Absolute Properties of the Eclipsing Binary Star V396 Cassiopeiae

Abstract

We present 6450 differential observations in the V filter measured by a robotic telescope, as well as 28 pairs of radial velocities from high-resolution spectroscopic observations of the detached EA-type, 5.505 day period, double-lined eclipsing binary star V396 Cas. Absolute dimensions of the components are determined with good precision (better than 1% in the masses and radii) for the purpose of testing various aspects of theoretical modeling. We obtain 2.398 ± 0.022 M⊙ and 2.592 ± 0.013 R⊙ for the hotter, larger, more massive and more luminous photometric primary (star A), and 1.901 ± 0.016 M⊙ and 1.779 ± 0.010 R⊙ for the cooler, smaller, less massive and less luminous photometric secondary (star B). The effective temperatures and interstellar reddening of the stars are accurately determined from uvbyβ photometry: 9225 ± 150 K for the primary and 8550 ± 120 K for the secondary, corresponding to spectral types of A1 and A3, and 0.119 mag for Eb-y. The metallicity of the stars appears to be significantly less than solar. The stars are located at a distance of about 560 pc near the plane of the Galactic disk. The orbits of the stars are apparently circular, and spectral line widths give observed rotational velocities that are not synchronous with the orbital motion for both components. The components of V396 Cas are main-sequence stars with an age of about 420 Myr according to models.