Hot Inner Winds from T Tauri Stars

Abstract

P-Cygni components in the Hα and other strong permitted lines have been known in Classical T Tauri Stars for several decades. These features trace mass loss from the source and, in particular, diagnose the mass loss close to the star. However, the exact nature of this mass loss including the driving mechanism and its thermal structure are still not well known. Recently, renewed effort has been expended to constrain the thermal structure of this inner wind in these sources, and there is now evidence that the temperature in these flows reach a few ×10, 000 K. However, there is considerable debate over just how hot these winds get. This contribution provides a review of the observational evidence related to the inner winds of T Tauri stars, focussing on the evidence which constrains the thermal structure of the flow.