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We present observational results of the submillimeter H2O and SiO linestoward a candidate high-mass young stellar object Orion Source I using ALMA.The spatial structures of the high excitation lines at lower-state energies of>2500 K show compact structures consistent with the circumstellar disk and/orbase of the northeast-southwest bipolar outflow with a 100 au scale. Thehighest excitation transition, the SiO (v=4) line at band 8, has the mostcompact structure. In contrast, lower-excitation transitions are more extendedthan 200 au tracing the outflow. Almost all the line show velocity gradientsperpendicular to the outflow axis suggesting rotation motions of thecircumstellar disk and outflow. While some of the detected lines show broadline profiles and spatially extended emission components indicative of thermalexcitation, the strong H2O lines at 321 GHz, 474 GHz, and 658 GHz withbrightness temperatures of >1000 K show clear signatures of maser action.

ALMA observations of submillimeter H2O and SiO lines in Orion Source I