2009ApJ...696...66Q

We present Submillimeter Array observations toward the 10^4.7 L_☉ star-forming region G240.31+0.07, in the J = 2-1 transition of ¹²CO and ¹³CO and at 1.3 mm continuum, as well as the ¹²CO and ¹³CO observations from the Caltech Submillimeter Observatory to recover the extended emission filtered out by the interferometer. Maps of the ¹²CO and ¹³CO emission show a bipolar, wide-angle, quasi-parabolic molecular outflow, roughly coincident with an infrared nebula revealed by the Spitzer 3.6 and 4.5 µm emission. The outflow has ∼98 M_☉ molecular gas, making it one of the most massive molecular outflows known, and resulting in a very high mass-loss rate of 4.1x10^–3 M_☉/yr over a dynamical timescale of 2.4x10⁴ yr. The 1.3 mm continuum observations with a 4''x3'' beam reveal a flattened dusty envelope of ∼150 M_☉, which is further resolved with a 1".2 x 1'' beam into three dense cores with a total mass of ∼40 M_☉. The central mm core, showing evidence of active star formation, approximately coincides with the geometric center of the bipolar outflow thus most likely harbors the powering source of the outflow. Overall, our observations provide the best case to date of a well defined wide-angle molecular outflow in a higher than 10⁴ L_☉star-forming region. The outflow is morphologically and kinematically similar to low-mass protostellar outflows but has two to three orders of magnitude greater mass, momentum, and energy, and is apparently driven by an underlying wide-angle wind, hence further supports that high-mass stars up to late-O types, even in a crowded clustering environment, can form as a scaled-up version of low-mass star formation.