Reaction rates for the s-process neutron source 22Ne+{\alpha}

TL;DR

This paper provides updated, statistically rigorous reaction rates for the 22Ne+α neutron source in the s-process, reducing nucleosynthesis uncertainties in stellar models through recent experimental data and Monte Carlo analysis.

Contribution

The study introduces new, statistically robust reaction rates for 22Ne+α based on recent experiments and Monte Carlo methods, improving s-process nucleosynthesis predictions.

Findings

Uncertainties in s-process nucleosynthesis are significantly reduced.

New reaction rates are consistent with recent experimental data.

Some ambiguities in current data still require further investigation.

Abstract

The 22Ne({\alpha},n)25Mg reaction is an important source of neutrons for the s-process. In massive stars responsible for the weak component of the s-process, 22Ne({\alpha},n)25Mg is the dominant source of neutrons, both during core helium burning and in shell carbon burning. For the main s-process component produced in Asymptotic Giant Branch (AGB) stars, the 13C({\alpha},n)16O reaction is the dominant source of neutrons operating during the interpulse period, with the 22Ne+{\alpha} source affecting mainly the s-process branchings during a thermal pulse. Rate uncertainties in the competing 22Ne({\alpha},n)25Mg and 22Ne({\alpha},{\gamma})26Mg reactions result in large variations of s-process nucleosynthesis. Here, we present up-to-date and statistically rigorous 22Ne+{\alpha} reaction rates using recent experimental results and Monte Carlo sampling. Our new rates are used in post-processing nucleosynthesis calculations both for massive stars and AGB stars. We demonstrate that the nucleosynthesis uncertainties arising from the new rates are dramatically reduced in comparison to previously published results, but several ambiguities in the present data must still be addressed. Recommendations for further study to resolve these issues are provided.