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Astron. Astrophys. 318, 461-465 (1997)


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Temperature determination of the cool DO white dwarf HD 149499 B from EUVE observations

S. Jordan 1, R. Napiwotzki 2, D. Koester 1 and T. Rauch 1, 3

1 Institut für Astronomie und Astrophysik der Universität, D-24098 Kiel, Germany
2 Dr. Remeis-Sternwarte, Sternwartstr. 7, D-96049 Bamberg, Germany
3 Lehrstuhl Astrophysik, Universität Potsdam, Am Neuen Palais 10, D-14469 Potsdam, Germany

Received 29 April 1996 / Accepted 19 July 1996

Abstract

We present a LTE model atmosphere analysis of the EUVE medium and long wavelength spectrum of the cool DO white dwarf HD 149499 B. This observation in the spectral range 230-700 Å supplements a previous analysis of an ORFEUS spectrum between 912 and 1170 Å which yielded the atmospheric parameters [FORMULA] K and [FORMULA] and a hydrogen-to-helium number ratio of [FORMULA]. The EUVE data are in full agreement with the ORFEUS result and allow a more precise determination of the effective temperature ([FORMULA] K) and the interstellar hydrogen column density ([FORMULA] cm-2). None of the features in the EUVE spectrum could be identified with any additional absorber besides helium. Exploratory calculations with fully metal blanketed LTE model atmospheres show that the metal abundances predicted by current diffusion theory are clearly at variance with the observed spectrum.

Key words: stars: fundamental parameters – stars: individual: HD 149499 B – stars: white dwarfs – ultraviolet: stars

Send offprint requests to: S. Jordan
\thanks{Based on observations with the EUVE and ROSAT satellites}
© European Southern Observatory (ESO) 1997

Online publication: July 8, 1998

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