The evolution of young stars, protostellar jets & bipolar outflows - A unification scheme

Close links between jet evolution and protostellar evolution are beginning to be understood. Firstly, stellar jets are reviewed here, establishing the accretion-outflow connection. Then, outflows from young stars are reviewed, suggesting a synchronised development in the star and outflow. This yields a unification scheme in which rising molecular jets dominate the early protostellar epoch, followed by a jet-driven outflow stage and, finally, a bow-driven ballistic stage. This scheme is quantified, yielding the systematic changes in the bolometric, mechanical and shock luminosities and the cross-over phase from dense molecular jets to light atomic jets.