Binaries in star clusters and the origin of the field stellar population.

Many, possibly most, stars form in binary and higher order multiple systems. Therefore, the properties and frequency of binary systems provide strong clues to the star-formation process, and constraints on star-formation models. However, the majority of stars also form in star clusters in which the birth binary properties and frequency can be altered rapidly by dynamical processing. Thus, we almost never see the birth population, which makes it very difficult to know whether star formation (as traced by binaries, at least) is universal or whether it depends on the environment. In addition, the field population consists of a mixture of systems from different clusters that have all been processed in different ways.