Dependence of S-Process Nucleosynthesis in Massive Stars on Triple-Alpha and 12C(a,g)16O Reaction Rate Uncertainties

TL;DR

This study investigates how uncertainties in key nuclear reaction rates during helium burning in massive stars influence the synthesis of heavy elements via the s-process, affecting our understanding of stellar nucleosynthesis and elemental abundances.

Contribution

It provides a detailed analysis of the sensitivity of s-process nucleosynthesis to reaction rate uncertainties and their impact on element production in massive stars.

Findings

s-process production factors vary significantly with reaction rate changes

using different solar abundance standards alters nucleosynthesis outcomes

later burning phases significantly influence post-supernova element yields

Abstract

We have studied the sensitivity of s-process nucleosynthesis in massive stars to +/- 2 sigma variations in the rates of the triple alpha and 12C(a,g)16O reactions. We simulated the evolution of massive stars from H-burning through Fe-core collapse, followed by a supernova explosion. We found that: the production factors of s-process nuclides between 58Fe and 96Zr change strongly with changes in the He burning reaction rates; using the Lodders (2003) solar abundances rather than those of Anders and Grevesse (1989) reduces s-process nucleosynthesis; later burning phases beyond core He burning and the shell C burning have a significant effect on post-explosive production factors. We also discuss the implications of the uncertainties in the helium burning rates for evidence of a new primary neutron capture process (LEPP) in massive stars.