Proper motions in multiple systems

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<~14.5mag. I have measured for the first time the common proper motion of two new wide systems containing very low mass components, Koenigstuhl 2 AB and 3 A-BC.

Together with Koenigstuhl 1 AB and 2M 0126-50 AB, they are among the widest systems in their respective classes (r=450-11900AU). I have determined the minimum frequency of field wide multiples (r>100AU) 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.