We present high-resolution images of the submillimeter SiO line emissions of a massive young stellar object Orion Source I using the Atacama Large Millimeter/ Submillimeter Array (ALMA) at band 8. We detected the 464 GHz SiO v=4 J=11-10 line in Source I, which is the first detection of the SiO v=4 line in starforming regions, together with the 465 GHz 29SiO v=2 J=11-10 and the 428 GHz SiO v=2 J=10-9 lines with a resolution of 50 AU. The 29SiO v=2 J=11-10 and SiO v=4 J=11-10 lines have compact structures with the diameter of 80 AU. The spatial and velocity distribution suggest that the line emissions are associated with the base of the outow and the surface of the edge-on disk. In contrast, SiO v=2 J=10-9 emission shows a bipolar structure in the direction of northeast-southwest low-velocity outow with 200 AU scale. The emission line exhibits a velocity gradient along the direction of the disk elongation. With the assumption of the ring structure with Keplerian rotation, we estimated the lower limit of the central mass to be 7 M and the radius of 12 AU r 26 AU.
|Publication status||Published - Jan 22 2019|
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