巡天项目中的白矮星搜寻  

The Searches of White Dwarfs in the Sky Survey Projects

作　　者：孔啸[1,2] 罗阿理 KONG Xiao;LUO A-li(Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy ofSciences, Beijing 100101, China;University of Chinese Academy of Sciences, Beijing 100049, China)

机构地区：[1]中国科学院国家天文台光学天文重点实验室,北京100101 [2]中国科学院大学,北京100049

出　　处：《天文学进展》2019年第3期287-303,共17页Progress In Astronomy

基　　金：国家自然科学基金(11390371/4);973项目(2014CB845700)

摘　　要：首先,描述了白矮星的颜色特点和光谱型分类。白矮星是大多数恒星的终极状态,它会随着时间的推移而逐渐冷却。根据表面大气成分,它被划分成DA和DB等不同的光谱型。对某一颗白矮星来说,其光谱型分类可能会随着时间的推移而发生变化,这主要是由于其大气包层中的元素含量被对流过程改变引起的。为了对各类光谱型有更深入的研究,样本的完备性不可或缺。得益于近十几年来大型巡天项目的开展(如斯隆数字巡天、郭守敬望远镜的光谱巡天等),目前通过光谱证认的白矮星已超过4×10~4颗,其中绝大多数是H主导的DA型白矮星,另外还包含2 000多颗He主导的DB白矮星。此外,GALEX项目和GAIA卫星分别提供了有价值的白矮星紫外数据、空间位置和速度等信息。这些数据和信息对于白矮星的研究工作起到了非常大的促进作用。随后,对白矮星的大气参数、质量和运动学等内容作了简单的总结。人们利用模板匹配测量了绝大多数已知白矮星的大气参数,并获得了DB型白矮星的有效温度与紫外颜色间的线性关系。基于斯隆数字巡天的光谱数据,白矮星的质量分布和质量-半径关系也得到了较深入的研究。小质量白矮星具有较大的速度弥散,而大质量的则相反。最后,讨论了白矮星的形成和演化机制,这些机制都是基于现有的理论模型得到的。随着巡天项目中白矮星样本的增加,现有的模型会逐渐被修正和完善,新的模型也将随之建立。This review first describes the color characteristics and spectral classifications of white dwarfs(WD), which are the end product of evolution of 97% stars. According to the composition of atmosphere, they are divided into different spectral types including hydrogendominated(DA), helium-dominated(DB or DO) WDs, etc. In order to conduct an in-depth research of WDs, e.g. their formation and evolution process, physical properties, kinematics and atmospheric models, the completeness of the samples becomes indispensable. Benefit from the development of large-scale sky-survey projects in the past decades, such as the Sloan Digital Sky Survey(SDSS) and the spectral survey of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST), the number of spectroscopically confirmed WDs has reached more than 40 000. The majority are DA WDs, while the others include more than 2 000 DBs. In addition, valuable ultraviolet and astrometric(parallax, proper motion,spatial position, etc.) data are available now, which are provided by the Galaxy Evolution Explorer(GALEX) project, and the Global Astrometric Interferometer for Astrophysics(GAIA) satellite, respectively. These data have greatly deepened the understandings of WDs. Subsequently, the latest researches of atmospheric parameters, mass and kinematics of WDs are briefly summarized. Finally, this review discusses the formation and evolution of WDs, which are based on the existing theoretical models. With the increasing number of WD samples, the existing models would be continuously revised and improved, and new models may also be established.

关 键 词：白矮星 星表 巡天 

分 类 号：P145.5[天文地球—天体物理]