What is the Origin of the Rest of the Elements?

Abstract

All the nuclei from carbon to lead, and even beyond to thorium and uranium, are produced by nuclear reactions in stars. The reactions that produce each group of nuclei operate under conditions of density and temperature that characterize the phase of stellar evolution in which these reactions occur. Thus helium is made in hydrogen burning, carbon and oxygen are produced in helium burning, neon and more oxygen are made carbon burning, and so forth until the final phase of nucleosynthesis that occurs in massive stars makes iron and nickel. Along the way, during helium burning, heavier nuclei up to bismuth are synthesized. Massive stars ultimately explode as supernovae, which enables another process that produces nuclei as heavy as thorium and uranium. This chapter provides the basic features of all of these processes, as well as some of the basic characteristics of supernovae.