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

Abstract

We report on neon abundances derived from Spitzer high resolution spectral data of eight Wolf-Rayet (WR) stars using the forbidden line of [Ne III] 15.56 μm. Our targets include four WN stars of subtypes 4-7, and four WC stars of subtypes 4-7. We derive ion fraction abundances γ of Ne2+ for the winds of each star. The ion fraction abundance is a product of the ionization fraction Qi in stage i and the abundance by number 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.