Radioactive isotopes in the interstellar medium

TL;DR

Radioactive isotopes in the interstellar medium offer a novel way to study its dynamics and material flows through decay measurements, providing new insights into nucleosynthesis and interstellar processes.

Contribution

This paper introduces radioactive decay measurements as a new method for studying the interstellar medium's dynamics and composition.

Findings

Radioactive decay provides a natural clock for interstellar processes.

Measurements of gamma rays and isotope abundances reveal material flows.

Radioactive isotopes have enabled breakthrough insights into the interstellar medium.

Abstract

Radioactive components of the interstellar medium provide an entirely-different and new aspect to the studies of the interstellar medium. Injected from sources of nucleosynthesis, unstable nuclei decay along their trajectories. Measurements can occur through characteristic gamma rays that are emitted with the decay, or in cosmic material samples through abundances of parent and daughter isotopes as they change with decay. The dynamics and material flows within interstellar medium are thus accessible to measurement, making use of the intrinsic clock that radioactive decay provides. We describe how measurements of radioactive decay have obtained a break-through in studies of the interstellar medium, after first summarizing the characteristics of radioactivity and the sources of unstable nuclei.