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Analysis of the X-ray emission of OB stars II: B stars

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Research in Astronomy and Astrophysics 2019年第8期19卷 143-150页

作者： Elizaveta Ryspaeva Alexander Kholtygin crimean astrophysical observatory NauchnyCrimeaRussia Saint-Petersburg State University Saint-PetersburgRussia Institute of Astronomy Russian Academy of SciencesRussia

This paper is the second part of an investigation into the mechanism for the origin of X-rays in early-type stars. Archival X-ray observations of 25 B stars, obtained by the XMM-Newton satellite, are analysed. We check two hypotheses on the origin of X-ray emission: the Magnetically Confined Wind Shock Model(MCWS) and Pollock’s paradigm. For all studied stars, the mean ratio of the half widths at half maximum to the terminal velocities appears to be R ≈ 0.15-0.20 in contradiction to Pollock’s hypothesis that R ≈ 0.5. We checked three possible consequences of the MCWS model: correlations between the hardness of the X-ray spectra for B stars and terminal wind velocities, mass loss rates and magnetic *** was shown that such correlations are marginal or even absent both for magnetic and non-magnetic B stars.

关键词： stars:early-type stars:spectra:X-ray

GSC 4560–02157: a new long-period eclipsing cataclysmic variable star

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Research in Astronomy and Astrophysics 2015年第7期15卷 1005-1011页

作者： Anton V.Khruslov Anatoly V.Kusakin Elena A.Barsukova Vitaly P.Goranskij Azamat F.Valeev Nikolay N.Samus Institute of Astronomy Russian Academy of Sciences Fesenkov astrophysical Institute Special astrophysical observatory Russian Academy of Sciences Sternberg Astronomical Institute Lomonosov Moscow State University

We study the newly discovered variable star GSC 4560-02157. CCD photometry was performed in 2013-2014 at the Tien Shan Astronomical observatory,and a spectrum was obtained with the 6-m telescope of the Special astrophysical observatory in June, 2014. GSC 4560-02157 is demonstrated to be an eclipsing variable star（P = 0.265359d）. All its flat-bottom primary minima are approximately at the same brightness level, but the star＇s out-of-eclipse brightness and brightness at secondary minima vary considerably（by up to 0.6m） from cycle to cycle. Moreover,there are short-term（time scale of 0.03-0.04 days） small-amplitude brightness variations out of eclipse. This behavior suggests a cataclysmic nature for the star, which is confirmed with a spectrum taken on 2014 June 5. The spectrum shows numerous emissions of the hydrogen Balmer series, He Ⅰ and He Ⅱ.

关键词： stars: dwarf novae -- binaries: eclipsing -- stars: individual: GSC 4560-02157

On the correctness of orbital solutions obtained from a small set of *** of HIP 53731

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Research in Astronomy and Astrophysics 2020年第11期20卷 321-324页

作者： Arina Mitrofanova Vladimir Dyachenko Anatoly Beskakotov Yury Balega Alexander Maksimov Denis Rastegaev Sergey Komarinsky Special astrophysical observatory of the russian academy of sciences Nizhnij ArkhyzRussia 369167

HIP 53731 is a binary consisting of stars of the spectral types K0 and *** orbit of this object was constructed previously by Cvetkovic et *** improved by *** should be noted that there is a 180°ambiguity in the position angles of some published *** interferometric observations were obtained in 2007–2020(21 measurements)at the 6-m telescope of the SAO RAS(BTA)by the authors of this *** analysis of new data together with previously published ones made it possible to construct an accurate orbit of HIP 53731 and to halve the already known values of the orbital period of the *** a result of the study,the mass sum,the masses of each component and their spectral types were determined by two independent *** to the qualitative classification of orbits,the orbital solution has grade 2–"good"(observations cover more than half of the orbital period and correspond to different phases).

关键词： techniques high angular resolution,speckle interferometry stars low-mass,fundamental parameters stars binaries spectroscopic stars individual HIP 53731

Automatic detection and correction algorithms for magnetic saturation in the SMFT/HSOS longitudinal magnetograms

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Research in Astronomy and Astrophysics 2021年第3期21卷 158-166页

作者： Hai-Qing Xu Suo Liu Jiang-Tao Su Yuan-Yong Deng Andrei Plotnikov Xian-Yong Bai Jie Chen Xiao Yang Jing-Jing Guo Xiao-Fan Wang Yong-Liang Song Key Laboratory of Solar Activity National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China School of Astronomy and Space sciences University of Chinese Academy of SciencesBeijing 100049China crimean astrophysical observatory Russian Academy of SciencesNauchnyCrimea298409Russi

A longitudinal magnetic field often suffers the saturation effect in a strong magnetic field region when the measurement is performed at a single-wavelength point and linear calibration is *** this study,we develop a method that can judge the threshold of saturation in Stokes V/I observed by the Solar Magnetic Field Telescope(SMFT)and correct it *** procedure is to first perform the second-order polynomial fit to the Stokes V/I vs.I/I_(m)(I_(m) is the maximum value of Stokes I)curve to estimate the threshold of saturation,then reconstruct Stokes V/I in a strong field region to correct for *** algorithm is demonstrated to be effective by comparing with the magnetograms obtained by the Helioseismic and Magnetic Imager(HMI).The accuracy rate of detection and correction for saturation is~99.4%and~88%respectively among 175 active *** advantages and disadvantages of the algorithm are discussed.

关键词： Sun:sunspots Sun:magnetic field Methods:data analysis

Photometric and Spectroscopic Analysis of LBV Candidate J004341.84+411112.0 in M31

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Research in Astronomy and Astrophysics 2022年第1期22卷 237-244页

作者： A.Sarkisyan Sholukhova Fabrika A.Valeev A.Valcheva P.Nedialkov A.Tatamikov Special astrophysical observatory of russian academy of sciences Niznij Arkhyz 369167Karachai-CherkessiaRussia crimean astrophysical observatory Russian Academy of SciencesNauchnyi 298409Russia Department of Astronomy Sofia University5 J.Bourchier BlvdSofia 1164Bulgaria Sternberg Astronomical Institute Moscow M.V.Lomonosov State UniversityUniversitetskiy Prospekt 13Moscow 119234Russia

We study Luminous Blue Variable(LBV)candidate J004341.84+411112.0 in the Andromeda *** present optical spectra of the object obtained with the 6 m telescope of BTA SAO *** candidate shows typical LBV features in its spectra:broad and strong hydrogen lines and the He I lines with P Cygni *** remarkable spectral resemblance to the well known LBV P Cygni suggests a common nature of the objects and supports LBV classification of J004341.84+*** estimate the temperature,reddening,radius and luminosity of the star using its spectral energy *** bolometric luminosity of the candidate(M_(bol)=-10.41±0.12 mag)is quite similar to those of known LBV stars in the Andromeda *** analyzed a ten year light curve of the object in R *** candidate demonstrates photometric variations of the order of 0.4 mag,with an overall brightness increasing trendΔR>0.1 ***,the corresponding color variations of the object are fully consistent with LBV behavior when a star become cooler and brighter in the optical spectral range with a nearly constant bolometric ***-type variability of the object,similarity of its spectrum and estimated luminosity to those of known LBVs allow us to classify J004341.84+411112.0 as an LBV.

关键词： stars:early-type stars:massive stars:variables:S Doradus stars:Wolf Rayet techniques:photometric techniques:spectroscopic galaxies:individual(KIC 8098300)

Analysis of the X-ray emission from OB stars Ⅲ: low-resolution spectra of OB stars

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Research in Astronomy and Astrophysics 2020年第7期20卷 161-171页

作者： Elizaveta Ryspaeva Alexander Kholtygin crimean astrophysical observatory NauchnyCrimea 298409Russia Saint-Petersburg State University Saint-Petersburg 198504Russia Institute of Astronomy Russian Academy of Sciencesul.Pyatniskaya 48Moscow 119017Russia

This paper is the third in our series of papers devoted to the investigation of X-ray emission from OB *** our two previous papers,we study the high-resolution X-ray spectra of 32 O stars and 25 B stars to investigate the correlations between the properties of X-ray emission and stellar *** checked if the X-ray hardness and post-shock plasma temperature grow with increasing stellar magnetic field,mass loss rate and terminal wind *** previous analysis of high-resolution spectra showed that the correlations are weak or even *** the present paper,we analyzed low-resolution X-ray spectra,using model-independent X-ray hardness values for checking the above mentioned *** establish that X-ray luminosities LX weakly depend on the stellar magnetic *** the same time,Lx ∝ M0.5 and LX ∝ Ekin0.5,where M is the mass loss rate and Ekin is the kinetic energy of the *** X-ray luminosities decrease with growing magnetic confinement parameter η.We also argue that there is an additional(probably non-thermal) component contributed to the stellar X-ray emission.

关键词： stars:early-type stars:spectra:X-Ray

High Resolution Spectroscopy of Halo Stars in the Near UV and Blue Region I. Spectra in the Wavelength Region 3550-5000 A

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Chinese Journal of Astronomy and Astrophysics 2006年第5期6卷 579-587页

作者： V. G. Klochkova Gang Zhao S. V. Ermakov V. E. Panchuk National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 Special astrophysical observatory Russian Academy of Sciences Nighnij Arkhyz 369167Karachai-Cherkessia Russia

An atlas of high resolution （R = 60 000） CCD-spectra in the wavelength range 3500-5000A is presented for four objects in metallicity range -3.0 〈 [Fe/H] 〈 -0.6, temperature range 4750 〈 Teff 〈 5900K, and surface gravity range 1.6 〈 Igg 〈 5.0. We describe the calibration of the stellar atmospheric parameters using Alonso＇s formula based on the method of infrared flux and outline the determination of the abundances of a total number of 25 chemical elements. An analysis of the abundance determination errors for different chemical elements is carried out, and a method is provided for the observations and reduction of spectral material. Properties of the method of producing an atlas of spectra and line identifications are described.

关键词： stars halo stars - stars G, K-type - stars spectra - stars UV-spectra

Research on the HIP 18856 binary system

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Research in Astronomy and Astrophysics 2021年第3期21卷 69-72页

作者： Polina Efremova Arina Mitrofanova Vladimir Dyachenko Anatoly Beskakotov Alexander Maksimov Denis Rastegaev Yury BalegaSergey Komarinsky Kazan Federal University Kazan 420008Russia Special astrophysical observatory of the russian academy of sciences Nizhnij ArkhyzRussia 369167

The results of a study on the binary HIP 18856 and construction of its orbit are *** observational data were obtained at the BTA of SAO RAS in ***,Cvetkovic et *** the orbit for this ***,it is based on six measurements,which cover a small part of the *** positional parameters of the ESA astrometric satellite Hipparcos published speckle interferometric data(Mason et al.,Balega et al.,Horch et al.)and new ones were used in this *** on the new orbital parameters,the mass sum was calculated and the physical parameters of the components were *** obtained orbital and fundamental parameters were compared with the data from the study by Cvetkovic et al..The comparison shows that the new orbital solution is better than the old one,since it fits new observational data *** based on a qualitative evaluation performed by Worley&Heintz,the new orbit was classified as"reliable",which means data cover more than half of the orbit with sufficient quantities of residuals of measurements.

关键词： techniques:high angular resolution,speckle interferometry stars:low-mass,fundamental parameters stars:binaries:spectroscopic stars:individual:HIP 18856

Variability of emission lines in the optical spectra of the Herbig Be binary system HD 200775

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Research in Astronomy and Astrophysics 2019年第3期19卷 31-34页

作者： Anastasia P.Bisyarina ANDrey M.Sobolev Stanislav Yu.Gorda Anatoly S.Miroshnichenko Astronomical observatory of the Ural Federal University Department of Physics and Astronomy University of North Carolina at Greensboro Main (Pulkovo) Astronomical observatory of the russian academy of sciences Fesenkov astrophysical Institute

In our previous papers we have improved the value of the orbital period of the binary Herbig Be star HD 200775 and showed that the [O I] and Si II 6347 and 6371 ?A emission lines displayed variations which correlate with the orbital period. In this paper we provide evidences that other broad emission lines of metals in the spectra of HD 200775 also exhibit variability, which is probably related to the orbital cycle of the binary. Analysis was performed based on the high-resolution spectral data collected over a time span of 6 years at the Kourovka Astronomical observatory of the Ural Federal University(Russia) and the Three College observatory of the University of North Carolina at Greensboro(USA) as well as archival spectral data compiled since 1994. We report new data points in the radial velocity curve of the He I 5876 ?A line near the extremal values of the radial velocity.

关键词： techniques spectroscopic-stars variables T Tauri,Herbig Ae/Be-stars individual HD 200775