球状星团M2中恒星元素的天体物理来源探究

发布时间：2017-12-27 08:00

本文关键词：球状星团M2中恒星元素的天体物理来源探究　出处：《河北师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：我们的宇宙大约形成于140Gyr年前的一次大爆炸。球状星团是星系中古老的、寿命很长的成员,被称为星系演化的活化石。观测表明,球状星团M2中α元素、Fe族元素和中子俘获元素的丰度随样本星[Fe/H]的变化呈现出不同的变化趋势。对样本星中元素丰度来源的研究可以帮助我们更好的理解球状星团M2形成的历史和化学演化进程。本文主要包括两部分:第一部分首先给出了独立于星系化学演化的五分量元素丰度模型及其计算方法。其次对球状星团M2中14颗样本星(6颗r-only星,4颗s星,4颗metal rich星)的元素丰度进行了拟合,并给出了最佳拟合结果。通过对计算结果的系数分布情况进行分析得出,在样本星所观测的金属丰度范围内,r-过程分量对元素丰度的贡献一直处于主要地位。weak s-过程分量和SNe Ia分量虽然对元素丰度的贡献较少,但是随着[Fe/H]的增大其贡献也缓慢增加。4颗s星具有典型的s-过程特征,s-过程贡献超丰。另外,文中给出的整体拟合效果图也验证了我们的计算方法是可行有效的。第二部分对计算结果给出了分析和讨论。对样本星的α元素、Fe族元素和中子俘获元素的天体物理来源进行了分析讨论,并给出了本文的结论。本文所选取样本星的观测金属丰度范围较窄(-1.8[Fe/H]-0.9),在观测范围内,大质量星的primary过程分量对α元素和Fe族元素丰度的贡献都起了明显的主导作用,并且primary分量对α元素和Fe族元素的贡献随着[Fe/H]的增加,呈现出不同程度的缓慢下降的趋势。与此同时,SNe Ia分量和大质量星的secondary过程分量对α元素和Fe族元素丰度的贡献随着样本星[Fe/H]的增加缓慢上升。较轻的中子俘获元素Y元素和Zr元素的丰度主要是来源于main s-过程分量和week r-过程分量,其对元素丰度的贡献随[Fe/H]的增加变化缓慢;而较重的中子俘获元素的天体物理来源为main r-过程分量和main s-过程分量,对于比Eu重的元素,main r-过程分量的贡献作用一直处于主导地位。4颗s星在样本星中比较特别,main s-过程分量对其元素丰度的贡献超丰,这可能与其受到了低质量AGB星的污染有关。
[Abstract]:Our universe was formed about a big bang 140Gyr years ago. Globular cluster is an old and long life member of the galaxy, known as a living fossil of the evolution of galaxies. The observations show that the abundance of alpha, Fe and neutron capture elements in the globular cluster M2 varies with the variation of the sample star [Fe/H]. The study of the source of the element abundance in the sample star can help us better understand the history and chemical evolution process of the formation of the globular cluster M2. This paper mainly consists of two parts. In the first part, the five component element abundance model independent of the evolution of Galaxy chemistry and its calculation method are given. Secondly, the element abundance of 14 sample stars (6 r-only stars, 4 s stars, 4 metal rich stars) in the globular cluster M2 is fitted, and the best fitting results are given. Through the analysis of the coefficient distribution of the calculated results, it is concluded that the contribution of the r- process components to the abundances of elements is always in the leading position in the range of metallicity observed by the sample stars. The contribution of the weak s- process component and the SNe Ia component to the element abundance is less, but with the increase of [Fe/H], its contribution also increases slowly. The 4 s stars have typical s- process features, and the s- process has a great contribution. In addition, the overall fitting effect diagram presented in this paper also proves that our calculation method is feasible and effective. The second part gives the analysis and discussion of the calculation results. The astrophysical sources of the alpha, Fe and neutron capture elements of the sample star are analyzed and discussed, and the conclusion of this paper is given. This paper observed metallicity range sample stars narrow (-1.8[Fe/H]-0.9), in the observation range, the contribution of primary component star of alpha elements and Fe group element abundances have played a leading role obviously, and the primary component of alpha elements and Fe elements contribution with the increase of [Fe/H], showing different degrees of slow decline. At the same time, the contribution of the secondary process component of the SNe Ia component and the mass star to the abundances of the alpha and Fe elements increases slowly with the increase of the sample star [Fe/H]. The abundance of lighter neutron capture elements Y and Zr elements are mainly derived from the main s- component and week r- component, the contribution of element abundance changes slowly with the increase of [Fe/H]; and astrophysical sources of heavier neutron capture elements for the main r- component and main s- component, for more than Eu heavy elements, the contribution main r- process component has been in a dominant position. The 4 s stars are more special among the sample stars, and the component of the main s- process contributes to the abundance of its element abundance, which may be related to the pollution of low mass AGB stars.
【学位授予单位】：河北师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P154.12

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