HIGH-RESOLUTION IMAGING OF CIRCUMSTELLAR GAS AND DUST IN UZ TAURI - COMPARING BINARY AND SINGLE-STAR DISK PROPERTIES

We present lambda = 1.3 and 3 mm aperture synthesis imaging of the mul tiple T Tauri system UZ Tauri, UZ Tau is a hierarchical triple compose d of a single star, UZ Tau E, 530 AU distant from a 50 AU binary, UZ T an W. Both dust and gas emission from the close binary are at least a factor of four lower than from the single star. Since UZ Tau E and W h ave similar stellar masses, luminosities, and ages, we conclude that t he mass of dust and gas associated with UZ Tau W is reduced solely by the influence of a close companion. The disk emission from UZ Tau E is best interpreted as a circumstellar disk similar to those around othe r single T Tauri stars. In a 1''-resolution aperture synthesis map, CO (2-->1) emission is coincident with the continuum peak and elongated with a size of 300 AU (FWHM); a velocity gradient is seen along the lo ng axis, consistent with rotation in a gaseous disk. The emission is e longated at position angle 19 degrees, the same as the PA of previous polarization measurements. A disk model fit to the continuum spectral energy distribution (SED) of UZ Tau E yields a disk mass of 0.06 M.. I n contrast, no CO emission is detected from UZ Tau W, and its 1.3 mm c ontinuum emission is unresolved in a 1'' (FWHM) beam (corresponding to a 70 AU radius). The small extent of the emission and dynamical consi derations imply that the 50 AU binary cannot be surrounded by any appr eciable circumbinary disk; its mm-wave emission is from circumstellar disks around one or both components. The mass of the circumstellar mat erial is in the range 0.002-0.04 M.; the large uncertainty is due to t he unknown temperature and surface density distributions of the materi al, The properties of the UZ Tau E disk are similar to those inferred for the early solar nebula; such a disk could give rise to a planetary system like our own. The mass of the UZ Tau W disk(s) is only margina lly consistent with a ''minimum mass solar nebula.'' The constraints o n disk size in UZ Tau W indicate that reduced mm-wave flux may be link ed to a disparity in the size of disks (and therefore of planetary sys tems) around single and binary stars. (C) 1996 American Astronomical S ociety.