富金属EA型密近双星伴星天体特性的观测与研究

The National Major Scientific Projects LAMOST (Large Sky Area Multi-Object Fiber Spectroscopic Telescope) has obtained stellar atmospheric parameters of more than 2000 EA-type binaries, and a number of metal-rich EA-type close binaries have been found. The high metal abundance of these binary stars suggests that they may be very young. However, the orbital periods are short. It requires a long time scale for formation, which is clearly contradictory. One possibility is that there is a third body in the system, by extracting angular momentum of the system, the progenitor stars rapidly evolve into the present short-period binary stars. Another possibility is that there are compact companion stars such as neutron stars or black holes around these binary stars, and these compact objects contaminate the central binary stars by supernova explosion, making the central binaries have high metal abundance. These make the metal-rich EA-type close binaries an important laboratory for studying the formation of close binaries and searching for compact companion stars such as black holes. Based on follow-up observations of the metal-rich EA-type close binaries using the medium and small telescopes at home and abroad and the analysis of the light travel time effect, this research project plans to study on characteristics of companion stars orbiting around these binaries, search for a new type of black hole candidate which is relatively far away from a binary star and is not influenced by companion stars. The results of this research will not only provide important information on the formation and evolution of close binary stars, but also the limits to theory of structure and evolution of massive star, and improve our understanding of the formation and evolution of black holes.

国家重大科学工程LAMOST的光谱巡天获得了2000多颗EA型双星的恒星大气参量，并发现了一批富金属EA型密近双星。这些双星很高的金属丰度揭示了它们可能很年轻，而轨道周期却又很短，需要很长的形成时标，这显然是相互矛盾的。一种可能是因为系统中存在第三天体，并通过抽取角动量使得前身星快速演化成现在的短周期双星。另外一种可能是双星中存在中子星或黑洞等致密伴星，这些致密天体通过超新星爆炸形成的过程中污染了中心双星，使其具有高金属丰度。这就使得富金属EA型双星成为研究密近双星形成和搜寻黑洞等致密伴星天体的重要场所。项目计划利用国内外中小口径望远镜对富金属EA型密近双星进行后续观测，通过光时轨道效应等的分析，研究它们的伴星天体特性，搜寻双星外较远距离的、不受伴星影响的新类型黑洞候选体。研究结果能为密近双星形成演化提供重要的信息，对大质量恒星结构演化理论提供必要的限制，丰富人们对黑洞形成演化的认识。

本项目将光谱特征、测光解轨、光时轨道效应分析以及LAMOST、TESS和Gaia等地空观测信息有机结合起来，对富金属EA型密近双星等的伴星天体特性进行研究。发现由活动相接双星，单谱双星和目视伴星组成的物理上存在联系的特殊五星系统，揭示伴星天体在密近双星的形成演化过程中起着非常重要的作用，为研究密近双星的形成和演化提供天然实验室；发现轨道不共面的“三胞胎”三星组成的特殊多星系统，为探讨双星和多星系统的形成演化提供重要的信息，提高了人们对恒星系统多样性的认识；近距离伴星天体的发现对检验恒星形成以及恒星动力学相互作用理论具有重要的作用，为短周期密近双星近距离伴星天体的研究提供了观测依据；发现新形成的大质量相接双星含有大质量的第三天体，有助于探讨第三天体对大质量相接双星形成的影响；发现短周期大质量连体双胞胎双星，并发现围绕双胞胎双星转动的独立演化黑洞候选体，揭示了黑洞伴星通过抽取角动量促使大质量双胞胎双星的形成，等等。获得本项目资助的SCI论文共15篇；项目负责人获云南省中青年学术和技术带头人称号，入选中国科学院西部青年学者和官渡区科技创新团队负责人，项目负责人及2名主要参与者入选云南省青年拔尖人才；项目培养博士研究生2名，其中1人获2022年中国科学院院长优秀奖，另有在培博士生1名和硕士生2名；新增硕士生导师1名和科研项目8项。