Am食双星的观测与研究

发布时间：2018-12-21 14:09

【摘要】：Am食双星是包含有Am型化学组成特殊星的一类食双星系统。化学组成特殊星(Chemically Peculiar Star,即CP星)是一类具有特殊化学元素丰度的恒星,它们的形成和演化一直是天体物理研究中没有解决的问题。化学组成特殊星主要由A型和B型主序星组成,Am型化学组成特殊星是其中双星比例最高的一类,可以达到90%以上,且很多被发现处于食双星中。众所周知,食双星是人们获得恒星质量、半径等基本物理参量的重要渠道,通过对Am食双星的观测研究,可以得到这类CP星精确的基本物理参量以及物质交流等信息,从而更好的研究CP星的起源和演化。本文中我们对CP星进行了简单综述,并以2009年Renson和Manfroid发表的Ap/Am星表为基础,给出了一个目前较为完备的Am食双星星表。从此星表中,我们选取了两个周期小于一天的Am食双星V1073Cyg和TYC6408-989-1进行观测研究,主要结果如下:1、我们对Am食双星进行调研补充,发现17个Am食双星未在73个Am食双星之列,并将其列在Am食双星增补表中,给出其周期和光谱型等信息。我们对Am食双星的周期进行统计分析,发现其周期分布的峰值是2-4天,其中2-3天分布最多,长周期则比较少,周期小于一天的也比较少,目前只有四个系统,即:TYC6408-989-1、V1073Cyg、V2787Ori和IW Per。其中IW Per为增补的Am食双星之一。2、对W UMa型Am食双星V1073Cyg进行测光观测、光变曲线解轨分析以及轨道周期分析。轨道周期分析表明,V1073Cyg的O-C曲线呈现出周期持续减少的同时叠加周期性震荡变化。周期减小率约为-4.91(±0.93)×10-8d yr-1。周期减小可能是两子星间物质交流和系统角动量损失的综合效应所致。同时,周期为84.52(±0.52)年、半振幅为4.95(±0.42)AU的周期性震荡可能是一颗质量约为0.488M的第三天体的光时轨道效应引起的。光变曲线分析显示该系统是一个过相接双星系统,探测到其第三光的光度约占系统总光度的20%。光变曲线分析与O-C分析关于第三天体的结论很好的符合,这说明此系统很可能是一个Am型三星系统。3、TYC6408-989-1展示出EB型的连续光变,用丽江70厘米望远镜得到V波段完整光变曲线,我们对该系统进行了首次的测光分析研究。综合光变曲线解轨分析显示该系统可以收敛于三种模型,质量比范围为0.205-0.274,它很可能是一个临近相接的密近双星系统。我们将进一步对该系统进行观测,以期获得多波段的观测数据对其进行详细研究。
[Abstract]:Am binary star is a kind of binary star system which contains Am type chemical composition special star. Chemically composed special star (Chemically Peculiar Star, (CP star) is a class of stars with special chemical element abundance. Their formation and evolution has been an unsolved problem in astrophysics. The chemical composition of special stars is mainly composed of A type and B type principal order stars, and Am type chemical composition special stars are the highest proportion of binary stars, can reach more than 90%, and many have been found in the binary stars. As we all know, binary stars are an important way for people to obtain basic physical parameters such as stellar mass and radius. Through the observation and study of Am binary stars, we can obtain the accurate basic physical parameters and material exchange information of this kind of CP stars. Thus, the origin and evolution of CP stars are better studied. In this paper, we give a brief review of CP stars, and based on the Ap/Am catalogue published by Renson and Manfroid in 2009, we present a relatively complete catalogue of binary stars in Am. From this catalog, we selected two Am binary stars, V1073Cyg and TYC6408-989-1, which have a period of less than one day. The main results are as follows: 1. It is found that 17 Am binary stars are not included in the 73 Am binary stars, and they are listed in the supplement table of Am binary stars. The information of their periods and spectral types are given. By statistical analysis of the period of Am binary star, we find that the peak value of the period distribution is 2-4 days, of which 2-3 days are the most, the long period is less, and the period is less than one day. At present, there are only four systems. Namely: TYC6408-989-1,V1073Cyg,V2787Ori and IW Per. Among them, IW Per is one of the supplementary binary stars of Am. The optical measurements of W UMa type Am binary star V1073Cyg, the analysis of optical transformation curve and the analysis of orbital period are carried out. The orbit period analysis shows that the O-C curve of V1073Cyg shows a continuous decrease of period and superimposed periodic oscillation. The period reduction rate is about -4.91 (卤0.93) 脳 10 ~ (-8) d yr-1.. The decrease of the period may be due to the combined effect of the material exchange between the two subsatellites and the angular momentum loss of the system. At the same time, the periodic oscillation with a period of 84.52 (卤0.52) years and a half amplitude of 4.95 (卤0.42) AU may be caused by the photo-time orbital effect of a third celestial body with a mass of about 0.488M. The optical curve analysis shows that the system is an overphase binary system, and the third luminosity of the system is about 20% of the total luminosity of the system. The optical curve analysis is in good agreement with the O-C analysis on the third celestial body, which indicates that the system is probably a Am Samsung system. 3TYC6408-989-1 shows the continuous light variation of the EB model. Using Lijiang 70cm telescope to obtain the complete V band optical curve, we have carried out the first photometric analysis of the system. The results show that the system can converge to three models and the mass ratio ranges from 0.205-0.274. It is very likely that the system is a close binary-star system. We will make further observations of the system in order to obtain multi-band observation data to study it in detail.
【学位授予单位】：中国科学院研究生院(云南天文台)
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P144.9

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