Molecular and atomic jets in young low-mass stars: Properties and origin

The key characteristics of molecular and atomic ejection from young stars are summarized, with emphasis on similarities across evolutionary stages, and the need for efficient magnetic collimation and ejection extracting a large fraction of the accretion power. The jet kinematics, and its dust and molecular content, are confronted to steady MHD jet models, and the probable contribution of non-steady processes is pointed out.