The chemical abundances of metal-poor stars provide important clues to explore stellar formation history and set significant constraints on models of the r-process .
In this work , we find that the abundance patterns of the light and iron group elements of the main r-process stars are very close to those of the weak r-process stars .
Based on a detailed abundance comparison , we find that the weak r-process occurs in supernovae with a progenitor mass range of \sim 11 - 26 M _ { \odot } .
Using the SN yields given by Heger & Woosley and the abundances of the weak r-process stars , the weak r-process yields are derived .
The SNe with a progenitor mass range of 15 M _ { \odot } < M < 26 M _ { \odot } are the main sites of the weak r-process and their contributions are larger than 80 % .
Using the abundance ratios of the weak r-process and the main r-process in the solar system , the average yields of the main r-process are estimated .
The observed correlations of the [ neutron-capture/Eu ] versus [ Eu/Fe ] can be explained by mixing of the two r-process abundances in various fractions .