Hot methanol from the inner region of the HH 212 protostellar system
The mechanisms leading to the formation of disks around young stellar objects (YSOs) and to the launching of the associated jets are crucial to the understanding of the earliest stages of star and planet formation. HH 212 is a privileged laboratory to study a pristine jet-disk system. Therefore we investigate the innermost region ( t = 1,2 states) have upper energies above 500 K. They originate from a compact ( uv plane of various velocity channels of the strongest high-excitation lines. The blue- and red-shifted velocity centroids are shifted roughly symmetrically on either side of the jet axis, indicating that the line-of-sight velocity beyond 0.7 km s -1 from systemic is dominated by rotational motions. The velocity increases moving away from the protostar further indicating that the emission of methanol is not associated with a Keplerian disk or rotating-infalling cavity, and it is more likely associated with outflowing gas. We speculate that CH 3 OH traces a disk wind gas accelerated at the base. The launching region would be at a radius of a few astronomical units from the YSO.