engleski

The Beta Cephei variable in the eclipsing binary HD92024: I. Determination of the orbit

HD92024 is a member of the open cluster NGC 3293 ; it is only eclipsing binary system with a beta Cephei component known in the southern hemisphere. This paper presents the first spectroscopic analysis of the single-lined binary and provides an orbital analysis based on recent high-resolution spectroscopy and photometry. A procedure to derive orbital elements with minimal influence of the pulsational line-profile variations on the radial velocities is applied, and we find the stellar masses to be 15+/-3 Msun and 3.0+/-0.5 Msun respectively, and radii of 8.4+/-0.8 Rsun, 2.1+/-0.4 Rsun. The temperatures are 25500+/-500 K and 12500+/-1000 K. The surface gravity values of log g = 3.77+/-0.08 and 4.27+/-0.18 indicate that the binary consists of an evolved early B-type primary and a late-B main sequence companion. The resulting distance 2.8+/-0.3 kpc and systemic velocity -16 km/s confirm cluster membership. Theoretical stellar models indicate an age of 10-13 Myr, somewhat higher than the literature value for the brighter members of NGC 3293.

eclipsing binaries; spectroscopic binaries; oscillations

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