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 out—ow and examine the interaction between the energetic out—owing 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 emis- sion 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 out—ow H 2 is approximately 6 ) 104 yr old with a mass of about 50¨60 and mass out—ow rate M _ M0 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 _ . out—ow appears to be bounded on most sides by higher density gas traced by C18O emission. Shocks identi—ed 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 —ow. The most likely interpretation appears to be that the knots trace the working surfaces of a collimated jet that precesses through an angle of D45i. 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. Subject headings: H II regionsISM: jets and out—owsISM: moleculesstars: formation