检索结果-内蒙古大学图书馆

SN 2018hfm: A Low-Energy Type II Supernova with Prominent Signatures of Circumstellar Interaction and Dust Formation

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Zhang, Xinghan Wang, Xiaofeng Sai, Hanna Niculescu-Duvaz, Maria Filippenko, Alexei V. Zheng, WeiKang Brink, T.G. Lin, Han Zhang, Jicheng Cai, Yongzhi Mo, Jun Zhang, Jujia Baron, E. DerKacy, J.M. Huang, F. Zhang, T.-M. Tsinghua University Beijing100084 China Bejing Planetarium Beijing Academy of Science and Technology Beijing100044 China Department of Physics and Astronomy University College London Gower St. LondonWC1E 6BT United Kingdom Department of Astronomy University of California BerkeleyCA94720-3411 United States Miller Institute for Basic Research in Science Univerisity of California BerkeleyCA94720 United States Yunnan Observatories Chinese Academy of Sciences Kunming650011 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 20A Datun Road Chaoyang District Beijing100012 China Homer L. Dodge Department of Physics and Astronomy University of Oklahoma NormanOK73019 United States Department of Astronomy Shanghai Jiao Tong University Shanghai200240 China Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing10101 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing101408 China

We present multiband optical photometric and spectroscopic observations of an unusual Type II supernova, SN 2018hfm, which exploded in the nearby (d ≈ 34.67 Mpc) dwarf galaxy PGC 1297331 with a very low star-formation rate (0.0270 M yr−1) and a subsolar metallicity environment (∼ 0.5 Z). The V-band light curve of SN 2018hfm reaches a peak with value of −18.69 ± 0.64 mag, followed by a fast decline (4.42 ± 0.13 mag (100 d)−1). After about 50 days, it is found to experience a large flux drop (∼ 3.0 mag in V), and then enters into an unusually faint tail, which indicates a relatively small amount of 56Ni synthesised during the explosion. From the bolometric light curve, SN 2018hfm is estimated to have low ejecta mass (∼ 1.3 M) and low explosion energy (∼ 1050 erg) compared with typical SNe II. The photospheric spectra of SN 2018hfm are similar to those of other SNe II, with P Cygni profiles of the Balmer series and metal lines, while at late phases the spectra are characterised by box-like profiles of Hα emission, suggesting significant interaction between the SN ejecta and circumstellar matter. These box-like emission features are found to show increasing asymmetry with time, with the red-side component becoming gradually weaker, indicating that dust is continuously formed in the ejecta. Based on the dust-estimation tool damocles, we find that the dust increases from ∼ 10−6 M to 10−4–10−3 M between +66.7 d and +389.4 d after explosion. Copyright © 2021, The Authors. All rights reserved.

关键词： Dust

The escape of hydrogen-rich atmosphere of exoplanet: mass loss rates and the absorptions of stellar lyman α

学校读者我要写书评

暂无评论

arXiv 2019年

作者： Yan, D.D. Guo, J.H. Yunnan Observatories Chinese Academy of Sciences P.O. Box 110 Kunming650011 China 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

Detection of an Orphan X-ray Flare from a Blazar Candidate EP240709a with Einstein Probe

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Liu, Mingjun Zhang, Yijia Wang, Yun Xue, Rui Buckley, David Howell, D. Andrew Jin, Chichuan Li, Wenxiong Monageng, Itumeleng Pan, Haiwu Sun, Ning-Chen Tinyanont, Samaporn Wang, Lingzhi Yuan, Weimin An, Jie Andrews, Moira Anutarawiramkul, Rungrit Butpan, Pathompong Cheng, Huaqing Dai, Cui-Yuan Dai, Lixin Farah, Joseph Feng, Hua Fu, Shaoyu Guo, Zhen Jiang, Shuaiqing Li, An Li, Dongyue Liang, Yifang Liu, Heyang Liu, Xing Liu, Yuan Mao, Jirong McCully, Curtis Newsome, Megan Gonzalez, Estefania Padilla Pan, Xin Sun, Xinxiang Terreran, Giacomo Wang, Ze-Rui Wu, Qinyu Xiao, Hubing Xiong, Dingrong Xu, Dong Xu, Xinpeng Xue, Suijian Yang, Haonan Yang, Jun Zhang, Jin Zhang, Wenda Zhang, Wenjie Zou, Hu National Astronomical Observatories Chinese Academy of Sciences 20A Datun Road Beijing100101 China School of Astronomy and Space Science University of Chinese Academy of Sciences 19A Yuquan Road Beijing100049 China Department of Astronomy Tsinghua University Beijing100084 China Key Laboratory of Dark Matter and Space Astronomy Purple Mountain Observatory Chinese Academy of Sciences Nanjing210034 China Department of Physics Zhejiang Normal University Jinhua321004 China South African Astronomical Observatory Cape Town7935 South Africa Department of Astronomy University of Cape Town Rondebosch7701 South Africa Department of Physics University of the Free State Bloemfontein9300 South Africa Las Cumbres Observatory 6740 Cortona Drive Suite 102 GoletaCA93117-5575 United States Department of Physics University of California Santa BarbaraCA93106-9530 United States Institute for Frontiers in Astronomy and Astrophysics Beijing Normal University Beijing102206 China National Astronomical Research Institute of Thailand 260 Moo 4 Donkaew Maerim Chiang Mai50180 Thailand National Astronomical Observatories Chinese Academy of Sciences Beijing China CAS Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing China School of Astronomy and Space Science Nanjing University Nanjing210023 China Key Laboratory of Modern Astronomy and Astrophysics Nanjing University Ministry of Education Nanjing210023 China Department of Physics University of Hong Kong Pokfulam Road Hong Kong Las Cumbres Observatory 6740 Cortona Drive Suite 102 GoletaCA93117-557 United States Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China Instituto de Física y Astronomía Universidad de Valparaíso ave. Gran Bretaña 1111 Casilla 5030 Valparaíso Chile Millennium Institute of Astrophysics Nuncio Monseñor Sotero Sanz 100 Of. 104 Providencia Santiago Chile

Blazars are often observed to flare across multiple wavelengths. Orphan flares from blazars have been only detected a few times, providing an opportunity to understand the structure of the jet in the accreting system. We report a remarkable orphan X-ray flare from a blazar candidate EP240709a, detected by Einstein Probe (EP) in July 2024. The multi-band spectral properties and variability support EP240709a as a high-energy peaked BL Lacertae-type object. The flux in 0.5-10 keV increases by at least 28 times to the value of low state in 2020, with non-detection of remarkable flaring in other bands during the same period. EP240709a exhibits the harder-when-brighter tendency in the X-ray band during the orphan flare, while its infrared-optical spectra are featureless. We employ one-zone and two-zone leptonic synchrotron self-Compton models to perform the spectral energy distribution fitting. Detecting this rare orphan flare shows the potential of EP in discovering peculiar activities from AGN in high-cadence X-ray sky surveys. © 2024, CC BY.

关键词： Probes

Performance of the Stellar Abundances and atmospheric Parameters Pipeline adapted for M dwarfs I. Atmospheric parameters from the spectroscopic module

学校读者我要写书评

暂无评论

arXiv 2025年

作者： Olander, Terese Gent, Matthew R. Heiter, Ulrike Kochukhov, Oleg Bergemann, Maria Magg, Ekaterina Cassisi, Santi Kovalev, Mikhail Morel, Thierry Miller, Nicola J. Souto, Diogo Shan, Yutong Rojas-Ayala, Bárbara Delgado-Mena, Elisa Wang, Haiyang S. Department of Physics and Astronomy Uppsala University Box 516 UppsalaSE-751 20 Sweden Max Planck Institute for Astronomy Heidelberg69117 Germany Institut de Recherche en Astrophysique et Planétologie Université de Toulouse CNRS IRAP UMR 5277 14 Avenue Edouard Belin Toulouse31400 France INAF Osservatorio Astronomico d’Abruzzo Via M. Maggini s/n Teramo64100 Italy INFN Sezione di Pisa Largo Pontecorvo 3 Pisa56127 Italy Yunnan Observatories China Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Institute Université de Liège Quartier Agora Allée du 6 Août 19c Bât. B5c LiègeB4000 Belgium Departamento de Física Universidade Federal de Sergipe Av. Marcelo Deda Chagas S/N SE São CristóvãoCep 49.107-230 Brazil Centre for Planetary Habitability Department of Geosciences University of Oslo Sem Sælands Vei 2b Oslo0315 Norway Institut für Astrophysik Georg-August-Universität Friedrich-Hund-Platz 1 Göttingen37077 Germany Instituto de Alta Investigación Universidad de Tarapacá Casilla 7D Arica Chile CAUP Universidade do Porto Rua das Estrelas PortoPT4150-762 Portugal CSIC-INTA Camino Bajo del Castillo s/n Madrid Villanueva de la Cañada28692 Spain Center for Star and Planet Formation Globe Institute The University of Copenhagen Øster Voldgade 5-7 København K1350 Denmark

Context. M dwarfs are important targets in the search for Earth-like exoplanets due to their small masses and low luminosities. Several ongoing and upcoming space missions are targeting M dwarfs for this reason, and the ESA Plato mission is one of these. Aims. In order to fully characterise a planetary system the properties of the host star must be known. For M dwarfs we can derive effective temperature, surface gravity, metallicity, and abundances of various elements from spectroscopic observations in combination with photometric data. Methods. The Stellar Abundances and atmospheric Parameters Pipeline (SAPP) has been developed to serve as a prototype for one of the stellar science softwares within the Plato consortium. The pipeline combines results from a spectroscopy, a photometry, an interferometry, and an asteroseismology module to derive stellar parameters for FGK-type stars. We have modified the pipeline to be able to analyse the M dwarf part of the Plato target sample. The current version of the pipeline for M dwarfs mostly relies on spectroscopic observations. The module processing these data is based on the machine learning algorithm The Payne and fits a grid of model spectra to an observed spectrum to derive effective temperature and metallicity. We use spectra in the H-band, as the near-infrared region is beneficial for M dwarfs because there are fewer molecular lines and they are brighter in this wavelength region than in the optical. A method based on synthetic spectra was developed for the continuum normalisation of the spectra, taking into account the pseudo-continuum formed by numerous lines of the water molecule. Photometry is used to constrain the surface gravity. Results. We tested the modified SAPP on spectra of M dwarfs from the APOGEE survey. Our validation sample of 26 stars includes stars with interferometric observations and binaries. We found a good agreement between our derived values and reference values from a range of previous studies.

关键词： Photometers

Populations of accreting white dwarfs

学校读者我要写书评

暂无评论

Proceedings of the International Astronomical Union 2019年第S343期14卷 371-372页

作者： Chen H.-L. Woods T.E. Yungelson L. Gilfanov M. Han Z. Yunnan Observatories CAS Kunming 650011 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming 650011 China Center for Astronomical Mega-Science Chinese Academy of Science Beijing 100012 China Institute of Gravitational Wave Astronomy School of Physics and Astronomy University of Birmingham Birmingham B15 2TT United Kingdom Institute of Astronomy RAS 48 Pyatnitskaya Str. Moscow 119017 Russian Federation Max Planck Institute for Astrophysics Karl-Schwarzschild-Str. 1 Garching b. München 85741 Germany Space Research Institute of Russian Academy of Sciences Profsoyuznaya 84/32 Moscow 117997 Russian Federation

Using a hybrid binary population synthesis approach, we modelled the formation and evolution of populations of accreting white dwarfs (WDs) for differing star formation histories. We found that the delay time distribution of SNe Ia in the single degenerate scenario is inconsistent with observations. Additionally, we found that our predicted X-ray and UV emission of populations of accreting WDs are consistent with the X-ray luminosities of early-type galaxies observed by Chandra and the HeII 4686 Å/Hβ line ratio measured in stacked SDSS spectra of passively evolving galaxies. Moreover, we found that the majority of current novae in elliptical-like galaxies have low-mass WDs, long decay times, long recurrence periods and are relatively faint. In contrast, the majority of current novae in spiral-like galaxies have massive WDs, short decay times, short recurrence periods and are relatively bright. Our predicted distribution of mass-loss timescales in an M31-like galaxy is consistent with observations for Andromeda. © International Astronomical Union 2019.

关键词： cataclysmic variables stars:novae white dwarfs

A shock flash breaking out of a dusty red supergiant

学校读者我要写书评

暂无评论

arXiv 2023年

作者： Li, Gaici Hu, Maokai Li, Wenxiong Yang, Yi Wang, Xiaofeng Yan, Shengyu Hu, Lei Zhang, Jujia Mao, Yiming Riise, Henrik Gao, Xing Sun, Tianrui Liu, Jialian Xiong, Dingrong Wang, Lifan Mo, Jun Iskandar, Abdusamatjan Xi, Gaobo Xiang, Danfeng Wang, Lingzhi Sun, Guoyou Zhang, Keming Chen, Jian Lin, Weili Guo, Fangzhou Liu, Qichun Cai, Guangyao Zhou, Wenjie Zhao, Jingyuan Chen, Jin Zheng, Xin Li, keying Zhang, Mi Xu, Shijun Lyu, Xiaodong Castro-Tirado, A.J. Chufarin, Vasilii Potapov, Nikolay Ionov, Ivan Korotkiy, Stanislav Nazarov, Sergey Sokolovsky, Kirill Hamann, Norman Herman, Eliot Physics Department Tsinghua University Beijing100084 China Nanjing210023 China The School of Physics and Astronomy Tel Aviv University Tel Aviv69978 Israel Key Laboratory of Optical Astronomy National Astronomical Observatories of China CAS Beijing100101 China Department of Astronomy University of California BerkeleyCA94720-3411 United States Beijing Planetarium Beijing Academy of Science and Technology Beijing100044 China McWilliams Center for Cosmology Department of Physics Carnegie Mellon University 5000 Forbes Ave PittsburghPA15213 United States Yunnan Observatories CAS Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China National Astronomical Observatories of China CAS Beijing100101 China Skjeivik Observatory Forsand Strand4110 Norway Xinjiang Astronomical Observatory CAS Urumqi830011 China Mitchell Institute for Fundamental Physics and Astronomy Texas A&M University College StationTX77843 United States School of Astronomy and Space Science University of CAS Beijing100049 China South America Center for Astronomy National Astronomical Observatories CAS Beijing100101 China Xingming Observatory Urumqi830000 China Glorieta de la Astronomia s/n GranadaE-18008 Spain Unidad Asociada al CSIC Departamento de Ingenieria de Sistemas y Automatica Escuela de Ingenierias Universidad de Malaga Malaga29071 Spain G. M. Grechko Nizhny Novgorod Planetarium Revolutsionnaya st. 20 Nizhny Novgorod603002 Russia Minin University Ulyanova st. 1 Nizhny Novgorod603002 Russia Ka-Dar/Astroverty Karachay-Cherkessia Nizhny Arkhyz369167 Russia Vedrus Observatory Krasnodar Krai Azovskaya353245 Russia Crimean Astrophysical Observatory RAS Nauchnyi 298409 Crimea Department of Astronomy University of Illinois at Urbana-Champaign 1002 W. Green Street UrbanaIL61801 United States Sternberg Astronomical In

Shock breakout emission is light that arises when a shockwave, generated by core-collapse explosion of a massive star, passes through its outer envelope. Hitherto, the earliest detection of such a signal was at several hours after the explosion1, though a few others had been reported2-7. The temporal evolution of early light curves should reveal insights into the shock propagation, including explosion asymmetry and environment in the vicinity, but this has been hampered by the lack of multiwavelength observations. Here we report the instant multiband observations of a type II supernova (SN 2023ixf) in the galaxy M101 (at a distance of 6.85±0.15 Mpc8), beginning at ∼1.4 hours after the explosion. The exploding star was a red supergiant with a radius of about 440 solar radii. The light curves evolved rapidly, on timescales of 1−2 hours, and appeared unusually fainter and redder than predicted by models9-11 within the first few hours, which we attribute to an optically thick dust shell before it was disrupted by the shockwave. We infer that the breakout and perhaps the distribution of the surrounding dust were not spherically symmetric. Copyright © 2023, The Authors. All rights reserved.

关键词： Explosions

CONTACT BINARIES AT THE SHORT PERIOD CUT-OFF I. STATISTICS AND THE FIRST PHOTOMETRIC INVESTIGATIONS OF TEN TOTALLY ECLIPSING SYSTEMS

学校读者我要写书评

暂无评论

arXiv 2019年

作者： Li, Kai Xia, Qi-Qi Michel, Raul Hu, Shao-Ming Guo, Di-Fu Gao, Xing Chen, Xu Gao, Dong-Yang Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment Institute of Space Sciences Shandong University Weihai264209 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Observatorio Astronómico Nacional Instituto de Astronomía Universidad Nacional Autónoma de México Apartado Postal 877 EnsenadaB.C.22830 Mexico Xinjiang Astronomical Observatory 150 Science 1-Street Urumqi830011 China

The period distribution of contact binaries exhibits a very sharp short period cut-off at 0.22 days. In order to provide valuable information on this short period limit, we observed ten totally eclipsing contact binaries with orbital periods near this cut-off. By detailed analysis using W-D code, we determined that two of these systems are A-subtype contact binaries while the others are W-subtype contact binaries and all the targets show shallow contact configurations. Half of the targets exhibit stellar spot activity and four of them have third light. A statistical work on well studied USPCBs was carried out, and physical parameters of fifty-five USPCBs were obtained. Some common properties for these systems were derived. Due to the study of the period-color diagram of USPCBs, we found that the period-color relation of USPCBs is different from other W UMa type contact binaries and USPCBs are metal poor old stars. In addition, the evolutionary states of these systems were discussed by constructing the color-density diagram. We derived that the evolutionary states of the two components of USPCBs show identical characteristics of other contact binaries despite slower evolutionary status caused by smaller mass. We suggested that both the fully convective limit claimed by Rucinski (1992) and the AML theory recommended by Stepien (2006) can produce the short period cut-off and a tertiary companion is very important during the formation of the short period contact binaries by removing angular momentum from the host eclipsing pairs under certain circumstances. Copyright © 2019, The Authors. All rights reserved.

关键词： Stars

Insight-HXMT and GECAM-C observations of the brightest-of-all-time GRB 221009A

学校读者我要写书评

暂无评论

arXiv 2023年

作者： An, Zheng-Hua Antier, S. Bi, Xing-Zi Bu, Qing-Cui Cai, Ce Cao, Xue-Lei Camisasca, Anna-Elisa Chang, Zhi Chen, Gang Chen, Li Chen, Tian-Xiang Chen, Wen Chen, Yi-Bao Chen, Yong Chen, Yu-Peng Coughlin, Michael W. Cui, Wei-Wei Dai, Zi-Gao Hussenot-Desenonges, T. Du, Yan-Qi Du, Yuan-Yuan Du, Yun-Fei Fan, Cheng-Cheng Frontera, Filippo Gao, He Gao, Min Ge, Ming-Yu Gong, Ke Gu, Yu-Dong Guan, Ju Guo, Dong-Ya Guo, Zhi-Wei Guidorzi, Cristiano Han, Da-Wei He, Jian-Jian He, Jun-Wang Hou, Dong-Jie Huang, Yue Huo, Jia Ji, Zhen Jia, Shu-Mei Jiang, Wei-Chun Kann, David Alexander Klotz, A. Kong, Ling-Da Lan, Lin Li, An Li, Bing Li, Chao-Yang Li, Cheng-Kui Li, Gang Li, Mao-Shun Li, Ti-Pei Li, Wei Li, Xiao-Bo Li, Xin-Qiao Li, Xu-Fang Li, Yan-Guo Li, Zheng-Wei Liang, Jing Liang, Xiao-Hua Liao, Jin-Yuan Lin, Lin Liu, Cong-Zhan Liu, He-Xin Liu, Hong-Wei Liu, Jia-Cong Liu, Xiao-Jing Liu, Ya-Qing Liu, Yu-Rong Lu, Fang-Jun Lu, Hong Lu, Xue-Feng Luo, Qi Luo, Tao Ma, Bin-Yuan Ma, Fu-Li Ma, Rui-Can Ma, Xiang Maccary, Romain Mao, Ji-Rong Meng, Bin Nie, Jian-Yin Orlandini, Mauro Ou, Ge Peng, Jing-Qiang Peng, Wen-Xi Qiao, Rui Qu, Jin-Lu Ren, Xiao-Qin Shi, Jing-Yan Shi, Qi Song, Li-Ming Song, Xin-Ying Su, Ju Sun, Gong-Xing Sun, Liang Sun, Xi-Lei Tan, Wen-Jun Tan, Ying Tao, Lian Tuo, You-Li Turpin, Damien Wang, Jin-Zhou Wang, Chen Wang, Chen-Wei Wang, Hong-Jun Wang, Hui Wang, Jin Wang, Ling-Jun Wang, Peng-Ju Wang, Ping Wang, Wen-Shuai Wang, Xiang-Yu Wang, Xi-Lu Wang, Yu-Sa Wang, Yue Wen, Xiang-Yang Wu, Bo-Bing Wu, Bai-Yang Wu, Hong Xiao, Sheng-Hui Xiao, Shuo Xiao, Yun-Xiang Xie, Sheng-Lun Xiong, Shao-Lin Xiong, Sen-Lin Xu, Dong Xu, He Xu, Yan-Jun Xu, Yan-Bing Xu, Ying-Chen Xu, Yu-Peng Xue, Wang-Chen Yang, Sheng Yang, Yan-Ji Yang, Zi-Xu Ye, Wen-Tao Yi, Qi-Bin Yi, Shu-Xu Yin, Qian-Qing You, Yuan Yu, Yun-Wei Yu, Wei Yu, Wen-Hui Zeng, Ming Zhang, Bing Zhang, Bin-Bin Zhang, Da-Li Zhang, Fan Zhang, Hong-Mei Zhang, Juan Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences 19B Yuquan Road Beijing100049 China Institut für Astronomie und Astrophysik Kepler Center for Astro and Particle Physics Eberhard Karls Universität Sand 1 Tübingen72076 Germany College of Physics Hebei Key Laboratory of Photophysics Research and Application Hebei Normal University Hebei Shijiazhuang050024 China Department of Physics and Earth Science University of Ferrara Via Saragat 1 Ferrara44122 Italy Department of Astronomy Beijing Normal University Beijing100875 China CAS Key Laboratory for Research in Galaxies and Cosmology Department of Astronomy University of Science and Technology of China Hefei230026 China Department of Astronomy Tsinghua University Beijing100084 China Southwest Jiaotong University Chengdu610092 China INAF Osservatorio di Astrofisica e Scienza dello Spazio di Bologna Via Piero Gobetti 101 Bologna40129 Italy University of Chinese Academy of Sciences Chinese Academy of Sciences Beijing100049 China College of physics Sciences Technology Hebei University No. 180 Wusi Dong Road Lian Chi District Hebei Baoding071002 China INFN - Sezione di Ferrara Via Saragat 1 Ferrara44122 Italy Physics and Space Science College China West Normal University China Yunnan Observatories Chinese Academy of Sciences Yunnan Province Kunming650011 China Key Laboratory of Space Astronomy and Technology National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China School of Astronomy and Space Science Nanjing University Nanjing210093 China School of Physics and Optoelectronics Xiangtan University Yuhu District Hunan Xiangtan411105 China Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing Guizhou Normal University Guiyang550001 China Institute of Astrophysics Central China Normal University Wuhan430079 China Nevada Center for Astrophysics Department of Physics and Astronomy University of

GRB 221009A is the brightest gamma-ray burst ever detected since the discovery of this kind of energetic explosions. However, an accurate measurement of the prompt emission properties of this burst is very challenging due to its exceptional brightness. With joint observations of Insight-HXMT and GECAM-C, we made an unprecedentedly accurate measurement of the emission during the first ∼1800 s of GRB 221009A, including its precursor, main emission (ME, which dominates the burst in flux), flaring emission and early afterglow, in the hard X-ray to soft gamma-ray band from ∼ 10 keV to ∼ 6 MeV. Based on the GECAM-C unsaturated data of the ME, we measure a record-breaking isotropic equivalent energy (Eiso) of ∼ 1.5 × 1055 erg, which is about eight times the total rest-mass energy of the Sun. The early afterglow data require a significant jet break between 650 s and 1100 s, most likely at ∼ 950 s from the afterglow starting time TAG, which corresponds to a jet opening angle of ∼ 0.7◦ (ηγn)1/8, where n is the ambient medium density in units of cm−3 and ηγ is the ratio between γ-ray energy and afterglow kinetic energy. The beaming-corrected total γ-ray energy Eγ is ∼ 1.15 × 1051 (ηγn)1/4 erg, which is typical for long GRBs. These results suggest that this GRB may have a special central engine, which could launch and collimate a very narrowly beamed jet with an ordinary energy budget, leading to exceptionally luminous gamma-ray radiation per unit solid angle. Alternatively, more GRBs might have such a narrow and bright beam, which are missed by an unfavorable viewing angle or have been detected without distance measurement. Copyright © 2023, The Authors. All rights reserved.

关键词： Gamma rays

An 18.9-minute Blue Large-Amplitude Pulsator Crossing the "Hertzsprung Gap" of Hot Subdwarfs

学校读者我要写书评

暂无评论

arXiv 2022年

作者： Lin, Jie Wu, Chengyuan Wang, Xiaofeng Németh, Péter Xiong, Heran Wu, Tao Filippenko, Alexei V. Cai, Yongzhi Brink, Thomas G. Yan, Shengyu Zeng, Xiangyun Luo, Yangping Xiang, Danfeng Zhang, Jujia Zheng, WeiKang Yang, Yi Mo, Jun Xi, Gaobo Zhang, Jicheng Iskandar, Abdusamatjan Esamdin, Ali Jiang, Xiaojun Sai, Hanna Wei, Zixuan Chen, Liyang Guo, Fangzhou Chen, Zhihao Li, Wenxiong Lin, Weili Lin, Han Zhang, Xinghan Physics Department Tsinghua Center for Astrophysics Tsinghua University Beijing100084 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Beijing Planetarium Beijing Academy of Sciences and Technology Beijing100044 China Astronomical Institute of the Czech Academy of Sciences Fričova 298 Ondřejov25165 Czech Republic *** Fo tér 1 Malomsok8533 Hungary Research School of Astronomy & Astrophysics Australian National University Canberra2611 Australia 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 School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing100049 China Institute of Theoretical Physics Shanxi University Taiyuan030006 China Department of Astronomy University of California BerkeleyCA94720-3411 United States Center for Astronomy and Space Sciences China Three Gorges University Yichang443000 China Department of Astronomy China West Normal University Nanchong637002 China Department of Astronomy Beijing Normal University Beijing100875 China Xinjiang Astronomical Observatory Chinese Academy of Sciences Urumqi830011 China National Astronomical Observatories of China Chinese Academy of Sciences Beijing100012 China The School of Physics and Astronomy Tel Aviv University Tel Aviv69978 Israel

Blue large-amplitude pulsators (BLAPs) represent a new and rare class of hot pulsating stars with unusually large amplitudes and short periods. Up to now, only 24 confirmed BLAPs have been identified from more than one billion monitored stars, including a group with pulsation period longer than ∼ 20 min (classical BLAPs, hereafter) and the other group with pulsation period below ∼ 8 min (high-gravity BLAPs ). The evolutionary path that could give rise to such kinds of stellar configurations is unclear. Here we report on a comprehensive study of the peculiar BLAP discovered by the Tsinghua University - Ma Huateng Telescopes for Survey (TMTS), TMTS J035143.63+584504.2 (TMTS-BLAP-1). This new BLAP has an 18.9 min pulsation period and is similar to the BLAPs with a low surface gravity and an extended helium-enriched envelope, suggesting that it is a classical BLAP1 at the shortest-period end. In particular, the long-term monitoring data reveal that this pulsating star has an unusually large rate of period change, P/P = 2.2×10-6yr-1. Such a significant and positive value challenges its origins from both helium-core pre-white-dwarfs and core helium-burning subdwarfs, but is consistent with that derived from shell helium-burning subdwarfs. The particular pulsation period and unusual rate of period change indicate that TMTS-BLAP-1 is at a short-lived (∼ 106yr) phase of shell-helium ignition before the stable shell-helium burning;in other words, TMTS-BLAP-1 is going through a "Hertzsprung gap" of hot subdwarfs. The discovery of TMTS-BLAP1 possibly opens a new window to explore those rare pulsators that evolved from stripped-envelope stars. Copyright © 2022, The Authors. All rights reserved.

关键词： Helium