本文選題：中子俘獲 + 魯棒性��； 參考：《河北師范大學》2015年博士論文

【摘要】：歷史上,Ge一直被認為是中子俘獲元素。Ge的太陽系r-過程豐度是通過太陽系總的豐度減去s-過程豐度得到的。而最近觀測的貧金屬星HD 108317的Ge豐度卻低于太陽系的剩余r-過程豐度大約1.2個dex。根據貧金屬星的Ge豐度和恒星產量的比較,我們發(fā)現貧金屬星的Ge豐度不是來自于大質量星的primary產量,而主要來自于r-過程。根據對貧金屬星的觀測,我們獲得了weak r-過程和main r-過程的Ge豐度。中子俘獲過程對太陽系中的Ge豐度的貢獻比為59%,這意味著太陽系中Ge的剩余豐度的貢獻比為41%。我們發(fā)現Ge的剩余豐度來自于大質量星的secondary產量。這意味著太陽系中的Ge不是單純的由中子俘獲過程產生。球狀星團Palomar 1(Pal 1)異常的化學豐度能夠為我們研究球狀星團和銀河系的關系提供重要的信息。我們研究了pal 1中α元素、Fe峰元素和中子俘獲元素的豐度。我們發(fā)現在相同的金屬豐度下,Pal 1的SNe Ia和main s-過程分量大于盤星的相應的分量,同時Pal 1的primary分量小于盤星的相應分量。Pal 1和盤星中的F e豐度主要起源于SNe Ia和primary分量。盡管Pal 1和盤星中的α元素的豐度主要產生于primary過程,但Pal 1中的primary分量貢獻小于盤星中相應的貢獻。Pal 1和盤星中Fe峰元素V和Co主要起源于primary分量和secondary分量,但大質量星對Pal 1的貢獻低于大質量星對盤星的貢獻。盤星中的Y豐度主要起源于weak r-分量,而Pal 1中main s-分量和main r-分量對Y的貢獻接近weak r-分量的貢獻。Pal 1和盤星中的Ba豐度主要起源于main s-分量和main r-分量。我們的計算結果意味著Pal 1中異常的元素豐可以被Pal 1的前身系統的初始質量函數的top-light特性所解釋。許多工作都致力于調查貧金屬星HD 140283的中子俘獲元素的天體物理來源,然而到目前還沒有一個明確的結論。利用豐度分解的方法,我們發(fā)現貧金屬星HD 140283是一顆weak r-過程星,而計算結果顯示它的Ba豐度卻主要來自于main r-過程。這是HD140283的豐度比[Ba/Eu]=-0.58±0.15接近main r-過程豐度比的原因。根據對六顆weak r-星豐度的比較,我們發(fā)現它們的元素豐度具有魯棒性。進一步,我們發(fā)現對六顆極端main r-過程星([Eu/Fe]1.5),不僅重中子俘獲元素具有魯棒性,而且輕中子俘獲元素也具有魯棒性。兩類r-過程星的豐度魯棒性可以被用來限制r-過程理論并且可以用來調查恒星元素豐度的天體物理來源。
[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 偽 -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 偽 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 鹵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.
【學位授予單位】：河北師范大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：P148

【引證文獻】

相關期刊論文 前1條

1 龔景;;淺談天體物理中重離子與小分子冰之間的關系[J];科技展望;2016年18期

，

本文編號：1829155