Astronomy Letters-A Journal of Astronomy and Space Astrophysics最新文献_第10页

Peculiarities of Open Star Clusters with High Vertical Velocities from the Region of the Sco–Cen OB Association 具有高垂直速度的疏散星团的特性

IF 0.9 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2023-11-25 DOI: 10.1134/S1063773723070010

V. V. Bobylev, A. T. Bajkova

{"title":"Peculiarities of Open Star Clusters with High Vertical Velocities from the Region of the Sco–Cen OB Association","authors":"V. V. Bobylev, A. T. Bajkova","doi":"10.1134/S1063773723070010","DOIUrl":"10.1134/S1063773723070010","url":null,"abstract":"We have studied the kinematics of a unique sample of young open star clusters (OSCs) with high vertical velocities, (15<W<40) km s({}^{-1}). The characteristics of these clusters were taken from the catalogue by Hunt and Reffert (2023), where their mean proper motions, line-of-sight velocities, and distances were calculated using Gaia DR3 data. These OSCs are located within 0.6 kpc of the Sun and form two clumps: one in the region of the Sco–Cen OB association and the other one in the region of the Per OB3–Per OB2 associations. The OSC group of 47 members in the region of the Sco–Cen association is shown to expand along the (y) axis, (partial V/partial y=51pm 12) km s({}^{-1}) kpc({}^{-1}). This group also has a positive rotation around the (z) axis with an angular velocity of (71pm 11) km s({}^{-1}) kpc({}^{-1}) and a negative rotation around the (x) axis with an angular velocity of (-35pm 5) km s({}^{-1}) kpc({}^{-1}). Based on the velocities of 27 OSCs from the region of the Per OB3–Per OB2 associations, we have found no gradients differing significantly from zero. We have studied the kinematics of more than 1700 stars selected by Luhman (2022) as probable members of the Sco–Cen OB association. These stars are shown to have no high vertical velocities. The expansion coefficient of the stellar system in the (xy) plane has been found from all stars to be (K_{xy}=43.2pm 2.2) km s({}^{-1}) kpc({}^{-1}). Based on stars from the three UCL, LCC, and V1062 Sco groups with a mean age ({sim}20) Myr, for the first time we have found a volume expansion coefficient of the stellar system differing significantly from zero, (K_{xyz}=43.2pm 3.4) km s({}^{-1}) kpc({}^{-1}).","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"49 7","pages":"410 - 420"},"PeriodicalIF":0.9,"publicationDate":"2023-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136104888","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}

引用次数: 0

Investigation of the Flaring Activity of BL Lac in July–November 2021 2021年7月至11月BL Lac扩口活性调查

IF 0.9 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2023-10-03 DOI: 10.1134/S1063773723050067

L. S. Ugol’kova, M. S. Pshirkov, V. P. Goranskij, N. P. Ikonnikova, B. S. Safonov, A. M. Tatarnikov, E. V. Shimanovskaya, M. A. Burlak, M. D. Afonina

{"title":"Investigation of the Flaring Activity of BL Lac in July–November 2021","authors":"L. S. Ugol’kova, M. S. Pshirkov, V. P. Goranskij, N. P. Ikonnikova, B. S. Safonov, A. M. Tatarnikov, E. V. Shimanovskaya, M. A. Burlak, M. D. Afonina","doi":"10.1134/S1063773723050067","DOIUrl":"10.1134/S1063773723050067","url":null,"abstract":"The source BL Lac exhibited an enhanced activity from August 2020 to July 2022. This activity peaked in July–August 2021. In this period the source reached historic brightness maxima in various energy ranges. Observations of this nonstandard maximum were carried out by the SAI staff of the Crimean Station of SAI and with the telescopes of the Caucasus Mountain Observatory (CMO SAI MSU). Optical and near-infrared photometric data as well as optical polarimetric data were obtained. When investigating the correlation between the optical and gamma-ray fluxes and between the optical and infrared fluxes, its high degree with an almost zero lag was confirmed—this means that the emission regions spatially coincide or are very close together. The degree of linear polarization in the investigated period changed in a wide range, reaching 20({%}), with an anticorrelation between the degree of linear polarization and the brightness of the object having been observed. A similar pattern of variation was also observed in the preceding flares of this object. The changes in the electric vector position angle (EVPA) show a dependence on the rate of change of the object’s brightness. The EVPA changed greatly during flares and slowly at the times of a slow change in the intensity.","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"49 5","pages":"216 - 228"},"PeriodicalIF":0.9,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50447187","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}

引用次数: 0

Counter-Rotating Gaseous Disk and Star Formation in the S0 Galaxy NGC 934 反旋转气态盘与S0星系NGC 934的恒星形成

IF 0.9 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2023-10-03 DOI: 10.1134/S1063773723050043

O. K. Sil’chenko, A. V. Moiseev, D. V. Oparin, D. V. Zlydneva, D. V. Kozlova

引用次数: 0

Cosmic Abundance of Iron 宇宙铁丰度

IF 0.9 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2023-10-03 DOI: 10.1134/S1063773723050018

N. N. Chugai

引用次数: 0

Spectral and Temporal Analysis of the Supergiant Fast X-ray Transient IGR J16195–4945 with SRG/ART-XC SRG/ART-XC超巨星快X射线瞬态IGR J16195–4945的光谱和时间分析

IF 0.9 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2023-10-03 DOI: 10.1134/S106377372305002X

M. N. Satybaldiev, I. A. Mereminskiy, A. A. Lutovinov, D. I. Karasev, A. N. Semena, A. E. Shtykovsky

{"title":"Spectral and Temporal Analysis of the Supergiant Fast X-ray Transient IGR J16195–4945 with SRG/ART-XC","authors":"M. N. Satybaldiev, I. A. Mereminskiy, A. A. Lutovinov, D. I. Karasev, A. N. Semena, A. E. Shtykovsky","doi":"10.1134/S106377372305002X","DOIUrl":"10.1134/S106377372305002X","url":null,"abstract":"We present the results of the analysis of the SRG/ART-XC observation of the Supergiant Fast X-ray Transient IGR J16195-4545 performed on March 3, 2021. Six bright flares are present in the light curve, with no significant change in hardness occuring during these flares. The spectrum is described with an absorbed power law model with a high energy exponential cutoff showing heavy absorption, with (N_{textrm{H}}=(12pm 2)times 10^{22}text{ cm}^{-2}) and (Gamma=0.56pm 0.15), (E_{textrm{cut}}=13pm 2) keV. Adopting the Bayesian block decomposition of the light curve, we measured the properties of the observed flares (duration, rise time, waiting time, released energy and pre-flare luminosity), which are consistent with the quasi-spherical subsonic accretion model. The stellar wind velocity of the supergiant is estimated to be (v_{w}approx 500) km s({}^{-1}). Additionally, the system was found to have an unusual near-IR variability.","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"49 5","pages":"249 - 256"},"PeriodicalIF":0.9,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50447185","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}

引用次数: 0

X-ray Halo of the Pulsar 4U 1538–52 from SRG Data SRG数据中脉冲星4U 1538–52的X射线晕

IF 0.9 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2023-10-03 DOI: 10.1134/S1063773723050031

A. E. Shtykovsky, A. A. Lutovinov, R. A. Krivonos, M. R. Gilfanov, P. S. Medvedev, I. A. Mereminskiy, V. A. Arefiev, S. V. Molkov, R. A. Sunyaev

{"title":"X-ray Halo of the Pulsar 4U 1538–52 from SRG Data","authors":"A. E. Shtykovsky, A. A. Lutovinov, R. A. Krivonos, M. R. Gilfanov, P. S. Medvedev, I. A. Mereminskiy, V. A. Arefiev, S. V. Molkov, R. A. Sunyaev","doi":"10.1134/S1063773723050031","DOIUrl":"10.1134/S1063773723050031","url":null,"abstract":"We present the first results of the SRG observation of the pulsar 4U 1538–52 based on ARC-XC and eROSITA data. An extended emission in the form of a halo is detected around the source in the 0.5–8 keV energy band. Our simulation has shown that its surface brightness distribution can be described by a two-component model composed of a flat disk ({sim}250^{primeprime}) in radius and a (beta)-model with a characteristic size ({sim}480^{primeprime}). We have constructed a broadband spectrum of 4U 1538–52 in the energy range 0.5–30 keV, which can be fitted by a weakly absorbed ((N_{textrm{H}}simeq 0.7times 10^{22}) cm({}^{-2})) power law with a high-energy cutoff. In addition, iron emission lines are detected in the pulsar spectrum at 6–7 keV. We show that the observed halo spectrum is considerably softer (a power-law index ({simeq}2.8)) than the pulsar spectrum (a power-law index ({simeq}0.9)), consistent with the predictions of theoretical models for the X-ray scattering by dust.","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"49 5","pages":"240 - 248"},"PeriodicalIF":0.9,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50447186","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}

引用次数: 0

Properties of the Flare Energy Release in Force-Free Magnetic Flux Ropes 无力磁通绳索中火炬能量释放的特性

IF 0.9 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2023-10-03 DOI: 10.1134/S1063773723050055

A. A. Solov’ev, E. A. Kirichek

{"title":"Properties of the Flare Energy Release in Force-Free Magnetic Flux Ropes","authors":"A. A. Solov’ev, E. A. Kirichek","doi":"10.1134/S1063773723050055","DOIUrl":"10.1134/S1063773723050055","url":null,"abstract":"A straight cylindrical, electrically shielded magnetic flux rope is considered as the upper part of a weakly curved magnetic loop whose footpoints are fixed in the photosphere. All parameters of the flux rope depend on one variable—the distance (r) from the axis of its symmetry. As the flux rope rises into the rarefied solar atmosphere, the external pressure keeping the flux rope from lateral expansion drops continuously. At some critical value of it the longitudinal magnetic field of the flux rope vanishes on the magnetic surface where the longitudinal electric current changes its sign in accordance with the requirement for the total current to be shielded. At the same time, the azimuthal current and the force-free parameter near this surface grow indefinitely. Because of this growth, the electron drift velocity near this surface exceeds the ion-sound speed, leading to the excitation of a plasma ion-sound instability as a trigger of flare energy release. The plasma conductivity in the region of plasma turbulence drops by seven orders of magnitude. Rapid magnetic energy dissipation at the anomalous resistivity generates an inductive electric field in the plasma that exceeds considerably the Dreicer limit. This explains the efficient acceleration of particles in the region where the magnetic field weakens rapidly.","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"49 5","pages":"257 - 269"},"PeriodicalIF":0.9,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50447190","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}

引用次数: 0

Theoretical Mass Estimates for the Mira-Type Variable R Hydrae Mira型可变R Hydrae的理论质量估计

IF 0.9 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2023-09-04 DOI: 10.1134/S1063773723040023

Yu. A. Fadeyev

{"title":"Theoretical Mass Estimates for the Mira-Type Variable R Hydrae","authors":"Yu. A. Fadeyev","doi":"10.1134/S1063773723040023","DOIUrl":"10.1134/S1063773723040023","url":null,"abstract":"Calculations of stellar evolution at initial abundances of helium (Y=0.28) and heavier elements (Z=0.014) were done for stars with masses on the main sequence (1.7;M_{odot}leq M_{textrm{ZAMS}}leq 5.2;M_{odot}). Evolutionary sequences corresponding to the AGB stage were used for modelling the pulsation period decrease observed for almost two centuries in the Mira-type variable R Hya. Diminution of the period from (Piapprox) 495 d in the second half of the eighteenth century to (Piapprox 380) d in the 1950s is due to stellar radius decrease accompanying dissipation of the radiation–diffusion wave generated by the helium flash. For all the history of its observations R Hya was the fundamental mode pulsator. The best agreement with observations is obtained for eight evolutionary models with initial mass (M=4.8;M_{odot}) and the mass loss rate parameter of the Blöcker formula (0.03leqeta_{textrm{B}}leq 0.07). Theoretical mass estimates of R Hya are in the range (4.44;M_{odot}leq Mleq 4.63;M_{odot}), whereas the mean stellar radius ((421;R_{odot}leqbar{R}leq 445;R_{odot})) corresponding to the pulsation period (Piapprox 380) d agrees well with measurements of the angular diameter by methods of the optical interferometric imaging.","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"49 4","pages":"167 - 174"},"PeriodicalIF":0.9,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47221506","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}

引用次数: 0

The Cepheids V371 Per and OGLE-LMC-CEP-2132: The First Crossing of the Instability Strip 造父变星V371 Per和OGLE-LMC-CEP-2132:不稳定带的首次交叉

IF 0.9 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2023-09-04 DOI: 10.1134/S1063773723040011

L. N. Berdnikov, E. N. Pastukhova

引用次数: 0

Secular Dynamics of a Number of Planets from the TESS Catalog Detected in Binary Star Systems 在双星系统中探测到的来自TESS目录的一些行星的长期动力学

IF 0.9 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2023-09-04 DOI: 10.1134/S1063773723040035

A. V. Mel’nikov, Yu. G. Kopylova

引用次数: 0