The iron abundance in hot central stars of planetary nebulae derived from IUE spectra

We present the first attempt to determine the iron abundance in hot central stars of planetary nebulae. We perform an analysis with fully metal-line b lanketed NLTE model atmospheres for a sample of ten stars (T-eff greater th an or similar to 70 000 K) for which high-resolution UV spectra are availab le from the IUE archive. In all cases lines of Fe VI or Fe VII can be ident ified. As a general trend, the iron abundance appears to be subsolar by 0.5 -1 dex, however, the S/N of the IUE spectra is not sufficient to exclude a solar abundance in any specific case. Improved spectroscopy by either FUSE or I-IST is necessary to verify the possibility of a general iron deficienc y in central stars. The suspected deficiency may be the result of gravitati onal settling in the case of three high-gravity objects. For the other star s with low gravity and high luminosity dust fractionation during the previo us AGE phase is a conceivable origin.