YNAO OpenIR  > 双星与变星研究组
短周期脉动变星的周期分析及伴星研究
李临甲
Subtype硕士
Thesis Advisor钱声帮
2009-06-02
Degree Grantor中国科学院研究生院(云南天文台)
Place of Conferral北京
Degree Discipline天体物理
Keyword脉动变星 测光观测 脉动周期 光时轨道效应
Abstract脉动变星作为物理变星的一种类型,是变星中数量最多的。根据其脉动周 期等物理量的区别,又可分成多个类型或次型。周期短于1天的脉动变星有3种 类型:天琴RR型星、盾牌delta型星和仙王beta型星。其中天琴RR型星的数量最多,观 测和研究的历史最长,人们对这类星的认识最为完善;盾牌delta型星由于其周期 短、存在不同脉动成分等特点成为现在研究的一个热点;仙王beta型星数量最少, 至今只发现100多颗,对其周期变化等方面的研究还正在起步阶段。 本文对这3类短周期脉动变星的基本特性做了简述,通过测光观测和O-C分 析方法,对一些盾牌delta型星样本进行了详细的研究,取得如下成果: 1、得出新的拟合O-C数据中光时轨道效应所造成的周期变化成分的公式, 相比前人的拟合,我们的方法在轨道偏心率e较大的情况下也能得到很好的拟合 结果。 2、在对SX Phe型星DY Peg进行观测和周期分析后,发现其脉动周期存在 长期线性减小,变化率为-8.8*10^-12days/day。此外O-C曲线中还存在周期 为41.7年我们解释为光时轨道效应造成的周期性变化成分,这表明DY Peg可能 存在伴星。通过计算,我们认为伴星很可能是一颗褐矮星。 3、在对盾牌delta型星AN Lyn进行观测和研究后,发现其脉动周期存在长期 线性增加,变化率为1.77*10^-10days/day,相比其他同类星的周期变化率要 大的多。O-C曲线中周期性的变化同样表明AN Lyn可能存在伴星,其质量下限 为0.91太阳质量,应该为一致密天体。此外我们还讨论了AN Lyn脉动振幅存在周期性 变化的现象,给出了可能的解释,并指出O-C数据可能存在跳变的情况。 4、对100多颗天琴RRab型星的周期变化做了统计,发现周期变化率绝对值 大的星的金属丰度[Fe/H]大多低于-1.0,推测金属丰度会限制脉动周期的变化; 还发现金属丰度与脉动周期的新的可能的关系。对785颗天琴RR型星做了脉动 幅度的统计,发现同一脉动幅度的变星存在平均视星等的上限。
Other AbstractMany variables are pulsation variables.They can be divided into several types or subtypes depend on the pulsation period.The pulsation variables with period less than one day have three types:RR Lyr type stars,delta Sct type stars and beta Cep type stars.The observation and research of RR Lyr type stars have long history,and the understanding of this type stars is well.The studies of delta Sct type stars are pop because of their short pulsation period and different pulsation modes.The number of beta Cep type stars is not many and only about 100 ones were found.The research on the period of this type is few. In this paper,we used the O-C method,analyzed some stars of delta Sct type and obtained the results as follow: 1.We proposed a new fitting formulae to fit the periodic change which caused by the light travel time effect in the O-C curve.And our new method can fit the data well even when the eccentricity of the orbit is high. 2.After observed and analyzed the SX Phe type star DY Peg,we found a continuous decrease of period at a rate of -8.8*10^-12days/day and a periodic change with about 41.7yrs.The periodic component could be introduced as the existence of a companion which is likely a brown dwarf. 3.After observed and analyzed the delta Sct type stars AN Lyn,we found a continuous increase of period at a rate of 1.44*10^-10days/day which was larger than the values of other delta Sct type stars.Periodic change with 23.2yrs existing in the O-C curve indicated a companion with mass greater than 0.936Msun.We considered it may be a compact object.The phenomenon of the periodic change of pulsation amplitude of AN Lyn were also discussed and explained. 4.According the the statistical study of the period change of more than 100 RRab type stars,we found most stars with high value of period change show low metallicity which were less than -1.0,and presumed that the metallicity would re- strict the change of the pulsation period.We also found a possible relation between the metallicity and pulsation period,and the upper limit of mean magnitude for the RR Lyr type star with the same amplitude.
Subject Area天文学
Pages64
Language中文
Document Type学位论文
Identifierhttp://ir.ynao.ac.cn/handle/114a53/5974
Collection双星与变星研究组
Recommended Citation
GB/T 7714
李临甲. 短周期脉动变星的周期分析及伴星研究[D]. 北京. 中国科学院研究生院(云南天文台),2009.
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