The Araucaria Project. Determination of the LMC Distance from Late-Type Eclipsing Binary Systems: I. OGLE-051019.64-685812.3

TL;DR

This paper determines the distance to the Large Magellanic Cloud using detailed analysis of a specific eclipsing binary system, achieving a precise measurement that aids in calibrating cosmic distance scales.

Contribution

It presents a new, accurate distance measurement to the LMC using a detailed analysis of a double-lined eclipsing binary system, improving the calibration of the cosmic distance scale.

Findings

Distance modulus of 18.50 mag with 3% uncertainty

Detailed physical parameters of the binary system obtained

Method shows potential for 1% accuracy with more data

Abstract

We have analyzed the double-lined eclipsing binary system OGLE-051019.64-685812.3 in the LMC which consists of two G4 giant components with very similar effective temperatures. A detailed analysis of the OGLE I-band light curve of the system, radial velocity curves for both components derived from high-resolution spectra, and near-infrared magnitudes of the binary system measured outside the eclipses has allowed us to obtain an accurate orbit solution for this eclipsing binary, and its fundamental physical parameters. Using a surface brightness-(V-K) color relation for giant stars we have calculated the distance to the system and obtain a true distance modulus of 18.50 mag, with an estimated total uncertainty of ~ 3 %. More similar eclipsing binary systems in the LMC which we have discovered and for which we are currently obtaining the relevant data will allow us to better check on the systematics of the method and eventually provide a distance determination to the LMC accurate to 1 percent, so much needed for the calibration of the distance scale.