A HIGHLY COLLIMATED, YOUNG, AND FAST CO OUTFLOW IN OMC-1 SOUTH

摘要

We present high angular resolution (～1″), sensitive CO (2-1) line observations of the region OMC-1S in the Orion Nebula made using the Submillimeter Array. We detect the CO (2-1) high-velocity outflow that was first found by Rodriguez-Franco et al. with the IRAM 30 m telescope. Our observations resolve the outflow, whose velocity-integrated emission has a deconvolved width of 0.89″ ± 0.06″ (390 AU) and a projected length of ～48″ (21,000 AU) with very high redshifted and blueshifted gas with velocities of about ±80 km s~(-1). This outflow is among the most collimated (～3°) and youngest outflows (600 yr) that have been reported. The data show that this collimated outflow has been blowing in the same direction during the last 600 years. At high velocities, the CO (2-1) outflow traces an extremely collimated jet, while at lower velocities, the CO emission traces an envelope possibly produced by entrainment of ambient gas. Furthermore, we also detect for the first time a millimeter wavelength continuum source associated with a class Ⅰ protostar that we suggest could be the possible exciting source for this collimated outflow. However, the bolometric luminosity of this source appears to be far too low to account for the powerful molecular outflow.