K. Werner(1), K. Bagschik(2), T. Rauch(1), and R. Napiwotzki(3)
(1)Institut für Astronomie und Astrophysik, Astronomie, Universität
Tübingen, Waldhäuser Str. 64, D-72076 Tübingen, Germany
(2)Sternwarte Bonn, Auf dem Hügel 71, D-53121 Bonn, Germany
(3)Dr. Remeis-Sternwarte, Universität Erlangen-Nürnberg, Sternwartstr. 7, D-96049 Bamberg, Germany
accepted by Astronomy & Astrophysics
Abstract. We have performed a search for old planetary nebulae around hot white dwarfs by direct H alpha narrow-band imaging. The 16 examined objects are white dwarfs representing different spectral subtypes, comprising DA and various non-DA stars, among them being PG 1159 stars and white dwarfs exhibiting spectral signatures of ongoing mass-loss by ultra-hot winds.
The search was entirely negative - with one possible exception: PG 0109+111, which is the most massive DO white dwarf known (M = 0.74 M_sun) and among the hottest DOs (T_eff = 110 000 K). An asymmetric nebulosity extends about 5 arcmin from the star to the south-west, and there are hints that it extends even further out. If our detection is in fact the first definite case of a PN around a DO white dwarf it needs to be investigated by detailed spectroscopic observations.
Key words: stars: evolution - stars: AGB and post-AGB - white dwarfs - planetary nebulae: general
Paper (322k gzip'ed Postscript including figures)
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Jürgen Barnstedt (barnstedt AT astro.uni-tuebingen.de)
Last updated 04-Aug-1997