Wide‐Angle Wind‐driven Bipolar Outflows: High‐Resolution Models with Application to Source I of the Becklin‐Neugebauer/Kleinmann‐Low OMC‐I Region

We carry out high resolution simulations of the inner regions of a wide anglewind driven bipolar outflow using an Adaptive Mesh Refinement code. Our codefollows H-He gas with molecular, atomic and ionic components and the associatedtime dependent molecular chemistry and ionization dynamics with radiativecooling. Our simulations explore the nature of the outflow when a sphericalwind expands into a rotating, collapsing envelope. We compare with keyobservational properties of the outflow system of Source I in the BN/KL region. Our calculations show that the wind evacuates a bipolar outflow cavity in theinfalling envelope. We find the head of the outflow to be unstable and that itrapidly fragments into clumps. We resolve the dynamics of the strong shearlayer which defines the side walls of the cavity. We conjecture that this layeris the likely site of maser emission and examine its morphology and rotationalproperties. The shell of swept up ambient gas that delineates the cavity edgeretains its angular momentum. This rotation is roughly consistent with thatobserved in the Source I SiO maser spots. The observed proper motions andline-of-sight velocity are approximately reproduced by the model. The cavityshell at the base of the flow assumes an X-shaped morphology which is alsoconsistent with Source I. We conclude that the wide opening angle of theoutflow is evidence that a wide-angle wind drives the Source I outflow and nota collimated jet.Comment: 27 pages, 10 figure