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Astron. Astrophys. 320, 181-184 (1997)


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On the mass of the white dwarf in UZ Fornacis *

Axel D. Schwope 1, Sabine Mengel 1 and Klaus Beuermann 2

1 Astrophysikalisches Institut Potsdam, An der Sternwarte 16, D-14482 Potsdam, Germany (ASchwope@aip.de)
2 Universitätssternwarte Göttingen, Geismarlandstraße 11, D-37083 Göttingen, Germany

Received 11 July 1996 / Accepted 23 August 1996

Abstract

We present phase-resolved spectroscopy of the eclipsing AM Herculis star UZ For obtained when the system was in its low state of accretion. Faint residual H [FORMULA] -emission and NaI absorption were used to trace the secondary star and infer its orbital velocity [FORMULA]. The measured radial velocity amplitude of NaI [FORMULA] km s-1 suggests a low-mass white dwarf with [FORMULA] [FORMULA] (1 [FORMULA] -errors). The H [FORMULA] emission line on the other hand, visible only for part of the orbital cycle and supposed to originate only on the illuminated hemisphere facing the white dwarf, displays a similar radial velocity amplitude, [FORMULA] km s-1. The standard [FORMULA] -correction applied by us then suggests a white dwarf mass of up to 1 [FORMULA]. Compared with earlier results the new ones enlarge the window in which the white dwarf mass may lie and resolves the conflict between mass estimates based on photometry and spectroscopy. They leave some ambiguity in the location of emission and absorption components in these and former observations.

Key words: accretion – cataclysmic variables – AM Herculis binaries – stars: UZ For – stars: eclipsing

* Based on observations collected at the European Southern Observatory, La Silla, Chile.

Send offprint requests to: Axel D. Schwope

© European Southern Observatory (ESO) 1997

Online publication: July 3, 1998

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