Short-Lived s-Process Gamma-Ray Lines in Type II Supernovae

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Science  01 Apr 1988:
Vol. 240, Issue 4848, pp. 60-62
DOI: 10.1126/science.240.4848.60


The nuclear abundances in the helium-burning shells of presupernova stellar models are calculated. For stars of over 20 solar masses the 22Ne(α,n)23 Mg reaction produces enough neutrons on a sufficiently short time scale for the s-process to produce 59Fe (half-life = 45 days) and 60Co (half-life = 5.3 years). These isotopes are expected to survive the passage of the shock, and gamma rays from their decays should be detectable from most galactic type II supernovae with the NASA Gamma Ray Observatory. Because of its great distance and low metallicity, these lines are not expected to be observable from supernova 1987A.