Magneto-Centrifugal Origin for Protostellar Jets Validated through
  Detection of Radial Flow at the Jet Base
  Jets can facilitate the mass accretion onto the protostars in star formation.
They are believed to be launched from accretion disks around the protostars by
magneto-centrifugal force, as supported by the detections of rotation and
magnetic field in some of them. Here we report a radial flow of the
textbook-case protostellar jet HH 212 at the base to further support this
jet-launching scenario. This radial flow validates a central prediction of the
magneto-centrifugal theory of jet formation and collimation, namely, the jet is
the densest part of a wide-angle wind that flows radially outward at distances
far from the (small, sub-au) launching region. Additional evidence for the
radially flowing wide-angle component comes from its ability to reproduce the
structure and kinematics of the shells detected around the HH 212 jet. This
component, which can transport material from inner to outer disk, could account
for the chondrules and Ca-Al-rich inclusions detected in the Solar System at
large distances.
