Astronomy and Astrophysics, volume 424, 657-663 (2004/9-3)
Identification of a DO white dwarf and a PG 1159 star in the ESO SN Ia progenitor survey (SPY).
WERNER K., RAUCH T., NAPIWOTZKI R., CHRISTLIEB N., REIMERS D. and KARL C.A.
Abstract (from CDS):
We present high-resolution VLT spectra of a new helium-rich DO white dwarf (HE 1314+0018
) and a new PG 1159 star (HE 1429-1209
), 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
=160000K, logg=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
≃60000K, however, the HeII 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.
stars: abundances - stars: evolution - stars: AGB and post-AGB - stars: white dwarfs - stars: individual: HE 1429-1209 - stars: individual: HE 1314+0018
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