2020MNRAS.498.2676C

The first generation of metal-free (Population III) stars are crucial for the production of heavy elements in the earliest phase of structure formation. Their mass scale can be derived from the elemental abundance pattern of extremely metal-poor (EMP) stars, which are assumed to inherit the abundances of uniformly mixed supernova (SN) ejecta. If the expanding ejecta maintains its initial stratified structure, the elemental abundance pattern of EMP stars might be different from that from uniform ejecta. In this work, we perform numerical simulations of the metal enrichment from stratified ejecta for normal core-collapse SNe (CCSNe) with a progenitor mass 25 M_☉ and explosion energies 0.7-10 B (1 B = 10⁵¹ erg). We find that SN shells fall back into the central minihalo in all models. In the recollapsing clouds, the abundance ratio [M/Fe] for stratified ejecta is different from the one for uniform ejecta only within ±0.4 dex for any element M. We also find that, for the largest explosion energy (10 B), a neighbouring halo is also enriched. Only the outer layers containing Ca or lighter elements reach the halo, where [C/Fe] = 1.49. This means that C-enhanced metal-poor stars can form from the CCSN even with an average abundance ratio [C/Fe] = -0.65.