Wind-disk shocks around T Tauri stars

It is suggested that the winds of T Tauri stars are heated at distances of 50-100 AU by oblique shocks with circumstellar disks, producing the observed high-velocity forbidden-line emission. The low shock velocities characteristic of this model provide low-excitation emission and line profiles in reasonable agreement with observations. The blueshifted character of the observed emission is explained by a combination of disk occultation of the receding flow, plus a modest collimation of the observable wind by the disk envelope. Instabilities at the wind-disk interface may be important in producing the observed emission.