  A sample of 14 pre-main sequence visual binary systems in southern
star-forming regions were imaged at 2 um with the Keck I telescope to search
for tertiary companions, scattered-light disks, and compact nebulae at linear
scales of 5-100 AU. Speckle holography was used to produce images with
diffraction-limited resolution and high dynamic range, and photometry in four
filters between J (1.25 um) and L' (3.8 um) was used to provide a diagnostic of
the infrared excess. Of the 14 visual binary systems studied, 9 contain
components which show evidence for resolved structure. Two of them (WSB 18 and
B59-1) have well-resolved tertiary companions separated from the primary stars
by ~100 mas. The remainder are only marginally resolved at the diffraction
limit of the telescope. Sz 116, AS 205, Elias 2-22, ESO H alpha 282, and B59-2
each have one component which is marginally-resolved along one axis and
unresolved on the perpendicular axis, consistent with tertiaries at separations
between ~6 and 40 mas. If all of these systems are hierarchical triples, then
fully half of the nominal binaries in the sample are triple. The primaries in
Elias 2-49 and WSB 71 are marginally resolved along all position angles,
suggesting the presence of dust halos. No disks were unambiguously detected in
the sample.
