ON THE WIDTHS OF EMISSION-LINES IN SPECTRA OF WC9 STARS OF DIFFERENT KINDS

There are at least two kinds of Wolf-Rayet stars: (1) the "ordinary", massive, luminous Population I WR stars; (2) a subset of the central stars of planetary nebulae, showing WR spectra. Somehow the concept has evolved that the WC9 central stars of planetary nebulae have systematically weaker and narrower emission lines than their substantially more massive Pop.I counterparts. Our purpose is to show convincingly that the concept is wrong: the emission lines of the central star of the bonafide planetary nebula He 2-99 are as broad as, or broader (and stronger) than those of several Pop.I WC9 stars. Therefore, widths or strengths of emission lines cannot be used as a criterion to decide if a given WC9 star is a low-mass post-asymptotic-giant-branch (post-AGB) central star of a planetary nebula or a massive, Pop.I WC9 star. The differences between different WC9 spectra do not necessarily imply a large difference in stellar mass; they can be explained by assuming that the corresponding stars are at different distances from the Eddington limit. In addition, we have reclassified HD 167362, the central star of the planetary nebula SwSt 1, as Of-WR(C).