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题名:
相接双星的观测与统计研究
作者: 姜天雨
学位类别: 硕士
学位专业: 天体物理
学位授予日期: 2009-06-02
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: 李立芳
学科分类: 天文学
关键词: 相接双星  ;  光变曲线  ;  测光解轨  ;  轨道周期  ;  动力学演化
中文摘要: 本论文主要通过对目标源进行测光观测和对样本进行统计分析的方法对W UMa型相接双星进行研究。首先介绍了W UMa型相接双星的一些观测特征和统计性质。然后,通过统计研究方法,对相接双星的动力学稳定性和演化状态进行了研究。论文还通过测光观测对两颗W UMa型相接双星进行了研究,给出了它们的测光解。另外,通过O-C图对它们的轨道周期变化进行了研究,并对引起它们轨道周期变化的可能原因进行了探讨。具体取得了以下主要研究成果: 1. 对一个包含130颗W UMa型相接双星样本的相关参数进行了统计研究。揭示出相接双星的两类次型(A次型和W次型)在演化状态上可能并没有差别,而只是处于热弛豫振荡的不同阶段。W次型和A次型系统的“质量-半径”及“质量-光度”图则暗示相接双星的两子星之间可能存在大量的能量转移。由理论上主星的相对能量转移率与质量比之间的关系,估计出在相接双星的质量比约为0.55时主星的相对能量转移率达到最大。相接双星的总质量与总角动量之间的关系图则预示,相接双星系统的质量比随总质量的 衰减而逐渐减小。当相接双星的质量比到达截止质量比(约为0.076)时,其系统可能由于动力学不稳定性在1000-10000年内并合为一颗快速自转的单星(如蓝离散星或FK Com型巨星)。 2. 利用云南天文台1米望远镜对相接双星BI CVn进行了测光观测。采用WD解轨程序对新得到的光变曲线以及前人得到的视向速度曲线同时进行解轨,给出了BI CVn的黑子模型测光解及绝对物理参量。并据此对BI CVn的距离和演化状态进行了讨论。 3. 通过O-C图对相接双星BI CVn的周期变化进行了分析,由轨道周期的长期衰减率估计了两子星之间可能的物质转移率。相接双星BI CVn的轨道周期还存在周期性的变化。这可能由第三天体伴星或子星的磁活动所引起。根据这两种可能情况分别估计了第三天体及子星磁活动的相关参数。 4. 对相接双星CW Cas的BV光曲线进行了初步分析,得到了BV光曲线的测光解。证实了CW Cas为W次型的浅相接双星。通过O-C图对相接双星CW Cas的轨道周期变化进行了初步分析,显示其轨道周期存在一个长期的连续衰减趋势。同时对CW Cas可能所处的演化阶段进行了分析。
英文摘要: In this thesis I present the investigation of W UMa-type binaries based on photometric observation and statistic analysis. First of all, an introduction about the observational and statistic properties of W UMa-type binaries are presented. Then, the dynamical stability and evolutionary status of W UMa-type binaries are studied statistically. The photometric analysis of two W UMa-type binaries are described and the photometric resolutions are given in the following part. Besides, the changes in the orbital periods of the two systems are analyzed based on O-C diagrams, and the possible explanations for the changes are discussed. The results obtained in this thesis are mainly consisted as follows: 1. An sample including 130 W UMa-type systems is analyzed statistically based upon their orbital and physical parameters. It is found that there is no evolutionary difference between this two subtypes of W UMa-type systems. A- and W-type systems are probably in different stages of thermal Relaxation Oscillations. The mass-radius and mass-luminosity diagrams indicate that a large amount of energy should be transferred between the two components of W UMa-type systems. From the relation between the relative energy transfer rate of the primary component and the mass ratio of W UMa-type systems, it can be seen that the relative energy transfer rate peaks at a mass ratio of about 0.55. As indicated in the M-L diagram which shows the relation between the total mass and the total angular momentum of W UMa-type systems, there is a tendency for a decreasing total mass with decreasing mass ratio. When their mass ratios are decreased to the cut-off mass ratio (about 0.076), W UMa-type systems will merge into the rapidly rotating stars within 1000-10000 yr, such as blue stragglers and FK Com stars. 2. New CCD photometric observations for BI CVn were carried out with the 1-meter reflecting telescope at Yunnan Observatory. By means of the Wilson-Devinney (WD) code, a simultaneous solution of light and radial velocity curves with dark spot model and the absolute parameters are obtained for this contact binary system. A discussion is made upon the distance to the system and the evolutionary status of BI CVn. 3. According to the O-C diagrams, the changes in the orbital period of BI CVn are studied. The mass transfer rate between the components is estimated based on the secular decrease in the orbital period. There is also a small-amplitude oscillation superposed on the secular decrease in its orbital period change, which might be caused either by the presence of a third body or the solar-like magnetic activity cycles of the components in the system. Then the related parameters are estimated corresponding to this two possible explanations. 4. A preliminary photometric analysis is made and the photometric resolution is given for the BV light curves of the W UMa-type system CW Cas. It confirmed the classification of W-type for this marginal contact system. Based on O-C diagram, the changes in the orbital period of CW Cas are studied preliminarily. It is found that there is a tendency with secular decrease in the orbital period changes of CW Cas.
语种: 中文
总页数: 86
内容类型: 学位论文
URI标识: http://ir.ynao.ac.cn/handle/114a53/4658
Appears in Collections:大样本恒星演化研究组_学位论文

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