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

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 M ⊙ , R = 1.357 ± 0.019 R ⊙ , and L = 7.02 ± 0.050 L ⊙ for the hotter and more luminous primary component and M = 0.200 ± 0.007 M ⊙ , R = 1.238 ± 0.013 R ⊙ , and L = 1.57 ± 0.09 L ⊙ for the Roche lobe-filling secondary.