Institut für Astronomie und Astrophysik
Abteilung AstronomieSand 1, D-72076 Tübingen, Germany
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K. Werner (1), T. Rauch (1,2), R. Napiwotzki (3), N. Christlieb (4), D. Reimers (4), and C.A. Karl (2)
(1) Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, D-72076 Tübingen, Germany
(2) Dr.-Remeis-Sternwarte, Universität Erlangen-Nürnberg, Sternwartstraße 7, D-96049 Bamberg, Germany
(3) Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK
(4) Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg, Germany
To be published in: A&A
Abstract. We present high-resolution VLT spectra of a new helium-rich DO white dwarf (HE1314+0018) and a new PG1159 star (HE1429-1209), which we identified in the ESO SPY survey. We performed NLTE model atmosphere analyses and found that the PG1159 star is a low-gravity, extremely hot (Teff =160 000 K, log(g)=6) star, having a carbon-helium dominated atmosphere with considerable amounts of oxygen and neon (He=38%, C=54%, O=6%, Ne=2% by mass). It is located within the planetary nebula nuclei instability strip, hence, future searches for an associated PN as well as for stellar pulsations might be successful. The DO white dwarf is a unique object. From the relative strength of neutral and ionized helium lines we found Teff ~60 000 K, however, the He-II lines are extraordinarily strong and cannot be fitted by any model. Similar problems were encountered with hot subdwarfs and white dwarfs showing signatures of a super-hot wind. The reason is unknown.
Preprint (486 kb PDF file including figures)
Astrophysics (astro-ph): astro-ph/0407355
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Last modified 30 Jan 2013