Accretion Disks around Young Objects. II. Tests of Well‐mixed Models with ISM Dust

We construct detailed vertical structure models of irradiated accretion disksaround T Tauri stars with interstellar medium dust uniformly mixed with gas.The dependence of the structure and emission properties on mass accretion rate,viscosity parameter, and disk radius is explored using these models. Thetheoretical spectral energy distributions (SEDs) and images for allinclinations are compared with observations of the entire population ofClassical T Tauri stars (CTTS) and Class I objects in Taurus. In particular, wefind that the median near-infrared fluxes can be explained within the errorswith the most recent values for the median accretion rates for CTTS. We furthershow that the majority of the Class I sources in Taurus cannot be Class IIsources viewed edge-on because they are too luminous and their colors would beconsistent with disks seen only in a narrow range of inclinations. Our modelsappear to be too geometrically thick at large radii, as suggested by: (a)larger far-infrared disk emission than in the typical SEDs of T Tauri stars;(b) wider dark dust lanes in the model images than in the images of HH30 and HKTau/c; and (c) larger predicted number of stars extincted by edge-on disks thanconsistent with current surveys. The large thickness of the model is aconsequence of the assumption that dust and gas are well-mixed, suggesting thatsome degree of dust settling may be required to explain the observations.Comment: 41 pages, 13 figures, accepted in Ap