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Abstract
We present 800 $\mu$m photometry of pre-main-sequence binary stars. Combining our observations with published photometry, we find that binaries with projected separations between 1 and 50-100 AU have lower submillimeter fluxes than wider binaries or single stars, implying reduced disk masses. These data do not necessarily imply a reduction in disk surface densities outside of cleared gaps. IRAS 60 $\mu$m fluxes show that most binaries have circumstellar disks.
We then present $\lambda$ = 1.3 and 3 mm imaging of UZ Tauri, a quadruple composed of a spectroscopic binary, UZ Tau E, 530 AU distant from a 50 AU binary, UZ Tau W. Both dust and gas emission from UZ Tau W are a factor of four lower than from UZ Tau E, implying that the disk mass associated with UZ Tau W is reduced solely by the influence of a companion with a separation comparable to a typical disk radius. The disk emission from UZ Tau E is similar to that from single T Tauri stars, with strong CO emission and a disk mass of 0.06 $M\sb\odot$. No CO emission is detected from UZ Tau W; it has no appreciable circumbinary disk, and it has one or two circumstellar disks with masses in the range of 0.002-0.04 $M\sb\odot$.
Finally, we present a study of disk clearing by pre-main-sequence binaries with separations less than 1 AU. Several binaries have spectral energy distributions (SEDs) with little near-infrared excess, requiring that their inner disks be optically thin. Other binaries show large near- and mid-infrared excesses; however, the excesses in these binaries can be reproduced by a model in which a gap is cleared but is filled with very low-surface-density dust. Thus, all binaries studied show SEDs that are consistent with (but in some cases do not require) the presence of cleared regions in their disks at the predicted locations.
We conclude that most pre-main-sequence binaries have disks. Binaries with separations comparable to typical disk radii have greatly reduced disk masses, while binaries with much larger or smaller separations can retain disks that are similar to those around single stars.
