Extremely high velocity gas from the massive young stellar objects in IRAS?17233-3606

摘要

Context. Molecular outflows from high-mass youngstellar objects provide an excellent way to study the star formationprocess, and investigate if they are scaled-up versions of theirlow-mass counterparts. Aims. We selected the nearby massive star formingregion IRAS17233-3606 in order to study the kinematics andphysics along the molecular outflow(s) originating from this source. Methods. We observed IRAS17233-3606 in CO,a typical tracer of gas associated with molecular outflow, with theSubmillimeter Array in the (2-1) transition, and with the APEXtelescope in the higher excitation (6-5) line. Additional infrared H2observations were performed with the UKIRT telescope. The CO data wereanalysed using a LVG approach. Results. Our data resolve the previously detectedmolecular outflow into at least three different components, one of themwith a high collimation factor (4), and characterised byemission at extremely high velocities ( 120$ -->kms-1).The estimate of the kinematical outflow parameters are typical ofmassive YSOs, and in agreement with the measured bolometric luminosityof the source. The kinematic ages of the flows are in the range102-103yr, andtherefore point to young objects that still have not reached the mainsequence. Key words: ISM: jets and outflows - ISM:molecules - stars: individual: IRAS 17233-3606 - stars: formation