A Multiwavelength Study of Outflows in OMC-2/3

Abstract

We present new ? = 1-0 S(1) H 2, 12CO J = 2 ? 1, and 12CO J = 3 ? 2 observations of the star-forming clouds OMC-2 and OMC-3, one of the densest known groupings of outflows from low-mass young stellar objects (YSOs) in the sky. High-velocity 12CO J = 2 ? 1 gas in this region suggests that previously discovered H 2 flows are driving and entraining molecular outflows. However, the large number of sources and flows within the narrow molecular filament means it is difficult to make a firm association of molecular outflow gas with H 2 flows, except for in the case of the bipolar east-west H flow. A number of Herbig-Haro (HH) objects, including ones far to the west and east of the main ridge, are identified with H 2 knots. High-resolution spectroscopy in the ? = 1-0 S(1) line of 10 H 2 knots shows line profiles consistent with dual forward and reverse shocks. C-shock modeling suggest that asymmetries seen in suspected bow shocks could be evidence of varying magnetic field orientations throughout the cloud. One of the bow shocks in the H flow, YBD-5, can be successfully modeled by a 100 km s -1 C-shock propagating into a magnetized, 10 6 cm -3 medium, although the observations and limitations within the computer code itself do not entirely rule out J-shocks. Mass spectra of the H flow are broken power laws, which might be evidence for a jet that has two entrainment mechanisms for accelerating ambient molecular gas into the outflow. The H 2 luminosity in this flow is many times smaller than the CO mechanical luminosity, but this fact cannot rule out the possibility that a narrow highly collimated jet drives the molecular outflow, owing to uncertainties in extinction, outflow dynamic times, cooling contributions from other lines, and the wind model used. Outflows from OMC-2/3 are likely to contribute to the turbulent pumping of gas within the molecular ridge north of the Orion Nebula. High-velocity gas clumps north of the sources investigated here may represent evidence of additional undiscovered outflows from young stars.