Stellar C III Emissions as a New Classification Parameter for [WC] Central Stars

Abstract

We report detection of stellar C III λ1909 emission in IUE echelle spectra of early-type [WC] central stars of planetary nebulae (CSPNs). Additionally, stellar C III emission at 2297 Å is observed in early- and late-type [WC] CSPNs. Inclusion of these C III features for abundance determinations may resolve a conflict of underabundance of C/O for early-type [WC2]-[WC4] CSPNs. A linear dependence on stellar C III λ2297 equivalent widths can be used to indicate a new classification of type-[WCUV] central stars.