The Neon Abundance of Galactic Wolf-Rayet Stars
  The fast, dense winds which characterize Wolf-Rayet (WR) stars obscure   their underlying cores, and complicate the verification of evolving   core and nucleosynthesis models. Core evolution can be probed by   measuring abundances of wind-borne nuclear processed elements,   partially overcoming this limitation. Using ground-based mid-infrared   spectroscopy and the 12.81um [NeII] emission line measured in   four Galactic WR stars, we estimate neon abundances and compare to   long-standing predictions from evolved-core models. For the WC star   WR121, this abundance is found to be >~11x the cosmic   value, in good agreement with predictions. For the three less-evolved   WN stars, little neon enhancement above cosmic values is measured, as   expected. We discuss the impact of clumping in WR winds on this   measurement, and the promise of using metal abundance ratios to   eliminate sensitivity to wind density and ionization structure. 
J.D.T. Smith (Steward Observatory) and J.R. Houck (Cornell Univ.)