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

R Ignace^1, J Cassinelli^2, G Tracy^2, E Churchwell^2, H Lamers^3

^1 Department of Physics, Astronomy, & Geology, East Tennessee State University
^2 Department of Astronomy, University of Wisconsin
^3 Astronomical Institute, Utrecht University

We report on neon abundances derived from {it Spitzer} high resolution
spectral data of eight Wolf-Rayet (WR) stars using the forbidden line
of [ion{Ne}{3}] 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 $gamma$ of Ne$^{2+}$ for the winds of each star.
The ion fraction abundance is a product of the ionization fraction
$Q_{rm i}$ in stage $i$ and the abundance by number ${cal A}_E$ 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.

Reference: Astrophysical Journal
Status: Manuscript has been accepted