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Abteilung Astronomie

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Preprint A/96

Discovery and analysis of a hydrogen-rich PG 1159 star

S. Dreizler(1,2), K. Werner(1), U. Heber(2), and D. Engels(3)

(1)Institut für Astronomie und Astrophysik der Universität, D-24098 Kiel, Germany
(2)Dr.-Remeis-Sternwarte, Universität Erlangen-Nürnberg, Sternwartstr. 7, D-96049 Bamberg, Germany
(3)Hamburger Sternwarte, Gojenbergsweg 112, D-21029 Hamburg, Germany

accepted by Astronomy & Astrophysics

Abstract. The discovery of a new peculiar PG 1159 star by follow-up spectroscopy of candidates selected from objective-prism plates of the Hamburg Schmidt Survey is presented. From a NLTE model atmosphere analysis an effective temperature of 130000 +/- 10000 K and a surface gravity of log g = 6.2 +/- 0.2 are determined, which together with the high carbon abundance place HS 2324+3944 in the region of low gravity PG 1159 stars. The detection of hydrogen, however, makes HS 2324+3944 unique amongst the PG 1159 stars. While three central stars of Planetary Nebulae have spectra similar to HS 2324+3944, hydrogen could not be detected up to now in any PG 1159 star not associated with a nebula. The abundances of helium, carbon and nitrogen (C/He = 0.3, N/He < 2*10^{-3}) are similar to that of `normal' PG 1159 stars while the O abundance is found to be somewhat lower than `normal' (O/He = 2-10*10^{-3}).

Key words: stars: abundances - stars: atmospheres - stars: evolution - stars: fundamental parameters - stars: individual: HS 2324+3944

Paper (519k gzip'ed Postscript including figures)

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Jürgen Barnstedt (barnstedt AT astro.uni-tuebingen.de)
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