Astron. Astrophys. 362, 673-682 (2000)

The BF Aurigae system ^*

A close binary at the onset of mass transfer

J. Kallrath ¹ and K.G. Strassmeier <sup>**  2,3

1</sup> BASF-AG, ZDP/C-C13, 67056 Ludwigshafen, Germany (josef.kallrath@basf-ag.de)
² Institut für Astronomie, Universität Wien, Türkenschanzstrasse 17, 1180 Wien, Austria (strassmeier@astro.univie.ac.at)
³ Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany (kstrassmeier@aip.de)

Received 28 January 2000 / Accepted 28 April 2000

Abstract

Because the question of the mass ratio of the early-type system BF Aur has not yet fully been clarified, we present and analyse new UBV photometry and nearly contemporaneous radial velocity observations. From a simultaneous least squares analysis of the photometric light curves and the new radial velocity curves we derive a mass ratio of . With even much more accurate photometric and spectroscopic data the mass ratio remains weakly defined. The resulting stellar parameters are consistent with line ratios derived from old and our new spectra and available Strömgren indices. We confirm earlier conclusions that BF Aur is detached and that the more massive component is almost filling its Roche lobe. New data indicating a period change support the interpretation that mass exchange has already started or is about to start.

Key words: stars: individual: BF Aur stars: binaries: eclipsing stars: early-type stars: binaries: close stars: evolution

* Tables A1-A5 are available electronically only at the CDS via anonymous ftp (130.79.128.5) ftp://cdsarc.u-strasbg.fr/pub/cats/J/A+A/362/673 or http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/362/673
** Visiting Astronomer, Kitt Peak National Observatory, operated by the Association of Universities for Research in Astronomy, Inc. under contract with the National Science Foundation

Send offprint requests to: K.G. Strassmeier, AIP

© European Southern Observatory (ESO) 2000

Online publication: October 24, 2000

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