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Paper: Properties and Distances of Eclipsing Binary Stars in the Andromeda Galaxy
Volume: 435, Binaries – Key to Comprehension of the Universe
Page: 375
Authors: Vilardell, F.; Ribas, I.; Jordi, C.; Fitzpatrick, E. L.; Guinan, E. F.; Tsodikovich, Y.; Mazeh, T.
Abstract: We present the results of a project aimed at determining the first direct distance to the Andromeda Galaxy (M 31) from EBs. A photometric survey was carried out in the North-Eastern part of M 31, providing light curves for almost 4000 variable stars, with over 400 EBs and 400 Cepheids. After a preliminary selection, four EBs were selected for spectroscopic follow up with the Gemini-North telescope. The analysis performed revealed the fundamental properties of several massive stars. Two of these EBs were used to determine a direct distance to M 31 of (m–M)0=24.36±0.08 mag. The other two EBs provided a direct determination of masses and radii of massive stars in another galaxy, enabling a comparison with stellar evolutionary models. In addition, one of these systems is the most massive EB with apsidal motion ever reported, enabling the analysis of the distribution of matter in the interior of stars with masses larger than 40 M.
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