Aims. Investigations of stellar and tidal evolutionof binarystars with giant components are rare. In this paper, we willinvestigate such features in three binary systems for which at leastone component is a giant star. As some of these giants seem to be inthe blue loop, it is an excellent opportunity to investigate thesensitivity of core overshooting on their location in the HR Diagram.We expect that these characteristics shall serve as an incentive toobservers to investigate such kinds of binaries, increasing theaccuracy of measurements and the number of systems to test theevolutionary models. Methods. Prior to performing the study of thecircularizationand synchronization levels, an analysis of the capability of ourstellar evolutionary models to reproduce the observed masses, radii andeffective temperatures is carried out. Next, the differential equationsof tidal evolution are integrated and the corresponding critical timesare compared with the inferred age of the system and with the observedeccentricity and rotational velocities (when available). Results. We have found good agreement between ourstellar models and the astrophysical properties of And, V2291 Oph and SZ Cen by adopting a moderate core overshootingamount ().Three mechanisms were used to try to explain the observed levels ofcircularization and synchronization: the hydrodynamical mechanism,turbulent dissipation and radiative damping. In the cases of And and SZ Cen, for which the rotational velocities are available, byassuming solid body rotation for both stars of each system we havefound that the theoretical ratio between the rotational velocitiesat the inferred ages are in good agreement with the observationalratios. Key words: stars: binaries: general - stars:evolution - stars: rotation
展开▼
