Radiation driven atmospheres of O-type stars: constraints on the mass-luminosity relation of central stars of planetary nebulae

Recent advances in the modelling of stellar winds driven by radiation pressure make it possible to fit many wind-sensitive features in the UV spectra of hot stars, opening the way for a hydrodynamically consistent determination of stellar radii, masses, and luminosities from the UV spectrum alone. It is thus no longer necessary to assume a theoretical mass-luminosity relation. As the method has been shown to work for massive O-stars, we are now able to test predictions from the post-AGB evolutionary calculations quantitatively for the first time. Here we present the first rather surprising consequences of using the new generation of model atmospheres for the analysis of a sample of central stars of planetary nebulae.