The ejection-accretion connection in young stars: Testing MHD disk winds

Jets are ubiquitous in young accreting stars at all evolutionary stages, from deeply embedded protostars aged less than 0.1Myr to optically revealed 10Myr old T Tauri stars. The similar jet collimation at all ages is shown to require an effective magnetic collimation within the inner disk regions (inside 20 AU). This fact, and the high ejection to accretion ratio _ 10%, appear to favor the presence of MHD disk winds. Ejection out to > 0.1 AU could explain the velocity drop and rotation signatures across the jets, and their dust and molecular content.