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 interferometric observations of 33 young star systems located in Taurus-Auriga. Our goal was to compare the distribution, and hence the evolution, of the circumstellar material around young star singles and binaries. The sample included 2 triples, 16 binaries, 14 singles, and one object of unknown multiplicity. We detected 2.7 mm continuum emission in 12 systems 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 continuum decreased from similar to 30 mJy to similar to 0 mJy in less than six months. We find that the singles are, on average, stronger 2.7 continuum sources than the multiples, consistent with Osterloh & Beckwith's (1995) finding at 1.3 mm. Significant estimates of the sizes have been obtained for 8 singles. They imply large (R > 150 AU) disks, with 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) with 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 emission, 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 circumstellar disk scenario, we find that, in all cases, disk masses derived 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 limit.