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

1. Introduction: the BF Aurigae system

BF Aur (=HD 32419=BD+41^o1051; =, =+41^o 13´ 13", P=) was discovered as an eclipsing binary by Morgenroth (1935) and has a long history in eclipsing binary research briefly summarized by Kallrath & Kämper (1992; KK hereafter). The spectral classification, B5V (Roman 1956) and confirmed by Popper (1980), was found roughly consistent with normal main-sequence components of about .

KK's analysis used UBV data by Mannino et al. (1964), as well as Strömgren indices and the line ratio. It puts some bounds on the mass ratio which they determine as . Their analysis shows some preference for a solution in which the stars almost fill their Roche lobes.

Van Hamme's (1993b) analysis based on the Mannino et al. (1964) photometric data and the radial velocities by Mammano et al. (1974) shows that multiple reflection does not play an important role. According to his least squares fits obtained with the 1993 version of the Wilson-Devinney (WD) model, BF Aur appears to be detached with very similar components filling approximately 95% to 97% of their Roche lobes.

Demircan et al. (1997) used new UBV photometry that they obtained during 19 nights in August 1988 and March 1989 and the Mammano et al. (1974) radial velocity curves in a simultaneous least-squares analysis. However, they could not overcome the ambiguity in the photometric data and ask for more accurate radial velocity data before claiming uniqueness.

We analyze new, much more accurate, photometric and spectroscopic data simultaneously and try again to decide whether BF Aur is detached or semi-detached and whether the primary minimum is a transit or an occultation. We aim to give a precise mass ratio and the absolute parameters of the system and discuss the evolutionary status of BF Aur in the light of the available spectroscopic and photometric evidence, including the period change obtained by Demircan et al. (1997).

© European Southern Observatory (ESO) 2000

Online publication: October 24, 2000
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