A New Search for Nebulae Surrounding Wolf-Rayet Stars

Extract

We have used the plate data from An Emission Line Survey of the Milky Way by Parker, Gull and Kirschner(1979) to make a new search for ring nebulae around Wolf-Rayet stars. The Survey consists of narrow-band interference filter direct imagery centered on the emission lines of Hα + [N II] at λ6570, [O III] at λ5007, and [S II] at λ6730. We have discovered at least five new ring nebulae. of the fifteen ring nebulae we were able to detect on the Survey, including our new discoveries, eleven were brighter in the [O III] bandpass than in the Hα + [N II] bandpass, and were filamentary in [O III]. All of the nebulosities we were able to detect were rated on the basis of three criteria:

1. 1) Sharp, filamentary structure present in any or all bandpasses.

2. 2) Wolf-Rayet star centered in projected nebulosity, or, if off-center, the segment of the ring nearest the star proportionally brighter than the rest of the ring.

3. 3) Absence of any O stars within the nebulosity, or O star in off-centered position not adjacent to the brightest or sharpest portion of the ring.