A REMARKABLE MULTILOBE MOLECULAR OUTFLOW - RHO-OPHIUCHI EAST, ASSOCIATED WITH IRAS 16293-2422

Rho Ophiuchi East is one of the molecular outflows discovered in the Nagoya CO survey of star formation regions (Fukui et al.) and was independently discovered by Wootten and Loren. IRAS 16293-2422 is the driving source of the outflow. We have made a detailed observational study of this outflow source in the J = 1-0 and J = 2-1 transitions of carbon monoxide and in the (J, K) = (1, 1) and (2, 2) transitions of ammonia with angular resolutions of 17″-80″. The high-velocity CO emission has been resolved into four compact separate lobes, consisting of two pairs of bipolar lobes, in addition to an extended monopolar blueshifted lobe. We present four possible interpretations for the multiple distribution of the high-velocity molecular gas: (1) three driving engines, (2) two driving engines with strong time variation, (3) two driving engines, one of which is precessing, and (4) dynamical interaction of the high-velocity gas with the dense cloud core. We show that precession does not reproduce the detailed distribution of the high-velocity gas, and we discuss the importance of the dynamical interaction of the outflow with the ambient molecular gas in formation of the CO lobes. The NH3 cloud has a size of ∼2′.5 × 2′.5, being peaked at 1′.7 east of IRAS 16293-2422. This NH3 peak is located just toward the edge of one of the compact blue CO lobes, showing a blueshift of ∼0.5 km s-1 from the rest of the NH3 cloud. The momentum involved in the NH3 peak is nearly equal to that of the CO lobe. Thus, we suggest that the CO lobe has dynamically interacted with the NH3 core, resulting in the acceleration of the NH3 core by 0.5 km s-1. This provides the first direct evidence for an outflow accelerating interstellar molecular gas, strongly suggesting the dynamical importance of outflow in cloud cores where stars are formed.