Absolute Properties of the Eclipsing Binary Star V459 Cassiopeiae

Abstract

We present 5064 differential observations in the V filter measured by a robotic telescope, as well as 30 pairs of radial velocities from high-resolution spectroscopic observations, of the detached, EA-type, 8.46 day period double-lined eclipsing binary star V459 Cas. Absolute dimensions of the components are determined with good precision (better than 1.6% in the masses and radii) for the purpose of testing various aspects of theoretical modeling. We obtain 2.02 ± 0.03 M⊙ and 2.009 ± 0.013 R⊙ for the hotter, larger, more massive and more luminous photometric primary (star A), and 1.96 ± 0.03 M⊙ and 1.965 ± 0.013 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: 9140 ± 300 K for the primary, 9100 ± 300 K for the secondary—corresponding to spectral types of A1—and 0.186 mag for Eb-y. The orbits are eccentric, and spectral line widths give observed rotational velocities that are much faster than synchronous for both components. The components of V459 Cas are main-sequence stars with an age of about 525 Myr according to models.