Enrichment of s-Process Elements in the Progenitor of SN 1987A

Abstract Existing calculations of s-process nucleosynthesis in massive stars such as Sk −69° 202 show enhancements in the He-burning shells which, when mixed to the surface, lead to Sc, Sr, and Ba enrichments of factors of 2 to 15. Abundances derived from the supernova absorption lines using a simple scattering model yield enhancements of this magnitude. Thus, the observed and predicted s-process abundances are roughly in accord, although the Ba/Sr ratio derived for the supernova may be higher than the s-process can account for.