* Astronomy

Title: The araucaria project. An accurate distance to the late-type double-lined eclipsing binary OGLE SMC113.3 4007 in the Small Magellanic Cloud
Authors: Dariusz Graczyk, Grzegorz Pietrzynski, Ian B. Thompson, Wolfgang Gieren, Bogumil Pilecki, Andrzej Udalski, Igor Soszynski, Zbigniew Kolaczkowski, Rolf-Peter Kudritzki, Fabio Bresolin, Piotr Konorski, Ronald Mennickent, Dante Minniti, Jesper Storm, Nicolas Nardetto, Paulina Karczmarek

We have analysed the long period, double-lined eclipsing binary system OGLE SMC113.3 4007 (SC10 137844) in the SMC. The binary lies in the north-eastern 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 371.6 days. Using extensive high-resolution spectroscopic and multi-colour 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 - colour relation for giant stars. This method is very 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.

Read more (175kb, PDF)