METHANOL IN PROTOSTELLAR OUTFLOWS - SINGLE-DISH AND INTERFEROMETRIC MAPS OF NGC-1333 IRAS-2

We report high-resolution mapping observations of the 2(k)-1(k), 3(k)- 2(k), and 5(k)-4(k) thermal lines of CH3OH toward the young bipolar ou tflow driven by the Class 0 object NGC 1333/IRAS 2. Only weak emission has been detected towards the position of the central object, while s trong methanol lines have been observed towards the endpoints of the o utflow lobes, where the CH3OH abundance is enhanced by a factor simila r to 300. The methanol emission is confined in two jets, with a collim ation factor of about 20: redshifted emission comes from the south-eas t lobe, while blueshifted lines are detected towards the north-west. S tatistical equilibrium calculations have been used to fit the relative intensities of the observed transitions. These lead us to the conclus ion that the ambient gas surrounding the protostar has a density simil ar to that of the high velocity gas in the shocked regions (similar to 10(6) cm(-3)). Interferometric maps with a resolution of 3 '' show th at the blueshifted lobe consists of several ''bullets'' indicating tha t episodic mass loss has occurred. The age estimate is similar or equa l to 2-5 10(3) yr. The high-velocity redshifted emission comes from a structure which becomes ''V-like'' at velocities close to that of the ambient gas. These results fit nicely with recent magnetohydrodynamica l models where a working surface with a cone-like shape creates elonga ted naked jets containing bullets in their interior.