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题名	小质量红巨星非径向振动模式的规避相交现象
作者	郭军军
学位类别	硕士
答辩日期	2013
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	李焱
关键词	恒星:脉动-恒星:红巨星
其他题名	Avoided crossing between non-radial modes in low mass RGB stars
学位专业	天体物理
中文摘要	在红巨星阶段，P模式振动和G模式振动同时出现，并且它们的频率在很大的范围内重合。由于它们的频率变化率不同， 致使两种模式的振动频率会接近而发生规避相交作用。对于球谐度 $l$ = 1, 2 和 3 的非径向本征模，他们的声波传播区域与重力波传播区域之间的间隔大小的不同导致耦合效率也不一样。 在这篇文章里，我们给出了所选模型的数值计算结果。发现球谐度 $l$ = 2 和 3的本征模比 $l$ = 1 的本征模需要在频率更接近的情况下才能彼此之间完全交换性质。并且球谐度$l$ = 2 和 3 的本征模的无量纲频率随演化体现出更好的规律性。为了详细的研究规避相交作用的影响， 我们选择具有最小归一化惯性参量的本征模作为P模，其它的作为G模。我们把球谐度 $l$ = 1, 2 和 3 的本征模分别作在频率栅状图和周期栅状图上，进一步的发现一些P模偏离了等频率间隔关系， 而伴随着这些P模的G模偏离了等周期间隔关系。接着，我们又研究了不同球谐度的G模对等周期间隔的偏离度 与它们的归一化惯性参量之间的关系。发现G模的频率越是与P模接近，它们的归一化惯性参量越小,偏离度也越大。但即使球谐度 $l$ = 2 和 3的 本征模发生了很强的耦合并且有很小的归一化惯性参量，它们仍然比球谐度 $l$ = 1 的本征模更好的服从那两个等间隔关系。因此，我们认为可以用更少的球谐度$l$ = 2 和 3的混合G模就能精确的测量出周期间隔。
英文摘要	The non-radial p modes and g modes appear simultaneously in the red giant stars. The variation rates of their frequencies are different along the stellar evolution so that their frequencies will become close and the avoided crossings arise between them. The separation between acoustic waves and gravity waves propagation regions for $l$ = 1, 2 and 3 is different which results in the coupling efficiency is different too. In this paper, we present the results of numerical computations of the models we choose. We find the two kinds of modes for $l$ = 2 and 3 need to be closer in frequency to exchange nature completely than the case for modes of $l$ = 1. Their scaled oscillation frequencies also present better regularity than modes of $l$ = 1 with evolution. In order to study the effect of avoided crossings in detail, we choose the mode which has the smallest mode inertia as p modes. We plot the two kinds of modes for $l$ = 1, 2 and 3 in frequency and period \'{e}chelle diagrams and find modes of $l$ = 2 and 3 fit better to the two relations of equally spaced in frequency and period than modes of $l$ = 1. Under careful observations of two kinds of \'{e}chelle diagrams of $l$ = 2 and 3, we still find some p modes shift a little from equally spaced in frequency and some g modes which are close to those p modes in period shift a little from equally spaced in period. Then, we study the relation between the deviation from equally spaced law in period and the mode inertia of g modes for different $l$. g modes of $l$ = 1 with a period closer to p modes has less inertia and the deviation is bigger in the period \'{e}chelle diagram and their deviation is obvious. However g modes of $l$ = 2 and 3 shift a little or almost have no deviation to equally spaced in period even though some of them may have strong coupling and close mode inertia as the p mode has. So, we suggest a possible method that the mixed g modes of $l$ = 2 and 3 could be used for measuring period spacing of g modes precisely with less observed mixed g modes than the case for $l$ = 1.
语种	中文
学科主题	天文学
内容类型	学位论文
源URL	[http://ir.ynao.ac.cn/handle/114a53/5336]
专题	云南天文台_恒星物理研究组
推荐引用方式 GB/T 7714	郭军军. 小质量红巨星非径向振动模式的规避相交现象[D]. 北京. 中国科学院研究生院（云南天文台）. 2013.

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