SIMBAD references

We present a study of broad-line O VI planetary nebulae nuclei (NGC 2452, NGC 5189, NGC 6905, NGC 7026, and IC 2003) in which we use the nebulae to derive the physical parameters of the central stars. From the study of the emission lines and the stellar continua we derive the effective temperatures and the luminosities of the stars, plasma characteristics and (limited) abundances. By locating the stars on the HR diagram we infer their evolutionary stages. We find that the O VI strength correlates with stellar luminosity, both for the broad-line and for the narrow-line O VI stars. By comparing observational data to theoretical results, we find good agreement between the observed pulsational periods and effective temperatures and those obtained with C-O pre-white dwarf models.