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arXiv 2021年

作者： Kang, Xiaoyu Chang, Ruixiang Kudritzki, Rolf-Peter Gong, Xiaobo Zhang, Fenghui 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 Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China LMU München Universitätssternwarte Scheinerstr. 1 München81679 Germany Institute for Astronomy University of Hawaii 2680 Woodlawn Drive HonoluluHI96822 United States University of Chinese Academy of Sciences Beijing100049 China

An analytical chemical evolution model is constructed to investigate the radial distribution of gas-phase and stellar metallicity for star-forming galaxies. By means of the model, the gas-phase and stellar metallicity can be obtained from the stellar-to-gas mass ratio. Both the gas inflow and outflow processes play an important role in building the final gas-phase metallicity, and there exists degeneracy effect between the gas inflow and outflow rates for star-forming galaxies. On the other hand, stellar metallicity is more sensitive to the gas outflow rate than to the gas inflow rate, and this helps to break the parameter degeneracy for star-forming galaxies. We apply this analysis method to the nearby disc galaxy M 101 and adopting the classical χ2 methodology to explore the influence of model parameters on the resulted metallicity. It can be found that the combination of gas-phase and stellar metallicity is indeed more effective for constraining the gas inflow and outflow rates. Our results also show that the model with relatively strong gas outflows but weak gas inflow describes the evolution of M 101 reasonably well. Copyright © 2021, The Authors. All rights reserved.

关键词： Astrophysics

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Investigations into the thermal non-equilibrium of W UMa-type contact binaries

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Research in Astronomy and Astrophysics 2018年第5期18卷 83-92页

作者： Xiao Xiong Liang Liu Sheng-Bang Qian Yunnan Observatories Chinese Academy of Sciences Kunming 650011 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing 100101 China University of Chinese Academy of Sciences Beijing 100049 China

Traditionally, some physical details（e.g., magnetic braking, energy transfer, angular momentum loss, etc.） have to be taken into consideration during investigations into the evolution of contact binaries. However, the real evolutionary processes which usually contain several of these physical mechanisms are very complicated as a result of strong interaction between components. To avoid dealing with these factors, a linear relationship is applied to the temperatures of components. It is found that the higher the mass ratio（M2/M1） of a contact system, the weaker the deviation from thermal *** this basis, a variation trend of fill-out factor（f） changing with mass ratio can be inferred, which is consistent with observations. Moreover, if we stick to this point of view, it should be natural that the number of semi-detached binaries in the predicted broken-contact phase of relaxation oscillations is less than the number in the contact phase.

关键词： stars binaries close - stars binaries eclipsing - stars evolution

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Multi-color light curves and orbital period research of eclipsing binary V1073 Cyg

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Research in Astronomy and Astrophysics 2018年第2期18卷 83-92页

作者： Xiao-Man Tian Li-Ying Zhu Sheng-Bang Qian Lin-Jia Li Lin-Qiao Jiang Yunnan Observatories Chinese Academy of Sciences Kunming 650216 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650216 China University of Chinese Academy of Sciences Beijing 100049 China School of Physics and Electronic Engineering Sichuan University of Science & Engineering Zigong 643000 China

New multi-color BVRcIc photometric observations are presented for the W UMa type eclips- ing binary V1073 Cyg. The multi-color light curve analysis with the Wilson-Devinney procedure yielded the absolute parameters of this system, showing that V 1073 Cyg is a shallow contact binary system with a fill-out factor f = 0.124（±0.011）. We collected all available times of light minima spanning 119yr, including CCD data to construct the O - C curve, and performed detailed O - C analysis. The O - C diagram shows that the period change is complex. A long-term continuous decrease and a cyclic vari- ation exist. The period is decreasing at a rate ofP = -1.04（±0.18） × 10-10 d cycle-land, with the period decrease, V1073 Cyg will evolve to the deep contact stage. The cyclic variation with a period of P3 = 82.7（±3.6） yr and an amplitude of A = 0.028（±0.002） d may be explained by magnetic activ- ity of one or both components or the light travel time effect caused by a distant third companion with M3（i1 = 90°） = 0.511 M⊙.

关键词： stars： binaries： close -- stars： binaries： eclipse -- stars： binaries： individual （V1073 Cyg）

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A photmetric study of the high-mass-ratio contact binary av puppis

arXiv

引用

arXiv 2019年

作者： Han, Quan-Wang Li, Li-Fang Jiang, Deng-Kai Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China University of the Chinese Academy of Sciences Beijing100049 China

The multi-color photometric light curves for a contact binary AV Puppis (AV Pup) in V RcIcbandpasses are presented, and they are analyzed by using of the 2013 version of theWilson-Devinney (W-D) code. The solutions suggest that AV Pup is a peculiar A-subtype W UMa contact binary with a high mass ratio (q = m2/m1= 0.896) and a fill-out factor (f = 10%). Combining with our newly determined times of minimum with those collected from literatures, the orbital period changes of this system are investigated. The O - C analysis shows that the orbital period of AV Pup is increasing at a rate of dP/dt = 4.83× 10-7days yr-1, which can be explained by mass transfer from the less massive component to the more massive one. Copyright © 2019, The Authors. All rights reserved.

关键词： Photometry

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The eccentricity enhancement effect of intermediate-mass-ratio-inspirals: Dark matter and black hole mass

arXiv

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arXiv 2020年

作者： Tang, Meirong Wang, Jiancheng 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

It was found that the dark matter (DM) in the intermediate-mass-ratio-inspiral (IMRI) system has a significant enhancement effect on the orbital eccentricity of the stellar massive compact object, such as a black hole (BH), which may be tested by space-based gravitational wave (GW) detectors including LISA, Taiji and Tianqin in future observations (Yue & Cao 2019). In this paper, we will study the enhancement effect of the eccentricity for an IMRI under different DM density profiles and center BH masses. Our results are as follows: (1) in terms of the general DM spike distribution, the enhancement of the eccentricity is basically consistent with the power-law profile, which indicates that it is reasonable to adopt the power-law profile;(2) in the presence of DM spike, the different masses of the center BH will affect the eccentricity, which provides a new way for us to detect the BH's mass;(3) considering the change of the eccentricity in the presence and absence of DM spike, we find that it is possible to distinguish DM models by measuring the eccentricity at the scale of about 105GM/c2. Copyright © 2020, The Authors. All rights reserved.

关键词： Galaxies

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A fast point-pattern matching algorithm based on statistical method

arXiv

引用

arXiv 2019年

作者： Zhang, Zhen-Jun Zhang, Yi-Gong Cheng, Xiang-Ming Wang, Jian-Cheng Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China

We propose a new pattern-matching algorithm for matching CCD images to a stellar catalogue based statistical method in this paper. The method of constructing star pairs can greatly reduce the computational complexity compared with triangle method. We use a subsample of the brightest objects from the image and reference catalogue, and find a coordinate transformation between the image and reference catalogue based on the statistical information of star pairs. Then all the objects are matched based on the initial plate solution. The matching process can be accomplished in several milliseconds for the observed images taken by Yunnan observatory 1-m telescope. Copyright © 2019, The Authors. All rights reserved.

关键词： Stars

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An upgraded interpolator of the radial basis functions network for spectral calculation based on empirical stellar spectral library

arXiv

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arXiv 2020年

作者： Cheng, Lian-Tao Zhang, Feng-Hui 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 University of Chinese Academy of Sciences Beijing100049 China

Stellar population synthesis is an important method in the galaxy and star-cluster studies. In the stellar population synthesis models, stellar spectral library is necessary for the integrated spectra of the stellar population. Usually, the stellar spectral library is used to the transformation between the stellar atmospheric parameters and the stellar spectrum. The empirical stellar spectral library has irreplaceable advantages than the theoretical library. However, for the empirical spectral library, the distribution of stars is irregularly in the stellar atmospheric parameter space, this makes the traditional interpolator difficult to get the accurate results. In this work, we will provide an improved radial basis function interpolator which is used to obtain the interpolated stellar spectra based on the empirical stellar spectral library. For this interpolator, we use the relation between the standard variance σ in the Gaussian radial basis function and the density distribution of stars in the stellar atmospheric parameter space to give the prior constraint on this σ. Moreover, we also consider the anisotropic radius basis function by the advantage of the local dispersion of stars in the stellar atmospheric parameter space. Furthermore, we use the empirical stellar spectral library MILES to test this interpolator. On the whole, the interpolator has a good performance except for the edge of the low-temperature region. At last, we compare this interpolator with the work in Cheng et al. (2018), the interpolation result shows an obvious improvement. Users can use this interpolator to get the interpolated spectra based on the stellar spectral library quickly and easily. Copyright © 2020, The Authors. All rights reserved.

关键词： Stars

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Off-centre carbon burning in He-accreting carbon-oxygen white dwarfs

arXiv

引用

arXiv 2019年

作者： Wu, Chengyuan Wang, Bo Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatories CAS Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China Centre for Astronomical Mega-Science CAS Beijing100012 China

The carbon-oxygen white dwarf (CO WD) + He star channel is one of the promising ways for producing type Ia supernovae (SNe Ia) with short delay times. Recent studies found that carbon under the He-shell can be ignited if the mass-accretion rate of CO WD is higher than a critical rate (about 2×10−6 M yr−1), triggering an inwardly propagating carbon flame. Previous studies usually supposed that the off-centre carbon flame would reach the centre, resulting in the formation of an oxygen-neon (ONe) WD that will collapse into a neutron star. However, the process of off-centre carbon burning is not well studied. This may result in some uncertainties on the final fates of CO WDs. By employing MESA, we simulated the long-term evolution of off-centre carbon burning in He-accreting CO WDs. We found that the inwardly propagating carbon flame transforms the CO WDs into OSi cores directly but not ONe cores owing to the high temperature of the burning front. We suggest that the final fates of the CO WDs may be OSi WDs under the conditions of off-centre carbon burning, or explode as iron-core-collapse SNe if the mass-accretion continues. We also found that the mass-fractions of silicon in the OSi cores are sensitive to the mass-accretion rates. Copyright © 2019, The Authors. All rights reserved.

关键词： Carbon

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Tianyu: search for the second solar system and explore the dynamic universe

arXiv

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arXiv 2024年

作者： Feng, Fabo Rui, Yicheng Du, Zhimao Lin, Qing Zhang, Congcong Zhou, Dan Cui, Kaiming Ogihara, Masahiro Yang, Ming Lin, Jie Cai, Yongzhi Yang, Taozhi Pang, Xiaoying Jian, Mingjie Li, Wenxiong Guo, Hengxiao Shi, Xian Shi, Jianchun Li, Jianyang Guo, Kangrou Yao, Song Chen, Aming Jia, Peng Tan, Xianyu Jenkins, James S. Jiang, Hongxuan Zhang, Mingyuan Li, Kexin Xiao, Guangyao Zheng, Shuyue Xuan, Yifan Zheng, Jie He, Min Jones, Hugh R.A. Song, Cuiying Tsung-Dao Lee Institute Shanghai Jiao Tong University Shengrong Road 520 Shanghai201210 China School of Physics and Astronomy Shanghai Jiao Tong University 800 Dongchuan Road Shanghai200240 China Shanghai200127 China Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China College of Surveying and Geo-Informatics Tongji University Shanghai20009 China CAS Key laboratory for Research in Galaxies and Cosmology Department of Astronomy University of Science and Technology of China Hefei230026 China School of Astronomy and Space Sciences University of Science and Technology of China Hefei230026 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China School of Physics Xi’an Jiaotong University Xi’an710049 China Department of Physics Xi’an Jiaotong-Liverpool University 111 Ren’ai Road Dushu Lake Science and Education Innovation District Suzhou215123 China Shanghai Key Laboratory for Astrophysics Shanghai Normal University 100 Guilin Road Shanghai200234 China Department of Astronomy Stockholm University AlbaNova University Center Roslagstullsbacken 21 Stockholm114 21 Sweden National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China School of Atmospheric Sciences Sun Yat-sen University Zhuhai519082 China College of Electronic Information and Optical Engineering Taiyuan University of Technology Taiyuan030024 China Instituto de Estudios Astrofísicos Facultad de Ingeniería y Ciencias Universidad Diego Portales Av. Ejército 441 Santiago Chile Casilla 36-D Santiago Chile Shandong Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment School of Space Science and Physics Institute of Space Sciences Shandong University Shandong Weihai264209 China CAS K

Giant planets like Jupiter and Saturn, play important roles in the formation and habitability of Earth-like planets. The detection of solar system analogs that have multiple cold giant planets is essential for our understanding of planet habitability and planet formation. Although transit surveys such as Kepler and Transiting Exoplanet Survey Satellite (TESS) have discovered thousands of exoplanets, these missions are not sensitive to long period planets due to their limited observation baseline. The Tianyu project, comprising two 1-meter telescopes (Tianyu-I and II), is designed to detect transiting cold giant planets in order to find solar system analogs. Featuring a large field of view and equipped with a high-speed CMOS camera, Tianyu-I will perform a high-precision photometric survey of about 100 million stars, measuring light curves at hour-long cadence. The candidates found by Tianyu-I will be confirmed by Tianyu-II and other surveys and follow-up facilities through multi-band photometry, spectroscopy, and high resolution imaging. Tianyu telescopes will be situated at an elevation about 4000 meters in Lenghu, chosen as the premier observation site in China. With a photometric precision of 0.1% for stars with V © 2024, CC BY.

关键词： Exoplanets

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Relation of Velocity Distribution and Mass for DA White Dwarfstwo

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Chinese Astronomy and Astrophysics 2018年第2期42卷 202-212页

作者： Gong, Xiao-bo Li, Li-fang Yunnan Observatories Chinese Academy of of Sciences Kunming 650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China University of Chinese Academy of Sciences Beijing 100049 China

White dwarfs are the evolutionary endpoint of the low-and-medium mass stars. In the studies of white dwarfs, the mass of white dwarf is an important physical parameter. In this paper, we give an analysis about the velocity distribution of DA white dwarfs in the Sloan Digital Sky Survey (SDSS), and hope to find the relation between mass and velocity distribution of white dwarfs. We get the radial velocity and tangential velocity of every DA white dwarf according to their proper motion and spectral shift. Through analyzing the velocity distribution of DA white dwarfs, we find that the small-mass white dwarfs, which are produced from the single-star evolution channel, have a relatively large velocity dispersion. © 2018

关键词： stars: evolution Stars: fundamental parameters Stars: white dwarfs

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