Comportamento da excentricidade em estrelas Subgigantes binárias sob ação das forças de maré

Abstract

In this work, we investigate binary systems in which at least one of the stars is located in the Subgiant Branch, aiming to understand the behavior of the orbital eccentricity of these systems in light of tidal theories. The analysis was based on astrometric measurements provided by the Gaia mission and photometric measurements by the Kepler mission. We specifically focused on eclipsing subgiant binary systems to examine the orbital eccentricity variation rate. We describe the analysis process, which included integrating databases from studies such as those by Mathur and Kirk, and the method for identifying stellar data. After filtering, we selected 123 subgiant binary systems and conducted the eccentricity analysis as a function of orbital period for 43 systems, whose behaviors were consistent with those observed in other stellar branches. The analysis of eccentricity for 38 stars indicated that the mass of the convective zone (mzc) interferes with tidal effects and should be considered for stars with an mzc greater than 0.05M⊙.