Nucleosynthesis in neutron-rich supernova ejecta

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.