TRUNCATED DISKS IN TW Hya ASSOCIATION MULTIPLE STAR SYSTEMS

We present high angular resolution (down to 0.''3 ∼ 13 AU in diameter) Submillimeter Array observations of the 880 μm (340 GHz) thermal continuum emission from circumstellar dust disks in the nearby HD 98800 and Hen 3-600 multiple star systems. In both cases, the dust emission is resolved and localized around one stellar component-the HD 98800B and Hen 3-600A spectroscopic binaries-with no evidence for circum-system material. Using two-dimensional Monte Carlo radiative transfer calculations, we compare the Submillimeter Array interferometer visibilities and broadband spectral energy distributions with truncated disk models to empirically locate the inner and outer edges of both disks. The HD 98800B disk appears to be aligned with the spectroscopic binary orbit, is internally truncated at a radius of 3.5 AU, and extends to only 10-15 AU from the central stars. The Hen 3-600A disk is slightly larger, with an inner edge at ∼1 AU and an outer radius of 15-25 AU. These inferred disk structures compare favorably with theoretical predictions of their truncation due to tidal interactions with the stellar companions.