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

{"title":"Recurrent Symbiotic Nova T Coronae Borealis before Outburst","authors":"N. A. Maslennikova,&nbsp;A. M. Tatarnikov,&nbsp;A. A. Tatarnikova,&nbsp;A. V. Dodin,&nbsp;V. I. Shenavrin,&nbsp;M. A. Burlak,&nbsp;S. G. Zheltoukhov,&nbsp;I. A. Strakhov","doi":"10.1134/S1063773723090037","DOIUrl":"10.1134/S1063773723090037","url":null,"abstract":"<p>The results of photometric and spectral observations of T CrB obtained in a wide range of wavelengths in 2011–2023 are presented. We use the near-IR light curves to determine a new ephemeris <span>(JD_{textrm{min}}=2455828.9+227.55E)</span> for the times of light minima when the red giant is located between the observer and the hot component. The flux ratio H<span>(alpha)</span>/H<span>(beta)</span> varied from <span>({sim}3)</span> to <span>({sim}8)</span> in 2020–2023, which may be due to a change in the flux ratio between the X-ray and optical ranges. It is shown that the value of H<span>(alpha)</span>/H<span>(beta)</span> anticorrelates with the rate of accretion onto the hot component of the system. Based on high-speed follow-up observations obtained on June 8, 2023, we detected a variability of the He II <span>(lambda 4686)</span> line with a characteristic time-scale of <span>({sim}25)</span> min, the amplitude of variability in the <span>(B)</span>-band was <span>({sim}0overset{textrm{m}}{.}07)</span>. Simulations of the near-IR light curves accounting for the ellipsoidal effect allowed us to obtain the parameters of the binary system: the Roche lobe filling factor of the cool component <span>(mu=1.0)</span>, the mass ratio <span>(q=M_{textrm{cool}}/M_{textrm{hot}}in[0.5,0.77])</span>, the orbital inclination <span>(iin[55^{circ},63^{circ}])</span>. A comparison of the light curve obtained in 2005–2023 with the 1946 outburst template made it possible to predict the date of the upcoming outburst—January 2024.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"49 9","pages":"501 - 515"},"PeriodicalIF":1.1,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139645006","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":"Estimation of the Galactocentric Distance of the Sun from Cepheids Close to the Solar Circle","authors":"V. V. Bobylev","doi":"10.1134/S1063773723090025","DOIUrl":"10.1134/S1063773723090025","url":null,"abstract":"<p>Based on Cepheids located near the solar circle, we have determined the Galactocentric distance of the Sun <span>(R_{0})</span> and the Galactic rotation velocity at the solar distance <span>(V_{0})</span>. For our analysis we used a sample of <span>({sim})</span>200 classical Cepheids from the catalogue by Skowron et al. (2019), where the distances to them were determined from the period–luminosity relation. For these stars the proper motions and line-of-sight velocities were taken from the Gaia DR3 catalogue. The values of <span>(R_{0})</span> found lie within the range 7.8–8.3 kpc, depending on the heliocentric distance of the sample stars, on the adopted solar velocity relative to the local standard of rest, and on whether or not the perturbations caused by the Galactic spiral density wave are taken into account. The dispersion of the <span>(R_{0})</span> estimates is <span>({sim})</span>2 kpc. Similarly, the values of <span>(V_{0})</span> lie within the range 240–270 km s<span>({}^{-1})</span> with a dispersion of the estimates of 70–90 km s<span>({}^{-1})</span>. We consider the following estimates to be the final ones: <span>(R_{0}=8.24pm 0.20)</span> kpc and <span>(V_{0}=268pm 8)</span> km s<span>({}^{-1})</span> found by taking into account the perturbations from the Galactic spiral density wave.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"49 9","pages":"493 - 500"},"PeriodicalIF":1.1,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139645328","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":"Strong Scattering Effects in the Emission of Soft Gamma-Ray Bursts","authors":"E. M. Urvachev,&nbsp;D. S. Shidlovski,&nbsp;S. I. Blinnikov,&nbsp;S. I. Glazyrin","doi":"10.1134/S1063773723080042","DOIUrl":"10.1134/S1063773723080042","url":null,"abstract":"<p>When a light beam enters a scattering-dominated medium, the radiation is isotropized. Part of the radiation goes backwards, leading to non-monotonicity in the radiation energy density profile inside this medium. There arises a local maximum at which the energy density at a scattering albedo <span>({sim}1)</span> is severalfold greater than that without scattering at the same extinction. This effect is studied numerically in one-dimensional and two-dimensional simulations. It is demonstrated that a local maximum of the radiation energy density arises in the medium, whose value depends on the optical depth of the region. This effect can manifest itself, for example, when the radiation from a gamma-ray burst (GRB) enters heated regions in the interstellar medium. The presence of scattering in the GRB radiation generation region, near the front of strong shocks, affects the radiation pattern. The structure of such shocks is remarkable for the presence of a preshock preheating tail. Strong scattering in this region leads to the escape of a significant fraction of the radiation sideways and backwards in the shock reference frame, forming additional tails in the angular distribution of GRB radiation after the relativistic transformation to the laboratory frame. This effect is also studied numerically in three-dimensional simulations.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"49 8","pages":"445 - 453"},"PeriodicalIF":1.1,"publicationDate":"2024-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139482903","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":"Comparative Modeling of the 2012b Outburst of Supernova 2009ip","authors":"E. M. Urvachev,&nbsp;S. I. Blinnikov,&nbsp;S. I. Glazyrin,&nbsp;D. S. Shidlovski","doi":"10.1134/S1063773723080054","DOIUrl":"10.1134/S1063773723080054","url":null,"abstract":"<p>The September 2012 outburst of the type IIn supernova 2009ip was simulated using two independent codes, STELLA and FRONT. The <span>(UBVRI)</span> light curves obtained agree well with one another and with observational data. Special attention is given to the dynamics of the emerging dense shell, which determines the luminosity of the object and is used for the direct method of determining the distance to the supernova. Two-dimensional spectral radiation-hydrodynamics computations of the SN 2009ip model were carried out, which confirmed the conclusion about the stability of this shell on the times scales of the method application.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"49 8","pages":"454 - 464"},"PeriodicalIF":1.1,"publicationDate":"2024-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139482412","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 Nature of the Rapid Color Changes of the UX Ori Star RY Lupi at Deep Minima","authors":"D. V. Dmitriev,&nbsp;V. P. Grinin","doi":"10.1134/S1063773723080017","DOIUrl":"10.1134/S1063773723080017","url":null,"abstract":"<p>We propose an explanation for the rapid color changes on the color–magnitude diagrams observed by Gahm et al. in the T Tauri star RY Lup during its deep minima. Our calculations have shown that the hot accretion spot on the stellar surface in combination with the inhomogeneous structure of the gas–dust clouds obscuring the star can be responsible for these changes. The observed rate of of the color changes allows one to estimate the velocity of the screen across the stellar disk <span>({approx}100)</span> km s<span>({}^{-1})</span>. This velocity is close to the typical gas velocities near T Tauri stars.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"49 8","pages":"465 - 474"},"PeriodicalIF":1.1,"publicationDate":"2024-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139482537","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":"SDSS J085414.02+390537.3—A New Asynchronous Polar","authors":"A. I. Kolbin,&nbsp;M. V. Suslikov,&nbsp;V. Yu. Kochkina,&nbsp;N. V. Borisov,&nbsp;A. N. Burenkov,&nbsp;D. V. Oparin","doi":"10.1134/S1063773723080029","DOIUrl":"10.1134/S1063773723080029","url":null,"abstract":"<p>Based on data from the ZTF photometric survey, we have revealed asynchrony of the polar SDSS J085414.02+390537.3. A beat period <span>(P_{textrm{beat}}=24.6pm 0.1)</span> days, during which the system changes its brightness by <span>({approx}3^{m})</span>, is distinguished in the light curves. Power peaks at the white-dwarf rotation period <span>(P_{textrm{spin}}=113.197pm 0.001)</span> min and orbital period <span>(P_{textrm{orb}}=113.560pm 0.001)</span> min are revealed in the periodograms, with the corresponding polar asynchrony being <span>(1-P_{textrm{orb}}/P_{textrm{spin}}=0.3{%})</span>. The photometric behavior of the polar points to a change of the main accreting pole during the beat period. Based on the Zeeman splitting of the H<span>(beta)</span> line, we have estimated the mean magnetic field strength of the white dwarf to be <span>(B=28.5pm 1.5)</span> MG. The magnetic field strength near the magnetic pole has been found by modeling the cyclotron spectra to be <span>(B=34pm 2)</span> MG. The Doppler tomograms in the H<span>(beta)</span> line exhibit a distribution of emission sources typical for polars in velocity space with evidence of the transition of the accretion stream from the ballistic trajectory to the magnetic one.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"49 8","pages":"475 - 485"},"PeriodicalIF":1.1,"publicationDate":"2024-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139482643","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":"Explanation of the Anomalous Outburst Activity of Comet 29P/Schwassmann–Wachmann 1: The Hypothesis about the Existence of Large Satellites","authors":"Yu. D. Medvedev,&nbsp;S. R. Pavlov","doi":"10.1134/S1063773723080030","DOIUrl":"10.1134/S1063773723080030","url":null,"abstract":"<p>We explain the anomalous outburst activity of comet 29P/Schwassmann–Wachmann 1 by the existence of satellites touching the surface of the comet nucleus at the pericenters of their orbits. It is assumed that the satellites move in eccentric orbits and a large amount of dust, the reflection of light from which causes periodic outbursts in brightness (BAA 2023), is ejected as a result of their collisions with the dust layer of the nucleus. Depending on the depth of penetration of the satellites into the dust layer, outbursts in comet brightness of various intensities occur. An improvement of the comet orbit by invoking positional observations allows the preferred direction of the ejection of material to be determined from the photocenter offset, which we interpret as the direction of the velocity vector of the largest satellite at the pericenter. The results of our numerical simulations of the ejection and subsequent motion of dust particles caused by the contact of the satellite with the dust layer of the comet nucleus explain the formation of the structures observed in the comet: the dust jets and their mirror symmetry as well as the extent of the region of material ejection from the surface of the comet nucleus.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"49 8","pages":"486 - 491"},"PeriodicalIF":1.1,"publicationDate":"2024-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139482595","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":"Optical Identification of Galaxy Clusters among SRG/eROSITA X-ray Sources Based on Photometric Redshift Estimates for Galaxies","authors":"I. A. Zaznobin,&nbsp;R. A. Burenin,&nbsp;A. V. Meshcheryakov,&nbsp;M. R. Gilfanov,&nbsp;N. S. Lyskova,&nbsp;P. S. Medvedev,&nbsp;S. Yu. Sazonov,&nbsp;R. A. Sunyaev","doi":"10.1134/S1063773723080066","DOIUrl":"10.1134/S1063773723080066","url":null,"abstract":"<p>We discuss an algorithm whereby the massive galaxy clusters detected in the SRG/eROSITA all-sky survey are identified and their photometric redshifts are estimated. For this purpose, we use photometric redshift estimates for galaxies and WISE forced photometry. To estimate the algorithm operation quality, we used a sample of 634 massive galaxy clusters from the Planck survey with known spectroscopic redshifts in the range <span>(0.1&lt;z_{textrm{spec}}&lt;0.6)</span>. The accuracy of the photometric redshift estimates for this sample is <span>(delta z_{textrm{phot}}/(1+z_{textrm{phot}})approx 0.5{%})</span>, the fraction of large deviations is 1.3<span>({%})</span>. We show that these large deviations arise mainly from the projections of galaxy clusters or other large-scale structures at different redshifts in the X-ray source field. Measuring the infrared (IR) luminosities of galaxy clusters allows one to estimate the reliability of the optical identification of the clusters detected in the SRG/eROSITA survey and to obtain an additional independent measurement of their total gravitational masses, <span>(M_{500})</span>. We show that the masses <span>(M_{500})</span> of the galaxy clusters estimated from their IR luminosity measurements have an accuracy <span>(sigma_{log M_{500}}=0.124)</span>, comparable to the accuracy of the mass estimation for the galaxy clusters from their X-ray luminosities.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"49 8","pages":"431 - 444"},"PeriodicalIF":1.1,"publicationDate":"2024-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139482644","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":"Transient Events in the Circumnuclear Regions of AGNs and Quasars As Sources of Imitations of Proper Motions","authors":"I. M. Khamitov,&nbsp;I. F. Bikmaev,&nbsp;M. R. Gilfanov,&nbsp;R. A. Sunyaev,&nbsp;P. S. Medvedev,&nbsp;M. A. Gorbachev","doi":"10.1134/S1063773723060038","DOIUrl":"10.1134/S1063773723060038","url":null,"abstract":"<p>This paper is an extension of the study by Khamitov et al. (2022) with regard to the catalog and the astrophysical interpretation of the imitation of significant proper motions in active galactic nuclei (AGNs) and quasars based on data from the Gaia space observatory. We present a sample of SRG/eROSITA X-ray sources in the eastern Galactic hemisphere (<span>({0^{circ}&lt;l&lt;180^{circ}})</span>) having significant proper motions in the Gaia EDR3 measurements with the confirmed extragalactic nature of the objects. The catalog consists of 248 extragalactic sources with spectroscopically measured redshifts. The catalog includes all of the objects available in the SIMBAD database and coincident with the identified optical counterpart within 0.5 arcsec. Eighteen sources with spectroscopically measured redshifts from observations with the Russian–Turkish 1.5-m telescope RTT-150 (Khamitov et al. 2022) have been additionally included in the catalog. The sources in the catalog are AGNs of various types (Sy1, Sy2, LINER), quasars, radio galaxies, and star-forming galaxies. The imitation of significant proper motions can be explained (by the VIM effect previously known in astrometry) by the presence of transient events on the line of sight in the vicinity of AGNs and quasars (within the Gaia optical resolution element). Among such astrophysical events are supernova outbursts, tidal disruption events in binary AGNs, the variability of high-mass supergiants, the presence of OB associations against the background of AGNs with a variable brightness, etc. The model of outbursts with a fast rise–exponential decay profile allows the variable positional parameters of most sources observed in Gaia to be described. This approach can be used as an independent way of detecting transient events in the vicinity of AGNs (on scales of several hundred parsecs in the plane of the sky) based on data from the SRG/eROSITA catalogs of X-ray sources and the optical Gaia catalog.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"49 6","pages":"271 - 300"},"PeriodicalIF":0.9,"publicationDate":"2023-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138454554","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":"Determination of the Spiral Pattern Speed in the Milky Way from Young Open Star Clusters","authors":"V. V. Bobylev,&nbsp;A. T. Bajkova","doi":"10.1134/S1063773723060014","DOIUrl":"10.1134/S1063773723060014","url":null,"abstract":"<p>We have estimated the spiral pattern speed in the Galaxy <span>(Omega_{p})</span> from a large sample of young open star clusters (OSCs). For this purpose, we have used 2494 OSCs younger than 50 Myr. Their mean proper motions, line-of-sight velocities, and distances were calculated by Hunt and Reffert (2023) based on data from the Gaia DR3 catalogue. Three methods have been applied to estimate <span>(Omega_{p})</span>. They all are based on the linear Lin–Shu spiral density wave theory. We have obtained an estimate of <span>(Omega_{p}=24.26pm 0.52)</span> km s<span>({}^{-1})</span> kpc<span>({}^{-1})</span> by the first method, which is most reliable in our view, using the velocity perturbations <span>(f_{R})</span> and <span>(f_{theta})</span> found through a spectral analysis of the radial, <span>(V_{R})</span>, and residual rotation, <span>(Delta V_{rm circ})</span>, velocities. Using the second method, we have found the velocity perturbations <span>(f_{R})</span> and <span>(f_{theta})</span> by solving the basic kinematic equations together with the Galactic rotation parameters and obtained an estimate of <span>(Omega_{p}=23.45pm 0.53)</span> km s<span>({}^{-1})</span> kpc<span>({}^{-1})</span>. We have found <span>(Omega_{p}=28.9pm 2.8)</span> km s<span>({}^{-1})</span> kpc<span>({}^{-1})</span> by the third method based on an analysis of the position angles of OSCs at their birth time <span>(theta_{rm birth})</span>.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"49 6","pages":"320 - 330"},"PeriodicalIF":0.9,"publicationDate":"2023-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136236929","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}