The massive molecular outflow from CRL 2136 IRS 1

Maps of rotational CO emission toward the star-formation region CRL 2136 reveal an arcminute-scale bipolar outflow that appears to be driven by the massive young stellar objects IRS 1. The projected outflow axis is roughly perpendicular to the disk plane previously inferred from near-infrared images and polarization maps. High-velocity wings are present in both (12)CO and (13)CO spectra, suggesting the (12)CO optical depths in the outflowing gas are large; we estimate the high-velocity gas contains approximately 50 solar mass, making this molecular outflow one of the more massive known. We find that the region within approximately 1 min of CRL 2136 constitutes a significant concentration of the molecular mass in the ambient cloud. Submillimeter photometry and mapping shows that CRL 2136 is a strong, extended source of continuum emission. The emission likely arises with grains heated to 40-60 K by IRS 1. Comparison of the estimated thermal dust mass (approximately 1 solar mass within approximately 8 sec of IRS 1), the mass in high-velocity gas, and the scattering dust mass we derived previously suggests that the gas-to-dust mass ratio in the outflow is between approximately 10 and approximately 100, where the value depends on what proportion of the submillimeter emission originates with dust in the ambient cloud and/or circumstellar disk. The apparent extreme youth of IRS 1 compared with the dynamical age of the outflow, and the tremendous mass of swept-up molecular material, suggests the outflow began early in the formation of the young stellar object and implies the outflow cannot be radiatively driven. We present evidence that infall toward IRS 1 is ongoing; transfer of angular momentum from this infalling material may drive the outflow.