The Clusters Ages Experiment (CASE). II. The Eclipsing Blue Straggler OGLEGC 228 in the Globular Cluster 47 Tuc

Abstract

We use photometric and spectroscopic observations of the eclipsing binary OGLEGC 228 (V228) to derive the masses, radii, and luminosities of the component stars. Based on measured systemic velocity, proper motion, and distance, the system is a blue straggler member of the globular cluster 47 Tuc. Our analysis shows that V228 is a semidetached Algol. We obtain M=1.512+/-0.022 Msolar, R=1.357+/-0.019 Rsolar, and L=7.02+/-0.050 Lsolar for the hotter and more luminous primary component and M=0.200+/-0.007 Msolar, R=1.238+/-0.013 Rsolar, and L=1.57+/-0.09 Lsolar for the Roche lobe-filling secondary. This paper utilizes data obtained with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.