Supernova Nucleosynthesis

Abstract

Theoretical studies strongly suggest that supernova environments represent the likely site of the synthesis of the bulk of the heavy elements (A ≳ 20) observed in nature. From the point of view of nucleosynthesis, one has the advantage that constructive nuclear transformations proceed in the shock-induced ejection of both core and envelope material, ensuring that the resulting abundance distributions will not be distorted by subsequent evolution. Hydrodynamic studies of possible supernova mechanisms predict promising conditions both for the synthesis of elements through the vicinity of iron by charged-particle reactions (Arnett et al, 1971) and for the r-process neutron-capture synthesis of heavier nuclei (Arnett and Truran, 1970). Unfortunately, hydrodynamic studies have yet to provide a thoroughly consistent supernova model (see the review by K. Sato in these proceedings). The well studied carbon-detonation (Arnett, 1969a) and neutrino-transport (Colgate and White, 1966) mechanisms both encounter severe problems which have not yet been resolved. Dynamic events triggered by the creation of electron-position pairs (Barkat et al., 1967; Fraley, 1968) require more massive carbon-oxygen cores than are found to arise in the course of evolution of normal stars.