检索结果-内蒙古大学图书馆

SSRN 2022年

作者： Zubairi, Ahmed Waqas Zhou, Xiao Lajs, Eduardo Ferncndez Zhu, Liying Liao, Wenping Soonthornthum, Boonrucksar Zhang, Bin Sarotsakulchai, Nopphadon Yunnan Observatories Chinese Academy of Sciences Kunming650216 China University of Chinese Academy of Sciences Yuquan Road 19 Sijingshang Block Beijing100049 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing100101 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences P.O. Box 110 Kunming650216 China Facultad de Ciencias Astronmicas y Geofisicas Universidad Nacional de La Plata Buenos Aires La Plata1900 Argentina Instituto de Astroflsica de La Plata CCT La plata - CONICET UNLP Argentina National Astronomical Research Institute of Thailand 260 Moo 4 T. Donkaew A. Maerim Chiangmai50180 Thailand School of Physics and Electronic Science Guizhou Normal University Guiyang550001 China

New BVRI light curves of the short period binary system, {\astrobj}, are presented. Photometric solutions were derived using the 2015 version of Wilson–Devinney code. The complete eclipses of the light curves of {\astrobj}\, enable us to determine high-precision photometric parameters of the binary system. The new solution suggest that {\astrobj}\, is a low mass ratio ($q=0.145$) deep contact binary with a contact degree of $f =74.19\%$. Based on all available times of light minimum, we analyzed the long-term period changes of {\astrobj}. A decrease rate of $dP/dt=-9.01\times 10^{-8} days/yr$ was determined. The continuous period decrease can be explained by the mass transfer from the primary component to the secondary and angular momentum loss via magnetic stellar wind. A conservative mass transfer rate of $1.876 \times 10^{-8} M_{\odot} yr^{-1}$ and angular momentum loss rate at $6.25 \times 10^{39} Kg\,m^2\,s^{-1} \, yr^{-1}$ were derived. As the orbital period decreases, the contact degree of {\astrobj}\, will become deeper and finally it will evolve into a single rapid-rotating star. © 2022, The Authors. All rights reserved.

关键词： Mass transfer

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Stellar populations of a sample of optically selected AGN-host dwarf galaxies

arXiv

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arXiv 2020年

作者： Cai, Wei Zhao, Yinghe Zhang, Hong-Xin Bai, Jin-Ming Liu, Hong-Tao Yunnan Observatories Chinese Academy of Sciences Kunming652016 China University of Chinese Academy of Sciences Beijing100049 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 CAS Key Laboratory for Research in Galaxies and Cosmology Department of Astronomy University of Science and Technology of China Hefei Anhui230026 China

In this paper we present our studies on the stellar populations and star formation histories (SFHs) for the Reines et al. sample of 136 dwarf galaxies which host active galactic nuclei (AGNs), selected from the Sloan Digital Sky Survey Data Release 8. We derive stellar populations and reconstruct SFHs for these AGN-host dwarfs using the stellar population synthesis code STARLIGHT. Our results suggest that these AGN-host dwarfs have assembled their stellar masses within a narrow period of time with the stellar mass-weighted ages in the range of 109 − 1010 yr, but show a wide diversity of SFHs with the luminosity-weighted stellar ages in the range of 107 − 1010 yr. The old population (t > 109 yr) contributes most to the galaxy light for the majority of the sample;the young population (t 8 yr) also appears in significant but widely varying fractions, while the intermediate-age population (108 9 yr) in general contributes less to the optical continuum at 4020 Å. We also find that these dwarfs follow a similar mass-metallicity relation to normal star-forming galaxies, indicating that AGNs have little effect on the chemical evolution of the host galaxy. We further investigate the relation between the derived SFHs and morphology of the host galaxy, and find no correlation. Comparing the SFHs with the luminosity of the [O iii] λ5007 line (L[O iii]), we find that there exists a mild correlation when L[O iii] > 1039 erg s−1, indicating that there is a physical connection between star formation and AGN activities in these dwarf galaxies. Copyright © 2020, The Authors. All rights reserved.

关键词： Galaxies

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SN 2019ein: A Type Ia Supernova Likely Originated from a Sub-Chandrasekhar-Mass Explosion

arXiv

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arXiv 2022年

作者： Xi, Gaobo Wang, Xiaofeng Li, Wenxiong Mo, Jun Zhang, Jujia Liu, Jialian Chen, Zhihao Filippenko, Alexei V. Zheng, Weikang Brink, Thomas G. Zhang, Xinghan Sai, Hanna Ehgamberdiev, Shuhrat A. Mirzaqulov, Davron Zhang, Jicheng Physics Department Tsinghua Center for Astrophysics Tsinghua University Beijing100084 China Beijing Planetarium Beijing Academy of Science and Technology Beijing100044 China The School of Physics and Astronomy Tel Aviv University Tel Aviv69978 Israel 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 20A Datun Road Chaoyang District Beijing100012 China Department of Astronomy University of California BerkeleyCA94720-3411 United States Ulugh Beg Astronomical Institute Uzbekistan Academy of Sciences Tashkent100052 Uzbekistan National University of Uzbekistan Tashkent100174 Uzbekistan Department of Astronomy Beijing Normal University Beijing100875 China

We present extensive optical photometric and spectroscopic observations for the nearby Type Ia supernova (SN Ia) 2019ein, spanning the phases from ∼ 3 days to ∼ 330 days after the explosion. This SN Ia is characterized by extremely fast expansion at early times, with initial velocities of Si II and Ca II being above ∼ 25, 000–30,000 km s−1. After experiencing an unusually rapid velocity decay, the ejecta velocity dropped to ∼ 13, 000 km s−1 around maximum light. Photometrically, SN 2019ein has a moderate post-peak decline rate (Δm15(B) = 1.35 ± 0.01 mag), while being fainter than normal SNe Ia by about 40% (with MBmax ≈ −18.71 ± 0.15 mag). The nickel mass synthesized in the explosion is estimated to be 0.27–0.31 M from the bolometric light curve. Given such a low nickel mass and a relatively high photospheric velocity, we propose that SN 2019ein likely had a sub-Chandrasekhar-mass white dwarf (WD) progenitor, MWD . 1.22 M . In this case, the explosion could have been triggered by a double-detonation mechanism, for which 1- and 2-dimensional models with WD mass MWD ≈ 1 M and a helium shell of 0.01 M can reasonably produce the observed bolometric light curve and spectra. The predicted asymmetry as a result of double detonation is also favored by the redshifted Fe II and Ni II lines observed in the nebular-phase spectrum. Possible diversity in origin of high velocity SNe Ia is also discussed. Copyright © 2022, The Authors. All rights reserved.

关键词： Supernovae

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ONe WD+He star systems as the progenitors of IMBPs

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Proceedings of the International Astronomical Union 2019年第S346期14卷 478-479页

作者： Wang, Bo Liu, Dongdong Yunnan Observatories Chinese Academy of Sciences Kunming 650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650216 China

Previous theoretical studies can only explain part of the observed intermediate-mass binary pulsars (IMBPs) with short orbital periods. Note that an ONe white dwarf (WD) accreting mass from a He star may experience the accretion-induced collapse process and eventually form IMBPs, known as the ONe WD+He star scenario. By investigating the evolution of a large number of ONe WD+He star binaries, we found that the ONe WD+He star scenario can form IMBPs including pulsars with 5 - 340 ms spin periods, and the orbital periods range from 0.04 to 900 d. Compared with the observed IMBPs, this scenario can cover almost all of the IMBPs with short orbital periods. Thus, we suggest that the ONe WD+He star channel is responsible for the formation of IMBPs with short orbital periods. © International Astronomical Union 2019.

关键词： binaries: close stars: evolution stars: neutron white dwarfs

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Photometric Analysis of Asteroids in the Phocaea Region

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The Astronomical Journal 2025年第1期170卷 35-35页

作者： Xiaoyun Xu Xiaobing Wang Karri Muinonen Shenghong Gu Antti Penttilä Fukun Xu Leilei Sun Jing Huang Pengfei Zhang Ao Wang Yunnan Observatories Chinese Academy of Sciences Kunming 650216 People’s Republic of China wangxb@*** University of Chinese Academy of Sciences Beijing 100049 People’s Republic of China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650216 People’s Republic of China Department of Physics P.O. box 64 FI-00014 University of Helsinki Finland Center for Lunar and Planetary Sciences Institute of Geochemistry Chinese Academy of Sciences Guiyang People’s Republic of China Department of Physics Yuxi Normal University Yuxi 653100 People’s Republic of China

The Phocaea asteroid family, one of the large ancient families located in the inner main belt, may be the sources of near-Earth asteroids (NEAs) due to the nearby 3:1 mean motion resonance with Jupiter, the ν6 secular resonance, and the Yarkovsky and Yarkovsky–O'Keefe–Radzievskii–Paddack (YORP) effects. Thus, understanding the influence of the Yarkovsky and YORP effects on the Phocaea family is one of the keys to figuring out the source of NEAs. However, the physical properties of most of the Phocaea family members are unknown at present. We perform a photometric analysis for 44 asteroids in the Phocaea region using photometric data obtained by ground-based and space-based telescopes (i.e., the Transiting Exoplanet Survey Satellite and Gaia). Based on the derived physical properties, we find significant footprints of the Yarkovsky and YORP effects on the Phocaea family members. Selecting five asteroids nearby the inside boundary of the V shape in the absolute-magnitude semimajor-axis (H, a) space, we estimate their densities considering their migration in semimajor-axis arises from the Yarkovsky effect. The bulk density of (852) Wladilena (3.54 g cm⁻³) suggests a link to the H chondrite meteorites. Incorporating the grain density of the H chondrites, we estimate the macroporosities of the asteroids (290) Bruna, (1164) Kobolda, and (587) Hypsipyle, respectively, as 41%, 47%, and 65%, implying rubble pile structures. Considering the H chondrites link to asteroid (25) Phocaea, we suggest the parent body of the Phocaea family has been composed of H chondrite like material and the Phocaea family may be one of the sources of H chondrite meteorites.

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A closer look at non-interacting he stars as a channel for producing the old population of type Ia supernovae

arXiv

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arXiv 2020年

作者： Liu, Zheng-Wei Stancliffe, Richard J. 396 Yangfangwang Guandu District Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China Center for Astronomical Mega-Science CAS 20A Datun Road Chaoyang District Beijing100012 China Milne Centre for Astrophysics Department of Physics & Mathematics University of Hull HU6 7RX United Kingdom

The nature of the progenitors of type Ia supernovae (SNe Ia) remains a mystery. Binary systems consisting of a white dwarf (WD) and a main-sequence (MS) donor are potential progenitors of SNe Ia, in which a thermonuclear explosion of the WD may occur when its mass reaches the Chandrasekhar limit during accretion of material from a companion star. In the present work, we address theoretical rates and delay times of a specific MS donor channel to SNe Ia, in which a helium (He) star + MS binary produced from a common envelope event subsequently forms a WD + MS system without the He star undergoing mass transfer by Roche lobe overflow. By combining the results of self-consistent binary evolution calculations with population synthesis models, we find that the contribution of SNe Ia in this channel is around 2.0 × 10−4 yr−1. In addition, we find that delay times of SNe Ia in this channel cover a range of about 1.0–2.6 Gyr, and almost all SNe Ia produced in this way (about 97 %) have a delay time of & 1 Gyr. While the rate of SN Ia in this work is about 10% of the overall SN Ia rate, the channel represents a possible contribution to the old population (1–3 Gyr) of observed SNe Ia. Copyright © 2020, The Authors. All rights reserved.

关键词： White dwarfs

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Lithium evolution of giant stars observed by LAMOST and Kepler

arXiv

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arXiv 2021年

作者： Zhang, Jinghua Shi, Jian-Rong Yan, Hong-Liang Li, Yaguang Gao, Qi Li, Chun-Qian Zhang, Xianfei Liu, Shuai Bi, Shaolan Zhao, Gang Li, Yan CAS Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing100101 China School of Physics University of Sydney NSW2006 Australia Stellar Astrophysics Centre Department of Physics and Astronomy Aarhus University Ny Munkegade 120 Aarhus CDK-8000 Denmark Department of Astronomy Beijing Normal University Beijing100875 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing100012 China

Mapping lithium evolution for evolved stars will provide restrictions and constraints on the fundamental stellar interior physical processes, which further shed light on our understanding of the theory of stellar structure and evolution. Based on a sample of 1,848 giants with known evolutionary phases and lithium abundances from the LAMOST-kepler and LAMOST-K2 fields, we construct mass-radius diagrams to characterize the evolutionary features of lithium. The stars at red giant branch (RGB) phase show natural depletion along with their stellar evolution, particularly, there is no obvious crowd stars with anomalously high Li abundances near the bump. Most of the low-mass stars reaching their zero-age sequence of core-helium-burning (ZAHeB) have Li abundances around ∼1.0 dex, which show an increase of Li abundance by ∼0.6 dex compared to the stars above the bump of RGB. This suggests the helium flash can be responsible for moderate Li production. While for super Li-rich stars, some special mechanisms should be considered during helium flash. Other scenarios, such as merger, could also be interpretations given the Li-rich stars can be found at anytime during the steady state phase of core He-burning. During the core He-burning (HeB) phase, there is no indication of obvious lithium depletion. © 2021, CC BY.

关键词： Lithium

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High Velocity Runaway Binaries from Supernovae in Triple Systems

arXiv

引用

arXiv 2019年

作者： Gao, Yan Li, Jiao Jia, Shi Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China University of Chinese Academy of Sciences

Recent studies on hypervelocity stars (HVSs) have generated a need to understand the high velocity limits of binary systems. If runaway binary systems with high movement speeds well in excess of 200km/s were to exist, it would have implications on how HVS candidates are selected, and our current understanding of how they form needs to be reinforced. In this paper, we explore the possibility that such high velocity runaway binaries (HVRBs) can be engendered by supernova explosions of the tertiary in close hierarchical triple systems. We find that such explosions can lead to significant remnant binary velocities, and demonstrate via constraining the velocity distribution of such HVRBs that this mechanism can lead to binaries with centre of mass velocities of 350 km/s or more, relative to the original centre of mass of the progenitor triple system. This translates into potential observations of binaries with velocities high enough to escape the Galaxy, once the Galactic rotational velocity and objects of Large Magellanic Cloud origins are considered. Copyright © 2019, The Authors. All rights reserved.

关键词： Systems (metallurgical)

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Recurring tidal disruption events a decade apart in IRAS F01004-2237

arXiv

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arXiv 2024年

作者： Sun, Luming Jiang, Ning Dou, Liming Shu, Xinwen Zhu, Jiazheng Dong, Subo Buckley, David Cenko, S. Bradley Fan, Xiaohui Gromadzki, Mariusz Liu, Zhu Wang, Jianguo Wang, Tinggui Wang, Yibo Wu, Tao Yang, Lei Zhang, Fabao Zhang, Wenjie Zhang, Xiaer Department of Physics Anhui Normal University Anhui Wuhu241002 China CAS Key Laboratory for Researches in Galaxies and Cosmology Department of Astronomy University of Science and Technology of China Anhui Hefei230026 China School of Astronomy and Space Sciences University of Science and Technology of China Hefei230026 China Center for Astrophysics Guangzhou University Guangzhou510006 China Department of Astronomy School of Physics Peking University 5 Yiheyuan Road Haidian District Beijing100871 China Kavli Institute of Astronomy and Astrophysics Peking University 5 Yiheyuan Road Haidian District Beijing100871 China National Astronomical Observatories Chinese Academy of Science 20A Datun Road Chaoyang District Beijing100101 China South African Astronomical Observatory P.O. Box 9 Observatory Cape Town7935 South Africa Astrophysics Science Division NASA Goddard Space Flight Center MC 661 GreenbeltMD20771 United States Steward Observatory University of Arizona 933 North Cherry Avenue Rm. N204 TucsonAZ85721-0065 United States Astronomical Observatory University of Warsaw Al. Ujazdowskie 4 Warszawa00-478 Poland Max-Planck-Institut für Extraterrestrische Physik Gießenbachstraße 1 Garching85748 Germany Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatories Kunming650011 China

Context. In theory, recurring tidal disruption events (TDEs) may occur when a close stellar binary encounters a supermassive black hole, if one star is captured and undergoes repeating partial TDEs, or if both stars are tidally disrupted (double TDEs). In addition, independent TDEs may be observed over decades in some special galaxies where the TDE rate is extremely high. Exploring the diversity of recurring TDEs and probing their natures with rich observational data help to understand these mechanisms. Aims. We report the discovery of a second optical flare that occurred in September 2021 in IRAS F01004-2237, where the first flare occurred in 2010 has been reported, and present a detailed analysis of multi-band data. We aim to understand the nature of the flare and explore the possible causes of the recurring flares. Methods. We describe our analysis of the position of the flare, the multi-band light curves (LCs), the optical and ultraviolet (UV) spectra, and the X-ray LC and spectra. Results. The position of the flare coincides with the galaxy centre with a precision of 650 pc. The flare peaks in ∼ 50 days with an absolute magnitude of ∼ −21 and fades in two years roughly following L ∝ t−5/3. It maintains a nearly constant blackbody temperature of ∼22,000 K in the late time. Its optical and UV spectra show hydrogen and helium broad emission lines with full width at half maxima of 7,000–21,000 km s−1 and He II/Hα ratio of 0.3–2.3. It shows weak X-ray emission relative to UV emission, with X-ray flares lasting for +1.4. These characters are consistent with a TDE, ruling out the possibilities of a supernova or an active galactic nuclei flare. With a TDE model, we infer a peak UV luminosity of 3.3 ± 0.2 × 1044 erg s−1 and an energy budget of 4.5 ± 0.2 × 1051 erg. Conclusions. A TDE caused the flare that occurred in 2021. The two optical flares separated by 10.3 ± 0.3 years can be interpreted as repeating partial TDEs, double TDEs, or two independent TDEs. Although no

关键词： Budget control

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Accreting CO material onto ONe white dwarfs towards accretion-induced collapse

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Research in Astronomy and Astrophysics 2018年第3期18卷 121-128页

作者： Cheng-Yuan Wu Bo Wang Yunnan Observatories Chinese Academy of Sciences Kunming 650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650216 China University of Chinese Academy of Sciences Beijing 100049 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing 100012 China

The final outcomes of accreting ONe white dwarfs（ONe WDs） have been studied for several decades,but there are still some issues that are not resolved. Recently,some studies suggested that the deflagration of oxygen would occur for accreting ONe WDs with Chandrasekhar masses. In this paper,we aim to investigate whether ONe WDs can experience accretion-induced collapse（AIC） or explosions when their masses approach the Chandrasekhar limit. Employing the stellar evolution code Modules for Experiments in Stellar Astrophysics（MESA）,we simulate the longterm evolution of ONe WDs with accreting CO material. The ONe WDs undergo weak multicycle carbon flashes during the mass-accretion process,leading to mass increase of the WDs. We found that different initial WD masses and mass-accretion rates influence the evolution of central density and temperature. However,the central temperature cannot reach the explosive oxygen ignition temperature due to neutrino cooling. This work implies that the final outcome of accreting ONe WDs is electroncapture induced collapse rather than thermonuclear explosion.

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

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