The molecular outflow and possible precessing jet from the massive young stellar object IRAS20126+4104


D. Shepherd (1,2), K.C. Yu (3), J. Bally (3), L. Testi (4,2)

(1) National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801, USA

(2) Division of Mathematics, Physics and Astronomy, MS105-24, California Institute of Technology, Pasadena, CA 91125, USA

(3) Center for astrophysics and Space Astronomy, CB 389, University of Colorado, Boulder, CO 80309

(1) Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze, Italy


We present images of the molecular gas in the IRAS20126+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 ar 12.5um and 17.9um, near-infrared images in the Ks band (2.17um) and H2 line emission, and optical Halpha and [SII] images. We show that the molecular outflow is approximately 6x10^4 years old with a mass of about 50-60 Msun and mass outflow rate Mdot_f~8x10^-4 Msun/yr. The driving source is located near the center of the >300 Msun molecular cloud and the mass of the disk plus circumstellar envelope traced by millimeter continuum emission is ~50 Msun. The outflow appears to be bounded on most sides by higher density gas traced by C18O emission. Shocks identified by H2 and [SII] emission knots follow a NW-SE jet close to the young stellar object and then rotate more N-S 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 which precesses through an angle of ~45deg. Possible mechanisms that could produce the jet precession include tidal interactions between the disk and a companion star in a non-coplanar orbit or an anisotropic accretion event that dramatically altered the angular momentum vector of the disk.

Mantained by: Leonardo Testi