The araucaria project: An accurate distance to the late-type double-lined eclipsing binary OGLE SMC113.3 4007 in the small magellanic cloud

We have analyzed the long-period, double-lined eclipsing binary system OGLE SMC113.3 4007 (SC10 137844) in the Small Magellanic Cloud. The binary lies in the northeastern part of the galaxy and consists of two evolved, well-detached, non-active G8 giants. The orbit is eccentric with e = 0.311, and the orbital period is 371.6days. Using extensive high-resolution spectroscopic and multi-color photometric data, we have determined a true distance modulus of the system of m - M = 18.83 ± 0.02 (statistical) ± 0.05 (systematic) mag using a surface-brightness-color relation for giant stars. This method is insensitive to metallicity and reddening corrections and depends only very little on stellar atmosphere model assumptions. Additionally, we derived very accurate, at the level of 1%-2%, physical parameters of both giant stars, particularly their masses and radii, making our results important for comparison with stellar evolution models. Our analysis underlines the high potential of late-type, double-lined detached binary systems for accurate distance determinations to nearby galaxies.