The araucaria project. An accurate distance to the late-type double-lined eclipsing binary ogle smc113.3 4007 in the small magellanic cloud

TL;DR

This study accurately measures the distance to a binary star system in the Small Magellanic Cloud using spectroscopic and photometric data, providing precise stellar parameters and demonstrating the method's insensitivity to metallicity and reddening.

Contribution

The paper presents a new, highly precise distance measurement to a late-type eclipsing binary in the SMC, with detailed stellar parameters, using a surface brightness - color relation that minimizes model dependencies.

Findings

Distance modulus of 18.83 mag with 0.02 (stat) and 0.05 (sys) mag uncertainties.

Stellar masses and radii determined with 1-2% accuracy.

Demonstrates the effectiveness of late-type eclipsing binaries for galaxy distance measurements.

Abstract

We have analyzed 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-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 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.