S-266 - A RING NEBULA AROUND A GALACTIC B[E]-SUPERGIANT

A narrow-band H alpha image and high-resolution spectroscopy have been obtained in order to investigate the nature of S 266 and its central star MWC 137. The analysis of the stellar and nebular spectra suggests that MWC 137 is a B[e] supergiant located greater than or equal to 6 kpc away from the Sun and not a Herbig Ae/Be star, as it has been trad itionally classified. Moreover, the morphology and other properties of the nebula suggest that S 266 is a ring nebula, probably produced by the interaction of stellar winds with the ambient interstellar medium or unprocessed ejected matter. This result would imply that S 266 is t he first ring nebula around a B[e] supergiant known in the Galaxy.