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 mu m. Our targets include four WN stars of subtypes 4-7, and four WC stars of subtypes 4-7. We derive ion fraction abundances gamma of Ne2+ for the winds of each star. The ion fraction abundance is a product of the ionization fraction Q(i) in stage i and 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.