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

{"title":"Faraday Modulation of the Dispersion Delay of Pulses from the Pulsar B0329+54","authors":"V. V. Vdovin,&nbsp;S. V. Logvinenko,&nbsp;E. M. Loskutov,&nbsp;V. M. Malofeev,&nbsp;A. M. Feigin,&nbsp;V. V. Kocharovsky","doi":"10.1134/S1063773726700039","DOIUrl":"10.1134/S1063773726700039","url":null,"abstract":"<p>Based on observations of the pulsar B0329+54 with the LPA telescope at the Pushchino Radio Astronomy Observatory, we show that the Faraday rotation of the polarization plane of the polarized part of the main pulse leads not only to the well-known frequency modulation of the signal intensity, but also to two new effects: (i) a periodic frequency modulation of the time of arrival of its peak at the antenna receiving a linearly polarized emission and (ii) a frequency–time drift of the emerging bands of signal minima and maxima in the main-pulse propagation time interval. The detection of these effects constrains the admissible schemes and mechanisms for the generation of a partially polarized emission and allows one not only to improve significantly the accuracy of determining the dispersion measure, but also to judge the relative shift of the profiles of the unpolarized and linearly polarized parts of the main pulse as well as their asymmetry and steepness for pulsars with a large rotation measure. Under certain conditions, using such effects, it is possible to obtain information about the geometry and motion of the emission sources in pulsar magnetospheres and about the rotation of the polarization plane of the main pulse, which, in particular, can reveal a shear of neutron-star magnetic field lines in the regions of generation and limiting polarization of radiation.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 10","pages":"620 - 630"},"PeriodicalIF":0.8,"publicationDate":"2026-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147738816","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":"Influence of Electric Current Filamentation on the Efficiency of Energy Release in Coronal Magnetic Loops","authors":"T. V. Simonova,&nbsp;V. V. Zaitsev","doi":"10.1134/S1063773726700052","DOIUrl":"10.1134/S1063773726700052","url":null,"abstract":"<p>The conditions for filamentation in coronal magnetic loops are investigated. In such loops fairly large electric currents can exist and manifestations of current self-focusing effects are possible. For typical parameters of coronal magnetic loops filamentation is shown to arise at currents exceeding <span>(5times 10{{}^{9}})</span> A. The characteristic thickness of the filaments and their total number are determined for typical plasma parameters and electric currents in loops. As a rule, the cross sections of the filaments have a total area smaller than the cross-sectional area of the coronal magnetic loop. For this reason, the phenomenon of filamentation leads to an increase in the total energy release from the system of filaments at the same total current that existed in the original homogeneous loop. At a typical number of filaments observed in experimental data the total energy release from the loop is shown to increase approximately by an order of magnitude. This effect vanishes at a sufficiently large number of filaments, when the total area of their cross sections almost coincides with the cross-sectional area of the loop.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 10","pages":"640 - 643"},"PeriodicalIF":0.8,"publicationDate":"2026-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147738814","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 Permeable Particle Model to Describe the Collisional Evolution of Dust Clusters in Protoplanetary Gas–Dust Disks","authors":"A. V. Rusol","doi":"10.1134/S1063773725700653","DOIUrl":"10.1134/S1063773725700653","url":null,"abstract":"<p>The development of the permeable particle method for the dust cluster evolution problems is proposed. The key element that describes the rheological properties of porous dust clusters and affects the results of their collisional evolution is the coefficient of restitution. The continuous and discontinuous formulations of the relation for the coefficient of restitution during collisions are given. A parametric study of the dependence of the coefficient of restitution on the cluster characteristics and the relative collision energy has been carried out. Clusters with a high fractal dimension are shown to have a distinct bounce threshold during collisions. The evolution of a system of 20 000 clusters with various electric charges has been simulated numerically. It is shown that in the absence of other factors, electrostatic interactions can lead to a rapid growth of cluster agglomerates. However, the weakness of individual mechanical bonds between clusters makes such agglomerates unstable to destruction not only due to the collisions, but also due to the increasing repulsive force of similarly charged clusters in the agglomerate. It is shown that when the external influence of the gaseous medium is taken into account, spatially extended structures are formed in the cluster system. The velocity field of a turbulent vortex is considered as an external influence on a system of electrically charged clusters. It is shown that in this case, a filamentary structure is formed on the vortex axis, with its central part being occupied by clusters with a low fractal dimension and the densest clusters with a high fractal dimension being concentrated near its surface.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 9","pages":"563 - 578"},"PeriodicalIF":0.8,"publicationDate":"2026-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147626313","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":"Sunspot Group Area Index and the Waldmeier Rule","authors":"A. A. Osipova,&nbsp;Yu. A. Nagovitsyn,&nbsp;S. N. Fedoseeva","doi":"10.1134/S1063773725700641","DOIUrl":"10.1134/S1063773725700641","url":null,"abstract":"<p>We consider the applicability of the classical Waldmeier rule or effect, i.e., the relationship between the amplitude of the 11-year solar cycle and the length of its rising branch (rise time), to a series of total sunspot areas. We show that the absence of a correlation revealed by some authors is associated with the influence of quasi-biennial oscillations and the choice of a smoothing method. We propose a new proxy series of yearly mean sunspot group area that is free from the quasi-biennial component and Gnevyshev gaps. For this series we have estimated the correlation coefficient between the solar cycle amplitude and the length of the rising branch, <span>(Rapprox 0.8)</span>, confirming the universality of the Waldmeier rule. Values of <i>R</i> up to 0.99 have been reached in the modified formulations that relate the amplitude to the maximum and mean activity growth rates, making them promising for an early prediction of the solar cycle amplitude.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 9","pages":"579 - 585"},"PeriodicalIF":0.8,"publicationDate":"2026-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147626314","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":"Investigation of the Type Ic-BL Supernova SN 2020adow","authors":"D. Yu. Tsvetkov,&nbsp;N. N. Pavlyuk,&nbsp;N. P. Ikonnikova,&nbsp;M. A. Burlak,&nbsp;A. A. Belinski,&nbsp;I. M. Volkov,&nbsp;A. V. Dodin,&nbsp;S. A. Potanin,&nbsp;N. I. Shatsky,&nbsp;V. A. Echeistov","doi":"10.1134/S1063773725700665","DOIUrl":"10.1134/S1063773725700665","url":null,"abstract":"<p>We present <i>UBVRI</i> photometry for the type Ic-BL supernova SN 2020adow over the period from <span>(-6)</span> to 98 days relative to maximum light and 11 spectra in the interval from <span>(-7)</span> to 47 days. We have determined the following basic parameters of its light curves: the dates and magnitudes at maximum light, the decline rates at two stages of evolution, and the peak absolute magnitude <span>(M_{V}={-}18overset{textrm{m}}{.}0)</span>. The light curves of SN 2020adow in absolute <span>(V)</span> magnitudes and the color curves are compared with the corresponding curves for type Ic and Ic-BL supernovae. We have modeled the spectra with the SYN++ code, identified the main absorption lines, and determined the ejecta expansion velocities.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 9","pages":"525 - 535"},"PeriodicalIF":0.8,"publicationDate":"2026-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147626317","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":"Flaring Activity of Stars within 30 Parsecs from TESS Data for a Sample of Stars with X-ray Emission from the SRG/eROSITA Catalog","authors":"M. A. Gorbachev,&nbsp;I. F. Bikmaev,&nbsp;I. M. Khamitov,&nbsp;M. R. Gilfanov,&nbsp;R. A. Sunyaev,&nbsp;P. S. Medvedev","doi":"10.1134/S1063773725700628","DOIUrl":"10.1134/S1063773725700628","url":null,"abstract":"<p>We perform a comparative analysis of the optical flaring activity of two groups (with and without X-ray emission, according to SRG/eROSITA data) of cool FGKM stars within 30 pc of the Sun based on data from the TESS space observatory. About 4800 sources within 30 pc in the eastern Galactic hemisphere have been identified based on the Gaia DR3 catalog and correlated with the SRG/eROSITA catalog of X-ray sources. As a result, we have identified 1309 X-ray sources and 3104 sources without X-ray activity. For these sources we have searched for the light curves and the manifestations of flaring activity based on data from the TESS space observatory. We show that the group of stars with X-ray activity exhibits a much higher optical flaring activity compared to the group of stars without X-ray emission. We have measured the energies of flares for both groups of stars and constructed their energy distributions.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 9","pages":"551 - 562"},"PeriodicalIF":0.8,"publicationDate":"2026-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147626312","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":"Coronal Activity of Stars in the Blanco 1 Open Cluster from SRG/eROSITA All-Sky Survey Data","authors":"I. M. Khamitov,&nbsp;I. F. Bikmaev,&nbsp;M. R. Gilfanov,&nbsp;R. A. Sunyaev,&nbsp;M. A. Gorbachev,&nbsp;S. S. Panarin,&nbsp;P. S. Medvedev","doi":"10.1134/S106377372570063X","DOIUrl":"10.1134/S106377372570063X","url":null,"abstract":"<p>Using data from the all-sky X-ray survey with the eROSITA telescope onboard the SRG orbital observatory and the optical catalog of Blanco 1 cluster members constructed from Gaia data, we have investigated the X-ray emission from cluster stars. Of the 723 cluster members located in the eastern Galactic part of the sky, eROSITA detects X-ray emission from 110 stars, thereby increasing the number of known sources by more than a factor of 2. At the Blanco 1 distance (<span>({sim}234)</span> pc) the median eROSITA sensitivity in this sky region corresponds to a 0.3–2.3 keV luminosity <span>(L_{X}sim 1.1times 10^{29})</span> erg s<span>({}^{-1})</span>, allowing more than 60<span>(%)</span> of the solar-type stars to be detected within the Blanco 1 tidal radius. For one source a strong (more than a factor of 10) X-ray variability on a time scale of six months has been recorded. This is a late-M star. The <span>(R_{X}=log(L_{X}/L_{textrm{bol}}))</span> distribution of Blanco 1 stars is bimodal. The left peak at <span>(R_{X}sim{-}4.2)</span> is formed by FGK stars, while the right peak at <span>(R_{X}sim{-}3.1)</span> consists predominantly of K and M stars. A comparison of the properties of X-ray sources in the similarly aged Blanco 1 and Pleiades clusters has shown a high level of consistency, pointing to a common evolutionary scenario for the X-ray activity of stars in these clusters.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 9","pages":"536 - 550"},"PeriodicalIF":0.8,"publicationDate":"2026-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147626318","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":"Direct Detection of the Non-thermal X-ray Emission from the Arches Star Cluster","authors":"R. Krivonos,&nbsp;A. Vikhlinin,&nbsp;A. Bykov,&nbsp;S. Sazonov,&nbsp;M. Clavel","doi":"10.1134/S1063773725700586","DOIUrl":"10.1134/S1063773725700586","url":null,"abstract":"<p>The compact stellar clusters have emerged as particularly promising candidates for cosmic rays (CR) accelerators. The star clusters, recently observed in <span>(gamma)</span>-rays, are also known sources of non-thermal X-ray emission, which is due to synchrotron or inverse-Compton scattering of relativistic electrons. Thus, the search for the non-thermal X-ray emission from stellar clusters is of particular interest. Until recent time the X-ray emission of the Arches star cluster in the Galactic Center was mixed with non-thermal emission of the surrounding molecular cloud, associated with reflection of hard X-ray irradiation. This reflected emission has been observed to fade, giving us a chance to characterize intrinsic non-thermal emission of the Arches cluster. In this work we demonstrate that Fe <span>(Kalpha)</span> line emission at 6.4 keV, attributed to the reflected non-thermal emission of the molecular cloud in 2000–2010, is not detected in deep observations with <i>XMM–Newton</i> in 2020 and <i>Chandra</i> in 2022, leaving stellar cluster well isolated. We showed that the Arches non-thermal emission is localized in the cluster’s core and characterized by a relatively weak, hard (<span>(Gammaapprox 1.5)</span>) power-law spectral continuum with 2–10 keV flux of <span>({sim}10^{-13})</span> erg s<span>({}^{-1})</span> cm<span>({}^{-2})</span>.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 8","pages":"476 - 486"},"PeriodicalIF":0.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147606901","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 Contribution of the Bow Shock Pulsar Wind Nebula PSR J0437-4715 to the Observed Fluxes of GeV–TeV Positrons and Antiprotons","authors":"A. E. Petrov,&nbsp;A. M. Bykov","doi":"10.1134/S1063773725700598","DOIUrl":"10.1134/S1063773725700598","url":null,"abstract":"<p>The orbital observatories PAMELA and AMS-02 have detected a significant excess in the cosmic-ray (CR) positron flux at energies above several tens of GeV. The measured values exceed those expected in models of secondary origin of positrons due to inelastic collisions of CR nuclei with the interstellar matter. This excess may be due to the annihilation or decay of hypothetical dark matter particles or, alternatively, to the contribution of local sources of primary positrons, particularly pulsars. In contrast, the antiproton fluxes observed by AMS-02 at energies above GeV are consistent with the models of their secondary origin, taking into account the uncertainties. The ratio of the observed positron flux to the antiproton flux is virtually independent of energy in the range from 60 to 400 GeV. This behavior can be understood if the observed local spectra of positrons and antiprotons in the range of tens to hundreds of GeV are formed by the same source. The relativistic winds of pulsars inject accelerated electrons and positrons into the interstellar medium. Fast-moving pulsars form pulsar wind nebulae with bow shocks (BSPWNe), which accelerate both the freshly injected positrons and electrons of the pulsar wind and the hadrons and leptons of galactic CRs from the interstellar medium via the Fermi acceleration mechanism in colliding flows. Such a system can produce identical particle spectra regardless of the site of their injection. The nearest to the Earth millisecond pulsar PSR J0437-4715 forms a pulsar wind nebula (PWN) with a bow shock observable in optical and ultraviolet wavelengths. This BSPWN is a possible candidate for the main near-Earth ‘‘factory’’ of antiparticles along with the Geminga PWN. Considering PSR J0437-4715, we provide the Monte Carlo simulations of particle acceleration in its BSPWN and the analytical model of anisotropic diffusion in the local interstellar medium. We show that this pulsar’s contribution can explain the observed positron flux in the range from 30 GeV to 1 TeV, and simultaneously the antiproton flux at hundreds of GeV with an almost energy-independent positron-to-antiproton flux ratio. The model allows to reproduce the observed antiparticle fluxes if <span>({sim}25%)</span> of the PSR J0437-4715 pulsar wind power is transferred to accelerated positrons and electrons and used to re-accelerate antiprotons.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 8","pages":"487 - 497"},"PeriodicalIF":0.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147606900","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":"Rotation Periods of Stars in the Pleiades, Hyades, and Blanco 1 Open Clusters from Brightness Variations in TESS Data","authors":"M. A. Gorbachev,&nbsp;I. M. Khamitov,&nbsp;I. F. Bikmaev,&nbsp;M. V. Suslikov,&nbsp;R. I. Gumerov,&nbsp;A. E. Akhmetkhanova,&nbsp;E. A. Nikolaeva","doi":"10.1134/S1063773725700604","DOIUrl":"10.1134/S1063773725700604","url":null,"abstract":"<p>We use photometric data from the TESS space observatory and optical catalogs of stars in the Pleiades, Hyades, and Blanco 1 open clusters that contain 2226, 790, and 752 sources selected based on Gaia data. Using various statistical periodicity estimation methods, such as SNR and PDM, and taking into account the TESS angular resolution (<span>(1text{ pixel}=21^{primeprime})</span>), we have determined the periods for 635, 222, and 98 stars in the Pleiades, the Hyades, and Blanco 1, respectively. The search for periodic signals was limited to 13 days, since the light curve duration in one TESS sector is about 27 days, while the use of several successive sectors is made difficult by the zero-point offset of the instrumental flux between them. Supplementing our results by information from the VizieR database, we have found that the periods were estimated for 1290 (58<span>(%)</span>), 584 (74<span>(%)</span>), and 250 (33<span>(%)</span>) stars in the Pleiades, the Hyades, and Blanco 1, respectively. Among them, for 44, 28, and 12 sources in these clusters the periods have been determined for the first time. Thus, in this paper we present the most complete catalog of periods of stars in these clusters.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 8","pages":"498 - 515"},"PeriodicalIF":0.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147606913","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}