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Science China(Physics,Mechanics & Astronomy) 2015年第3期58卷 82-89页

作者： LYU Fen WANG YuanZhu LIANG YunFeng LIN TingTing HU YouDong LIANG EnWei Department of Physics and GXU-NAOC Center for Astrophysics and Space Sciences Guangxi University Purple Mountain Observatory Chinese Academy of Sciences Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences

The mono-frequency peak luminosity and the corresponding photon energy of the time-integrated （L~, Eg） and peak time （L~, ffp） vfv spectra were derived for a sample of 38 redshift-known Fermi GRBs by fitting the spectra with the Band function. It was found that Ept is generally consistent with Ep, and Lp is averagely three times larger than Lp. The slope of the Lp1 -Etp relation was consistent with that of the Lps - Eps relation. The photon indices in the peak time spectrum, particularly, the index of the low energy end was, were statistically larger than that in the time-integrated spectrum. These results indicate that Lp and Ep are dominated by Lp1 and Ept, respectively. The difference of the spectral indices between the time-integrated and peak time spectra may be because of the overlap effect of a series of time-resolved spectra within a GRB. Our simulations, which were based on the observed spectral evolution and correlation between the energy flux and the peak energy within individual GRBs support our speculations. The Lt - Et, relation may be less contaminated by the overla!a effect, and it would may be an intrinsic feature of radiation ohvsics.

关键词： γ-ray sources γ-ray bursts gamma-rays： astronomical observations

The bright star survey telescope for the planetary transit survey in Antarctica

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Science Bulletin 2016年第5期61卷 383-390页

作者： Qiguo Tian Peng Jiang Fujia Du Jian Wang Zhengyang Li Xiaoyan Li Zhiyong Zhang Haiping Lu Xiangyan Yuan Huigen Liu Hui Zhang Luming Sun Liang Chang Jianguo Wang Shaohua Zhang Tuo Ji Xiheng Shi Jie Chen Guangyu Zhang Minghao Jia Jiajing Liu Junyan Zhou Xiang Pan Shucheng Dong Fengxin Jiang Hongfei Zhang Jilin Zhou Lifan Wang Hongyan Zhou Polar Research Institute of China Shanghai 200136 China School of Astronomy and Space Science Nanjing UniversityNanjing 210093 China National Astronomical Observatories/Nanjing Institute of Astronomical Optics and Technology Chinese Academy of Sciences Nanjing 210042 China State Key Laboratory of Technologies of Particle Detection and Electronics Department of Modern Physics University of Science and Technology of China Hefei 230026 China Key Laboratory of Modern Astronomy and Astrophysics(Nanjing University) Ministry of Education Nanjing 210093China Key Laboratory for Research in Galaxies and Cosmology Department of Astronomy University of Science and Technology of China Chinese Academy of Sciences Hefei 230026 China National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Kunming 650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China Purple Mountain Observatory Chinese Academy of ScienceNanjing 210008 China

Transiting extrasolar planets(exoplanets),especially those orbiting bright stars, are desired for study of the diversity of planetary compositions, internal structures and atmospheres beyond our solar system. Dome A at Antarctica is a promising site for planetary transit surveys,where the continuous darkness and the large clear-sky fraction in the winter months greatly enhance the detection efficiency. The Chinese Small Telescope ARray and the Antarctic Survey Telescopes are the first facilities that have been operated at Dome A for use in exoplanet surveys. To increase the sky coverage, a low-temperature-resistant wide-field robotic telescope, named the bright star survey telescope(BSST), has been developed to join the ongoing planetary transit survey in Antarctica. The BSST has an aperture size of 300 mm and is equipped with a largeframe 4K×4K CCD camera to receive starlight from a 3.°4×3.°4 field of view. The BSST was operated at Lijiang observatory in April and May 2015 for a test *** precision of 3.5 mmag was achieved for stars with V～11 mag using 75 s exposures. The transiting events of two Jupiter-size exoplanets, HAT-P-3b and HATP-12 b, were observed on May 10 and May 20, 2015,respectively.

关键词： Instrumentation Exoplanet Photometry Antarctic Site

A Gamma-ray Pulsar Timing Array Constrains the Nanohertz Gravitational Wave Background

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arXiv 2022年

作者： Ajello, M. Atwood, W.B. Baldini, L. Ballet, J. Barbiellini, G. Bastieri, D. Bellazzini, R. Berretta, A. Bhattacharyya, B. Bissaldi, E. Blandford, R.D. Bloom, E. Bonino, R. Bruel, P. Buehler, R. Burns, E. Buson, S. Cameron, R.A. Caraveo, P.A. Cavazzuti, E. Cibrario, N. Ciprini, S. Clark, C.J. Cognard, I. Coronado-Blázquez, J. Crnogorcevic, M. Cromartie, H. Crowter, K. Cutini, S. D’Ammando, F. De Gaetano, S. de Palma, F. Digel, S.W. Di Lalla, N. Dirirsa, F. Fana Di Venere, L. Domínguez, A. Ferrara, E.C. Fiori, A. Franckowiak, A. Fukazawa, Y. Funk, S. Fusco, P. Gammaldi, V. Gargano, F. Gasparrini, D. Giglietto, N. Giordano, F. Giroletti, M. Green, D. Grenier, I.A. Guillemot, L. Guiriec, S. Gustafsson, M. Harding, A.K. Hays, E. Hewitt, J.W. Horan, D. Hou, X. Jóhannesson, G. Keith, M.J. Kerr, M. Kramer, M. Kuss, M. Larsson, S. Latronico, L. Li, J. Longo, F. Loparco, F. Lovellette, M.N. Lubrano, P. Maldera, S. Manfreda, A. Martí-Devesa, G. Mazziotta, M.N. Mereu, I. Michelson, P.F. Mirabal, N. Mitthumsiri, W. Mizuno, T. Monzani, M.E. Morselli, A. Negro, M. Nieder, L. Ojha, R. Omodei, N. Orienti, M. Orlando, E. Ormes, J.F. Paneque, D. Parthasarathy, Aditya Pei, Z. Persic, M. Pesce-Rollins, M. Pillera, R. Poon, H. Porter, T.A. Principe, G. Racusin, J.L. Rainò, S. Rando, R. Rani, B. Ransom, S.M. Ray, P.S. Razzano, M. Razzaque, S. Reimer, A. Reimer, O. Roy, J. Sánchez-Conde, M. Saz Parkinson, P.M. Scargle, J. Scotton, L. Serini, D. Sgrò, C. Siskind, E.J. Smith, D.A. Spandre, G. Spiewak, R. Spinelli, P. Stairs, I. Suson, D.J. Swihart, S.J. Tabassum, S. Thayer, J.B. Theureau, G. Torres, D.F. Troja, E. Valverde, J. Wadiasingh, Z. Wood, K. Zaharijas, G. Department of Physics and Astronomy Clemson University Kinard Lab of Physics ClemsonSC29634-0978 United States Santa Cruz Institute for Particle Physics Department of Physics Department of Astronomy and Astrophysics University of California at Santa Cruz Santa CruzCA95064 United States Università di Pisa Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy AIM CEA CNRS Université Paris-Saclay Université de Paris Gif-sur-Yvette F-91191 France Istituto Nazionale di Fisica Nucleare Sezione di Trieste TriesteI-34127 Italy Dipartimento di Fisica Università di Trieste TriesteI-34127 Italy Istituto Nazionale di Fisica Nucleare Sezione di Padova PadovaI-35131 Italy Dipartimento di Fisica e Astronomia "G. Galilei" Università di Padova PadovaI-35131 Italy Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy Dipartimento di Fisica Università degli Studi di Perugia PerugiaI-06123 Italy National Centre for Radio Astrophysics Tata Institute of Fundamental Research Pune411 007 India Dipartimento di Fisica "M. Merlin" Università e del Politecnico di Bari via Amendola 173 BariI-70126 Italy Istituto Nazionale di Fisica Nucleare Sezione di Bari BariI-70126 Italy W. W. Hansen Experimental Physics Laboratory Kavli Institute for Particle Astrophysics and Cosmology Department of Physics SLAC National Accelerator Laboratory Stanford University StanfordCA94305 United States Istituto Nazionale di Fisica Nucleare Sezione di Torino TorinoI-10125 Italy Dipartimento di Fisica Università degli Studi di Torino TorinoI-10125 Italy Laboratoire Leprince-Ringuet École polytechnique Centre national de la recherche scientifique Institut national de physique nucléaire de physique des particules Palaiseau F-91128 France Deutsches Elektronen Synchrotron Zeuthen D-15738 Germany Department of Physics and Astronomy Louisiana State University Baton RougeLA70803 United States Institut für Theoretische Physik and Astrophysik Unive

After large galaxies merge, their central supermassive black holes are expected to form binary systems whose orbital motion generates a gravitational wave background (GWB) at nanohertz frequencies. Searches for this background utilize pulsar timing arrays, which perform long-term monitoring of millisecond pulsars (MSPs) at radio wavelengths. We use 12.5 years of Fermi Large Area Telescope data to form a gamma-ray pulsar timing array. Results from 35 bright gamma-ray pulsars place a 95% credible limit on the GWB characteristic strain of 1.0 × 10−14 at 1 yr−1, which scales as the observing time span t−13/6obs. This direct measurement provides an independent probe of the GWB while offering a check on radio noise models. Copyright © 2022, The Authors. All rights reserved.

关键词： Pulsars

Optical quasi-periodic oscillation of the BL Lacertae object S5 0716+714 during the faint state

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arXiv 2017年

作者： Hong, Shanwei Xiong, Dingrong Bai, Jinming Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China School of Applied Technology Lijiang Teachers College Lijiang674199 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China

In order to search for the evidence of quasi-periodic oscillation (QPO) in blazar, multicolor optical observations of the BL Lacertae object S5 0716+714 were performed from 2005 to 2012. For I band on March 19 2010 with low variability amplitude and low flux level, the same quasi-periodic oscillation 50 minutes with 99% significance levels is confirmed by ZDCF method, Lomb-Scargle method, REDFIT and fitting sinusoidal curves. The observed QPO is likely to be explained by accretion disk variability. If the observed QPO indicates an innermost stable orbital period from the accretion disk, the QPO 50 min corresponds to a black hole mass of 5.03×106M☉ for a non-rotating Schwarzschild black hole and 3.2 × 107M☉ for a maximally rotating Kerr black hole. Copyright © 2017, The Authors. All rights reserved.

关键词： Gravitation

OPTICAL OBSERVATIONS OF THE YOUNG TYPE Ic SUPERNOVA SN 2014L IN M99

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arXiv 2018年

作者： Zhang, Jujia Wang, Xiaofeng Vinkó, József Wheeler, J. Craig Chang, Liang Yang, Yi Wang, Lifan Zhai, Qian Rui, Liming Mo, Jun Zhang, Tianmeng Zhang, Yu Wang, Jianguo Mao, Jirong Wang, Chuanjun Yi, Weimin Xin, Yuxin Li, Wenxiong Lun, Baoli Lu, Kaixing Sai, Hanna Zheng, Xiangming Zhang, Xiliang Zhou, Xu Bai, Jinming Chinese Academy of Sciences Kunming650216 China George P. and Cynthia Woods Mitchell Institute for Fundamental Physics & Astronomy Texas A. & M. University College StationTX77843 United States 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 20A Datun Road Chaoyang District Beijing100012 China Tsinghua University Beijing100084 China Konkoly Observatory Research Centre for Astronomy and Earth Sciences Konkoly Thege ut 15-17 Budapest1121 Hungary Department of Optics and Quantum Electronics University of Szeged Dómtér 9 SzegedH-6720 Hungary Department of Astronomy University of Texas at Austin AustinTX78712-1205 United States Department of Particle Physics and Astrophysics Weizmann Institute of Science Rehovot76100 Israel Chinese Academy of Sciences Beijing100012 China Chinese Academy of Sciences Urumqi830011 China

We present optical spectroscopic and photometric observations of the nearby type Ic supernova (SN Ic) SN 2014L. This SN was discovered by the Tsinghua-NAOC Transient Survey (TNTS) in the nearby type-Sc spiral galaxy M99 (NGC 4254). Fitting to the early-time light curve indicates that SN 2014L was detected at only a few hours after the shock breakout, and it reached a peak brightness of MV = −17.73 ± 0.28 mag (L = [2.06 ± 0.50] × 1042 erg s−1) approximately 13 days later. SN 2014L shows a close resemblance to SN 2007gr in the photometric evolution, while it shows stronger absorption features of intermediate-mass elements (especially Ca ii) in the early-time spectra. Based on simple modeling of the observed light curves, we derived the mass of synthesized 56Ni as MNi = 0.075 ±0.025 M1577, and the mass and total energy of the ejecta as Mej=1.00±0.20M1577 and Eej = 1.45 ±0.25 foe, respectively. Given these typical explosion parameters, the early detection, and the extensive observations, we suggest that SN 2014L could be a template sample for the investigation of SNe Ic. Copyright © 2018, The Authors. All rights reserved.

关键词： Photometry

Multi-color optical monitoring of the BL Lacertae object S5 0716+714 during the 2012 outburst

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arXiv 2017年

作者： Hong, Shanwei Xiong, Dingrong Bai, Jinming Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China Department of Mathematics and Computer Science Lijiang Teachers College Lijiang674199 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China

We have monitored the BL Lacertae object S5 0716+714 in the optical bands during 2012 January and February with long time spans on intraday timescales (>5 hr) and high time resolutions. During this monitoring period, the object shows violent flaring activity both in short and intraday timescales. The object has high value of duty cycle. The light curves detected as intraday variability (IDV) show variability of various shapes. The variability amplitude is from 12.81 per cent to 33.22 per cent, and the average value 19.92 ± 5.87 per cent. The overall magnitude variabilities are ΔB = 1m.24, ΔV = 1m.42, ΔR = 1m.3, ΔI = 1m.23 respectively. During the observations, the average change rate is = 0.035 ± 0.009 Mag/h during the ascent and = 0.035 ± 0.014 Mag/h during the descent. However, different cases are found on certain nights. There are good inter-bands correlations but not significant time lags for intraday and short timescales. The results of the autocorrelation function show that the variability timescales range from 0.054 day to 0.134 day. Most of nights show bluer when brighter (BWB) chromatic trend;a weak redder with brighter (RWB) trend is found;a few nights show no correlations between magnitude and color index. The BWB trend appears in the short timescales. During the flare the spectral index exhibits a clockwise loop for inter-nights. A shock-in-jet model and the shock wave propagating along a helical path are likely to explain the variability and color index variability. Copyright © 2017, The Authors. All rights reserved.

关键词： Shock waves

Erratum: 'Resolved Neutral Carbon Emission in Nearby Galaxies: [C i] Lines as Total Molecular Gas Tracers' (2019, ApJ, 880, 133)

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The Astrophysical Journal 2019年第2期883卷

作者： Qian Jiao Yinghe Zhao Nanyao Lu Yu Gao Dragan Salak Ming Zhu Zhi-Yu Zhang Xue-Jian Jiang Qinghua Tan Purple Mountain Observatory & Key Lab of Radio Astronomy Chinese Academy of Sciences (CAS) Nanjing 210033 People's Republic of China Yunnan Observatories & Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming 650011 People's Republic of China Center for Astronomical Mega-Science CAS 20A Datun Road Chaoyang District Beijing 100012 People's Republic of China China-Chile Joint Center for Astronomy (CCJCA) Camino El Observatorio 1515 Las Condes Santiago Chile National Astronomical Observatories & Key Lab of Radio Astronomy CAS Beijing 100012 People's Republic of China Purple Mountain Observatory & Key Lab of Radio Astronomy Chinese Academy of Sciences (CAS) Nanjing 210008 People's Republic of China School of Science and Technology Kwansei Gakuin University 2-1 Gakuen Sanda Hyogo 669-1337 Japan Institute for Astronomy University of Edinburgh Royal Observatory Blackford Hill Edinburgh EH9 3HJ UK ESO Karl Schwarzschild Strasse 2 D-85748 Garching Munich Germany The current zip code is corrected from that in the published article.

ET White Paper: To Find the First Earth 2.0

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arXiv 2022年

作者： Ge, Jian Zhang, Hui Zang, Weicheng Deng, Hongping Mao, Shude Xie, Ji-Wei Liu, Hui-Gen Zhou, Ji-Lin Willis, Kevin Huang, Chelsea Howell, Steve B. Feng, Fabo Zhu, Jiapeng Yao, Xinyu Liu, Beibei Aizawa, Masataka Zhu, Wei Li, Ya-Ping Ma, Bo Ye, Quanzhi Yu, Jie Xiang, Maosheng Yu, Cong Liu, Shangfei Yang, Ming Wang, Mu-Tian Shi, Xian Fang, Tong Zong, Weikai Liu, Jinzhong Zhang, Yu Zhang, Liyun El-Badry, Kareem Shen, Rongfeng Tam, Pak-Hin Thomas Hu, Zhecheng Yang, Yanlv Zou, Yuan-Chuan Wu, Jia-Li Lei, Wei-Hua Wei, Jun-Jie Wu, Xue-Feng Sun, Tian-Rui Wang, Fa-Yin Zhang, Bin-Bin Xu, Dong Yang, Yuan-Pei Li, Wen-Xiong Xiang, Dan-Feng Wang, Xiaofeng Wang, Tinggui Zhang, Bing Jia, Peng Yuan, Haibo Zhang, Jinghua Wang, Sharon Xuesong Gan, Tianjun Wang, Wei Zhao, Yinan Liu, Yujuan Chen, Yonghe Wei, Chuanxin Kang, Yanwu Yang, Baoyu Qi, Chao Liu, Xiaohua Zhang, Quan Zhu, Yuji Zhou, Dan Zhang, Congcong Yu, Yong Zhang, Yongshuai Li, Yan Tang, Zhenghong Wang, Chaoyan Wang, Fengtao Li, Wei Cheng, Pengfei Shen, Chao Li, Baopeng Pan, Yue Yang, Sen Gao, Wei Song, Zongxi Wang, Jian Zhang, Hongfei Chen, Cheng Wang, Hui Zhang, Jun Wang, Zhiyue Zeng, Feng Zheng, Zhenhao Zhu, Jie Guo, Yingfan Zhang, Yihao Li, Yudong Wen, Lin Feng, Jie Chen, Wen Chen, Kun Han, Xingbo Yang, Yingquan Wang, Haoyu Duan, Xuliang Huang, Jiangjiang Liang, Hong Bi, Shaolan Gai, Ning Ge, Zhishuai Guo, Zhao Huang, Yang Li, Gang Li, Haining Li, Tanda Lu, Yuxi Lucy Rix, Hans-Walter Shi, Jianrong Song, Fen Tang, Yanke Ting, Yuan-Sen Wu, Tao Wu, Yaqian Yang, Taozhi Yin, Qing-Zhu Gould, Andrew Lee, Chung-Uk Dong, Subo Yee, Jennifer C. Shvartzvald, Yossi Yang, Hongjing Kuang, Renkun Zhang, Jiyuan Liao, Shilong Qi, Zhaoxiang Yang, Jun Zhang, Ruisheng Jiang, Chen Ou, Jian-Wen Li, Yaguang Beck, Paul Bedding, Timothy R. Campante, Tiago L. Chaplin, William J. Christensen-Dalsgaard, Jørgen García, Rafael A. Gaulme, Patrick Gizon, Laurent Hekker, Saskia Huber, Daniel Khanna, Shourya Mathur, Savita Miglio, Andrea Mosser, Benoît Ong, J.M. Joel Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai China Tsinghua University Beijing China Nanjing University Nanjing China Sun Yat-Sen University Zhuhai China Tsung-Dao Lee Institute Shanghai Jiao Tong University Shanghai China Max Planck Institute for Solar System Research Göttingen Germany Max-Planck-Institute für Astronomie Heidelberg Germany Zhejiang University Hangzhou China University of Science and Technology of China Hefei China Taiyuan University of Technology Taiyuan China University of Maryland College ParkMD United States Boston University BostonMA United States Xinjiang Astronomical Observatory Chinese Academy of Sciences Xinjiang China Huazhong University of Science and Technology Wuhan China Purple Mountain Observatories Chinese Academy of Sciences Nanjing China Guizhou University Guiyang China National Astronomical Observatories Chinese Academy of Sciences Beijing China Yunnan University Kunming China Tel Aviv University Tel Aviv Israel Science Talent Training Center Gainesville United States Shanghai Institute of Technical Physics Chinese Academy of Sciences Shanghai China Xi'An Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi'An China Innovation Academy for Microsatellites Chinese Academy of Sciences Shanghai China Department of Astronomy The University of Geneva Versoix Switzerland University of Southern Queensland QLD Australia Research School of Astronomy & Astrophysics Australian National University ACT Australia Research School of Computer Science Australian National University ACT Australia Beijing Normal University Beijing China University of Cambridge Cambridge United Kingdom Dezhou University Dezhou China Jimei University Xiamen China Ohio State University ColumbusOH United States Korea Astronomy and Space Science Institute Daejon Korea Republic of Kavli Institute for Astronomy and Astrophysics Peking University Beijing China Center for Astrophysics Harvard

The ET mission is a wide-field and ultra-high-precision photometric survey mission being developed in China. This mission is designed to measure, for the first time, the occurrence rate and the orbital distributions of Earth-sized planets. ET consists of seven 30 cm telescopes to be launched to the Earth-Sun's L2 point. Six of these are transit telescopes with a FOV of 500 square degrees. Staring in the direction that encompasses the original Kepler field for four continuous years, this monitoring will yield tens of thousands of transiting planets, including the elusive Earth twins orbiting solar-type stars. The seventh is a 30 cm microlensing telescope that will monitor an area of 4 square degrees toward the galactic bulge. Combined with simultaneous ground-based KMTNet observations, it will measure masses of hundreds of long-period and free-floating planets. Together, the transit and the microlensing telescopes will revolutionize our understanding of terrestrial planets across a large swath of orbital distances and free space. In addition, the survey data will also facilitate studies in the fields of asteroseismology, Galactic archaeology, time-domain sciences, and black holes in binaries. © 2022, CC BY-NC-ND.

关键词： Planets

The orbital period – mass ratio relation of wide sdB+MS binaries and its application to the stability of RLOF.

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arXiv 2018年

作者： Vos, Joris Vucković, Maja Chen, Xuefei Han, Zhanwen Boudreaux, Thomas Barlow, Brad N. Østensen, Roy Németh, Péter Instituto de Física y Astronomía Universidad de Valparaiso Gran Bretaña 1111 Playa Ancha Valparaíso2360102 Chile Institut für Physik und Astronomie Universität Potsdam Karl-Liebknecht-Str. 24/25 Golm14476 Germany 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 Department of Physics High Point University One University Parkway High PointNC27268 United States Department of Physics Astronomy and Materials Science Missouri State University SpringfieldMO65804 United States Astronomical Institute of the Czech Academy of Sciences OndřejovCZ-25165 Czech Republic *** Malomsok8533 Hungary

Wide binaries with hot subdwarf-B (sdB) primaries and main sequence companions are thought to form only through stable Roche lobe overflow (RLOF) of the sdB progenitor near the tip of the red giant branch (RGB). We present the orbital parameters of eleven new long period composite sdB binaries based on spectroscopic observations obtained with the UVES, FEROS and CHIRON spectrographs. Using all wide sdB binaries with known orbital parameters, 23 systems, the observed period distribution is found to match very well with theoretical predictions. A second result is the strong correlation between the orbital period (P) and the mass ratio (q) in the observed wide sdB binaries. In the P-q plane two distinct groups emerge, with the main group (18 systems) showing a strong correlation of lower mass ratios at longer orbital periods. The second group are systems that are thought to be formed from higher mass progenitors. Based on theoretical models, a correlation between the initial mass ratio at the start of RLOF and core mass of the sdB progenitor is found, which defines a mass-ratio range at which RLOF is stable on the RGB. Copyright © 2018, The Authors. All rights reserved.

关键词： Giant stars

Binary population synthesis for the core-degenerate scenario of type Ia supernova progenitors

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Research in Astronomy and Astrophysics 2015年第10期15卷 1701-1712页

作者： Wei-Hong Zhou Bo Wang Xiang-Cun Meng Dong-Dong Liu Gang Zhao Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of Sciences University of Chinese Academy of Sciences Yunnan Minzu University Yunnan Observatories Chinese Academy of Sciences Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences

The core-degenerate （CD） scenario has been suggested to be a possible progenitor model of type Ia supernovae （SNe Ia）, in which a carbon-oxygen white dwarf merges with the hot CO core of a massive asymptotic giant branch star dur- ing their common-envelope phase. However, the SN Ia birthrates for this scenario are still uncertain. We conducted a detailed investigation into the CD scenario and then gave the birthrates for this scenario using a detailed Monte Carlo binary pop- ulation synthesis approach. We found that the delay times of SNe Ia from this sce- nario are -70 Myr- 1400 Myr, which means that the CD scenario contributes to young SN Ia populations. The Galactic SN Ia birthrates for this scenario are in the range of ~7.4×10^-5 yr^-1- 3.7 × 10^-4 yr^-1, which roughly accounts for -2%-10% of all SNe Ia. This indicates that, under the assumptions made here, the CD scenario only contributes a small portion of all SNe Ia, which is not consistent with the results of Ilkov ＆ Soker.

关键词： binaries： close -- stars： evolution -- supernovae： general