2014ApJ...791..123W

This work reports high spatial resolution observations toward the Orion KL region with high critical density lines of CH₃ CN (12₄-11₄) and CH₃OH (8_-1, 8_–70, 7_), as well as a continuum at ∼1.3 mm band. The observations were made using the Atacama Large Millimeter/Submillimeter Array with a spatial resolution of ∼1.''5 and sensitivity of about 0.07 K and ∼0.18 K for continuum and line, respectively. The observational results showed that the gas in the Orion KL region consists of jet-propelled cores at the ridge and dense cores east and south of the region that are shaped like a wedge ring. The outflow has multiple lobes, which may originate from an explosive ejection, and is not driven by young stellar objects. Four infrared bubbles were found in the Spitzer/IRAC emissions. These bubbles, the distributions of the previously found H₂jets, the young stellar objects, and molecular gas suggest that BN is the explosive center. The burst time was estimated to be ≤ 1300 yr. At the same time, signatures of gravitational collapse toward Source I and the hot core were detected with material infall velocities of 1.5 km/s and ∼0.6 km/s, corresponding to mass accretion rates of 1.2x10^–3 M_☉/yr and 8.0x10^–5 M_☉/yr, respectively. These observations may support the belief that high-mass stars form via the accretion model, similar to their low-mass counterparts.