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 $J = 3 \rightarrow 2$ transitions of 12 CO and 13 CO, $J = 4 \rightarrow 3$ transitions of HCO + and H 13 CO + , and $J = 7 \rightarrow 6$ 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 $M_{\odot}$; mass outflow rate ~$2\times10^{-2}$ $M_{\odot}$ yr -1 ; momentum ~$2\times10^3$ $M_{\odot}$ km s -1 and kinetic energy ~$9\times 10^{47}$ erg), and has a dynamical time scale of $6\times10^3$ yr. These parameters are consistent with the flow being driven by a young massive stellar object with $L_{\rm bol} \sim 6\times10^4$ $L_{\odot}$.