High Resolution Imaging of Molecular Outflows in Massive Young Stars

We present high angular resolution observations toward two massive star forming regions IRAS 18264-1152 and IRAS 23151+5912 with the Plateau de Bure Interferometer (PdBI) in the SiO (J=2-1) and HCO (J=1-0) lines and at 1.3 mm and 3.4 mm continuum, and with the Very Large Array (VLA) in the NH3 (J,K)=(1,1), (2,2) lines. The NH3 (1,1) and (2,2) emission is detected toward IRAS 18264-1152 only. For IRAS 18264-1152, the SiO observations reveal at least two quasi-perpendicular outflows with high collimation factors, and the most dominant feature is a redshifted jet-like outflow with very high velocities up to about ∆v = 60 kms with respect to the systemic velocity. The veryhigh-velocity component (∆v = 22− 60 kms) of this outflow is spatially offset from its high-velocity (∆v = 3 − 21 kms) component. The SiO line profiles and position-velocity characteristics of these two components suggest that this outflow can be driven by an underlying precessing jet. For IRAS 23151+5912,