Impacts of the ¹⁶O(¹⁶O, n)³¹S reaction rate on the evolution and nucleosynthesis in Pop III massive stars

摘要: We present a systematic investigation into the effect of the ¹⁶O(¹⁶O, n)³¹S reaction rate on the evolution and nucleosynthesis of Population III (Pop III) stars. We simulate the evolution of Pop III stars with initial masses of 15, 20, 30, and 40 M_⊙ from the zero-age main sequence through to core collapse. The ¹⁶O(¹⁶O, n) sup>31S reaction rate is investigated by factors of 0.1, 1.0, 5.0, and 10.0. Our results demonstrate that increasing this reaction rate prompts earlier onset and extended duration of core oxygen burning at lower temperatures and densities. A higher reaction rate also increases neutron excess in OSi-rich layers, thereby promoting the synthesis of neutron-rich isotopes. In particular, the yields of the odd-Z elements, P, Cl, K, and Sc, are enhanced while those beyond O burning, for example, Ti, are not sensitive to this reaction rate. By comparing with the observed abundances from extremely metal-poor stars, we find that increasing this reaction rate from the CF88 compilations by a factor of 5.0 leads to predicted abundance ratios [K/Ca] and [Sc/Ca] that fall within the observational ranges.