银河系中锗元素及球状星团Palomar 1中元素的天体物理来源

发布时间：2018-05-01 11:25

本文选题：中子俘获 + 鲁棒性　；参考：《河北师范大学》2015年博士论文

【摘要】：历史上,Ge一直被认为是中子俘获元素。Ge的太阳系r-过程丰度是通过太阳系总的丰度减去s-过程丰度得到的。而最近观测的贫金属星HD 108317的Ge丰度却低于太阳系的剩余r-过程丰度大约1.2个dex。根据贫金属星的Ge丰度和恒星产量的比较,我们发现贫金属星的Ge丰度不是来自于大质量星的primary产量,而主要来自于r-过程。根据对贫金属星的观测,我们获得了weak r-过程和main r-过程的Ge丰度。中子俘获过程对太阳系中的Ge丰度的贡献比为59%,这意味着太阳系中Ge的剩余丰度的贡献比为41%。我们发现Ge的剩余丰度来自于大质量星的secondary产量。这意味着太阳系中的Ge不是单纯的由中子俘获过程产生。球状星团Palomar 1(Pal 1)异常的化学丰度能够为我们研究球状星团和银河系的关系提供重要的信息。我们研究了pal 1中α元素、Fe峰元素和中子俘获元素的丰度。我们发现在相同的金属丰度下,Pal 1的SNe Ia和main s-过程分量大于盘星的相应的分量,同时Pal 1的primary分量小于盘星的相应分量。Pal 1和盘星中的F e丰度主要起源于SNe Ia和primary分量。尽管Pal 1和盘星中的α元素的丰度主要产生于primary过程,但Pal 1中的primary分量贡献小于盘星中相应的贡献。Pal 1和盘星中Fe峰元素V和Co主要起源于primary分量和secondary分量,但大质量星对Pal 1的贡献低于大质量星对盘星的贡献。盘星中的Y丰度主要起源于weak r-分量,而Pal 1中main s-分量和main r-分量对Y的贡献接近weak r-分量的贡献。Pal 1和盘星中的Ba丰度主要起源于main s-分量和main r-分量。我们的计算结果意味着Pal 1中异常的元素丰可以被Pal 1的前身系统的初始质量函数的top-light特性所解释。许多工作都致力于调查贫金属星HD 140283的中子俘获元素的天体物理来源,然而到目前还没有一个明确的结论。利用丰度分解的方法,我们发现贫金属星HD 140283是一颗weak r-过程星,而计算结果显示它的Ba丰度却主要来自于main r-过程。这是HD140283的丰度比[Ba/Eu]=-0.58±0.15接近main r-过程丰度比的原因。根据对六颗weak r-星丰度的比较,我们发现它们的元素丰度具有鲁棒性。进一步,我们发现对六颗极端main r-过程星([Eu/Fe]1.5),不仅重中子俘获元素具有鲁棒性,而且轻中子俘获元素也具有鲁棒性。两类r-过程星的丰度鲁棒性可以被用来限制r-过程理论并且可以用来调查恒星元素丰度的天体物理来源。
[Abstract]:Historically, it has been considered that the r-process abundance of the neutron capture element. GE in the solar system is derived from the total solar system abundance minus the S-process abundance. The GE abundance of the recently observed poor metal star HD 108317 is lower than the residual r-process abundance of the solar system by about 1.2 dextras. Based on the comparison of GE abundance and stellar output of the metal-poor stars, we find that the GE abundance of the metal-poor stars is mainly derived from the r-process rather than from the primary production of the large mass stars. The GE abundance of the weak r-process and the main r-process has been obtained according to the observations of the metal-poor stars. The contribution ratio of the neutron capture process to the GE abundance in the solar system is 59, which means that the contribution ratio of the remaining GE abundance in the solar system is 41. We found that the residual abundance of GE comes from the secondary production of large mass stars. This means that GE in the solar system is not simply produced by neutron capture processes. The anomalous chemical abundance of globular cluster Palomar 1(Pal 1 can provide important information for us to study the relationship between globular cluster and the Milky way. We have studied the abundance of 伪 -Fe peak elements and neutron capture elements in pal _ 1. We find that the SNe Ia and main s- process components of Pal 1 are larger than the corresponding components of the disk star under the same metal abundance, and the primary component of Pal 1 is smaller than the corresponding component. Pal 1 and F e abundance of the disk star mainly originate from the SNe Ia and primary components. Although the abundance of 伪 element in Pal 1 and disk star mainly originates from primary process, the contribution of primary component in Pal 1 is smaller than that in disk star. Pal 1 and Fe peak elements V and Co in disk star mainly originate from primary component and secondary component. However, the contribution of large mass stars to Pal 1 is lower than that of large mass stars to disk stars. The Y abundance in disk star mainly originates from weak r-component, while the contribution of main s- component and main r-component in Pal 1 to Y is close to that of weak r-component .Pal1 and Ba abundance in disk star mainly originate from main s- component and main r- component. Our results imply that the abundance of elements in Pal 1 can be explained by the top-light properties of the initial mass function of the predecessor system of Pal 1. Much work has been done to investigate the astrophysical origin of neutron capture elements in the poor metal star HD 140283. However, there is no clear conclusion yet. By means of abundance decomposition, we find that HD 140283 is a weak r-process star, but its Ba abundance is mainly derived from main r-process. This is why the abundance ratio of HD140283 [Ba/Eu] -0.58 卤0.15 approaches that of main r-process. By comparing the abundance of six weak r-stars, we find that their element abundance is robust. Furthermore, we have found that six extreme main r-process stars ([Eu/Fe] 1.5g) are robust not only to heavy neutron capture elements, but also to light neutron capture elements. The abundance robustness of two classes of r-process stars can be used to limit the r-process theory and to investigate the astrophysical sources of stellar element abundance.
【学位授予单位】：河北师范大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：P148

【引证文献】