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。

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.