Abstract
The authors present spectroscopic observations of two recently discovered shell nebulae around Wolf-Rayet stars in the Large Magellanic Cloud (LMC). One of these shells, around the WN4 star Br 13, shows much stronger [N II] and He I lines than in LMC H II regions having similar excitation, strong evidence that the shell contains freshly synthesized and ejected nitrogen and helium from the interior of the W-R progenitor. The authors estimate that N and He are enhanced by at least a factor of two over their average interstellar abundances in the LMC. The second shell, associated with the WN1 star Br 2, shows normal LMC interstellar abundances, and is more likely a wind-blown structure which is dominated by interstellar material. The spectrum is characterized by unusually strong [O III] and He II emission, indicative that Br 2 in an unusually hot W-R star.
