Contact binaries at different evolutionary stages  

作　　者：Sheng-Bang Qian Li-Ying Zhu Liang Liu Xu-Dong Zhang Xiang-Dong Shi Jia-Jia He Jia Zhang 

机构地区：[1]Yunnan Observatories,Chinese Academy of Sciences,Kunming 650216,China [2]School of Physics and Astronomy,Yunnan University,Kunming 650091,China [3]Key Laboratory for the Structure and Evolution of Celestial Objects,Chinese Academy of Sciences,Kunming 650216,China [4]Center for Astronomical Mega-Science,Chinese Academy of Sciences,Beijing 100101,China [5]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Research in Astronomy and Astrophysics》2020年第10期229-248,共20页天文和天体物理学研究（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.11933008,11922306,11773066 and 11903076);the Open Project Program of the Key Laboratory of Optical Astronomy,National Astronomical Observatories,Chinese Academy of Sciences。

摘　　要：Contact binaries consist of two strongly interacting component stars where they are filling their critical Roche lobes and sharing a common envelope.Most of them are main-sequence stars,but some of them are post main-sequence systems.They are good astrophysical laboratories for studying several problems such as the merging of binary stars,evolution of the common envelope,the origin of luminous red nova outbursts and the formation of rapidly rotating single stars with possible planetary systems.A large number of contact binary candidates were detected by several photometric surveys around the world and many of them were observed by the LAMOST spectroscopic survey.Based on follow-up observations,the evolutionary states and geometrical structures of some systems were understood well.In this review,we will introduce and catalog new stellar atmospheric parameters(i.e.,the effective temperature(Teff),the gravitational acceleration(log(g)),metallicity([Fe/H])and radial velocity(Vr))for 9149 EW-type contact binaries that were obtained based on low-and medium-resolution spectroscopic surveys of LAMOST.Then we will focus on several groups of contact binary stars,i.e.,marginal contact binary systems,deep and low-mass ratio contact binary stars,binary systems below the short-period limit of contact binaries and evolved contact binaries.Marginal contact binaries are at the beginning of the contact stage,while deep and low-mass ratio contact binary stars are at the final evolutionary stage of tidally locked binaries.Several statistical relations including the period-temperature relation are determined well by applying LAMOST data and their formation and evolutionary states are reviewed.The period-color relation of M-type binaries reveals that there are contact binaries below the short-period limit.Searching for and investigating contact binaries near and below this limit will help us to understand the formation of contact binary systems and a new prediction for the short-period limit is about 0.15 d.Some evolved contact binari

关 键 词：binaries:eclipsing stars:late-type stars:low-mass stars:formation stars:evolution 

分 类 号：P15[天文地球—天文学]