Neon Abundances from a Spitzer /IRS Survey of Wolf‐Rayet Stars

Abstract

We report on neon abundances derived from Spitzer high resolutionspectral data of eight Wolf-Rayet ( WR) stars using the forbiddenline of [ Ne III] 15.56 mu m. Our targets include four WN stars ofsubtypes 4-7, and four WC stars of subtypes 4-7. We derive ion fractionabundances gamma of Ne2+ for the winds of each star. The ion fractionabundance is a product of the ionization fraction Q(i) in stage iand the abundance by number A(E) of element E relative to all nuclei.Values generally consistent with solar are obtained for the WN stars,and values in excess of solar are obtained for the WC stars.