1998A&A...335..266B

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 outflow driven by the Class 0 object NGC 1333/IRAS 2. Only weak emission has been detected towards the position of the central object, while strong methanol lines have been observed towards the endpoints of the outflow lobes, where the CH₃OH abundance is enhanced by a factor ∼300. The methanol emission is confined in two jets, with a collimation factor of about 20: redshifted emission comes from the south-east lobe, while blueshifted lines are detected towards the north-west. Statistical equilibrium calculations have been used to fit the relative intensities of the observed transitions. These lead us to the conclusion that the ambient gas surrounding the protostar has a density similar to that of the high velocity gas in the shocked regions (∼10⁶cm^–3). Interferometric maps with a resolution of 3" show that the blueshifted lobe consists of several ``bullets'' indicating that episodic mass loss has occurred. The age estimate is ≃2-5x10<sup>3</sup>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 magnetohydrodynamical models where a working surface with a cone-like shape creates elongated naked jets containing bullets in their interior.