The production of proton-rich isotopes beyond iron: The $\gamma$ process in stars

TL;DR

This paper reviews how the gamma process in stars produces proton-rich isotopes beyond iron, emphasizing the importance of nuclear physics data for understanding stellar nucleosynthesis of p nuclei.

Contribution

It provides a comprehensive overview of the gamma process mechanism and discusses current experimental efforts to obtain nuclear reaction rates relevant to stellar environments.

Findings

The gamma process is the primary mechanism for p nuclei production.

Experimental nuclear physics is crucial for determining reaction rates far from stability.

Understanding p nuclei constrains models of supernova nucleosynthesis.

Abstract

Beyond iron, a small fraction of the total abundances in the Solar System is made of proton-rich isotopes, the p nuclei. The clear understanding of their production is a fundamental challenge for nuclear astrophysics. The p nuclei constrain the nucleosynthesis in core-collapse and thermonuclear supernovae. The $\gamma$ process is the most established scenario for the production of the p nuclei, which are produced via different photodisintegration paths starting on heavier nuclei. A large effort from nuclear physics is needed to access the relevant nuclear reaction rates far from the valley of stability. This review describes the production of the heavy proton-rich isotopes by the $\gamma$ process in stars, and explores the state of the art of experimental nuclear physics to provide nuclear data for stellar nucleosynthesis.