Introduction

Wolf-Rayet Shell Nebulae (WRSN) provide a “quick look” at an intermediate stage of evolution of massive stars between the main sequence O stage and their ultimate demise as SNII. During this evolutionarily brief epoch, the O star develops a strong wind which affects the surrounding ISM, and can even have significant mass loss which enriches the ISM with H-burning products –specifically He and N (Maeder 1990). Therefore, studies of these objects are both interesting and important regarding the physics of wind-shock effects on the ISM and in the role they have in galactic chemical evolution.

In this short contribution I will present some of the results of two recent students of mine who completed Ph.D. theses studying the morphology and spectra of the WRSN NGC 6888 (Mitra 1990) and NGC 2359 (Jernigan 1988). A more comprehensive review of the literature on WRSN is given by the fine paper by L. Smith in this volume. The theses studies incorporated CCD imagery mapping of the ionization structure of the nebulae in the emission lines of Hβ, [OIII]λ5007, Hα, [NII]λ6583, & [SII]λ6717+30; followed by spectroscopy of parts of the two nebulae that were of special interest from the imagery. Herein I will note some of the spectroscopic results regarding the hot wind-driven gas; the imagery mapping is available in their theses and moreso in a forthcoming Atlas of CCD Imagery of Galactic HII Regions (Hester et al. 1994).