| Abstract
| - The spectroscopic binary CPD -59°2628 (Sp = O9.5 V) 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 $P=1\fd47$ which is consistent with the spectroscopy-binary period by Solivella & Niemela ([CITE]). We use this period to rematch the misidentified radial velocities from Levato et al. ([CITE]) 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 $2.6\pm0.1$ kpc and it has a systemic velocity of -19 km s -1, confirming its membership in the cluster Trumpler 16 (radial velocity -23.5 km s -1). The temperatures are 32 000 K for the hotter star ( A) and 30 000 K for the cooler ( B). We determine the absolute dimensions (solar units): $M_A=14.0\pm2.0$, $R_A=5.29\pm0.26$, $M_B=11.7\pm1.8$ and $R_B=4.38\pm0.22$. By adopting $E(b-y)=0.306$, we get $M_{{\rm bol},A}=-6.3\pm0.1$, $M_{V,A}=-3.2\pm0.1$, $M_{{\rm bol},B}=-5.6\pm0.1$ and $M_{V,B}=-2.7\pm0.1$. Theoretical stellar models from Claret ([CITE]), 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.
|
