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-circle dot < M < 50 M-circle dot). 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.