Differences between stellar and laboratory reaction cross sections

TL;DR

This paper discusses how stellar plasma conditions alter nuclear reaction cross sections compared to laboratory measurements, emphasizing the importance of low-energy nuclear physics and thermal effects on target nuclei.

Contribution

It highlights the differences between stellar and laboratory nuclear reaction cross sections and challenges the assumption that modifications are always larger for endothermic reactions.

Findings

Low-energy nuclear properties need precise modeling for stellar reactions.

Modifications to cross sections are not always larger for endothermic reactions.

Recent studies suggest the proton optical potential requires adjustments.

Abstract

Nuclear reactions proceed differently in stellar plasmas than in the laboratory due to the thermal effects in the plasma. On one hand, a target nucleus is bombarded by projectiles distributed in energy with a distribution defined by the plasma temperature. The most relevant energies are low by nuclear physics standards and thus require an improved description of low-energy properties, such as optical potentials, required for the calculation of reaction cross sections. Recent studies of low-energy cross sections suggest the necessity of a modification of the proton optical potential. On the other hand, target nuclei are in thermal equilibrium with the plasma and this modifies their reaction cross sections. It is generally expected that this modification is larger for endothermic reactions. We show that there are many exceptions to this rule.