NUCLEOSYNTHESIS IN MASSIVE CORE-COLLAPSE SUPERNOVAE AS THE ORIGIN OF ABUNDANCES IN EXTREMELY METAL-POOR STARS

We calculate nucleosynthesis in Population (Pop) 111 supernovae (SNe) and compare the yields with various abundance patterns of extremely metal-poor (EMP) stars. We assume that the observed EMP stars are the second generation stars, which have the metal-abundance pattern of the Pop I11 SNe. Previous theoretical yields and observations do not match well, suggesting that the simplest supernova model cannot account for the observations. In this paper we consider high energy explosions, “low-density” explosions, and mixing-fallback models. We show that the abundance patterns of both C-normal and C-rich EMP stars with [Fe/H] _ 2) low [Fe/H] (2: -5 N -3.5) stars can be explained with the faint S N yield with little 56Ni ejection, which is similar t o SN1997D. Even we vary parameters, we still need a large explosion energy to obtain the large Co/Fe and Zn/Fe ratios observed in typical EMP stars.