Dissertation
Dissertation > Astronomy,Earth Sciences > Astronomy > Astrophysics > Stellar physics > Novae and supernovae

The Abundance Proportion Study of Main r-process and Weak r-process in Metal-poor Stars

Author ZhangYunPeng
Tutor ZhangBo
School Hebei Normal
Course Astrophysics
Keywords Metal-poor stars Neutron capture r-process s-process r- GREATEK Star
CLC P145.3
Type Master's thesis
Year 2011
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The metal-poor stars known as nucleosynthesis and galactic chemical evolution history of \To study the elemental abundances of testing the theory of nucleosynthesis and explore stellar formation has a very important significance . The s- process is already known : the nature of the r- process occurs in low- mass AGB stars , and need a high neutron density environment is still mysterious . The theoretical study of the r- process nucleosynthesis places infancy remains unclear , the proportion of the contribution of the metal-poor stars nucleosynthesis process of neutron capture element abundances . In this paper, based on the basic theory of nucleosynthesis , the proportion of r- over Cheng Chaofeng metal-poor star r - process and weak r- process using parametric methods , light elements , iron - group elements , light neutron capture elements from Ba to Pb heavy neutron capture elements in the main proportion of the r- process with the [Eu / Fe] distribution . After comparison of the proportion of each element is basically reasonable and effective , show that r- of Guo Cheng Zengfeng metal-poor stars with at least two different nucleosynthesis processes : the r- process , and the weak r- process to jointly contribute to the abundance of the neutron capture elements . The main r-process mainly produce heavy neutron capture elements for light neutron capture the element abundances contribution is weak r-process has an absolute advantage . The study also found that the apparent coefficient of samples of various metal-poor stars Star proportion of each element are not equal , the contribution ratio of the element abundances of neutron capture nucleosynthesis process varies with the atomic number , indicating that these elements nucleosynthesis process may produce in several different places . Early galactic chemical evolution of the light elements , heavy neutron capture elements of the r - process model can be seen that the s - process and r- process can be divided into two components , which decompose two different process nucleosynthesis contribution and calculate the proportion of its element abundances . Can nucleosynthesis process can quantify each component coefficients can be measured from the whole stellar nucleosynthesis, the major component of the process , so they know astrophysical environments and places of star formation . Although this calculation model there are inadequacies , but for sure , this may well be an effective way to observation element is the whole r- over Cheng Chaofeng metal-poor stars .

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