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

{"title":"Activity of the Star TOI-1268 and Mass Loss by the Atmosphere of Its Exoplanet","authors":"I. S. Savanov","doi":"10.1134/S1063773726700209","DOIUrl":"10.1134/S1063773726700209","url":null,"abstract":"<p>We present the results of our analysis of the manifestations of activity in the young K-type star TOI-1268 and our estimate of the possible mass loss rate from the atmosphere of its planet. The age of the star is 190–370 Myr. Based on TESS observations, we have concluded that the stellar surface is spotted. The fraction of the surface of TOI-1268 occupied by spots is 1.8–2.3<span>(%)</span> of its visible surface area, and in absolute terms (in millionths of the visible solar hemisphere, MSH) it lies in the range from 11 600 to 15 220 MSH. Our analysis of the long-term photometric variability of TOI-1268 points to the presence of an activity cycle <span>(textrm{Pcycl}sim 2750)</span> days (7.5 years). The planet TOI-1268 b is a hot Saturn (the orbital period is 8.16 days, the radius of the planet is <span>(R_{b}=9.1;R_{oplus})</span>, and its mass is <span>(M_{b}=96.4;M_{oplus})</span>). Based on our calculations using the energy-limited atmospheric escape model for TOI-1268 b, we have found that, depending on the stellar activity level, the mass loss rate from the atmosphere of the exoplanet <span>(dot{M})</span> can be in the range from <span>(2.3times 10^{10})</span> to <span>(1.4times 10^{10})</span> g s<span>({}^{-1})</span> for <span>(log R_{HK}^{prime}={-}4.30)</span> and <span>({-}4.41)</span>, respectively. The planet TOI-1268 b is remarkable in that it is located at the edge of the Neptune desert and is of interest from the viewpoint of studying the mechanisms responsible for the appearance of this desert and related to the origin of planets. In addition, one of the transit light curves for the planet contains information about the spot coverage on the stellar surface.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"52 2","pages":"82 - 86"},"PeriodicalIF":0.9,"publicationDate":"2026-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148823092","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":"Possible Sources of Iron Nuclei in Ultra-High-Energy Cosmic Rays","authors":"A. V. Uryson","doi":"10.1134/S1063773726700222","DOIUrl":"10.1134/S1063773726700222","url":null,"abstract":"<p>The origin of a cosmic-ray particle with an ultra-high energy of <span>(2.44times 10^{20})</span> eV recorded by the Telescope Array is discussed by assuming that it is a heavy nucleus, namely an iron or silicon nucleus. Iron is chosen as the heaviest element in cosmic rays, while silicon is chosen to find out how much the theoretical results obtained vary with the mass of the heavy nucleus. The constraints on the distances to the possible extragalactic sources of a heavy particle with such an energy are analyzed by assuming an extragalactic origin of this particle and using a routine calculation of the origin of cosmic rays in intergalactic space. These sources are discussed.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"52 2","pages":"87 - 92"},"PeriodicalIF":0.9,"publicationDate":"2026-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148823071","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 27-Day Cosmic Ray Intensity Variation during the Periods of Heliospheric Magnetic Field Inversion","authors":"M. V. Kravtsova,&nbsp;S. V. Olemskoy,&nbsp;V. E. Sdobnov","doi":"10.1134/S1063773726700180","DOIUrl":"10.1134/S1063773726700180","url":null,"abstract":"<p>We have investigated the anomalously large amplitudes of the 27-day cosmic ray intensity variation near the times of heliospheric magnetic field inversion detected in September–October 1979, December 1990–January 1991, June–July 1999, November–December 2014, and March–April 2023. We used ground-based measurements on the worldwide network of neutron monitors and GOES spacecraft. Our analysis was performed using the spectrographic global survey method within the model of cosmic-ray modulation by regular heliospheric electromagnetic fields. We show that in periods close to the times of large-scale (poloidal) solar magnetic field polarity reversal, at large inclinations of the interplanetary magnetic field (IMF), the IMF lines have a curvilinear configuration in both equatorial and meridional planes. Structures like magnetic traps, in which significant differences in the energy losses by cosmic ray particles are observed, arise in this case. Such situations leading to anomalously large amplitudes of the 27-day cosmic ray intensity variation depend both on the IMF configuration in different field sectors at a particular time and on the linear sizes and the location of the Earth in the trap region.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"52 2","pages":"93 - 99"},"PeriodicalIF":0.9,"publicationDate":"2026-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148823090","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":"Extended Gaseous Disk in the S0 Galaxy UGC 1382","authors":"O. K. Sil’chenko","doi":"10.1134/S1063773726700210","DOIUrl":"10.1134/S1063773726700210","url":null,"abstract":"<p>For the lenticular galaxy UGC 1382 with an extended counter-rotating gaseous disk, we have investigated the kinematics and metallicity of the ionized gas in the disk based on the archival panoramic spectroscopy data of the MUSE/VLT spectrograph. The gas in the outer disk has turned out to rotate strictly in the equatorial plane of the stellar disk, though with a spin turned through 180<span>({}^{circ})</span>. The ionized-gas metallicity gradient in the inner disk is a standard one for disk galaxies corresponding to an exponential surface brightness scale, while in the outer segment of the third-type (‘‘anti-truncated’’) stellar disk the gas metallicity gradient decreases sharply and approaches zero. The chemical structure of the outer gaseous disk is highly inhomogeneous, with probable inclusions from the accretion of the galaxy’s stripped satellites. We choose a composite scenario for the formation of the outer giant disk in the galaxy UGC 1382: laminar accretion from a cosmological filament strictly in the equatorial plane of the galaxy probably supplies the bulk of the cold gas, ensuring the formation of a thin cold gaseous disk, while the individual, not yet mixed regions correspond to the remnants of stripped low-mass satellites.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"52 2","pages":"57 - 69"},"PeriodicalIF":0.9,"publicationDate":"2026-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148823063","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-LTE Corrections for Determining the Europium Abundances in F–G–K Stars in a Wide Metallicity Range","authors":"L. I. Mashonkina,&nbsp;S. A. Yakovleva","doi":"10.1134/S1063773726700192","DOIUrl":"10.1134/S1063773726700192","url":null,"abstract":"<p>Europium plays a key role in studies of nucleosynthesis in the rapid (r-) process of neutron-capture nuclear reactions and the evolution of the abundances of r-process elements in galaxies. We improve the method for analyzing the Eu II lines in stellar spectra by using up-to-date data on the rate coefficients for inelastic processes in collisions with hydrogen atoms in the Eu II model atom. To test the method, based on high-resolution spectra and using classical, plane-parallel model atmospheres, we have determined the abundances for the Sun and selected stars with known atmospheric parameters from the Eu II 4129 and 6645 Å lines in various line formation scenarios. We show that abandoning the assumption of local thermodynamic equilibrium (the non-LTE approach) allows the abundances from these two lines to be reconciled within the error limits, while the LTE abundance difference is <span>({-}0.09)</span> dex for the Sun and from <span>({-}0.07)</span> to <span>({-}0.18)</span> dex for metal-poor stars. The europium abundance errors are reduced significantly when abandoning LTE. The non-LTE abundance corrections for 11 Eu II lines have been calculated for a grid of model atmospheres with effective temperatures, surface gravities, and metallicities corresponding to F–G–K stars. They are publicly accessible and can be used to refine the Eu abundances in stars in galactic chemical evolution studies.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"52 2","pages":"70 - 81"},"PeriodicalIF":0.9,"publicationDate":"2026-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148823091","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":"Destruction of the Interstellar Dust by a Supernova","authors":"E. O. Vasiliev","doi":"10.1134/S1063773726700179","DOIUrl":"10.1134/S1063773726700179","url":null,"abstract":"<p>Destruction of the interstellar dust proceeds primary behind supernova shocks. The previous estimates of the mass of the interstellar dust destroyed in the SN remnant do not take into account the physical properties of the ambient medium. Here we consider how some parameters, i.e. gas density and metallicity, can influence the destruction of the interstellar dust. We show that there are two regimes of the interstellar dust grains destruction in SN remnants: rapid and almost complete in compact low-mass SN remnants expanding in dense medium, and gradual and weak destruction in massive remnants evolving in the low-dense environment. When time for thermal sputtering is close to the dynamical one, i.e. to the SN remnant age, the mass of the interstellar dust destroyed in the SN remnant reaches its maximum value. We find that change of the ambient gas density results in the reduction of the dust mass logarithmically. We argue that dust cooling suppresses the interstellar dust destruction up to a factor of 1.6 by mass. This factor decreases for higher density of the ambient medium. We found that the dust mass depends linearly on gas metallicity as <span>(textrm{log}M_{d}simtextrm{[Z/H]})</span> or, in other words, on the dust-to-gas ratio as <span>(M_{d}simzeta_{d})</span>. In turn, the destruction efficiency is higher in low-metallicity environments due to relatively longer adiabatic phase. We point out that the mass of the interstellar dust destroyed per one SN in a high density environment of the high star formation regions like in local ultraluminous infrared and high-redshift massive galaxies is about several times smaller than that in the Milky Way diffuse medium.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"52 1","pages":"19 - 30"},"PeriodicalIF":0.9,"publicationDate":"2026-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148695605","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":"New Candidates for Measuring the Primordial Deuterium Abundance: Systematic Analysis of the SQUAD and KODIAQ Spectra","authors":"P. A. Kislitsyn,&nbsp;S. A. Balashev,&nbsp;A. V. Ivanchik","doi":"10.1134/S1063773726700131","DOIUrl":"10.1134/S1063773726700131","url":null,"abstract":"<p>The primordial deuterium abundance is one of the most sensitive observational tests of the standard cosmological model and the primordial nucleosynthesis theory. In this paper we perform a systematic analysis of high-resolution spectra from the SQUAD and KODIAQ catalogs aimed at searching for absorption systems suitable for measuring the D/H ratio. We have analyzed all 767 quasar spectra from these catalogs and, as a result, detected 46 new candidate systems for estimating the deuterium abundance. We have estimated the physical parameters of the medium in the chosen objects and modeled in detail the profiles of H I, D I, and metal absorption lines by the MCMC method for five systems. In contrast to the traditional approach oriented predominantly toward the most metal-poor systems with simple kinematics, the sample spans a wider range of physical characteristics of the interstellar medium. Our preliminary estimates of the D/H ratio confirm that the proposed approach is promising and show that extending the range of conditions under study increases the reliability of cosmological estimates, making it possible to investigate the dependence of the deuterium astration on metallicity and to refine the region where this effect may be neglected.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"52 1","pages":"2 - 7"},"PeriodicalIF":0.9,"publicationDate":"2026-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148695117","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":"Compton Gamma-Ray Telescope for Observations in the MeV Energy Range: The Concept and Simulations","authors":"Yu. A. Uvarov,&nbsp;A. M. Bykov,&nbsp;A. A. Lutovinov,&nbsp;D. D. Frederiks,&nbsp;A. L. Lysenko,&nbsp;E. E. Kholupenko,&nbsp;A. M. Krasilshchikov,&nbsp;G. I. Vasiliev,&nbsp;K. D. Komlev,&nbsp;Yu. V. Tuboltsev,&nbsp;A. A. Bogdanov,&nbsp;M. V. Ulanov,&nbsp;V. A. Arefiev,&nbsp;M. V. Buntov,&nbsp;V. V. Levin,&nbsp;A. F. Iyudin","doi":"10.1134/S1063773726700167","DOIUrl":"10.1134/S1063773726700167","url":null,"abstract":"<p>The photon energy range 0.3–10 MeV is of special interest for studying astrophysical objects of various origins. Gamma-ray spectroscopy of lines from the decay of unstable stellar nucleosynthesis isotopes and studies of nuclear cosmic-ray interactions and electron–positron pair annihilation are based on sensitive observations in this energy range. The MeV energy range accounts for a substantial part of the emission from supernovae, pulsars, gamma-ray burst sources, and accreting black holes. Observations of gamma-ray lines will allow the properties of strongly absorbed compact relativistic stars to be studied. Measuring the spectra and polarization of nonthermal continuum gamma-ray emission is needed to find out the nature of the gamma-ray emission from binary star systems with compact companions and powerful transient sources. At present, the orbital detectors in this energy range are several orders of magnitude less sensitive than both X-ray telescopes and gamma-ray detectors in the GeV and TeV energy ranges. This is related to the peculiarities of the MeV photon detection technology. Compton scattering, which was used in the CGRO/COMPTEL telescope that had operated in its orbit until 2000, offers one of the possibilities for detecting photons of such energies. In this paper we present the concept of an orbital Compton gamma-ray telescope in the energy range 0.3–10 MeV based on the modern technologies of double-sided silicon strip detectors (Si-DSSD), which allow the telescope sensitivity to be improved significantly. We present the results of our simulations of the characteristics of such a gamma-ray telescope in both full-scale and small-sized versions and make a comparison with the characteristics of the instruments in the completed CGRO/COMPTEL (NASA) and planned COSI (NASA) missions.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"52 1","pages":"42 - 55"},"PeriodicalIF":0.9,"publicationDate":"2026-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148695121","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":"Special Edition of the Journal Devoted to the Conference “High-Energy Astrophysics Today and Tomorrow-2025”","authors":"","doi":"10.1134/S106377372670012X","DOIUrl":"10.1134/S106377372670012X","url":null,"abstract":"<div><div><h3>Abstract</h3></div></div>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"52 1","pages":"1 - 1"},"PeriodicalIF":0.9,"publicationDate":"2026-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148695122","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":"Search For Massive Emission-Line Stars in the Galaxies NGC 1087, NGC 1433, and NGC 1566","authors":"O. N. Sholukhova,&nbsp;Yu. N. Solovyeva,&nbsp;A. S. Vinokurov,&nbsp;A. N. Sarkisyan","doi":"10.1134/S1063773726700155","DOIUrl":"10.1134/S1063773726700155","url":null,"abstract":"<p>Based on archival data from the MUSE (Multi Unit Spectroscopic Explorer) spectrograph of the VLT, we have selected 63 candidates for high-luminosity stars with intrinsic H<span>(alpha)</span> emission in the galaxies NGC 1087, NGC 1433, and NGC 1566. Based on our analysis of the spectra for the candidates and the photometry performed using the archival direct images obtained with the Hubble and James Webb Space telescopes, we have made a primary classification of all sources. The largest group comprises 28 unclassified objects with only broad Balmer hydrogen lines observed in their spectra. Thirteen more sources have been assigned to the group of unclassified objects with signatures of circumstellar envelopes, such as the Ca II triplet and/or an infrared excess. Twenty one sources have been classified as Wolf–Rayet stars or compact stellar associations including them. Four objects with Fe II, [Fe II] and/or [O I] and [Ca II] emission lines in their spectra have been classified as candidates for B[e] supergiants or yellow hypergiants. One source has been classified as a candidate for oxygen-rich supernova remnants, and one more object has shown a transient nature.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"52 1","pages":"31 - 41"},"PeriodicalIF":0.9,"publicationDate":"2026-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148695120","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}