Accretion shocks and winds in T Tauri stars

Abstract

The dynamics of accretion and outflow in the T Tauri stars (TTSs) is expected to be associated with the production of shocks. Accretion shocks are expected to occur at the locations on the stellar surface where the kinetic energy of the infalling material is released into heating. Wind shocks are expected to be generated in the wind, at the base of the high velocity jets. Both types of shocks are expected to occur at velocities of some few hundreths of km/s and high densities (> 10(6) cm(-3)) producing strong semiforbidden lines of O III], C III] and Si III] in the ultraviolet range. High resolution profiles of the Si III](1892) and C III](1908) lines are available for three pre-main sequence stars (AB Dor, RY Tau, RU Lup) in the IUE and BST Archives. In this contribution, evidence for shocks in the circumstellar environment of these sources is presented. In two out of the three cases studied, the shock is observed to occur in the wind, at the base of the optical jet. This is estimated to be at 0.2 AU from the base of the wind for RY Tau.