Colors of classical T Tauri stars in Taurus derived from Spitzer infrared spectrograph spectra:: Indication of dust settling

We analyzed Spitzer Infrared Spectrograph data of a representative sample of classical T Tauri stars in the Taurus star-forming region by computing color indices in wave bands that characterize the continuum emission from dust in circumstellar disks. We compared these indices to those derived from a grid of accretion disk models with varying inclination angles, mass accretion rates, and amounts of dust settling. We conclude that most T Tauri stars in our sample have experienced some degree of dust settling and grain growth in their disks, indicating disk evolution.