The β Cephei variable in the eclipsing binary HD 92024^*

I. Determination of the orbit

¹ Royal Observatory of Belgium, Ringlaan 3, 1180 Brussels, Belgium e-mail: lfreyham@vub.ac.be
² OBSS/WE, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
³ Department of Physics, University of Zagreb, Bijenička 32, 10000 Zagreb, Croatia
⁴ Institut d'Astrophysique et de Géophysique, Université de Liège, 17 Allée du 6 Août, 4000 Liège, Belgium
⁵ European Southern Observatory, Casilla 19001, Alonso de Cordova 3107, Vitacura, Santiago, Chile
⁶ Faculty of Electrical Engineering and Computing, Department of Applied Physics, University of Zagreb, Unska 3, 10000 Zagreb, Croatia

Received: 24 June 2004
Accepted: 28 August 2004

Abstract

HD 92024 is a member of the open cluster ; it is the only eclipsing binary system with a  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 and respectively, and radii of , . The temperatures are K and K. The surface gravity values of and indicate that the binary consists of an evolved early B-type primary and a late-B main sequence companion. The resulting distance kpc and systemic velocity -16 km s^-1 confirm cluster membership. Theoretical stellar models indicate an age of Myr, somewhat higher than the literature value for the brightest members of .