密近双星伴星天体的研究
文献类型：学位论文
| 作者 | 廖文萍 |
| 学位类别 | 博士 |
| 答辩日期 | 2010-06-07 |
| 授予单位 | 中国科学院研究生院（云南天文台） |
| 授予地点 | 北京 |
| 导师 | 钱声帮 |
| 关键词 | 密近双星 聚星 测光观测 轨道周期分析 光时轨道效应 |
| 学位专业 | 天体物理 |
| 中文摘要 | 双星是两颗恒星(又称子星)在相互引力作用下绕公共质心作闭合轨道运动的恒星系统。近几十年来天文学家发现越来越多的密近双星系统中存在较远的伴星天体（又称第三、第四等天体），像这样由三到十颗恒星在相互引力作用下聚集在一起而组成的多重恒星系称为聚星。按成员星的数目称为三合星（三星系统）、四合星（四星系统），并依次类推。密近双星伴星天体的搜寻与研究不仅对探讨密近双星的起源和演化具有重要作用，而且对一些特殊天体的发现有重大意义，因而近来成为恒星物理研究的一个重要领域！基于此，本博士论文在密近双星伴星天体的研究方面作了一系列工作。首次系统地从密近双星轨道周期变化的统计分析入手，探讨引起密近双星轨道周期呈周期性变化的最有可能的物理机制；同时，结合国内外的中小口径望远镜，对11颗密近双星样本作了观 测、分析与研究。取得的一系列研究成果如下： 1. 系统地从密近双星轨道周期变化的统计分析入手，发现密近双星轨道周期的变化与次星光谱型没有相关性，否定了美国天体物理学家Hall在20多年前提出的观点，揭示了引起密近双星轨道周期呈现周期性变化的最有可能的物理机制是系统中第三天体引起的光时轨道效应。 2. 给出了宇宙中作为第三天体被发现的恒星级黑洞候选体。通过对V Pup、WW Dra 和WY Per的轨道周期分析，发现这三颗密近双星中分别存在一个看不见的伴星天体，且质量分别不低于10.4、6.43 和2.55个太阳质量，说明伴星天体极有可能是恒星级黑洞候选体。这些密近双星外较远距离的黑洞伴星天体的发现能对大质量单星的演化和单个黑洞形成理论提供必要的限制。 3. 发现早型密近双星AD And 以及过相接双星样本V899 Her 和VZ Lib 的伴星天体是一颗密近双星，表明它们是由两个密近双星对组成的四星系统；同时对由两个密近双星对组成的四星系统HT Vir 的轨道周期进行分析，第一次发现其轨道周期存在周期性变化，并探讨了该周期性变化的原因；此外发现早型密近双星ZZ Cas 以及Algol 型密近双星RW Leo 的(O-C) 图中存在两个周期性振荡成分，表明它们也是聚星系统。 4. 发现绕休眠激变双星QS Vir 和磁激变双星DP Leo 转动的系外巨行星。QS Vir 是一颗由白矮星和红矮星组成的短周期(3.618h)休眠激变双星。我们通过对它轨道周期的分析，发现在距它4.2个天文单位处存在一颗巨行星(约6.4倍木星质量)。DP Leo 是第一颗被发现的具有很短周期(1.4967h)的磁激变双星，我们结合丽江2.4米新观测的资料和文献收集的资料对它进行了分析，发现它的第三天体是一颗距离为8.6个天文单位，质量为6.39倍木星质量的系外行星。 |
| 英文摘要 | A binary system can be simply defined as one containing two stars (also called component stars) that describe closed orbits around their common center of gravity, under the influence of their mutual gravitation. In recent decades, astronomers have discovered more and more distant companion objects (viz. the third and fourth body, etc.) in close binary systems, such system, consisting of three to ten stars that get together under the action of mutual gravitation, is so-called multiple star system. According to the number of member stars, it is called triple system stars, quadruple system stars, and so on. The study and search of companion stars in close binary systems can not only play an important role in the origin and evolution of close binaries, but also has significant meaning on discovery of some special objects, which has recently become an important field of the study of stellar physics! In view of this, a series of research work on companion stars in close binary systems were made in the present doctoral thesis. For the first time，explore the most probable physical mechanism of cyclic period changes in close binary via systemic statistics and analysis of orbital period changes. At the same time, combining small and medium sized telescopes at home and abroad, eleven close binary samples were observed and analyzed in this paper. A series of results are obtained as follows: 1. Starting from the statistical analysis of orbital period changes in close binary system, we find there is no relativity between orbital period changes and the spectral type of the secondary component，which does not support the conclusion derived by American astrophysicist Hall more than 20 years ago. It is indicated that the light travel time effect (LTTE) caused by the third body is the most probable physical explanation of the cyclic period changes in close binaries. 2. We find stellar candidate black holes in the universe, which are the third bodies moving around binary stars. By analyzing the orbital periods of V Pup, WW Dra and WY Per, we find that an unseen companion star exists with these binaries, and the lowest masses of them are 10.4Msun, 6.55Msun and 2.55Msun, respectively. It is suggested that these companion objects are very likely stellar candidate black holes. The discovery of these wide black hole companion stars around close binary systems, could provide the necessary restrictions to the evolution of massive single stars and the formation theory of single black holes. 3. We find the companion stars of early-type close binary AD And, and overcontact binaries V899 Her and VZ Lib are close binaries, respectively. It is indicated that these systems are quadruple systems containing two close binaries; At the same time, we analyze the orbital period changes of the quadruple system HT Vir, which is composed of two binaries. Cyclic period changes in orbital period is found for the first time, and the cause of the cyclic period changes is explored. Additionally, two periodic oscillations in the (O-C) diagrams of early-type binary ZZ Cas and Algol-type binary RW Leo are found by us, suggesting they are also multiple star systems. 4. We find a giant extrasolar planet in orbit around magnetic-braking hibernating cataclysmic variable QS Vir and the eclipsing polar DP Leo, respectively. With an orbital period of about 3.618h, QS Vir containing a white dwarf primary and a red dwarf, we find that the third body is a giant planet with a mass of 6.4MJupiter at a distance of 4.2 astronomical units (AU) from the binary, via the analysis of its orbital period; With a short orbital period of 1.4967h, DP Leo is a strongly magnetic cataclysmic binary. Combing the new observational data by using 2.4-m telescope at Yunnan Observatory and those compiled from literature, we analyze it. It is found that the third body is a giant extrasolar planet with a mass of 6.39MJupiter at a distance of 8.6 astronomical units (AU) from the binary. |
| 学科主题 | 天文学 |
| 语种 | 中文 |
| 公开日期 | 2016-05-03 |
| 页码 | 119 |
| 源URL | [http://ir.ynao.ac.cn/handle/114a53/5975]  |
| 专题 | 云南天文台_双星与变星研究组 |
| 推荐引用方式 GB/T 7714 | 廖文萍. 密近双星伴星天体的研究[D]. 北京. 中国科学院研究生院（云南天文台）. 2010. |
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来源：云南天文台
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