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arXiv 2023年

作者： Li, Yubin Mao, Jirong Qin, Jianbo Zheng, Xianzhong Liu, Fengshan Zhao, Yinghe Zhao, Xiaohong Yunnan Observatories Chinese Academy of Sciences Yunnan Province Kunming650011 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Beijing Chaoyang District100012 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China University of Chinese Academy of Sciences 19A Yuquan Road Beijing100049 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing210023 China National Astronomical Observatories Chinese Academy of Sciences 20A Datun Road Beijing Chaoyang District100101 China

GW170817 is the unique gravitational-wave (GW) event that is associated to the electromagnetic (EM) counterpart GRB 170817A. NGC 4993 is identified as the host galaxy of GW170817/GRB 170817A. In this paper, we particularly focus on the spatially resolved properties of NGC 4993. We present the photometric results from the comprehensive data analysis of the high spatial-resolution images in the different optical bands. The morphological analysis reveals that NGC 4993 is a typical early-type galaxy without significant remnants of major galaxy merger. The spatially resolved stellar population properties of NGC 4993 suggest that the galaxy center has passive evolution with the outskirt formed by gas accretion. We derive the merging rate of the compact object per galaxy by a co-evolution scenario of supermassive black hole and its host galaxy. If the galaxy formation is at redshift 1.0, the merging rate per galaxy is 3.2×10-4to 7.7×10-5within the merging decay time from 1.0 to 5.0 Gyr. The results provide the vital information for the ongoing GW EM counterpart detections. The HST data analysis presented in this paper can be also applied for the Chinese Space Station Telescope (CSST) research in the future. © 2023, CC0.

关键词： Gravity waves

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SN 2015bq: A luminous type ia supernova with early flux excess

arXiv

引用

arXiv 2021年

作者： Li, Liping Zhang, Jujia Dai, Benzhong Li, Wenxiong Wang, Xiaofeng Zhai, Qian Bai, Jinming School of Physics and Astronomy Yunnan University Kunming650091 China Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China The School of Physics and Astronomy Tel Aviv University Tel Aviv69978 Israel Tsinghua University Beijing100084 China

We present optical and ultraviolet (UV) observations of a luminous type Ia supernova (SN Ia) SN 2015bq characterized by the early flux excess. This SN reaches a B-band absolute magnitude at MB = −19.68 ± 0.41 mag and a peak bolometric luminosity at L = (1.75 ± 0.37) × 1043 erg s−1, with a relatively small post-maximum decline rate [∆m15(B) = 0.82 ± 0.05 mag]. The flux excess observed in the light curves of SN 2015bq a few days after the explosion, especially seen in the UV bands, might be due to the radioactive decay of 56Ni mixed into the surface. The radiation from the decay of the surface 56Ni heats the outer layer of this SN. It produces blue U − B color followed by monotonically reddening in the early phase, dominated iron-group lines, and weak intermediate-mass elements absorption features in the early spectra. The scenario of enhanced 56Ni in the surface is consistent with a large amount of 56Ni (M56Ni = 0.97 ±0.20 Mo) synthesized during the explosion. The properties of SN 2015bq are found to locate between SN 1991T and SN 1999aa, suggesting the latter two subclasses of SNe Ia may have a common origin. © 2021, CC BY.

关键词： Supernovae

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1SWASP J034439.97+030425.5:a short-period eclipsing binary system with a close-in stellar companion

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Research in Astronomy and Astrophysics 2020年第4期20卷 31-38页

作者： Bin Zhang Sheng-Bang Qian Jing-Jing Wang Qi-Jun Zhi Ai-Jun Dong Wei Xie Li-Ying Zhu Lin-Qiao Jiang School of Physics and Electronic Science Guizhou Normal UniversityGuiyang 550001China Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing Guizhou Normal UniversityGuiyang 550001China Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China University of Chinese Academy of Sciences Beijing 100049China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing 100101China China University of Petroleum-Beijing at Karamay Karamay 834000China School of Physics and Electronic Engineering Sichuan University of Science and EngineeringZigong 643000China

First multi-wavelength photometric light curves(LCs)of the short-period eclipsing binary(EB)1 SWASP J034439.97+030425.5(hereafter J0344)are presented and analyzed by using the 2013 version of the Wilson-Devinney(W-D)*** explain the asymmetric LCs of J0344,a cool star-spot on the less massive component was *** photometric solutions suggest that J0344 is a W-subtype shallow contact EB with a contact degree of f=4.9%±3.0%and a mass ratio of q=2.456±***,an obvious third light was detected in our *** calculated the average luminosity contribution of the third light to the total light,and that value reaches up to 49.78%.Based on the O-C method,the variations of the orbital period were studied for the first *** O-C diagram reveals a secular decrease superimposed on a cyclic *** orbital period decreases at a rate of d P/dt=-6.07×10-7 d yr-1,which can be explained by the mass transfer from the more massive component to the less massive ***,its O-C diagram also shows a cyclic oscillation with an amplitude of 0.0030 d and a period about 7.08 yr,which can be explained by the presence of a third body with a minimum mass of M3 min=0.15±0.02 M⊙.The third component may play an important role in the formation and evolution of J0344 by drawing angular momentum from the central system.

关键词： stars:binaries:close stars:binaries:eclipsing stars:individual(1SWASP J034439.97+030425.5)

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Photometric investigation of the eclipsing binary TX Herculis observed by LUT

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Research in Astronomy and Astrophysics 2019年第7期19卷 47-52页

作者： Li-Ying Zhu Xiao-Man Tian Xiao Zhou Lin-Jia Li Zhi-Hua Wang Yunnan Observatories Chinese Academy of SciencesKunming 650216China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing 100101China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China University of the Chinese Academy of Sciences Beijing 100049China

The lander of China’s Chang’E-3 spacecraft is equipped with a 15-cm telescope that is very useful for monitoring celestial objects in the ultraviolet(UV) band(245–340 nm).The Lunar-based Ultraviolet Telescope(LUT) is the first long-term lunar-based astronomical observatory,that can make uninterrupted observations of a target from the *** we present the continuous complete UV light curve of the eclipsing binary TX Herculis(TX Her).The analysis of the light curve suggests that TX Her is a detached *** dip in the light curve was explained by the emergence of a stellar dark spot on the less massive F0 type *** cyclic change of arrival eclipse times for the system reveals that it contains an additional stellar companion with a minimal mass of 0.35 M⊙ and a period of 48.92 yr,which is supported by the detected light contribution of the third body from light curve *** third body may play an important role in the formation of the present short-period system TX Her.

关键词： stars:binaries:close stars:binaries:eclipsing stars:individuals (TX Herculis) stars:multiple system stars:activity

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Effect of Tidal Torques on Rotational Mixing in Close Binaries

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Chinese Physics Letters 2018年第7期35卷 139-143页

作者：李志宋汉峰彭卫国 College of Physics Guizhou University Geneva Observatory University of Geneva Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences

The effect of tidal torques on rotational mixing in close binaries is investigated. It is found that spin angular momentum can attain a high value due to a strong tidal torque. Nitrogen and helium enrichment occurs early in the binary system that is triggered by tides. The stellar radius can reach a high value in the single star model with high initial velocities at the early stage of the evolution, but efficient rotational mixing can inhibit stellar expanding at the subsequent evolution. Central compactness is increased by the centrifugal force at the early stage of evolution but is reduced by rotational mixing induced by strong tides. The binary models with weak tides have high values of central temperature and stellar radius. Rotational mixing in single stars can slow down the shrinkage of convective cores, while convective cores can be expanded by strong tides in the binary *** rotational mixing induced by tides can cause the star to evolve towards high temperature and luminosity.

关键词： Tides

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

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

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

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

关键词： stars kinematics and dynamics-evolution-statistics

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PSR B0943+10: Mode Switch, Polar Cap Geometry, and Orthogonally Polarized Radiation

arXiv

引用

arXiv 2023年

作者： Cao, Shunshun Jiang, Jinchen Dyks, Jaroslaw Hao, Longfei Lee, Kejia Li, Zhixuan Lu, Jiguang Pan, Zhichen Wang, Weiyang Wang, Zhengli Xu, Jiangwei Xu, Heng Xu, Renxin Department of Astronomy School of Physics Peking University Beijing100871 China National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China Nicolaus Copernicus Astronomical Center Polish Academy of Sciences Rabiańska 8 Toruń87-100 Poland Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China Guizhou Radio Astronomical Observatory Guiyang550025 China CAS Key Laboratory of FAST National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing100049 China Guangxi Key Laboratory for Relativistic Astrophysics School of Physical Science and Technology Guangxi University Nanning530004 China

As one of the paradigm examples to probe into pulsar magnetospheric dynamics, PSR B0943+10 (J0946+0951) manifests representatively, showing mode switch, orthogonal polarization and subpulse drifting, frequently studied below 600 MHz. Here both integrated and single pulses are studied at a high frequency (1.25 GHz) with FAST. The mode switch is studied using a profile decomposition method. A phase space evolution for the pulsar's mode switch shows a strange-attractor-like pattern. The radiative geometry is proposed by fitting polarization position angles with the rotating vector model. The pulsar pulse profile is then mapped to the sparking locations on pulsar surface, and the differences between the main pulse's and the precursor component's radiative processes may explain the X-ray's synchronization with radio mode switch. Detailed single pulse studies on B0943+10's orthogonally polarized radiation are presented, which may support for certain models of radiative transfer of polarized emission. Especially, the difference in OPMs' circular polarization might reflect the cyclotron absorption in pulsar magnetospheres. B0943+10's B and Q modes evolve differently with frequency and have different proportions of orthogonal modes, which indicates possible magnetospheric changes during mode switch. For Q mode pulse profile, the precursor and the main pulse components are orthogonally polarized, and are probably originated from different depths in the magnetosphere. The findings could impact significantly on pulsar electrodynamics and the radiative mechanism related. Copyright © 2023, The Authors. All rights reserved.

关键词： Magnetosphere

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

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Astronomy and Astrophysics 2025年 693卷

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

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

关键词： Stars

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Monte-Carlo simulations on possible collimation effects of outflows to fan-beamed emission of ultraluminous accreting X-ray pulsars

arXiv

引用

arXiv 2022年

作者： Hou, X. You, Y. Ji, L. Soria, R. Zhang, S.N. Ge, M.Y. Tao, L. Zhang, S. Feng, H. Zhou, M. Tuo, Y.L. Song, L.M. Wang, J.C. Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Key Laboratory for Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China University of Chinese Academy of Sciences Chinese Academy of Sciences Beijing100049 China School of Physics and Astronomy Sun Yat-Sen University Zhuhai519082 China Sydney Institute for Astronomy School of Physics A28 The University of Sydney SydneyNSW2006 Australia Department of Astronomy Tsinghua University Beijing100084 China

Pulsating ultraluminous X-ray sources (PULXs) are accreting pulsars with apparent X-ray luminosity exceeding 1039 erg s−1. We perform Monte-Carlo simulations to investigate whether high collimation effect (or strong beaming effect) is dominant in the presence of accretion outflows, for the fan beam emission of the accretion column of the neutron stars in PULXs. We show that the three nearby PULXs (RX J0209.6−7427, Swift J0243.6+6124 and SMC X-3), namely the three musketeers here, have their main pulsed emission not strongly collimated even if strong outflows exist. This conclusion can be extended to the current sample of extragalactic PULXs, if accretion outflows are commonly produced from them. This means that the observed high luminosity of PULXs is indeed intrinsic, which can be used to infer the existence of very strong surface magnetic fields of ∼ 1013−14 G, possibly multipole fields. However, if strong outflows are launched from the accretion disks in PULXs as a consequence of disk spherization by radiation pressure, regular dipole magnetic fields of ∼ 1012 G may be required, comparable to that of the three musketeers, which have experienced large luminosity changes from well below their Eddington limit (2 × 1038 erg s−1 for a NS) to super-Eddington and their maximum luminosity fills the luminosity gap between Galactic pulsars and extragalactic PULXs. Copyright © 2022, The Authors. All rights reserved.

关键词： Luminance

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Period investigation of Algol systems TZ Eri and TU Her

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Research in Astronomy and Astrophysics 2019年第8期19卷 11-18页

作者： Zhi-Hua Wang Li-Ying Zhu Lin-Jia Li Xiao-Man Tian Yunnan Observatories Chinese Academy of SciencesKunming650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming650216China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing100101China University of Chinese Academy of Sciences Beijing100049China

TZ Eri and TU Her are both classic Algol-type systems(Algols). By observing and collecting times of minimum light, we constructed the O-C curves for the two systems. The long-time upward and downward parabolas shown in these diagrams are considered to be the result of the combination of mass transfer and angular momentum loss. The secular orbital period change rates are d P/dt = 4.74(±0.12) ×10-7 d yr-1 and d P/dt =-2.33(±0.01) × 10-6 d yr-1, respectively. There are also cyclic variations in their O-C curves which might be caused by the light-travel time effect(LTTE). A circumbinary star may exist in the TZ Eri system with a mass of at least 1.34 M⊙, while there are possibly two celestial bodies that almost follow a 2 : 1 resonance orbit around the TU Her binary pair. Their masses are at least 2.43 M⊙and 1.27 M⊙.

关键词： stars:binaries:close stars:binaries:eclipsing stars:individual (TZ Eri, TU Her)

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