EDP Sciences
Free access
Volume 424, Number 2, September III 2004
Page(s) 657 - 663
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20041157

A&A 424, 657-663 (2004)
DOI: 10.1051/0004-6361:20041157

Identification of a DO white dwarf and a PG 1159 star in the ESO SN Ia progenitor survey (SPY)

K. Werner1, T. Rauch1, 2, R. Napiwotzki3, N. Christlieb4, D. Reimers4 and C. A. Karl2

1  Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
    e-mail: werner@astro.uni-tuebingen.de
2  Dr.-Remeis-Sternwarte, Universität Erlangen-Nürnberg, Sternwartstraße 7, 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, 21029 Hamburg, Germany

(Received 24 April 2004 / Accepted 18 May 2004 )

We present high-resolution VLT spectra of a new helium-rich DO white dwarf ( HE1314+0018 ) and a new PG 1159 star ( HE1429-1209 ), which we identified in the ESO SPY survey. We performed NLTE model atmosphere analyses and found that the PG 1159 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 $\approx$ 60 000 K, however, the $\ion{He}{ii}$ 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.

Key words: stars: abundances -- stars: evolution -- stars: AGB and post-AGB -- stars: white dwarfs -- stars: individual: HE1429-1209 -- stars: individual: HE1314+0018

SIMBAD Objects

© ESO 2004