Protoplanetary disk data in Cha I and Lupus

We find a correlation between dust disk mass and mass accretion rate in Chamaeleon I with a slope that is close to linear, similar to the one recently identified in Lupus. We investigate the effect of stellar mass and find that the intrinsic scatter around the best-fit M_dust_-M_*_ and dM_acc_/dt-M_*_ relations is uncorrelated.

We simulate synthetic observations of an ensemble of evolving disks using a Monte Carlo approach and find that disks with a constant {alpha} viscosity can fit the observed relations between dust mass, mass accretion rate, and stellar mass but overpredict the strength of the correlation between disk mass and mass accretion rate when using standard initial conditions. We find two possible solutions. In the first one, the observed scatter in M_dust_ and dM_acc_/dt is not primordial, but arises from additional physical processes or uncertainties in estimating the disk gas mass.