Orbital and physical parameters, and the distance of the eclipsing binary system OGLE-LMC-ECL-25658 in the Large Magellanic Cloud

TL;DR

This paper analyzes a detached eclipsing binary in the Large Magellanic Cloud to precisely determine its physical parameters and distance, contributing to accurate cosmic distance measurements and stellar evolution understanding.

Contribution

It provides high-precision orbital and physical parameters of OGLE-LMC-ECL-25658 and refines the distance to the LMC using combined photometric and spectroscopic data.

Findings

Derived stellar masses of 2.23 M_sun with <1% precision

Calculated LMC distance of 50.30 kpc with high accuracy

Confirmed consistency with previous LMC distance measurements

Abstract

We present an analysis of a new detached eclipsing binary, OGLE-LMC-ECL-25658, in the Large Magellanic Cloud. The system consists of two late G-type giant stars on an eccentric orbit and orbital period of ~200 days. The system shows total eclipses and the components have similar temperatures, making it ideal for a precise distance determination. Using multi-color photometric and high resolution spectroscopic data, we have performed an analysis of light and radial velocity curves simultaneously using the Wilson Devinney code. We derived orbital and physical parameters of the binary with a high precision of < 1 %. The masses and surface metallicities of the components are virtually the same and equal to 2.23 +/- 0.02 M_sun and [Fe/H] = -0.63 +/- 0.10 dex. However their radii and rates of rotation show a distinct trace of differential stellar evolution. The distance to the system was calculated using an infrared calibration between V-band surface brightness and (V-K) color, leading to a distance modulus of (m-M) = 18.452 +/- 0.023 (statistical) +/- 0.046 (systematic). Because OGLE-LMC-ECL-25658 is located relatively far from the LMC barycenter we applied a geometrical correction for its position in the LMC disc using the van der Marel et al. model of the LMC. The resulting barycenter distance to the galaxy is d_LMC = 50.30 +/- 0.53 (stat.) kpc, and is in perfect agreement with the earlier result of Pietrzynski et al.(2013).