Institut für Astronomie und Astrophysik

Abteilung Astronomie

Preprint 07a/98

FUV spectroscopy of DO and PG 1159 stars with ORFEUS

K. Werner(1), S. Dreizler(1), T. Rauch(1), J. Barnstedt(1), M. Gölz(1), W. Gringel(1), N. Kappelmann(1), G. Krämer(1), H. Widmann(1), L. Koesterke(2), S. Haas(3), U. Heber(3), I. Appenzeller(4), M. Grewing(5)

(1)Institut für Astronomie und Astrophysik, Astronomie, Universität Tübingen, Waldhäuser Str. 64, D-72076 Tübingen, Germany
(2)Institut für Physik, Universität Potsdam, Germany
(3)Sternwarte Bamberg, Universität Erlangen-Nürnberg, Germany
(4)Landessternwarte Heidelberg, Germany
(5)Institut de Radio Astronomie Millimétrique (IRAM), France

1999, Proc. 11th European Workshop on White Dwarfs, (J.-E.Solheim, E.G. Meistas, eds.), ASP Conference Series 169, 511-517

Abstract. We have performed FUV spectroscopy of PG 1159 type central stars of planetary nebulae and DO white dwarfs with ultrahigh ionization lines in order to study their wind properties.
For the PG 1159 stars we derive mass-loss rates of the order 10^{-7} - 10^{-8} M_sun/yr and conclude that their winds are radiatively driven. By comparison of model atmospheres we find that the high mass-loss rates in the PG 1159 progenitors, the [WC] central stars, are possibly maintained by multi-scattering processes.
The FUV spectra of the two inspected 'super-hot wind' DOs are dominated by unidentified opacity sources. UV and optical observations can be interpreted in terms of a radiation driven wind, which rapidly accelerates to a very high terminal speed (10000 km/s) in the strong gravitational field of the DO white dwarf. The origin of super-ionization remains unknown.

Key words: White Dwarfs, PG1159 stars, Central stars of PNe, Mass-Loss, UV Spectroscopy

Paper (192k gzip'ed Postscript including figures)

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Jürgen Barnstedt (barnstedt AT astro.uni-tuebingen.de) Last updated 06-Oct-1998