2001A&A...369..561F

The spectroscopic binary CPD-59°2628 (Sp=O9.5V) has been discovered to be a detached eclipsing binary, and we present an analysis based on new light curves, published spectroscopy and two new high-resolution spectra. uvby light curves from more than 2000 observations are analysed with the WINK and the Wilson-Devinney (WD) programs. Geometric distortions and photometric effects from the proximity of the components are included in the computations. The detached system has a close circular orbit of high inclination and high maximum projected velocities. We find a photometric period P=1.47d which is consistent with the spectroscopy-binary period by Solivella & Niemela (1999RMxAC...8..145S). We use this period to rematch the misidentified radial velocities from Levato et al. (1991ApJS...75..869L) and apply them in an analysis using the method of Lehmann-Filhes. We find that CPD-59°2628 is a young system close to the ZAMS. Its distance is 2.6±0.1kpc and it has a systemic velocity of -19km/s, confirming its membership in the cluster Trumpler 16 (radial velocity -23.5km/s). The temperatures are 32000K for the hotter star (A) and 30000K for the cooler (B). We determine the absolute dimensions (solar units): M_A=14.0±2.0, R_A=5.29±0.26, M_B=11.7±1.8 and R_B=4.38±0.22. By adopting E(b-y)=0.306, we get M_bol,A=-6.3±0.1, M_V,A=-3.2±0.1, M_bol,B=-5.6±0.1 and M_V,B=-2.7±0.1. Theoretical stellar models from Claret (1995), including convective-core overshooting and mass loss for a composition (X=0.70, Z=0.02), appear to fit the components at an age of ∼2 Myr.