Date : 7/18 (Wed) [15:00 - ] @F313
Speaker: Dr. Tomoya Hirota (NAOJ)
Title : High Resolution Radio Observations of the Heart of Orion Nebula
Abstract: The Orion Nebula is known as the nearest site of high-mass star formation at a distance of 420 pc. Among a number of newly born stars, the Radio Source I is recognized as an intriguing high mass protostar candidate driving powerful outflows, and hence, it can be one of the ideal laboratories for high-mass star-formation studies. By using VERA, we have measured the accurate distance and revealed spatial and velocity structures of Source I traced by the vibrationally excited SiO masers. It shows rotating and expanding motions around the circumstellar disk. The enclosed mass is estimated to be 8 Solar masses assuming the Keplerian rotation. In the subsequent recent ALMA observations, we have detected submillimeter H2O and SiO lines including high excitation vibrational transitions. The lower and higher excitation lines reveal the NE-SW bipolar outflow and the rotating disk with the diameter of 100~AU, respectively. Both of the disk and outflow show the rotation motions consistent with the SiO maser data taken with VERA. Our results suggest that the rotation of the outflow can be explained by a magneto-centrifugal disk wind model. In this talk, I will review our high-resolution observations of Source I and discuss details of its dynamical properties.


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