The Wo Wolf-Rayet Stars

Abstract

Sanduleak (1971) has listed five stars, not apparently associated with planetary nebulae, which show very strong O VI 3811,34 Å emission. He pointed out that two of them are in the Magellanic Clouds and have absolute magnitudes comparable to those of classical (Population I) Wolf-Rayet stars. O VI emission is know to occur in some classical Wolf-Rayet stars, but not with the extreme strength shown by the Sanduleak stars. We have obtained absolute optical spectrophotometry (3100 – 7400Å) of all five of these stars, using the UCL Image Photon Counting System and RGO Spectrograph on the Anglo- Australian Telescope. Figure 1 shows their relative flux distributions. Inspection shows that Sand 1 is very lightly reddened, Sand 2 and 3 have intermediate reddening, and Sand 4 and 5 are heavily reddened. IUE ultraviolet spectrophotometry has been obtained of the first three stars; Sand 4 and 5 are too heavily reddened for IUE spectra to be feasible.