A study of dynamical processes in the Orion KL region using ALMA-- Probing molecular outflow and inflow

Abstract

This work reports a high spatial resolution observations toward Orion KL region with high critical density lines of CH${}_3$CN (12${}_4$-11${}_4$) and CH${}_3$OH (8${}_{-1,8}$-7${}_{0,7}$) as well as continuum at $\sim$1.3 mm band. The observations were made using the Atacama Large Millimeter/Submillimeter Array with a spatial resolution of $\sim$1.5${}^{\prime \prime }$ and sensitives about 0.07 K and $\sim$0.18 K for continuum and line, respectively. The observational results showed that the gas in the Orion KL region consists of jet-propelled cores at the ridge and dense cores at east and south of the region, shaped like a wedge ring. The outflow has multiple lobes, which may originate from an explosive ejection and is not driven by young stellar objects. Four infrared bubbles were found in the Spitzer/IRAC emissions. These bubbles, the distributions of the previously found H${}_2$ jets, the young stellar objects and molecular gas suggested that BN is the explosive center. The burst time was estimated to be $\le$ 1300 years. In the mean time, signatures of gravitational collapse toward Source I and hot core were detected with material infall velocities of 1.5 km~s${}^{-1}$ and $\sim$ 0.6 km~s${}^{-1}$, corresponding to mass accretion rates of 1.2$\times$10${}^{-3}$M$_{\sun}$/Yr and 8.0$\times$10${}^{-5}$M$_{\sun}$/Yr, respectively. These observations may support that high-mass stars form via accretion model, like their low-mass counterparts.

arXiv commentAccepted to ApJ

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