A STUDY OF DYNAMICAL PROCESSES IN THE ORION KL REGION USING ALMA-PROBING MOLECULAR OUTFLOW AND INFLOW

This work reports high spatial resolution observations toward the Orion KL region with high critical density lines of CH3CN (124-114) and CH3OH (8-1,8-70,7), as well as a continuum at similar to 1.3 mm band. The observations were made using the Atacama Large Millimeter/Submillimeter Array with a spatial resolution of similar to 1.'' 5 and sensitivity of about 0.07 K and similar to 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 H-2 jets, the young stellar objects, and molecular gas suggest that BN is the explosive center. The burst time was estimated to be similar to 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(-1) and similar to 0.6 km s(-1), corresponding to mass accretion rates of 1.2 x 10-3M(circle dot)/yr and 8.0 x 10-5M(circle dot)/yr, respectively. These observations may support the belief that high-mass stars form via the accretion model, similar to their low-mass counterparts.