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Paper: Distances and Fundamental Properties of Eclipsing Binaries in the LMC and M31
Volume: 318, Spectroscopically and Spatially Resolving the Components of Close Binary Stars
Page: 261
Authors: Ribas, I.
Abstract: Accurate distance measurements to the Local Group galaxies are crucial to calibrating the cosmic distance scale and to determining the age and evolution of the Universe. As major rungs on the cosmic distance ladder, these galaxies serve as calibrators for distance indicators reaching beyond the Local Group. We are carrying out a program to measure accurately the distance to the Large Magellanic Cloud (LMC) and the Andromeda Galaxy (M31) using eclipsing binaries as indicators. The analysis combines the study of light and radial velocity curves, which yield stellar masses and radii, with a new analysis of the observed energy distributions, which yield effective temperatures, metallicities, and reddenings of the systems plus the distance. This robust method consists of a detailed study of well-understood objects (B stars) in a well-understood evolutionary phase (core H burning). Distances derived from eclipsing binaries are basically geometric and essentially free from many assumptions and uncertainties that plague other less direct methods. In addition to distance determination, extragalactic eclipsing binaries open a new perspective on the study of stellar structure and evolution. Stars in different galaxies have formed and evolved in environments with chemical histories that may differ from those of the solar neighborhood. Here I discuss the results obtained thus far for several systems in the LMC as well as the ongoing efforts to extend the program to M31.
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