We present Lick Natural Guide Star Adaptive Optics observations of the L8 brown dwarf Gliese 337C , which is resolved for the first time into two closely separated ( 0 \farcs 53 \pm 0 \farcs 03 ) , nearly equal magnitude components with a K _ { s } flux ratio of 0.93 \pm 0.10 .
Companionship is inferred from the absence of a 3 \farcs 6 offset source in 2MASS or photographic plate images , implying that the observed secondary component is a co-moving late-type dwarf .
With a projected separation of 11 AU and nearly equal-magnitude components , Gliese 337CD has properties similar to other known companion and field substellar binaries .
Its long orbital period ( estimated to be \sim 140-180 yr ) inhibits short-term astrometric mass measurements , but the Gliese 337CD system is ideal for studying the L/T transition at a fixed age and metallicity .
From a compilation of all known widely separated ( \gtrsim 100 AU ) stellar/brown dwarf multiple systems , we find evidence that the binary fraction of brown dwarfs in these systems is notably higher than that of field brown dwarfs , 45 ^ { +15 } _ { -13 } % versus 18 ^ { +7 } _ { -4 } % for analogous samples .
We speculate on possible reasons for this difference , including the possibility that dynamic ( ejection ) interactions which may form such wide pairs preferentially retain binary secondaries due to their greater combined mass and/or ability to absorb angular momentum .