Institut für Astronomie und Astrophysik

Abteilung Astronomie

Preprint 07b/98

Iron and nickel abundances in hot hydrogen-rich central stars of planetary nebulae

Deetjen, J.L., Dreizler, S., Rauch, T., Werner, K.

Institut für Astronomie und Astrophysik, Astronomie, Universität Tübingen, Waldhäuser Str. 64, D-72076 Tübingen, Germany

1999, Proc. 11th European Workshop on White Dwarfs, (J.-E.Solheim, E.G. Meistas, eds.), ASP Conference Series 169, 475-478

Abstract. We study UV spectra of the hottest H-rich central stars which are the immediate progenitors of DA white dwarfs. The primary aim is to analyze Fe and Ni lines. They allow to establish a reliable temperature scale and to study element diffusion processes in the atmosphere as well as dredge-up phases during the previous AGB evolution.
As a first step we extract high resolution spectra from the IUE final archive and present preliminary results here. In future we plan to obtain a set of HST spectra from a number of central stars which represent a temperature sequence. We employ metal line blanketed NLTE model atmospheres which are improved over previous models in respect to the high ionization stages of Fe and Ni to account for the very high T_eff.

Key words: white dwarfs, central stars of planetary nebulae, chemical abundances, atmospheres

Paper (64k gzip'ed Postscript including figures)

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Jürgen Barnstedt (barnstedt AT astro.uni-tuebingen.de) Last updated 06-Oct-1998