Astronomy Letters-A Journal of Astronomy and Space Astrophysics最新文献_第6页

Study of the Solar Wind Plasma Thermodynamics in the Solar Corona Based on the Charge State of Heavy Ions 基于重离子电荷状态的日冕中太阳风等离子体热力学研究

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2024-10-16 DOI: 10.1134/S106377372470021X

F. F. Goryaev, V. A. Slemzin

{"title":"Study of the Solar Wind Plasma Thermodynamics in the Solar Corona Based on the Charge State of Heavy Ions","authors":"F. F. Goryaev, V. A. Slemzin","doi":"10.1134/S106377372470021X","DOIUrl":"10.1134/S106377372470021X","url":null,"abstract":"The solar wind (SW) plasma thermodynamics in the solar corona is determined by the energy exchange with external sources and can be studied if information about physical plasma parameters, such as the SW temperature, density, flow velocity, etc., is known. Previously, Parker showed that within the one-fluid model the SW plasma state could be described by a polytropic function in which the pressure (p) and density (rho) are related by the relation (p/rho^{gamma}=textrm{const}) with the polytropic index (gamma). In present-day MHD models the application of a polytropic function instead of an approximate description of the plasma heating mechanisms speeds up the computation considerably. The polytropic index (gamma) can be estimated using the SW plasma parameters, but for the SW flows moving toward the Earth measuring such parameters presents certain difficulties. In this paper we consider a method to determine the polytropic index (gamma) for the SW flows at the stage of expansion in the corona from the SW plasma ion parameters measured in situ: the mean Fe ion charge (langletextrm{Q}_{text{Fe}}rangle) and the (textrm{O}^{7+/})\u0000 (textrm{O}^{6+}) ion density ratio. The relation between the ion parameters and the polytropic index (gamma) is established by solving the balance equations for the ionization and recombination processes in the SW plasma. The mean values of (gamma) in the corona at heights of ({approx})1–7 solar radii for the flows of the slow SW, the fast SW from coronal holes, and interplanetary coronal mass ejections have been obtained from the histograms of the SW ion parameters measured with the ACE/SWICS instrument in 2010.","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"50 6","pages":"408 - 419"},"PeriodicalIF":1.1,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443336","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

Non-LTE Nitrogen Abundances in the Sun and Selected A–F-Type Stars 太阳和部分 A-F 型恒星中的非 LTE 氮丰度

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2024-10-16 DOI: 10.1134/S1063773724700245

L. I. Mashonkina, T. A. Ryabchikova

{"title":"Non-LTE Nitrogen Abundances in the Sun and Selected A–F-Type Stars","authors":"L. I. Mashonkina, T. A. Ryabchikova","doi":"10.1134/S1063773724700245","DOIUrl":"10.1134/S1063773724700245","url":null,"abstract":"A new N I model atom has been constructed using the energy levels known from laboratory measurements and predicted in N I atomic structure calculations and up-to-date atomic data for calculating the radiative and collisional transition rates. The solar abundance (logvarepsilon_{odot,textrm{N}}text{(1D NLTE)}=7.92pm 0.03) has been determined from N I lines by the synthetic spectrum method with a classical one-dimensional (1D, MARCS) solar model atmosphere and by taking into account the departures from local thermodynamic equilibrium (non-LTE effects). By applying the 3D corrections of Amarsi et al. (2020), we have obtained (logvarepsilon_{odot,textrm{N}}(textrm{NLTE}+textrm{3D})=7.88pm 0.03) for the Sun. Based on high-resolution spectra, we have derived the non-LTE nitrogen abundances for 11 unevolved A–F-type stars with reliably determined atmospheric parameters. Non-LTE leads to a strengthening of N I lines, and the non-LTE effects grow with increasing effective temperature. For each of the stars the departures from LTE lead to a decrease in the root-mean-square (rms) abundance error compared to the LTE case. For superficially normal A stars non-LTE removes the enhancements relative to the solar nitrogen abundance obtained in an LTE analysis. The (lambda) Boo-type star HD 172167 (Vega) also has a nearly solar nitrogen abundance. Four Am stars exhibit a scatter, from a nitrogen underabundance with (textrm{[N/H]}=-0.44) to a nitrogen overabundance with (textrm{[N/H]}=0.39). The nitrogen abundances for the Sun and superficially normal A stars are consistent within the error limits with the nitrogen abundance in the interstellar gas and early B-type stars.","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"50 6","pages":"390 - 407"},"PeriodicalIF":1.1,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443337","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

Origin of ‘‘Bursts in Absorption’’ in the Jovian Decameter Radio Emission 十米射电发射中 "吸收爆发 "的起源

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2024-10-16 DOI: 10.1134/S1063773724700257

V. E. Shaposhnikov

引用次数: 0

New Active Galactic Nuclei Detected by the ART-XC and eROSITA Telescopes during the First Five SRG All-Sky X-ray Surveys. Part 2 前五次 SRG 全天空 X 射线巡天期间 ART-XC 和 eROSITA 望远镜探测到的新活动星系核。第二部分

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2024-09-11 DOI: 10.1134/S106377372470018X

G. S. Uskov, S. Yu. Sazonov, I. A. Zaznobin, M. R. Gilfanov, R. A. Burenin, E. V. Filippova, P. S. Medvedev, A. V. Moskaleva, R. A. Sunyaev, R. A. Krivonos, M. V. Eselevich

{"title":"New Active Galactic Nuclei Detected by the ART-XC and eROSITA Telescopes during the First Five SRG All-Sky X-ray Surveys. Part 2","authors":"G. S. Uskov, S. Yu. Sazonov, I. A. Zaznobin, M. R. Gilfanov, R. A. Burenin, E. V. Filippova, P. S. Medvedev, A. V. Moskaleva, R. A. Sunyaev, R. A. Krivonos, M. V. Eselevich","doi":"10.1134/S106377372470018X","DOIUrl":"10.1134/S106377372470018X","url":null,"abstract":"We present the results of our identification of 11 X-ray sources detected on the half of the sky (0^{circ}<l<180^{circ}) in the 4–12 keV energy band on the combined map of the first five all-sky surveys with the Mikhail Pavlinsky ART-XC telescope onboard the SRG observatory. All these sources were also detected by the SRG/eROSITA telescope in the 0.2–8 keV energy band, whose data have allowed us to improve their positions and to investigate their X-ray spectra. Five of them have been detected in X-rays for the first time, while the remaining ones have already been known previously, but their nature has remained unknown. We have taken optical spectra for nine sources with the 1.6-m AZT-33IK telescope at the Sayan Observatory (the Institute of Solar–Terrestrial Physics, the Siberian Branch of the Russian Academy of Sciences); for two more objects we have analyzed the archival spectra from SDSS and the 6dF survey. The objects are classified as Seyfert galaxies (seven Sy1, three Sy1.9, and one Sy2) at redshifts (z=0.029{-}0.258). Our analysis of the X-ray spectra has revealed a noticeable intrinsic absorption ((N_{textrm{H}}sim 10^{22}) cm({}^{-2})) in two of the four Seyfert 2 galaxies (Sy1.9–2). The spectrum of one more of them (SRGA J000132.9+240237) cannot be described within the model of an absorbed Comptonization continuum, which may point to a strong absorption and a significant contribution of the reflected radiation. However, the available SRG all-sky survey data are not enough to obtain reliable constraints on the absorption column density in this object, which is also interesting in that it is radio loud. Longer X-ray observations are required to refine the physical properties of this active galactic nucleus.","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"50 5","pages":"279 - 301"},"PeriodicalIF":1.1,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198689","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

Spectroscopic and Photometric Study of the New Eclipsing Polar Gaia23cer 新的极地食星 Gaia23cer 的光谱和光度研究

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2024-09-11 DOI: 10.1134/S1063773724700154

A. I. Kolbin, E. P. Pavlenko, V. Yu. Kochkina, A. S. Vinokurov, S. Yu. Shugarov, A. A. Sosnovskij, K. A. Antonyuk, O. I. Antonyuk, N. V. Pit’, M. V. Suslikov, E. K. Galimova, N. V. Borisov, A. N. Burenkov, O. I. Spiridonova

{"title":"Spectroscopic and Photometric Study of the New Eclipsing Polar Gaia23cer","authors":"A. I. Kolbin, E. P. Pavlenko, V. Yu. Kochkina, A. S. Vinokurov, S. Yu. Shugarov, A. A. Sosnovskij, K. A. Antonyuk, O. I. Antonyuk, N. V. Pit’, M. V. Suslikov, E. K. Galimova, N. V. Borisov, A. N. Burenkov, O. I. Spiridonova","doi":"10.1134/S1063773724700154","DOIUrl":"10.1134/S1063773724700154","url":null,"abstract":"We present the results of our optical study of the eclipsing polar Gaia23cer. We analyze the orbital brightness variability in high ((langle rrangleapprox 16.5^{m})) and low ((langle rrangleapprox 19.2^{m})) states. The system has an orbital period (P_{textrm{orb}}=102.0665pm 0.0015) min and exhibits deep eclipses with a duration (Delta t_{textrm{ecl}}=401.30pm 0.81) s. The spectra have a red cyclotron continuum with the Zeeman H(alpha) absorption triplet forming in a magnetic field with a strength (B=15.2pm 1.1) MG. The source of emission lines has a high radial velocity semi-amplitude ((Kapprox 450) km s({}^{-1})), and its eclipse lags behind the eclipse of the white dwarf. The mass (M_{1}=0.79pm 0.03;M_{odot}) and temperature (T=11,350pm 650) K of the white dwarf have been estimated by modelling the spectral energy distribution. The eclipse duration corresponds to a donor mass (M_{2}=0.10{-}0.13;M_{odot}) and an orbital inclination (i=84.3^{circ}{-}87.0^{circ}). The donor temperature was estimated to be (Tapprox 2900) K by modelling the elliptical variability and eclipse depth.","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"50 5","pages":"335 - 349"},"PeriodicalIF":1.1,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198693","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

Stripping of a Neutron Star in a Close Binary System in a Pair with a Black Hole 与黑洞成对的近双星系统中中子星的剥离

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2024-09-11 DOI: 10.1134/S1063773724700166

N. I. Kramarev, A. G. Kuranov, A. V. Yudin, K. A. Postnov

{"title":"Stripping of a Neutron Star in a Close Binary System in a Pair with a Black Hole","authors":"N. I. Kramarev, A. G. Kuranov, A. V. Yudin, K. A. Postnov","doi":"10.1134/S1063773724700166","DOIUrl":"10.1134/S1063773724700166","url":null,"abstract":"We consider the final evolutionary stages of a neutron star–black hole pair. According to the current paradigm, such systems eventually coalesce, which in some cases is accompanied by neutron-star tidal disruption. Using analytical methods, we show that the scenario of slow (of the order of several seconds) neutron-star stripping by the black hole is also possible, depending on the system parameters (the initial masses and intrinsic angular momenta of the components, the equation of state for the neutron star). Reaching the lower mass limit (about one tenth of the solar mass), the neutron star explodes to produce a comparatively powerful electromagnetic transient. Our population calculations show that the stripping mechanism is possible in 50–90(%) of the cases among all coalescing neutron star–black hole pairs, depending on the model assumptions about the evolution of close binary systems (the common-envelope efficiency parameter, the supernova explosion mechanism) and the initial metallicity of the stellar population. Because of the large mass of the ejected material, the kilonova emission in this scenario has good prospects of detection.","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"50 5","pages":"302 - 316"},"PeriodicalIF":1.1,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198690","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 Hybrid Nova V1405 Cas with an Oxygen–Neon or Carbon–Oxygen White Dwarf? 带有氧-氖或碳-氧白矮星的混合新星 V1405 Cas？

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2024-09-11 DOI: 10.1134/S1063773724700208

T. N. Tarasova

{"title":"The Hybrid Nova V1405 Cas with an Oxygen–Neon or Carbon–Oxygen White Dwarf?","authors":"T. N. Tarasova","doi":"10.1134/S1063773724700208","DOIUrl":"10.1134/S1063773724700208","url":null,"abstract":"Based on spectrophotometric observations, we have investigated the envelope of Nova V1405 Cas. The spectrophotometric evolution has shown that it belongs in its spectral characteristics to the rare type of hybrid novae. At the optically thick phase in the Balmer lines the profiles had a P Cyg shape; the radial velocities of the absorption components in the profiles pointed to ejecta with velocities reaching (RV=-1800) km s({}^{-1}). We have determined the maximum envelope expansion velocity from the half-width of the line profiles at the continuum level, which reached 3300 km s({}^{-1}) from the H({alpha}) line. We have obtained approximate estimates of the electron density (N_{e}=10^{7}) cm({}^{-3}), temperature (T_{e}=2times 10^{4}) K, and the abundances of some elements. We show that the neon and iron abundances for such electron density and temperature can differ from the solar ones insignificantly. The low neon abundance does not allow one to assert with confidence that the white dwarf in this nova is an oxygen–neon one. The mass of the envelope has been estimated to be ({sim}6times 10^{-5};M_{odot}).","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"50 5","pages":"317 - 328"},"PeriodicalIF":1.1,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198692","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 Ratio of the Areas of a Sunspot and Its Umbra: Two Populations of Sunspot Groups 太阳黑子与太阳伞的面积之比：太阳黑子群的两个种群

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2024-09-11 DOI: 10.1134/S1063773724700178

Yu. A. Nagovitsyn

引用次数: 0

Prospects for Measuring the Post-Newtonian (boldsymbol{gamma}) Parameter Using Two Satellites Equipped with Highly Stable Atomic Clocks 利用配备高稳定原子钟的两颗卫星测量后牛顿参数的前景

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2024-07-22 DOI: 10.1134/S1063773724700130

D. A. Litvinov

引用次数: 0

Activity of the Seyfert Galaxy NGC 7469 in 2016–2021: Observational (boldsymbol{UBVRI}) Data 2016-2021 年塞弗星系 NGC 7469 的活动：观测$$boldsymbol{UBVRI}$$数据

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2024-07-22 DOI: 10.1134/S1063773724700105

B. P. Artamonov, E. V. Shimanovskaya, V. V. Bruevich, O. Burkhonov, Sh. A. Egamberdiev

{"title":"Activity of the Seyfert Galaxy NGC 7469 in 2016–2021: Observational (boldsymbol{UBVRI}) Data","authors":"B. P. Artamonov, E. V. Shimanovskaya, V. V. Bruevich, O. Burkhonov, Sh. A. Egamberdiev","doi":"10.1134/S1063773724700105","DOIUrl":"10.1134/S1063773724700105","url":null,"abstract":"In 2015–2021 we carried out observations of the Seyfert 1 galaxy (SyG 1) NGC 7469 in Bessell (UBVRI) filters with the 1.5-m telescope of the Maidanak Observatory, which have continued the monitoring of NGC 7469 since 1990. We took (UBVRI) CCD frames and performed standard frame processing, including bias correction, sky background subtraction, flat fielding, cosmic-ray particle removal, etc. All our data were obtained on CCD cameras with deep cooling and subarcsecond seeing. We carried out the calibrations using several standard stars in the same frame as the galaxy. The results of our photometry in a 13.5 arcsec aperture are presented graphically in the visibility windows of the observed period. A slow (S) flare was detected on the constructed variability curves in the (UBVRI) filters; a slow increase in brightness is observed since 2015, reaching a maximum in 2019. The amplitude of the S flare is 0.5 mag in the (U) filter and decreases to zero in the (I) filter. On the color–color ((U-B)/(B-V)) diagrams the colors in a 5 arcsec aperture are bluer than those in a 30 arcsec aperture.","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"50 4","pages":"230 - 237"},"PeriodicalIF":1.1,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141775114","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