DO STAR-FORMING REGIONS HAVE DIFFERENT BINARY FRACTIONS

Two of the major contending theories for binary and multiple star form ation arc fragmentation driven by rotation during cloud collapse and g ravitational instability of massive protostellar disks. Implicit in th e literature on these two mechanisms is that the parameter space avail able for binary formation in a star forming region varies with the clo ud temperature. The sense of the difference is that binary formation i s more likely in low-temperature clouds. Observations of cloud conditi ons and of binary fractions among young stellar objects are approachin g the necessary level of detail to test this prediction; and there are hints in recent observations that such differences exist.