Tracing the structure of the Milky Way with detached eclipsing binaries from the VVV survey - I. The method and initial results

TL;DR

This study uses detached eclipsing binaries from the VVV survey to map the Milky Way's structure, achieving precise distance measurements that reveal spiral arms, the Bulge, and distant systems including the Sagittarius dwarf galaxy.

Contribution

It introduces a method combining OGLE-II light curves and VVV photometry to determine accurate distances to DEBs, aiding Galactic structure mapping.

Findings

Distances measured with better than 5% precision

Distribution of DEBs traces spiral arms and Bulge

Detection of systems beyond the Bulge to Sagittarius dwarf galaxy

Abstract

We present the first results of a project aiming to trace the spatial structure of the Milky Way using detached eclipsing binaries (DEBs) as distance indicators. A sample of DEBs from the OGLE-II catalogue was selected and their near infrared photometry was taken from the Vista Variables in the Via Lactea (VVV) survey. The I band OGLE-II light curves are used to create models of the DEBs, which together with the VVV photometry are compared with a set of theoretical isochrones. After correcting for stellar reddening, we find a set of absolute physical parameters of components of a given binary, including absolute magnitudes and distances. With this approach we can calculate the distances with the precision better than 5 per cent. Even though we have a few systems, the distribution is not homogeneous along the line of sight, and appears to follow the overall structure of the Galaxy - several spiral arms and the Bulge are distinguishable. A number of systems can be seen behind the Bulge, reaching even the distance to the Sagittarius dwarf galaxy.