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

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 ofDEBs from the OGLE-II catalogue was selected and their near-infrared photometry was takenfrom 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 aset 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. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.