Accretion Disks around T Tauri Stars

The authors examine the proposition that many T Tauri stars are still actively accreting material from a surrounding disk of material formed at the same time as the star. It is shown that the observations are both unified and explained if classical T Tauri stars are chromospherically active pre-main-sequence stars with accretion disks. Contemporaneous optical and ultraviolet observations, along with extensive photometric monitoring in the optical and infrared, are used to test disk models and to show that there is evidence for accretion in the range 5×10^-8 - 5×10^-7M_sun;yr^-1 from stars exhibiting strong ultraviolet excesses. These models also explain the infrared spectrum shortward of 10 μm and the total system luminosities.