Astronomy Letters-A Journal of Astronomy and Space Astrophysics最新文献

{"title":"Identification of Radio and Gamma-ray Pulsars in X-rays Using Data from the SRG/eROSITA All-Sky Survey","authors":"Yu. A. Shibanov,&nbsp;A. V. Karpova,&nbsp;D. A. Zyuzin,&nbsp;M. R. Gilfanov","doi":"10.1134/S1063773725700288","DOIUrl":"10.1134/S1063773725700288","url":null,"abstract":"<p>We have identified the radio and gamma-ray pulsars known in the eastern half of the sky in the soft X-ray band using data from the all-sky X-ray survey performed by the eROSITA telescope onboard the Spectrum–Roentgen–Gamma observatory. As a result, we have found new candidate counterparts for 12 pulsars of different ages and types at a confidence level <span>({gtrsim}3sigma)</span>. A comparable number has been previously identified in the western half of the sky. In total, this accounts for about 12<span>(%)</span> of the number of known pulsars that have already been detected in X-rays. We give estimates of the X-ray fluxes from the new counterparts, preliminary characteristics of their X-ray spectra, and brief descriptions of the properties of the pulsars themselves. The telescope has also detected 56 pulsars in the eastern half of the sky previously identified in X-rays by other observatories.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 3","pages":"127 - 137"},"PeriodicalIF":0.8,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145612990","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":"Geodetic Nutation of Celestial Bodies in the Jovian Satellite System","authors":"V. V. Pashkevich,&nbsp;A. N. Vershkov","doi":"10.1134/S1063773725700380","DOIUrl":"10.1134/S1063773725700380","url":null,"abstract":"<p>We investigate the relativistic effect of geodetic nutation in the rotation of Jupiter and its 94 satellites, for which the ephemerides are known, around their axes on an 800-year time interval. The most significant periodic terms of the geodetic rotation of these celestial bodies have been determined for the first time: (1) for Jupiter relative to the Solar System Barycenter and the plane of the mean orbit of Jupiter at epoch J2000.0 in the Euler angles, in the perturbing terms of the physical libration and in the absolute value of the angular rotation vector of the geodetic rotation of the body under study; (2) for eight regular (four inner (Metis J16, Adrastea J15, Amalthea J5, Thebe J14) and four Galilean (Io J1, Europa J2, Ganymede J3, Callisto J4)) satellites of Jupiter relative to: (a) the Solar System Barycenter and the plane of the mean orbit of the satellite under study at epoch J2000.0 in the Euler angles, in the perturbing terms of the physical libration and in the absolute value of the angular rotation vector of the geodetic rotation of the body under study; (b) the Solar System Barycenter and the plane of the mean orbit of the Jovian System Barycenter at epoch J2000.0 in the Euler angles, in the perturbing terms of the physical libration and in the absolute value of the angular rotation vector of the geodetic rotation of the body under study; (c) the Jovian System Barycenter and the plane of the mean orbit of the satellite under study at epoch J2000.0 in the perturbing terms of the physical libration and in the absolute value of the angular rotation vector of the geodetic rotation of the body under study; (3) for 86 irregular satellites (J6–J13, J17–J72, J5501–J5507, J5509–J5523) of Jupiter in the absolute value of the angular rotation vector of the geodetic rotation of the body under study relative to: (a) the Solar System Barycenter; (b) the Jovian System Barycenter. The calculated analytical values of the geodetic nutation of the celestial bodies under study can be used to numerically study the rotation of these bodies in the relativistic approximation.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 4","pages":"236 - 246"},"PeriodicalIF":0.8,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145612919","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":"On New X-ray Features of the Vela Pulsar Wind Nebula","authors":"K. P. Levenfish,&nbsp;G. A. Ponomaryov,&nbsp;A. N. Fursov","doi":"10.1134/S1063773725700318","DOIUrl":"10.1134/S1063773725700318","url":null,"abstract":"<p>Pulsar wind nebulae are the nearest space laboratories to Earth for studying a collisionless, strongly magnetized electron-positron plasma. One way to study this plasma is to construct relativistic magnetohydrodynamic (MHD) models of nebulae. These models aim to reveal, among other things, the nature of MHD structures in highly magnetized nebular flows responsible for the appearance of various features in X-ray images of nebulae—arcs, jets, tori, and so on. This paper examines the predictive potential of a recently constructed MHD model of a compact pulsar wind nebula with a double-torus X-ray morphology. The model predicts the following. Within the volume of a compact double-torus nebula, flows of highly magnetized plasma should be relativistic and quasi-laminar and may form regular folds. As they approach the outer boundary of the double torus, these flows should split into two parts. Large-scale plumes of magnetic plasma, splitting off from these flows toward the nebula’s equator, can sporadically penetrate into the opposite hemisphere of the nebula, where the plasma has reversed magnetic polarity. The base of the nebula’s leeward jet should be surrounded by a regular, toroidal magnetic vortex. We show that these predictions are supported by archival Chandra observations of Vela, the double-torus nebula of the pulsar PSR J0835–4510. The model also explains the origin of some of the diffuse X-ray emission around the double-torus of Vela.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 3","pages":"151 - 176"},"PeriodicalIF":0.8,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145612988","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":"Polarization and a Model for the Dust Shell of the Carbon-rich post-AGB Object IRAS 22272(+)5435 (V354 Lac)","authors":"N. P. Ikonnikova,&nbsp;B. S. Safonov","doi":"10.1134/S1063773725700367","DOIUrl":"10.1134/S1063773725700367","url":null,"abstract":"<p>We present the observations of the carbon-rich post-AGB object IRAS 22272<span>(+)</span>5435 performed in the 550, 625, and 880 nm bands by the method of differential speckle polarimetry with the 2.5-m telescope of the Caucasus Mountain Observatory. A shell has been detected at an angular distance of <span>(1^{primeprime})</span> from the star in all bands. The infrared (IR) source IRAS 22272<span>(+)</span>5435 is associated with the semiregular variable star V354 Lac. Apart the quasi-periodic variability caused by pulsations, an increase in the near-IR (<span>(KLM)</span>) brightness due to an additional dust ejection was observed in the period from 1996 to 2004 (Ikonnikova et al. 2025). We have constructed a model of the circumstellar dust shell that reproduces well (within the adopted model assumptions) the observed spectral energy distribution and the polarized flux distribution in the visible range. The model is consistent with the observations performed by the method of differential speckle polarimetry in 2020. We have obtained the following parameters of the star and its dust shell. For the distance <span>(d=1410)</span> pc derived from the Gaia DR3 parallax the luminosity of the star is <span>(L=6600,L_{odot})</span>. The dust shell in our model consists of four components formed by the isotropic wind and the superwind at the AGB stage as well as by the isotropic wind and the equatorial ejection at the post-AGB phase. The dust masses in these shells are <span>(3times 10^{-9})</span>, <span>(6.9times 10^{-7})</span>, <span>(3times 10^{-4})</span>, and <span>(1.3times 10^{-4},M_{odot})</span>, respectively. The increase in the IR flux in 1996–2004 is explained in the model by the separate ejection of a dust cloud with a mass of <span>(6times 10^{-10},M_{odot})</span> whose velocity is estimated to be 60 km s<span>({}^{-1})</span>.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 4","pages":"210 - 224"},"PeriodicalIF":0.8,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145612846","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":"SRG/ART-XC All-Sky X-ray Survey: Sensitivity Assessment Based on Aperture Photometry","authors":"N. Yu. Tyrin,&nbsp;R. A. Krivonos,&nbsp;V. A. Arefiev,&nbsp;R. A. Burenin,&nbsp;E. I. Zakharov,&nbsp;A. A. Lutovinov,&nbsp;S. Yu. Sazonov,&nbsp;A. D. Samorodova,&nbsp;E. V. Filippova,&nbsp;A. S. Abbakumov,&nbsp;V. V. Konoplev,&nbsp;F. V. Korotkov,&nbsp;V. N. Nazarov","doi":"10.1134/S106377372570029X","DOIUrl":"10.1134/S106377372570029X","url":null,"abstract":"<p>The Spectrum-Roentgen-Gamma (SRG) observatory continues to operate successfully in orbit at the Lagrange point L2. The <i>Mikhail Pavlinsky</i>\u0000 <i>ART-XC</i> telescope has demonstrated high efficiency in conducting X-ray surveys both over large sky regions and the entire celestial sphere. A recently published source catalog, based on data from the first four and partially completed fifth sky scans, contains 1545 objects detected in the 4–12 keV energy range. In this work, using the same sky survey data, we assess the sensitivity to point source detection across the celestial sphere based on X-ray aperture photometry—that is, we calculate the upper flux limit in the 4–12 keV band at any given significance level. The method is implemented using both Poisson statistics and Bayesian inference, with consistent results between the two approaches. This information is important for studying variable and transient X-ray sources, as well as sources that are not detected with sufficient statistical significance in the <i>ART-XC</i> all-sky survey. The <i>ART-XC</i> upper limit service is available at https://www.srg.cosmos.ru/uplim.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 3","pages":"138 - 142"},"PeriodicalIF":0.8,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145612989","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":"Total Solar Irradiance Variations from Data on the ({}^{mathbf{10}})Be Concentration in Antarctic Ice","authors":"M. G. Ogurtsov","doi":"10.1134/S1063773725700392","DOIUrl":"10.1134/S1063773725700392","url":null,"abstract":"<p>Recently, a series of long-term reconstructions of the total solar irradiance (TSI) has been obtained. They indicate that the amplitude of its secular variations does not exceed 1 W/m<span>({}^{2})</span>. Such a small amplitude suggests a very weak influence of TSI on the Earth’s climate change both in the past and in the future. In this paper it is shown that the data on the concentration of cosmogenic beryllium in Central Antarctica ices fit poorly into the small-amplitude scenario. The <span>({}^{10})</span>Be concentration variations in Antarctic ice indicate that the increase in TSI can reach 1.4–2.7 W/m<span>({}^{2})</span> after the end of the Maunder minimum (the end of the 17th century) and up to 3.4 W/m<span>({}^{2})</span> after the Spörer minimum (the first half of the 15th century). The causes of the remaining uncertainties and the direction of further studies are discussed.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 4","pages":"247 - 255"},"PeriodicalIF":0.8,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145612918","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":"Non-conservative Mass Transfer in the Neutron Star Stripping Model","authors":"N. I. Kramarev,&nbsp;A. V. Yudin","doi":"10.1134/S1063773725700306","DOIUrl":"10.1134/S1063773725700306","url":null,"abstract":"<p>The process of long-duration stable mass transfer (or stripping) in a close neutron star binary system is possible at a sufficiently large initial asymmetry of the component masses. At the final stage of the evolution of such systems the low-mass neutron star fills its Roche lobe, whereupon its mass is gradually transferred to the more massive component. At some instant of time the transfer stability is lost, causing the minimum-mass neutron star to explode. In the stripping calculations the effect of non-conservative mass transfer has been taken into account for the first time, leading to an increase in the duration of stable mass transfer from a few tenths of a second to a few seconds. This allows the time delay of 1.7 s between the loss of the gravitational-wave signal and the detection of the gamma-ray burst from the multimessenger event GW170817–GRB170817A to be naturally explained. The interaction of the envelope of the exploded minimum-mass neutron star with the matter ejected during non-conservative mass transfer may explain two episodes in the light curve of this gamma-ray burst.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 3","pages":"143 - 150"},"PeriodicalIF":0.8,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145612987","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 Impact of Metallicity on the Period–Luminosity Relation of Mira Variables","authors":"Yu. A. Fadeyev","doi":"10.1134/S106377372570032X","DOIUrl":"10.1134/S106377372570032X","url":null,"abstract":"<p>Evolution of stars with initial masses <span>(M_{textrm{ZAMS}}=1.1)</span>, <span>(1.3)</span>, and <span>(1.5;M_{odot})</span> and relative mass abundances of metals <span>(Z=0.006)</span> and 0.02 was computed from the main sequence up to the final AGB stage. Selected models of evolutionary sequences were used as initial conditions for solution of the equations of hydrodynamics describing pulsations of red giants, whereas for each evolutionary sequence of Mira variables pulsating in the fundamental mode we determined the theoretical period–luminosity relation. A change in the metal abundance is shown to substantially affect the period–luminosity relation because of significant growth of the slope with decreasing <span>(Z)</span>. In particular, Mira variables of the LMC (<span>(Z=0.006)</span>) with periods from 200 to 300 days are brighter by 0.2–0.5 mag than galactic Mira variables (<span>(Z=0.02)</span>) with same pulsation periods. The low boundary of fundamental mode pulsations changes from <span>(Piapprox 70)</span> day for <span>(Z=0.02)</span> to <span>(Piapprox 120)</span> day for <span>(Z=0.006)</span>.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 3","pages":"177 - 181"},"PeriodicalIF":0.8,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145612991","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":"Absorption in the 21 cm Hydrogen Line at (boldsymbol{z>10}) as a Sensitive Tool for the Construction of a Cosmological Model on Small Scales","authors":"Yu. N. Eroshenko,&nbsp;V. N. Lukash,&nbsp;E. V. Mikheeva,&nbsp;S. V. Pilipenko,&nbsp;M. V. Tkachev","doi":"10.1134/S1063773725700343","DOIUrl":"10.1134/S1063773725700343","url":null,"abstract":"<p>The cosmic microwave background absorption intensity in the 21 cm line of neutral hydrogen in the presence of additional power in the form of a ‘‘bump’’ in the spectrum of cosmological density perturbations is calculated. The main absorption-amplifying effect is the earlier birth of the first stars forming an ultraviolet radiation background. This radiation reduces the spin temperature of neutral hydrogen and, thus, amplifies the absorption in the 21 cm line. A comparison of various cosmological models (with and without a bump in the density perturbation spectrum) shows that it is possible to determine the probable position of the bump in the perturbation spectrum and, thus, to reconstruct the spectrum of cosmological perturbations on scales <span>(k&gt;1)</span> Mpc<span>({}^{-1})</span> from the position of the absorption frequency profile.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 4","pages":"189 - 197"},"PeriodicalIF":0.8,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145612920","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":"On the Quasi-periodic Decameter Radio Emission from Jupiter Associated with Ganymede","authors":"V. E. Shaposhnikov,&nbsp;V. V. Zaitsev","doi":"10.1134/S1063773725700379","DOIUrl":"10.1134/S1063773725700379","url":null,"abstract":"<p>We discuss the possibility of the realization of the plasma generation mechanism in the source of decameter radio emission associated with Ganymede and the explanation of the formation of quasi-periodic sequences of bursts of this radiation based on this mechanism. According to the model being discussed, the recorded quasi-periodic sequences of radiation pulses are a consequence of the realization of a pulsating regime of plasma wave conversion into extraordinary electromagnetic waves with a small refractive index in the source. The negative radiation frequency drift observed in the frequency–time spectrogram is due to the group delay of waves with a small refractive index and the dispersion of the medium. Based on the plasma model, we have estimated the plasma parameters in the generation region, which are in agreement with the data obtained through satellite measurements.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 4","pages":"225 - 235"},"PeriodicalIF":0.8,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145612917","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}