The Molecular Outflow and Possible Precessing Jet from the Massive Young Stellar Object IRAS 20126+4104

Abstract

We present images of the molecular gas in the IRAS 20126]4104 massive outÑow and examine the interaction between the energetic outÑowing material and the surrounding molecular cloud. Mosaic interferometric images in CO(1È0), 13CO(1È0), C18O(1È0), C17O(1È0), and millimeter continuum emission are compared with mid-infrared images at 12.5 and 17.9 km, near-infrared images in the band K s (2.17 km) and line emission, and optical Ha and [S II] images. We show that the molecular outÑow H 2 is approximately 6 ] 104 yr old with a mass of about 50È60 and mass outÑow rate M _ M 0 f D 8 ] 10~4 yr~1. The driving source is located near the center of the molecular cloud, and the mass M _ Z300 M _ of the disk plus circumstellar envelope traced by millimeter continuum emission is D50 The M _. outÑow appears to be bounded on most sides by higher density gas traced by C18O emission. Shocks identiÐed by and [S II] emission knots follow a NW-SE jet close to the young stellar object and then H 2 rotate more north-south along the edges of the CO Ñow. The most likely interpretation appears to be that the knots trace the working surfaces of a collimated jet that precesses through an angle of D45¡. Possible mechanisms that could produce the jet precession include tidal interactions between the disk and a companion star in a noncoplanar orbit or an anisotropic accretion event that dramatically altered the angular momentum vector of the disk.