The Formation of Multiple Systems in Clusters

Abstract

Binary stars provide a rich array of observational diagnostics which can in principle be used to test and calibrate star formation simulations. Moreover, binaries can be dynamically important within star clusters. In addition, the fact that binaries in certain separation ranges are either dynamically created or destroyed during star cluster evolution means that the properties of field binaries may be used to place constraints on the types of clusters in which they might have formed. To assess the outputs of simulations with regard to binary statistics, we must ensure that the simulations in question have an extremely high resolution i.e. the sink radius is significantly smaller than the separations of the binaries studied. We present an overview of such a simulation (Bate 2009) which, with a sink radius of 0.5 au and a sample of 1250 stars and brown dwarfs, allows us to robustly compare the statistics of binaries with separations down to au scales. We also review simulations which incorporate additional physical processes, however such complex calculations are computationally expensive and therefore presently are unable to provide a large enough sample to enable a proper statistical comparison with the observed properties of binaries.