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SN 2015bf: A fast declining type II supernova with flash-ionised signatures

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arXiv 2021年

作者： Lin, Han Wang, Xiaofeng Zhang, Jujia Lin, Weili Mo, Jun Filippenko, Alexei V. Zheng, WeiKang Brown, Peter J. Xiang, Danfeng Huang, Fang Cai, Yongzhi Zhang, Tianmeng Li, Xue Rui, Liming Zhang, Xinghan Sai, Hanna Zhao, Xulin Graham, Melissa L. Shivvers, I. Halevi, G. Yuk, H. Brink, Thomas G. Tsinghua University Beijing100084 China Beijing Planetarium Beijing Academy of Sciences and Technology Beijing100044 China Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China 20A Datun Road Chaoyang District Beijing100012 China Department of Astronomy University of California BerkeleyCA94720-3411 United States Miller Institute for Basic Research in Science University of California BerkeleyCA94720-3411 United States George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy Texas A&M University Department of Physics and Astronomy 4242 TAMU College StationTX77843 United States Department of Astronomy Shanghai Jiao Tong University Shanghai200240 China Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China School of Science Tianjin University of Technology Tianjin300384 China DiRAC Institute Department of Astronomy University of Washington Box 351580 SeattleWA98195 United States Homer L. Dodge Department of Physics and Astronomy University of Oklahoma 440 W. Brooks St. NormanOK73019 United States

We present optical and ultraviolet photometry, as well as optical spectra, for the type II supernova (SN) 2015bf. Our observations cover the phases from ∼ 2 to ∼ 200 d after explosion. The first spectrum is characterised by a blue continuum with a blackbody temperature of ∼ 24, 000 K and flash-ionised emission lines. After about one week, the spectra of SN 2015bf evolve like those of a regular SN II. From the luminosity of the narrow emission component of Hα, we deduce that the mass-loss rate is larger than ∼ 3.7 × 10−3 M☉ yr−1. The disappearance of the flash features in the first week after explosion indicates that the circumstellar material is confined within ∼ 6 × 1014 cm. Thus, we suggest that the progenitor of SN 2015bf experienced violent mass loss shortly before the supernova explosion. The multiband light curves show that SN 2015bf has a high peak luminosity with an absolute visual magnitude MV = −18.11 ±0.08 mag and a fast post-peak decline with a V-band decay of 1.22 ±0.09 mag within ∼ 50 d after maximum light. Moreover, the R-band tail luminosity of SN 2015bf is fainter than that of SNe II with similar peak by 1–2 mag, suggesting a small amount of 56Ni (∼ 0.009 M☉) synthesised during the explosion. Such a low nickel mass indicates that the progenitor of SN 2015bf could be a super-asymptotic-giant-branch star that collapsed owing to electron capture. Copyright © 2021, The Authors. All rights reserved.

关键词： Supernovae

GABE: Galaxy assembly with binary evolution

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arXiv 2019年

作者： Jiang, Zhen Wang, Jie Gao, Liang Zhang, Fenghui Guo, Qi Wang, Lan Pan, Jun Key Laboratory for Computational Astrophysics National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing100039 China Institute of Computational Cosmology Department of Physics University of Durham South Road DurhamDH1 3LE United Kingdom Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China

We developed a new semi-analytic galaxy formation model: Galaxy Assembly with Binary evolution (GABE). For the first time we introduce binary evolution into semi-analytic models of galaxy formation by using Yunnan-II stellar population synthesis model, which includes various binary interactions. When implementing our galaxy formation model onto the merger trees extracted from the Millennium simulation, it can reproduce a large body of observational *** find that in the local universe the model including binary evolution reduces the luminosity at optical and infrared wavelengths slightly, while increases the luminosity at ultraviolet wavelength significantly, especially in FUVband. The resulting luminosity function does not change very much over SDSS optical bands and infrared band, but the predicted colors are bluer, especially when FUVband is under consideration. The new model allows us to explore the physics of various high energy events related to the remnants of binary stars, e.g. type Ia supernovae, short gamma-ray bursts and gravitational wave events, and their relation with host galaxies in a cosmological context. Copyright © 2019, The Authors. All rights reserved.

关键词： Galaxies

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

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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

Connecting Low- and High-Redshift Weak Emission-Line Quasars via HST Spectroscopy of Lyα Emission

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arXiv 2022年

作者： Paul, Jeremiah D. Plotkin, Richard M. Shemmer, Ohad Anderson, Scott F. Brandt, W.N. Fan, Xiaohui Gallo, Elena Luo, Bin Ni, Qingling Richards, Gordon T. Schneider, Donald P. Wu, Jianfeng Yi, Weimin Department Of Physics University Of Nevada RenoNV89557 United States Department Of Physics University Of North Texas DentonTX76203 United States Department Of Astronomy University Of Washington Box 351580 SeattleWA98195 United States Department Of Astronomy & Astrophysics 525 Davey Lab The Pennsylvania State University University ParkPA16802 United States Institute For Gravitation And The Cosmos The Pennsylvania State University University ParkPA16802 United States Department Of Physics 104 Davey Lab The Pennsylvania State University University ParkPA16802 United States Steward Observatory University Of Arizona 933 N. Cherry Ave TucsonAZ85721 United States Department Of Astronomy University Of Michigan 1085 S. University Ave Ann ArborMI48109 United States School Of Astronomy And Space Science Nanjing University Jiangsu Nanjing210093 China Ministry Of Education Jiangsu Nanjing210093 China Institute For Astronomy University Of Edinburgh Royal Observatory EdinburghEH9 3HJ United Kingdom Department Of Physics Drexel University 32 S. 32nd Street PhiladelphiaPA19104 United States Department Of Astronomy Xiamen University Fujian Xiamen361005 China Yunnan Observatories Kunming650216 China Key Laboratory For The Structure And Evolution Of Celestial Objects Chinese Academy Of Sciences Kunming650216 China

We present ultraviolet spectroscopy covering the Lyα + N V complex of six candidate low-redshift (0.9 3) quasars, defined by a Lyα + N V rest-frame equivalent width (EW) threshold Copyright © 2022, The Authors.... 详细信息

关键词： Electromagnetic wave emission

High-precision asteroseismology in slowly pulsating b star: Hd 50230

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arXiv 2019年

作者： Tao, W.U. Li, Y.A.N. 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

SPB star HD 50230, in fact a hybrid B-type pulsator, has been observed by CoRoT least 137 days. A nearly equidistant period spacing pattern are found among 8 modes which are extracted from the oscillation spectrum with more than 500 frequencies. However, it is thought to be most likely accidental by Szewczuk et al. (2014). In the present work, we analyze the 8 modes in depth with the χ2-matching method. Based on the best fitting model (model MA), we find that they can be well explained as a sequences of consecutive dipolar (l, m) = (1, 0). The period discrepancies between observations and the best fitting model are within 100 s except for the outlier which is up to 300 s. Based on the calculated CMMs, we find that, for pure g-mode oscillations, the buoyancy radius Λ0 can be precisely measured with the χ2-matching method between observations and calculations. It represents the "Propagation time" of the g-mode from stellar surface to center. It is of Λ0 = 245.78 ± 0.59 µHz with a precision of 0.24%. In addition, we also find that HD 50230 is a metal-rich (Zinit = 0.034 − 0.043) star with a mass of M = 6.15 − 6.27 Mo. It is still located on hydrogen-burning phase with central hydrogen XC = 0.298 − 0.316 (or XC = 0.306+0.010−0.008), therefore has a convective core with a radius of Rcc = 0.525 − 0.536 Ro (or Rcc = 0.531+0.005 −0006 Ro). In order to well interpret the structure of observed period spacing pattern, the convective core overshooting (fov = 0.0175 − 0.0200) and the extra diffusion mixing (log Dmix = 3.7 − 3.9) should be taken into account in theoretical models. Copyright © 2019, The Authors. All rights reserved.

关键词： Stars

Asteroseismology of the pre-main-sequence d scuti pulsator ip persei

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arXiv 2019年

作者： Chen, Xinghao Li, Yan Yunnan Observatories Chinese Academy of Sciences P.O. Box 110 Kunming650216 China Key Laboratory for Structure and Evolution of Celestial Objects Chinese Academy of Sciences P.O. Box 110 Kunming650216 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

A grid of theoretical models are computed to fit the 9 oscillation modes of IP Per detected earlier from a multi-site ground-based campaign. Fitting results show that there are two sets of theoretical models that could reproduce the observed frequencies more or less euqally well. In view of other available spectroscopic and photometric measurements, our best fitting stellar parameters for IP Per are [formula presented] Myr. Meanwhile, IP Per is found to be a pre-main sequence star where CN cycle has not yet reached the equilibrium state. At present fourteen percent of C12have been turned into N14. Based on the best-fitting model, f6 is identified as a radial mode, f1and f2as two dipole modes, and f3, f4, f5, f7, f8, and f9as six quadrupole modes. Copyright © 2019, The Authors. All rights reserved.

关键词：

Observational constraints on the rastall gravity from rotation curves of low surface brightness galaxies

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arXiv 2019年

作者： Tang, Meirong Xu, Zhaoyi Wang, Jiancheng Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 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

The Rastall gravity is a modification of Einstein's general relativity, in which the energy-momentum conservation is not satisfied and depends on the gradient of the Ricci curvature. It is in dispute whether the Rastall gravity is equivalent to the general relativity (GR). In this work, we constrain the theory using the rotation curves of Low Surface Brightness (LSB) spiral galaxies. Through fitting the rotation curves of LSB galaxies, we obtain the parameter β of the Rastall gravity. The β values of LSB galaxies satisfy Weak Energy Condition (WEC) and Strong Energy Condition(SEC). Combining the β values of type Ia supernovae and gravitational lensing of elliptical galaxies on the Rastall gravity, we conclude that the Rastall gravity is equivalent to the general relativity. Copyright © 2019, The Authors. All rights reserved.

关键词： Galaxies

EXPLORING THE CONVECTIVE CORE OF THE HYBRID δ SCUTI-γ DORADUS STAR COROT 100866999 WITH ASTEROSEISMOLOGY

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arXiv 2019年

作者： Chen, Xinghao Li, Yan Zhang, Xiaobin Yunnan Observatories Chinese Academy of Sciences P.O. Box 110 Kunming650216 China Key Laboratory for Structure and Evolution of Celestial Objects Chinese Academy of Sciences P.O. Box 110 Kunming650216 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 Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China

We computed a grid of theoretical models to fit the δ Scuti frequencies of CoRoT 100866999 detected earlier from the CoRoT timeserials. The pulsating primary star is determined to be a main sequence star with a rotation period of 4.1+0−0..65 days, rotating slower than the orbital motion. The fundamental parameters of the primary star are determined to be M = 1.71+0−0..1304 M∙, Z = 0.012+0−0..004000, fov = 0.02+0−0..0002, Teff = 8024+249−297 K, L = 11.898+2−1..156847 L∙, log g = 4.166+0−0..013002, R = 1.787+0−0..040016 R∙, and Xc = 0.488+0−0..011020, matching well those obtained from the eclipsing light curve analysis. Based on the model fittings, p1 and p5 are suggested to be two dipole modes, and p3, p4, p6, and p7 to be four quadrupole modes. In particular, p4 and p7 are identified as two components of one quintuplet. Based on the best-fitting model, we find that p1 is a g mode and the other nonradial modes have pronounced mixed characters, which give strong constraints on the convective core. Finally, the relative size of the convective core of CoRoT 100866999 is determined to Rconv/R = 0.0931+0−0..00030013. Copyright © 2019, The Authors. All rights reserved.

关键词： Stars

Bayesian discrimination of the panchromatic spectral energy distribution modelings of galaxies

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arXiv 2019年

作者： Han, Yunkun Han, Zhanwen Fan, Lulu Yunnan Observatories 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 Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Institute of Space Science Shandong University Weihai264209 China

Fitting the multi-wavelength spectral energy distributions (SEDs) of galaxies is a widely used technique to extract information about the physical properties of galaxies. However, a major difficulty lies in the numerous uncertainties regarding almost all ingredients of the SED modeling of galaxies. The Bayesian methods provide a consistent conceptual basis for dealing with the problem of inference with many *** the Bayesian parameter estimation method have become quite popular in the field of SED fitting of galaxies, the Bayesian model comparison method, which is based on the same Bayes' rule, is still not widely used in this field. With the application of Bayesian model comparison method in a series of papers, we show that the results obtained with Bayesian model comparison are understandable in the context of stellar/galaxy physics. These results indicate that Bayesian model comparison is a reliable and very powerful method for the SED fitting of galaxies. Copyright © 2019, The Authors. All rights reserved.

关键词： Galaxies