Resolved Inner Jets from T Tauri Stars

Abstract

Understanding how jets are generated around an accreting object is of wide interest to the astrophysical community. A viable way to test observationally the proposed theories is to investigate the inner regions of jets emanated by nearby young stars in the T Tauri phase, that are not deeply embedded anymore in the formation material. Instruments working at sub-arcsecond angular resolution, like those on-board the Hubble Space Telescope, or mounted at ground-based telescopes equipped with Adaptive Optics, allow us to probe the flows in their acceleration and collimation region. The application to these data of new methodologies of analysis and spectral diagnostics have brought an impressive wealth of morphological, kinematical and physical information, providing the most stringent constraints to date for the various models. Here the recent determinations of jet widths, velocity fields, gas excitation parameters and mass outflow rates are reviewed. In addition, a critical discussion is offered on the available indications for jet rotation, i.e. that jets may indeed transport the excess angular momentum away from the system.