Infall and Outflow around the Hh 212 Protostellar System

HH 212 is a highly collimated jet discovered in H2 powered by a young Class 0 source, IRAS 054130104, in the L1630 cloud of Orion. We have mapped around it in 1.33 mm continuum, CO (J = 2−1), CO (J = 2 − 1), CO (J = 2 − 1), and SO (JK = 65 − 54) emission at ∼ 2.5 ′′ resolution with the Submillimeter Array. A dust core is seen in the continuum around the source. A flattened envelope is seen in CO around the source in the equator perpendicular to the jet axis, with its inner part seen in CO. The structure and kinematics of the envelope can be roughly reproduced by a simple edge-on disk model with both infall and rotation. In this model, the density of the disk is assumed to have a power-law index of p = −1.5 or −2, as found in other low-mass envelopes. The envelope seems dynamically infalling toward the source with slow rotation because the kinematics is found to be roughly consistent with a free fall toward the source plus a rotation of a constant specific angular momentum. A CO outflow is seen surrounding the H2 jet, with a narrow waist around the source. Jetlike structures are also seen in CO near the source aligned with the H2 jet at high velocities. The morphological relationship between the H2 jet and the CO outflow, and the kinematics of the CO outflow along the jet axis are both consistent with those seen in a jet-driven bow shock model. SO emission is seen around the source and the H2 knotty shocks in the south, tracing shocked emission around them. Subject headings: stars: formation — ISM: individual: HH 212 — ISM: jets and outflows.