Wide binaries in Taurus and Upper Sco

Our survey found 15 new binary systems (three in Taurus and 12 in Upper Sco) with separations of 3"-30" (500-5000AU) among all of the known members with masses of 2.5-0.012M_{sun}_. The total sample of 49 wide systems in these two regions conforms to only some expectations from field multiplicity surveys.

Higher mass stars have a higher frequency of wide binary companions, and there is a marked paucity of wide binary systems near the substellar regime. However, the separation distribution appears to be log-flat, rather than declining as in the field, and the mass ratio distribution is more biased toward similar-mass companions than the initial mass function or the field G-dwarf distribution. The maximum separation also shows no evidence of a limit at <~5000AU until the abrupt cessation of any wide binary formation at system masses of ~0.3M_{sun}_.