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Preprint 16b/07

KPD0005+5106: Hottest DO White Dwarf Much Hotter Than Assumed

K. Werner (1), T. Rauch (1), J. W. Kruk (2)

(1) Institute for Astronomy and Astrophysic, Kepler Center for Astro and Particle Physics, Eberhard Karls University, Tübingen, Germany
(2) Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA

To be published in: Proceedings of "Hydrogen-Deficient Stars" conference, held in Tübingen, Germany, Sept. 17-21, 2007.

Abstract. KPD0005+5106 is the hottest known helium-rich white dwarf. We have identified NeVIII lines in UV and optical spectra and conclude that it is significantly hotter than previously thought, namely Teff=200,000 K instead of 120,000 K. This is a possible explanation for the observed hard X-ray emission as being of photospheric origin. Concerning its evolutionary state, we suggest that KPD0005+5106 is not a descendant of a PG1159 star but more probably related to the O(He) stars and RCrB stars.
 

Preprint (69 kb PDF file including figures)
Astrophysics (astro-ph): 0710.4515

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