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

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 microns. 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 Ne 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 AE 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. Subject headings: stars: abundances — stars: mass-loss — stars: winds — stars: Wolf-Rayet