The majority of stars in the Universe, with a notable exception of M-dwarfs, are in binary or multiple systems. They play a major role in the evolution of stellar populations, and are at the origin of some of the most fascinating objects in modern astrophysics. They, for example, play a key role in the formation of supernovae and of other transients, are potential sources of gravitational waves, are argued to be at the origin of the ultraviolet excess detected in old galaxies, or are renowned distance calibrators in our Galaxy and beyond. Yet, the evolution of binary systems is still poorly understood theoretically and poorly constrained observationally. This is especially true for close systems experiencing mass transfer from one companion to the other. Stable Roche lobe overflow may lead, for example, to a widening of close binaries under certain circumstances, while very short-period systems are predicted from common-envelope evolution.
The field will benefit from the exceptional database that is being gathered by ESA’s Gaia mission. Launched at the end of 2013, the spacecraft is repeatedly observing more than one billion stars, several millions of which are expected to be eclipsing binaries. This unprecedented all-sky sample of eclipsing systems can serve as a proxy of the population of binary systems in the Galaxy and in the Magellanic Clouds. In addition to light curves and parallaxes, the spacecraft will provide, for bright objects, radial velocity curves, red and blue spectro-photometry, and stellar parameters. This ensemble of data on eclipsing binaries will offer a unique opportunity to analyze binary systems in different states of evolution, and eventually provide more reliable predictions for the occurence fractions of various binary evolution channels.
Key questions need first to be answered in order to achieve these studies. Among them are the identification of eclipsing binary parameters that can be extracted from large scale multi-epoch surveys, including Gaia, their link with observable properties of binary systems, and the efficiency of binary population synthesis models to predict various binary evolutionary channels based on eclipsing binary parameters extracted from large-scale multi-epoch surveys.
The purpose of this project is to clarify and answer those questions. The study will rely on space- and ground-based multi-epoch surveys of eclipsing binaries such as Kepler and OGLE, and on simulated Gaia-like eclipsing binary time series in advance of, and in preparation for the study of, real Gaia data of eclipsing binaries.