A submillimeter view of circumstellar dust disks in ρ Ophiuchi

We present new multiwavelength submillimeter continuum measurements of the circumstellar dust around 48 young stars in the rho Ophiuchi dark clouds. Supplemented with previous 1.3 mm observations of an additional 99 objects from the literature, the statistical distributions of disk masses and submillimeter colors are calculated and compared to those in the Taurus-Auriga region. These basic submillimeter properties of young stellar objects in both environments are shown to be essentially identical. As with their Taurus counterparts, the rho Oph circumstellar dust properties are shown to evolve along an empirical evolution sequence based on the infrared spectral energy distribution. The combined rho Oph and Taurus Class II samples (173 sources) are used to set benchmark values for basic outer disk characteristics: M-d similar to 0.005M(circle dot), M-d/M-* similar to 1%, and alpha similar to 2 (where F-nu proportional to nu(alpha) between 350 mu m and 1.3mm). The precision of these numbers is addressed in the context of substantial solid particle growth in the earliest stages of the planet formation process. There is some circumstantial evidence that disk masses inferred from submillimeter emission may be underestimated by up to an order of magnitude.