MILLIMETER-WAVE CONTINUUM MEASUREMENTS OF YOUNG STARS

New continuum observations at 1.3 mm of 121 young stars are presented; the majority of these objects have not been previously observed. The stars which are detected are interpreted assuming that the emission is thermal radiation from small particles entrained in circumstellar dis ks. Several new conclusions are drawn. 1. The presence of a companion star clearly affects the millimeter-wave continuum emission and, by im plication, the disks. Companions closer than about 100 AU inhibit disk formation. 2. Weak-line and naked T Tauri stars do, in fact, have les s millimeter-wave emission than classical T Tauri stars. It appears th at the reason is an absence of even cold particles, not simply lower l uminosities for an otherwise large reservoir of particles. An equivale nt width for H alpha of 0.4 nm appears to be a natural dividing line b etween detected and nondetected sources. 3. Within the uncertainties, there is no difference between the distribution of disk masses in the Cepheus IV association and Taurus-Auriga. 4. With better sensitivity, the distribution of disk masses can be seen to extend down below the a pproximate limit of 0.01 M. determined in the survey of Beckwith et al . (1990).