NEARBY SOLAR-TYPE STAR WITH A LOW-MASS COMPANION - NEW SENSITIVITY LIMITS REACHED USING SPECKLE IMAGING

We have imaged the low-mass companion to the nearby solar-type star Gliese 67 using two-dimensional infrared speckle imaging techniques. The binary has been resolved at J (1.25-mu-m), H (1.65-mu-m), and K (2.2-mu-m), allowing us to determine the magnitudes and colors of the components. In observations spanning 14 months, the secondary has been found at separations and position angles predicted by the astrometric orbit, and we calculate the component masses to be 0.97 and 0.29 M.. With a magnitude difference of 4.5 mag at K, these observations define a new sensitivity limit for companions at subarcsecond scales, 6-9 AU for the observations reported here of the Gliese 67 system. For the G dwarf/M dwarf pair, this brightness ratio corresponds to 7.5 mag at V, or a flux ratio of 1000. The data indicate that even greater sensitivity is possible, to companions six magnitudes fainter than their primaries in the infrared, thereby allowing us to search for very low-mass secondaries (approximately 0.1 M.) orbiting nearby solar-type stars.