SUPERNOVA HYDRODYNAMICS AND NUCLEOSYNTHESIS

Abstract

The evolution of matter ejected from the [Formula: see text] core of a collapsing massive star is examined with regard to nucleosynthesis. This material is processed to such extreme conditions of temperature and density that a neutron-rich nucléon gas results. Upon expansion and subsequent cooling it appears that sufficient seed nuclei are formed for neutron capture on a fast time scale (r process) to proceed. Excess neutrons decay late in the expansion, but burn-back to 4He is likely. This results in production of nuclear energy late in the expansion, and can provide sufficient thermal energy to explain the observed light output of supernovae in terms of the increasing transparency of a hot expanding mass of gas.