DUST AND GAS-DISTRIBUTION AROUND T-TAURI STARS IN TAURUS-AURIGA .1. INTERFEROMETRIC 2.7 MM CONTINUUM AND (CO)-C-13 J=1-0 OBSERVATIONS

We present new (CO)-C-13 J = 1 --> 0 and 2.7 mm continuum interferomet ric observations of 33 young star systems located in Taurus-Auriga. Ou r goal was to compare the distribution, and hence the evolution, of th e circumstellar material around young star singles and binaries. The s ample included 2 triples, 16 binaries, 14 singles, and one object of u nknown multiplicity. We detected 2.7 mm continuum emission in 12 syste ms at S/N > 5 and have probable detections for another 5. V 773 Tau, a weak emission line binary system, is remarkable in that its 2.7 mm co ntinuum decreased from similar to 30 mJy to similar to 0 mJy in less t han six months. We find that the singles are, on average, stronger 2.7 continuum sources than the multiples, consistent with Osterloh & Beck with's (1995) finding at 1.3 mm. Significant estimates of the sizes ha ve been obtained for 8 singles. They imply large (R > 150 AU) disks, w ith relatively flat density distribution (emissivity flatter than tau( -1.5)). The spectral energy distributions in the millimeter range can be fitted using a dust emissivity law K(n)u proportional to nu(beta) w ith value of beta in the range 0.5 to 1. Only DG Tau, Hare 6-5b and UY Aur have detectable (CO)-C-13 J = 1 --> 0 emission. (CO)-C-13 emissio n, but no 2.7 mm continuum, is also found in the LkH alpha 332 region and near FS Tau; however, it does not appear to be associated with the known stars. Interpreting the observational results in terms of the c ircumstellar disk scenario, we find that, in all cases, disk masses de rived from the dust emission at 2.7 mm are more than a factor of about 20 larger than the masses derived from the(13)CO J = 1 --> 0 upper li mit.