Nucleosynthesis in neutron-rich supernova ejecta

Abstract

Nucleosynthesis is studied in supernova ejecta that achieve nuclear statistical equilibrium with a characteristic neutron excess far greater than that customarily assigned to the production of the most abundant heavy elements. A small amount of such material will copiously produce the very neutron-rich isotopes of Ca, Ti, Cr, Fe, Ni, Zn, Se, and Kr. In particular, calculations demonstrate that the natural synthesis of several rare isotopes, 48Ca, 50Ti, 54Cr, 64Ni, 66,68Zn, 82Se, and 84Kr, may occur within stellar zones characterized by values of neutron excess η ≈ 0.1 - 0.2. The implications for isotopic excesses found in certain meteoritic inclusions, e.g., Allende EK-1-4-1, are discussed.