Element Abundances And Galactic Chemical Evolution

The dissertatation consists of two sections.The first one mainly intrduce the chemical evolution model and observational constrain,and the second mainly intrduce the ncleosyhthesis of r-process and the chemical evolution of Ba peak elementsThe formation and evolution of the Galaxy has long been a basic and important branch and one of the most active frontiers in the fields of astrophysics. There are several aspects in galactic evolution , such as dynamicas evolution, Chemical evolution and thermal evolution, etc. They provide reasonable explaination of the formation and evolution of galaxies in different facets. Among the evolution is the chemical evolution of the Galaxy showing its exceeding importance. The recognize to the Galaxy chemical evolution build up the basement of understanding the whole Galaxy evolution.and it can restrict and constrain the evolution and ncleosyhthesis of the stellar. The aim of the Galaxy chemical evolution research is to reproduce the element abundance patter of stars and gas in the Galaxy. Starting from a volume of gas whose mass, chemical composition and density are already known, observable parameters of Galaxy evolution are reproduced as a function of the time, applying knowledge of stellar formations, evolution and neclearsynthesis.On the bases of the Galaxy evolution theory, We use the therotical chemical evolution model of three zone (such as halo, thick disk and thin isk) and multi-phase (diffuse gas, molecular clouds, stars of both low and high mass, the remnants). By comparing with the observational constraints,such assurface densities, age-metallicity relation, G-dwarf metallicity distribution in the solar neighbourhood and the correlation between [ a /Fe] and [Fe/H],supernovae rates,infall rates.the rationality of the model is verified.Based on the theory model ,We calculate the abundance of neutron capture element. The average abundance distributions of heavy elements in metal-poor stars can provide fairlydirect and detailed information on the nucleosynthesis in every stage after the formation of galaxies. Furthermore, it can put more accurate constraints on the chemical evolution of neutron-capture elements. The solution to this problem will have important effect on the solution to a series of problems about nuclear astrophysics and the galactic evolution. This letter aiming at this respect, hints for neutron capture element are derived:1. Based on the adopted Galactic evolution scenario, together with the three-zone multi-phase model, observational features of the solar vicinty region can be well reproduced. Among those are particuly G-dwarf problem.The G-dwarf problem in halo and thin-disk can be solved.2. we derive the yield of the heavy elements in various supernova. Our yields increase with the mass of the progenitor main-sequence stars.Massive stars(i.e.18M