A survey of pre-main sequence (PMS) stars has been started in 1996 to study the statistics and properties of binaries among these young stars and constrain the models of star formation in collaboration with J. Bouvier (CFHT). The program is performed with complementary high angular observations made at ESO and CFHT with Adaptive Optics (AO) in the infra-red.
Our goal here is to identify each component of the binary system by its photometry and spectroscopy (Bouvier et al., 1996).