Eclipsing binaries in the OGLE variable star catalogue: long-period evolved systems

ABSTRACT Red giant stars are proving to be an exceptional source of information for testing models of stellar evolution, as photometric and spectroscopic analysis has opened up a window into their interiors, providing an exciting chance to develop highly constrained stellar models. In this study, we present a determination of precise fundamental physical parameters belonging to five detached, double-lined, eclipsing binary stars in the Large and Small Magellanic Clouds containing G- or early K-type giant stars with extended envelopes. We also derived the distances to the systems by using a temperature–colour relation and compared these distances with the measurements provided in the literature. The measured stellar masses are in the range 1.8–3.0 M⊙ and comparison with the PAdova and TRieste Stellar Evolution Code (PARSEC) isochrones gives ages between 0.4 and 1.1 Gyr. The derived uncertainties for individual masses and radii of components are better than 3 and 7 per cent, respectively, for these systems. Additionally, we performed atmospheric parameter determination and [M/H] analysis for each, where we disentangled the spectra.