Spectroscopic binary population of ONC and NGC2264

The inferred multiplicity fraction up to 10 au based on these observations is 5.3+/-1.2% for NGC 2264 and 5.8+/-1.1% for the ONC; these values are consistent with the distribution of binaries in the field in the relevant parameter range.

Eight of the multiple systems in the sample have enough epochs to perform an initial fit for the orbital parameters. Two of these sources are double-lined spectroscopic binaries; for them, we determine the mass ratio. Our reanalysis of the distribution of stellar radial velocities toward these clusters presents a significantly better agreement between stellar and gas kinematics than was previously thought.