THE MASSIVE MOLECULAR OUTFLOW FROM CRL-2136-IRS-1

Maps of rotational CO emission toward the star-formation region CRL 21 36 reveal an arcminute-scale bipolar outflow that appears to be driven by the massive young stellar object IRS 1. The projected outflow axis is roughly perpendicular to the disk plane previously inferred from n ear-infrared images and polarization maps. High-velocity wings are pre sent in both (CO)-C-12 and (CO)-C-13 spectra, suggesting the (CO)-C-12 optical depths in the outflowing gas are large; we estimate the high- velocity gas contains similar to 50 M., making this molecular outflow one of the more massive known. We find that the region within similar to 1' of CRL 2136 constitutes a significant concentration of the molec ular mass in the ambient cloud. Submillimeter photometry and mapping s hows 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. Co mparison of the estimated thermal dust mass (similar to 1 M. within si milar to 8'' of IRS 1), the mass in high-velocity gas, and the scatter ing dust mass we derived previously suggests that the gas-to-dust mass ratio in the outflow is between similar to 10 and similar to 100, whe re the value depends on what proportion of the submillimeter emission originates with dust in the ambient cloud and/or circumstellar disk. T he apparent extreme youth of IRS 1 compared with the dynamical age of the outflow, and the tremendous mass of swept-up molecular material, s uggests the outflow began early in the formation of the young stellar object and implies the outflow cannot be radiatively driven. We presen t evidence that infall toward IRS 1 is ongoing; transfer of angular mo mentum from this infalling material may drive the outflow.