TOWARD UNDERSTANDING THE NATURE OF THE YOUNG DETACHED BINARY SYSTEM HD 350731

Abstract

The young binary system HD 350731 is a noteworthy laboratory for studying early-type binaries with similar components. We present here an analysis of differential multi-color photometric and spectroscopic observations of the double-lined detached system. Accurate absolute parameters were determined for the first time from a simultaneous solution of the light and radial velocity curves. HD 350731 consists of two B8V-type components with masses and radii, respectively, of M-1= 2.91 +/- 0.13 M-circle dot, M-2= 2.80 +/- 0.14 M-circle dot, R-1= 2.11 +/- 0.05 R-circle dot, and R-2= 2.07 +/- 0.05 R-circle dot. The effective temperatures were determined based on analysis of disentangled spectra of the components and were derived to be 12,000 +/- 250 and 11,830 +/- 300 K for the primary and secondary components, respectively. The measured projected rotational velocities, 69.2 +/- 1.5 km s(-1) for the primary and 70.1 +/- 1.7 km s-1 for the secondary, were found to be closer to the pseudo-synchronous velocities of the components. Comparison with evolutionary models suggests an age of 120 +/- 35 Myr. Kinematic analysis of the unevolved binary system HD 350731 revealed that it belongs to the young thin-disk population of the Galaxy.