</i></b> &gt;, the average transverse component of the longitudinal magnetic field gradient in the vicinity of a point with its maximum value &lt;max∇ _⊥ <b><i>B z</i></b> &gt;, the maximum value of the transverse component of the longitudinal magnetic field gradient between pairs of spots in the AR max(∇ _⊥ <b><i>B </i></b>_<i>z</i> ) _<i>sp</i> . For calculating the denoted parameters, magnetograms of the <b><i>B</i></b> _z -components of the magnetic field vector at the level of the Sun’s photosphere obtained by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) are used. The statistical sample contains data on 75 ARs. The values of the analyzed parameters obtained over the time of monitoring are compared with the level of flare productivity of the AR (the flare index FI). It is shown that: 1. The <span>(langle overline{{nabla }_{perp }{{varvec{B}}}_{z}}rangle )</span> -FI dependence (the overhead line denotes averaging over the time of monitoring the AR) is quadratic with a correlation coefficient k = 0.54 while the spread in values of the quantity <span>(langle overline{{nabla }_{perp }{{varvec{B}}}_{z}}rangle )</span> is small (lying within a a range of 0.08-0.12 G km^-1 for the overwhelming majority of the studied regions) and differs very little for regions with low and high flare productivity, which may be explained by the dependence of ∇ _⊥ <b><i>B </i></b>_<i>z</i> on the area of the AR. 2. The dependence <span>(langle overline{{text{max}}{nabla }_{perp }{{varvec{B}}}_{z}}rangle )</span> -FI is quasilinear with a correlation coefficient k = 0.61. 3. The dependence <span>(overline{{text{max}}{nabla }_{perp }{{varvec{B}}}_{z}})</span> -FI is linear with a correlation coefficient k = 0.63. 4. The threshold values of the analyzed parameters are found: for <span>(langle overline{{nabla }_{perp }{{varvec{B}}}_{z}}rangle )</span> ≥ 0.078 G km^-1, for <span>(langle overline{{text{max}}{nabla }_{perp }{{varvec{B}}}_{z}}rangle )</span> ≥ 0.983 G km^-1, and for the parameter max(∇ _⊥ <b><i>B </i></b>_<i>z</i>) _<i>sp</i> ≥ 0.118G km^-1. For lower values of the analyzed parameters, no x-ray flares were recorded in any of the ARs of the analyzed sample.</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"67 1","pages":"67 - 79"},"PeriodicalIF":0.6,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140964523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photometric and Spectral Studies of a Group of Wolf-Rayet Galactic Stars. II. WC and WO Sequences","authors":"L. N. Kondratyeva,&nbsp;I. V. Reva,&nbsp;E. K. Denissyuk,&nbsp;S. A. Shomshekova,&nbsp;A. K. Aimanova","doi":"10.1007/s10511-024-09812-7","DOIUrl":"10.1007/s10511-024-09812-7","url":null,"abstract":"<p>Photometric and spectral observations of 7 stars in the WC and WO sequences were made at the Fesenkov Astrophysical Institute in 2021-2022. These observations served as the basis of estimates of the brightness of the objects in BVRc filters and the absolute fluxes of radiation in the emission lines. Changes in the brightness of WR 121 over the limits of 0^m.1-0^m.15 were recorded. Changes in the fluxes of emission lines were detected in the spectra of several of the objects, WR 4, WR 5, WR 121, and WR 128.</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"67 1","pages":"9 - 23"},"PeriodicalIF":0.6,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140964945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetic Field Structures of Chemically Peculiar Stars. II. HD98088, HD182180, HD221218, HD318107","authors":"Yu. V. Glagolevskij","doi":"10.1007/s10511-024-09814-5","DOIUrl":"10.1007/s10511-024-09814-5","url":null,"abstract":"<p>Based on published data on the magnitudes of the magnetic field, models are constructed of several magnetic stars of different types of peculiarity and the parameters of the magnetic field are obtained. Among the hot objects, differences are also discovered in the physical conditions in the regions of the magnetic equators and in the region near the magnetic poles, which are not yet amenable to interpretation.</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"67 1","pages":"35 - 47"},"PeriodicalIF":0.6,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141062255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Physical Acceptability of the Renyi Holographic Dark Energy Model Under the Hubble's Cutoff in f (T, B) Gravity","authors":"N. T. Karte,&nbsp;Kaplana Pawar,&nbsp;A. K. Dabre","doi":"10.1007/s10511-024-09820-7","DOIUrl":"10.1007/s10511-024-09820-7","url":null,"abstract":"<p>The paper deals with the investigations of the behaviour and physical acceptability of the spatially homogeneous and isotropic FLRW space-time filled with pressureless matter and Rényi holographic dark energy under the Hubble's IR-cutoff in the framework of f (T, B) gravity. We have calculated some cosmological parameters to study the astrophysical consequences of the constructed model. We discussed their behaviour during the cosmic evolution, in particular, the statefinder and EoS parameters. It is found that the constructed Rényi holographic dark energy model travels from Phantom, ΛCDM, and lastly enters &amp; remains in Quintessence dark energy era with the increase in redshift.</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"67 1","pages":"93 - 109"},"PeriodicalIF":0.6,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141062302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Digitized First Byurakan Survey Database Late-Type Stars Candidates. New Confirmations. II","authors":"K. K. Gigoyan,&nbsp;K. S. Gigoyan,&nbsp;A. Sarkissian,&nbsp;M. Meftah,&nbsp;S. Bekki,&nbsp;E. Karapetyan,&nbsp;F. Rahmatullaeva,&nbsp;G. R. Kostandyan","doi":"10.1007/s10511-024-09817-2","DOIUrl":"10.1007/s10511-024-09817-2","url":null,"abstract":"<p>Three new carbon C stars was confirmed among the sample of the Late-Type Stars candidates, selected on the Digitized First Byurakan Survey (DFBS) spectral plates. The 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 UV-excess (Markarian) galaxies. FBS spectral plates have been used long period to search and study faint LTS (C-type and M-type stars) at high Galactic latitudes. In this work we present Gaia DR3 photometric data, spectra, light curves, distances, high above/below Galactic plane, radial velocities (RV), and other important physical characteristics from the modern astronomical catalogues for three new confirmed DFBS C stars. The confirmation is based on Gaia DR3 BP/RP low-resolution spectral database. In our previous studies of the DFBS plates, these objects were presented as LTS candidates. One of the new confirmed objects is N-type C star, which is a Mira-type variable. Two remaining objects, are early CH-type giants at high Galactic latitudes. Most probably they present binary systems.</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"67 1","pages":"60 - 66"},"PeriodicalIF":0.6,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141064126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}