Southern Very Low Mass Stars and Brown Dwarfs in Wide Binary and Multiple Systems

The results of the Königstuhl survey in the Southern Hemisphere are presented. I have searched for common proper motion companions to 173 field very low mass stars and brown dwarfs with spectral types >M5.0 V and magnitudes J ≲ 14.5 mag. I have measured for the first time the common proper motion of two new wide systems containing very low mass components, Königstuhl 2 AB and 3 A-BC. Together with Königstuhl 1 AB and 2M 0126-50 AB, they are among the widest systems in their respective classes ( r = 450-11,900 AU). I have determined the minimum frequency of field wide multiples ( r > 100 AU) with late-type components at 5.0% ± 1.8% and the frequency of field wide late-type binaries with mass ratios q > 0.5 at 1.2% ± 0.9%. These values represent a key diagnostic of evolution history and low-mass star and brown dwarf formation scenarios. In addition, the proper motions of 62 field very low mass dwarfs are measured here for the first time.