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Astron. Astrophys. 324, L25-L28 (1997)

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Letter to the Editor

Mass and radius of the white dwarf in the binary V471 Tau from ORFEUS and HIPPARCOS observations

K. Werner and T. Rauch

1 Institut für Astronomie und Astrophysik der Universität, Waldhäuser Str. 64, D-72076 Tübingen, Germany

Received 13 May 1997 / Accepted 6 June 1997


We present a model atmosphere analysis of the white dwarf component in the K2V/DA eclipsing binary system V471 Tau, based upon FUV spectra obtained by the ORFEUS satellite. This system is regarded as the prototype of a post-common envelope WD [FORMULA] MS binary and, hence, is of considerable importance for our understanding of close binary evolution.

From a line profile fit to the FUV hydrogen Lyman series we obtain [FORMULA] =35 125 K and [FORMULA] =8.21. The HIPPARCOS trigonometric parallax measurement ([FORMULA] mas) confirms the Hyades membership of V471 Tau and we can derive the white dwarf radius. Together with its astrometric mass, which is known from analyses of the orbital parameters and which is compatible with our spectroscopic surface gravity determination, we can compare this individual WD to the theoretical mass-radius relation.

Key words: stars: individual: V471 Tau – stars: fundamental parameters – stars: atmospheres – binaries: eclipsing – white dwarfs – ultraviolet: stars

Send offprint requests to: K. Werner

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© European Southern Observatory (ESO) 1997

Online publication: May 26, 1998