We present images of the molecular gas in the IRAS 20126+4104 massive outflow and examine the interaction between the energetic outflowing material and the surrounding molecular cloud. Mosaic interferometric images in CO(1-0), 13CO(1-0), C18O(1-0), C17O(1-0), and millimeter continuum emission are compared with mid-infrared images at 12.5 and 17.9 μm, near-infrared images in the Ks band (2.17 μm) and H2 line emission, and optical Hα and [S II] images. We show that the molecular outflow is approximately 6 × 104 yr old with a mass of about 50-60 M☉ and mass outflow rate f ~ 8 × 10-4 M☉ yr-1. The driving source is located near the center of the 300 M☉ molecular cloud, and the mass of the disk plus circumstellar envelope traced by millimeter continuum emission is ~50 M☉. The outflow appears to be bounded on most sides by higher density gas traced by C18O emission. Shocks identified by H2 and [S II] emission knots follow a NW-SE jet close to the young stellar object and then rotate more north-south along the edges of the CO flow. The most likely interpretation appears to be that the knots trace the working surfaces of a collimated jet that precesses through an angle of ~45°. 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.
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