Discovery of an energetic bipolar molecular outflow towards IRAS 16547-4247

Abstract

Aims. We present molecular line observations of the molecular core associated with IRAS 16547-4247, which have allowed us to determine its physical and kinematical properties at angular resolutions of ∼18″. Methods. The observations were made using the Atacama Pathfinder Experiment Telescope in the J = 3 → 2 transitions of 12CO and 13CO, J = 4 → 3 transitions of HCO+ and H13CO+, and J = 7 → 6 transition of CS. Results. Our observations reveal the presence of a collimated bipolar outflow with lobes ∼0.7 pc in extent and aligned with the thermal jet located at the center of the core. The morphology and velocity structure of the flow are well described by a biconical outflow that is inclined from the line of sight by an angle of 84°, has a semi-opening angle of 14°, and in which the gas moves outwards with a constant total velocity, with respect to the cone apex, of ∼ 120 km s-1. The outflow is massive and energetic (flow mass ∼ 110 M⊙; mass outflow rate ∼2 × 10-2 M⊙ yr-1; momentum ∼2 × 103 M⊙ km s-1 and kinetic energy ∼9 × 1047 erg), and has a dynamical time scale of 6 × 103 yr. These parameters are consistent with the flow being driven by a young massive stellar object with Lbol ∼ 6 × 104 L⊙. © ESO 2007.