2000/06/23 by J. L. Deetjen, S. Dreizler, T. Rauch +1
Physics and Astronomy · #astro-ph
published as Astron. Astrophys. 348, 940-944 (1999) · 5 pages, 8 figures
arxiv created 2000/06/23 · arxiv updated 2009/12/01
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 blanketed NLTE model atmospheres for a sample of ten stars (Teff >= 70.000 K) for which high-resolution UV spectra are available from the IUE archive. In all cases lines of Fe VI or Fe VII can be identified. 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 HST is necessary to verify the possibility of a general iron deficiency in central stars. The suspected deficiency may be the result of gravitational settling in the case of three high-gravity objects. For the other stars with low gravity and high luminosity dust fractionation during the previous AGB phase is a conceivable origin.