检索结果-内蒙古大学图书馆

arXiv 2022年

作者： Li, Jiangdan Li, Jiao Liu, Chao Li, Chunqian Guo, Yanjun Wang, Luqian Chen, Xuefei Xing, Lifeng Hou, Yonghui Han, Zhanwen 396 Yangfangwang Guandu District Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China Key Lab of Space Astronomy and Technology National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China CAS Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China Nanjing Institute of Astronomical Optics & Technology National Astronomical Observatories Chinese Academy of Sciences Nanjing210042 China School of Astronomy and Space Science University of Chinese Academy of Sciences China

Binary evolution leads to the formation of important objects crucial to the development of astrophysics, but the statistical properties of binary populations are still poorly understood. The LAMOST-MRS has provided a large sample of stars to study the properties of binary populations, especially for the mass ratio distributions and the binary fractions. We have devised a Peak Amplitude Ratio (PAR) approach to derive the mass ratio of a binary system based on results obtained from its spectrum. By computing a cross-correlation function (CCF), we established a relationship between the derived mass ratio and the PARs of the binary systems. By utilizing spectral observations obtained from LAMSOT DR6 DR7, we applied the PAR approach to form distributions of the derived mass ratio of the binary systems to the spectral types. We selected the mass ratio within the range of 0.6 − 1.0 for investigating the mass-ratio distribution. Through a power-law fitting, we obtained the power index γ values of −0.42 ±0.27, 0.03 ±0.12, and 2.12 ±0.19 for A-, F-, and G-type stars identified in the sample, respectively. The derived γ-values display an increasing trend toward lower primary star masses, and G-type binaries tend to be more in twins. The close binary fractions (for P 150 d and q 0.6) in our sample for A, F and G binaries are 7.6 ± 0.5%, 4.9 ± 0.2% and 3.7 ± 0.1%, respectively. Note that the PAR approach can be applied to large spectroscopic surveys of stars. Copyright © 2022, The Authors. All rights reserved.

关键词： Surveys

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Distinguishing super-Nyquist frequencies via their temporal variation in γ Doradus stars from continuous photometry

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Astronomy and Astrophysics 2025年 693卷

作者： Wang, Xuan Zong, Weikai Ma, Xiao-Yu Charpinet, Stéphane Wu, Tao Wang, Haotian Institute for Frontiers in Astronomy and Astrophysics Beijing Normal University Beijing102206 China School of Physics and Astronomy Beijing Normal University Beijing100875 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Institute Université de Liège Allée du 6 Août 19C Liège4000 Belgium IRAP CNRS UPS CNES Université de Toulouse 14 Av. Edouard Belin Toulouse31400 France Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China University of Chinese Academy of Sciences Beijing100049 China Institute of Astronomy KU Leuven Celestijnenlaan 200D Leuven3001 Belgium

Given their tendency to mix in with real pulsations, the reflection of super-Nyquist frequencies (SNFs) pose a threat to asteroseismic properties. Although SNFs have been studied in several pulsating stars, a systematic survey remains to be explored. Here, we propose a method for identifying SNFs from Kepler and TESS photometry by characterizing their periodic frequency modulations using a sliding Fourier transform. After analyzing long-cadence photometry in the Kepler legacy, we identified 304 SNFs in 56 stars from 45 607 frequencies in ∼600 γ Doradus stars, corresponding to a fraction of approximately 0.67% and 9.2%, respectively. Most SNFs were detected in the frequency range of pressure mode over 120 μHz and the fraction of SNF detection increases as frequency up to ∼7%. We found only two potential SNFs mixed with gravity modes in two γ Doradus stars. These findings indicate that SNFs have a negligible impact on global seismic properties, such as those derived from period spacing in γ Doradus stars. However, we stress that SNFs must be carefully and systematically examined by this method in other pulsating stars, particularly δ Scuti and hot B subdwarf stars, to establish a solid foundation for the precise asteroseismolgy of various types of pulsators. © The Authors 2025.

关键词： Stars

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MULTI-COLOR AND TESS PHOTOMETRIC INVESTIGATION OF FOUR LOW MASS-RATIO CONTACT BINARY SYSTEMS

arXiv

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arXiv 2024年

作者： Zubairi, Ahmed Waqas Ergang, Zhao Shengbang, Qian Xiao, Zhou Lajús, Eduardo Fernández Kunming650216 China University of Chinese Academy of Sciences No.1 Yanqihu East Rd Huairou District Beijing101408 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences P. O. Box 110 Kunming650216 China Department of Astronomy Yunnan University Kunming650091 China Facultad de Ciencias Astronómicas y Geofísicas Universidad Nacional de La Plata Paseo del Bosques/n Buenos Aires La Plata1900 Argentina Instituto de Astrofísica de La Plata CCT La Plata CONICET UNLP La Plata1900 Argentina

We present the TESS and BV RcIc light curves solution of four low mass-ratio contact binary systems TIC 159102550), V1068 Her, MW Pav and TIC 321576458. Except MW Pav, all three systems have been studied for the first time. The BV RcIc observations of southern contact binary system, MW Pav, is carried out using 60cm Helen Sawyer Hogg (HSH) telescope located at Argentina. The TIC 321576458 is observed in BV RcIc with 70cm Sino-Thai telescope at Lijiang station of Yunnan Observatories. The period analysis of TIC 159102550 show anti-correlation between primary and secondary minima and no long term variation is reported. The systems V1068 Her and MW Pav show increasing period at dP/dt = 1.247(9) × 10−7days/yr and dP/dt = 2.256(6) × 10−7days/yr, respectively. Data for TIC 321576458 is too few to determine any periodic variations. The light curve analysis using Wilson-Divinney model shows that systems are low mass-ratio contact binaries. Out of four targets, two systems TIC 159102550 and V1068 Her, are shallow contact binary systems with fill-out factor of 20% and 14%, respectively. The two contact binaries MW Pav and TIC 321576458 are in deep contact state with fill-out factor 63% and 61%, respectively. V1068 Her shows EB-type light curve, however the temperature difference between the primary secondary component is only 17K, which indicates that system is in thermal contact. To understand the evolutionary status of these systems, the components are plotted on the mass-luminosity diagram. The primary companions are in the ZAMS zone while the secondary components of all the systems are away from TAMS which indicates that secondary is more evolved than the primary components. V1068 Her and MW Pav are expected to evolve into a single rapidly rotating star provided that they meet the well-know Hut's criterion. Through statistical investigation of more than hundred low mass-ratio contact binary systems including our targets, we have found that all of the low mass-ratio contac

关键词： Telescopes

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Reverberation mapping measurements of black hole masses and broad-line region kinematics in Mrk 817 and NGC 7469

arXiv

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arXiv 2021年

作者： Lu, Kai-Xing Wang, Jian-Guo Zhang, Zhi-Xiang Huang, Ying-Ke Xu, Liang Xin, Yu-Xin Yu, Xiao-Guang Ding, Xu Wang, De-Qing Feng, Hai-Cheng Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Department of Astronomy Xiamen University Fujian Xiamen361005 China Qian Xuesen Laboratory of Space Technology China Academy of Space Technology 104 Youyi Road Haidian District Beijing100094 China University of Chinese Academy of Sciences Beijing100049 China

We present the results from a spectroscopic monitoring campaign to obtain reverberation-mapping measurements and investigate the broad-line region kinematics for active galactic nuclei (AGN) of Mrk 817 and NGC 7469. This campaign was undertaken with the Lijiang 2.4-meter telescope, the median spectroscopic sampling is 2.0 days for Mrk 817 and 1.0 days for NGC 7469. We detect time lags of the broad emission lines including Hβ, Hγ, He II and He I for both AGNs, and including Fe II for Mrk 817 with respect to the varying AGN continuum at 5100 Å. Investigating the relationship between line widths and time lags of the broad emission lines, we find that the BLR dynamics of Mrk 817 and NGC 7469 are consistent with the virial prediction. We estimate the masses of central supermassive black hole (SMBH) and the accretion rates of both AGNs. Using the data of this campaign, we construct the velocity-resolved lag profiles of the broad Hγ, Hβ, and He I lines for Mrk 817, which show almost the same kinematic signatures that the time lags in the red wing are slightly larger than the time lags in the blue wing. For NGC 7469, we only clearly construct the velocity-resolved lag profiles of the broad Hγ and Hβ, which show very similar kinematic signatures to the BLR of Mrk 817. These signatures indicate that the BLR of Keplerian motion in both AGNs seemingly has outflowing components during the monitoring period. We discuss the kinematics of the BLR and the measurements including SMBH mass and accretion rates. © 2021, CC BY.

关键词： Kinematics

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Towards the merger of Hawking radiating black holes

arXiv

引用

arXiv 2020年

作者： Li, Huiquan Wang, Jiancheng Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing100012 China

We discuss the merger process of binary black holes with Hawking radiation taken into account. Besides the redshifted radiation to infinity, binary black holes can exchange radiation between themselves, which is first redshifted and then blueshifted when it propagates from one hole to the other. The exchange rate should be large when the temperature-divergent horizons are penetrating each other to form a single horizon with unique temperature. This will cause non-negligible mass and angular momentum transfer between the black holes during the merging process of the horizons. We further argue in the large mass ratio limit that the light hole whose local evaporation is enhanced by the competing redshift-blueshift effects will probably evaporate or decay completely before reaching the the horizon of the heavy one. We also discuss the possibility of testing Hawking radiation and even exploring the information loss puzzle in gravitational wave observations. Copyright © 2020, The Authors. All rights reserved.

关键词： Stars

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Evidence of stellar oscillations in the post-common envelop binary candidate ASASSN-V J205543.90+240033.5

arXiv

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arXiv 2023年

作者： Takata, Jumpei Kong, A.K.H. Wang, X.F. Song, F.F. Mao, J. Hou, X. Hu, C.-P. Lin, L.C.-C. Li, K.L. Hui, C.Y. Department of Astronomy School of Physics Huazhong University of Science and Technology Wuhan430074 China Institute of Astronomy National Tsing Hua University Hsinchu30013 Taiwan Yunnan Observatories Chinese Academy of Sciences Yunnan Province Kunming650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China University of Chinese Academy of Sciences Beijing100049 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Department of Physics National Changhua University of Education Changhua50007 Taiwan Department of Physics National Cheng Kung University Tainan701401 Taiwan Department of Astronomy and Space Science Chungnam National University Daejeon305-764 Korea Republic of

ASASSN-V J205543.90+240033.5 (ASJ2055) is a possible post-common envelope binary system. Its optical photometric data shows an orbital variation about 0.52 days and a fast period modulation of P0 ∼ 9.77 minute, whose origin is unknown. In this Letter, we report an evidence of the stellar oscillation of the companion star as the origin of the fast period modulation. We analyze the photometric data taken by TESS, Liverpool telescope, and Lulin One-meter Telescope. It is found that the period of the 9.77-minute signal measured in 2022 August is significantly shorter than that in 2021 July/August, and the magnitude of the change is of the order of |P0|/P0 ∼ 0.0008(4). Such a large variation will be incompatible with the scenario of the white dwarf spin as the origin of the 9.77-minute periodic modulation. We suggest that the fast periodic signal is related to the emission from the irradiated companion star rather than that of the white dwarf. Using existing photometric data covering a wide wavelength range, we estimate that the hot white dwarf in ASJ2055 has a temperature of Teff ∼ 80000 K and is heating the oscillating M-type main-sequence star with Teff ∼ 3500 K on its un-irradiated surface. The stellar oscillation of M-type main-sequence star has been predicted in theoretical studies, but no observational confirmation has been done. ASJ2055, therefore, has a potential to be a unique laboratory to investigate the stellar oscillation of a M-type main-sequence star and the heating effect on the stellar oscillation. © 2023, CC0.

关键词： White dwarfs

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Lijiang 2.4-meter Telescope and its instruments

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Research in Astronomy and Astrophysics 2019年第10期19卷 95-108页

作者： Chuan-Jun Wang Jin-Ming Bai Yu-Feng Fan Ji-Rong Mao Liang Chang Yu-Xin Xin Ju-Jia Zhang Bao-Li Lun Jian-Guo Wang Xi-Liang Zhang Mei Ying Kai-Xing Lu Xiao-Li Wang Kai-Fan Ji Ding-Rong Xiong Xiao-Guang Yu Xu Ding Kai Ye Li-Feng Xing Wei-Min Yi Liang Xu Xiang-Ming Zheng Yuan-Jie Feng Shou-Sheng He Xue-Li Wang Zhong Liu Dong Chen Jun Xu Song-Nian Qin Rui-Long Zhang Hui-Song Tan Zhi Li Ke Lou Jian Li Wei-Wei Liu Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing 100101 China University of Chinese Academy of Sciences Beijing 100049 China Astrophysics Center of Guangzhou University Guangzhou 510006China

The Lijiang 2.4-meter Telescope(LJT), the largest common-purpose optical telescope in China,has been available to the worldwide astronomical community since 2008. It is located at the Gaomeigu site,Lijiang Observatory(LJO), in the southwest of China. The site has very good observational *** its 10-year operation, several instruments have been equipped on the LJT. Astronomers can perform both photometric and spectral observations. The main scientific goals of LJT include recording photometric and spectral evolution of supernovae, reverberation mapping of active galactic nuclei, investigating the physical properties of binary stars and near-earth objects(comets and asteroids), and identification of exoplanets and all kinds of transients. Until now, the masses of 41 high accretion rate black holes have been measured, and more than 168 supernovae have been identified by the LJT. More than 190 papers related to the LJT have been published. In this paper, the general observation conditions of the Gaomeigu site is introduced at first. Then, the structure of the LJT is described in detail, including the optical, mechanical, motion and control system. The specification of all the instruments and some detailed parameters of the YFOSC is also presented. Finally, some important scientific results and future expectations are summarized.

关键词： telescopes Lijiang 2.4-m Telescope-instrumentation photometers-instrumentation spectrographs

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J115307.93+353528.2—Spectroscopic Twin Binary, Composed of Solar Like Stars. Orbital Solution from Poorly Resolved Double-line structure

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Research Notes of the AAS 2024年第7期8卷 175-175页

作者： Mikhail Yu. Kovalev Xuefei Chen Zhanwen Han Yunnan Observatories China Academy of Sciences Kunming 650216 People’s Republic of China mikhail.kovalev@*** Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 People’s Republic of China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing 100012 People’s Republic of China

We present a study of double-lined spectroscopic binary (SB2) J115307.93+353528.2 based on data from the Large Sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) medium resolution survey (MRS). We use full-spectrum fitting to derive radial velocities and spectral parameters, which suggest that this is a "twin" system of two nearly identical stars, which are similar to the Sun. The orbital solution tells us that it is relatively wide pair of stars on slightly eccentric orbit with period P ≃ 206 days. This result shows that LAMOST-MRS data can be used to detect such twin binaries even when double-line structure is poorly resolved in the spectra. Changes of $(V\sin i)$ $(V \sin i)$ values from single star model analysis allows us to reliably select su

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Three new late-type hypervelocity star candidates from Gaia DR2 with refined selection criteria

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Research in Astronomy and Astrophysics 2020年第3期20卷 170-184页

作者： Jiao Li Shi Jia Yan Gao Deng-Kai Jiang Thomas Kupfer Ulrich Heber Chao Liu Xue-Fei Chen Zhan-Wen Han Yunnan observatories Chinese Academy of SciencesKunming 650011China Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan observatoriesChinese Academy of SciencesKunming 650011China University of Chinese Academy of Sciences Beijing 100049China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing 100101China State Key Laboratory of Lunar and Planetary Sciences Macao University of Science and TechnologyMacaoChina Kavli Institute for Theoretical Physics University of CaliforniaSanta BarbaraCA 93106USA Department of Physics University of CaliforniaSanta BarbaraCA 93106USA Dr.Remeis-Sternwarte&ECAP University of Erlangen-NurnbergErlangenGermany Key Lab of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China

Several dozen hypervelocity star(HVS)candidates have been reported based on the second data release of Gaia(Gaia DR2).However,it has been proven that the radial velocities of some Gaia HVS candidates are not *** this paper,we employ refined astrometric criteria to re-examine Gaia DR2,arriving at a more reliable sample of HVS and high velocity star candidates than those found by previous *** develop a method called Binary Escape Probability Analysis to identify some HVS *** method allows us to work with stars having only two epochs of measured radial *** stars were usually discarded in previous similar studies.A scrutiny of our final results sheds light on selection effects present in our studies,which we propose to be the focus of future *** total,we find three late-type(2 G-type and 1 K-type)HVS and 21 high velocity star candidates,3 and 11 of which are new,*** by their historical trajectories,which we calculate,all three HVS candidates could not have had Galactic center *** monitoring is required to confirm their status.

关键词： stars kinematics and dynamics-evolution-statistics

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MODELING Hα AND HE 10830 TRANSMISSION SPECTRUM OF WASP-52B

arXiv

引用

arXiv 2022年

作者： Yan, Dongdong Seon, Kwang-Il Guo, Jianheng Chen, Guo Li, Lifang Yunnan Observatories Chinese Academy of Sciences P.O. Box 110 Kunming650011 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650011 China Korea Astronomy and Space Science Institute 776 Daedeokdae-ro Yuseong-gu Daejeon34055 Korea Republic of Astronomy and Space Science Major University of Science and Technology 217 Gajeong-ro Yuseong-gu Daejeon34113 Korea Republic of Key Laboratory of Planetary Sciences Purple Mountain Observatory Chinese Academy of Sciences Nanjing210023 China

Escaping atmosphere has been detected by the excess absorption of Lyα, Hα and He triplet (10830Å) lines. Simultaneously modeling the absorption of the Hα and He 10830 lines can provide useful constraints about the exoplanetary atmosphere. In this paper, we use a hydrodynamic model combined with a non-local thermodynamic model and a new Monte Carlo simulation model to obtain the H(2) and He(23S) populations. The Monte Carlo simulations of Lyα radiative transfer are performed with assumptions of a spherical stellar Lyα radiation and a spherical planetary atmosphere, for the first time, to calculate the Lyα mean intensity distribution inside the planetary atmosphere, necessary in estimating the H(2) population. We model the transmission spectra of the Hα and He 10830 lines simultaneously in hot Jupiter WASP-52b. We find that models with many different H/He ratios can reproduce the Hα observations well if the host star has (1) a high X-ray/extreme ultraviolet (XUV) flux (FXUV) and a relatively low X-ray fraction in XUV radiation (βm), or (2) a low FXUV and a high βm. The simulations of He 10830 Å triplet suggest that a high H/He ratio (∼ 98/2) is required to fit the observation. The models that fit both lines well confine FXUV to be about 0.5 times the fiducial value and βm to have a value around 0.3. The models also suggest that hydrogen and helium originate from the escaping atmosphere, and the mass-loss rate is about 2.8×1011 g s−1 © 2022, CC BY-NC-ND.

关键词： Radiative transfer

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