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R-Process Nucleosynthesis and Galactic Chemical Evolution of the Ba Peak Elements

Nucleosynthesis yield is a very important parameter of the Galactic chemical evolution model. We adopt the same method as Tsujimoto to derive the r-process yields of various mass SNe II at low metallicities from the new observed [Ba/Fe]-[Fe/H] trend. Furthermore, we present a new formula of r-process nucleosynthesis yields. We also consider the various neutron sources and set up four cases, namely A, B, C and D to calculate the abundance evolution of Ba peak elements in the solar neighbourhood. Our results show that the r-process could be associated with a secondary event in massive stars (i.e., 18 M⊙<M<50 M⊙). Therefore, the r-process could be associated with a secondary event in massive stars. Both the neutron source and the seed nuclei must be freshly manufactured by the stars instead of depending upon the initial metallicity abundance.