Stellar Chronology

Synonyms

Nuclear Cosmochronology; Nucleocosmochronology

Definition

Nucleocosmochronology. Use of radiogenic isotope ratios for determining ages of nucleosynthesis and other fractionations occurring in the galaxy and stars.

Introduction

Stars reflect the ongoing evolution of the galaxy as nuclidic abundances of metals (elements from carbon up in terms of proton number) are formed from the fusion reactions transforming light elements in to heavy. At the Fe abundance peak, fusion no longer releases energy, and elements heavier than iron are the result of two reaction pathways involving the addition of neutrons. The s-process involves the slow addition of neutrons, where slow indicates that the chances of beta decay is more likely than the chance of adding another neutron. The s-process therefore keeps the nucleosynthetic pathway close to the stable nuclides we see around us. The s-process stops at ²⁰⁹Bi, this being the heaviest stable nuclide. The site of the s-process is likely...