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Using Science Verification data from the Atacama LargeMillimeter/Submillimeter Array (ALMA), we have identified and imaged fiverotational transitions (J=5-4 and J=6-5) of the three silicon monoxideisotopologues 28SiO v=0, 1, 2 and 29SiO v=0 and 28Si18O v=0 in the frequencyrange from 214 to 246 GHz towards the Orion BN/KL region. The emission of theground-state 28SiO, 29SiO and 28Si18O shows an extended bipolar shape in thenortheast-southwest direction at the position of Radio Source I, indicatingthat these isotopologues trace an outflow (~18 km/s, P.A. ~50deg, ~5000 AU indiameter) that is driven by this embedded high-mass young stellar object (YSO).Whereas on small scales (10-1000 AU) the outflow from Source I has awell-ordered spatial and velocity structure, as probed by Very Long BaselineInterferometry (VLBI) imaging of SiO masers, the large scales (500-5000 AU)probed by thermal SiO with ALMA reveal a complex structure and velocity field,most likely related to the effects of the environment of the BN/KL region onthe outflow emanating from Source I.  The emission of the vibrationally-excited species peaks at the position ofSource I. This emission is compact and not resolved at an angular resolution of~1.5" (~600 AU at a distance of 420 pc). 2-D Gaussian fitting to individualvelocity channels locates emission peaks within radii of 100 AU, i.e. theytrace the innermost part of the outflow. A narrow spectral profile and spatialdistribution of the v=1 J=5-4 line similar to the masing v=1 J=1-0 transition,provide evidence for the most highly rotationally excited (frequency > 200 GHz)SiO maser emission associated with Source I known to date. The maser emissionwill enable studies of the Source I disk-outflow interface with future ALMAlongest baselines.

Outflow Structure and Velocity Field of Orion Source I: ALMA Imaging of SiO Isotopologue Maser and Thermal Emission