  A combination of high-resolution and wide-field imaging reveals two binary
stars and one triple star system among the sample of the first 11 stars with
planets detected by radial velocity variations. High resolution speckle or
adaptive optics (AO) data probe subarcsecond scales down to the diffraction
limit of the Keck 10-m or Lick 3-m, and direct images or AO images are
sensitive to a wider field, extending to 10" or 38", depending upon the camera.
One of the binary systems -- HD 114762 -- was not previously known to be a
spatially resolved multiple system; additional data taken with the combination
of Keck adaptive optics and NIRSPEC are used to characterize the new companion.
The second binary system -- Tau Boo -- was a known multiple with two
conflicting orbital solutions; the current data will help constrain the
discrepant estimates of periastron time and separation. Another target -- 16
Cyg B -- was a known common proper motion binary, but the current data resolve
a new third component, close to the wide companion 16 Cyg A. Both the HD 114762
and 16 Cyg B systems harbor planets in eccentric orbits, while the Tau Boo
binary contains an extremely close planet in a tidally-circularized orbit.
Although the sample is currently small, the proportion of binary systems is
comparable to that measured in the field over a similar separation range.
Incorporating the null result from another companion search project lowers the
overall fraction of planets in binary systems, but the detections in our survey
reveal that planets can form in binaries separated by less than 50 AU.
