Oral Presentation
title : Massive Star Formation in the Galactic Center 50km/s Molecular Cloud revealed by ALMA
Presenter: Kenta Uehara (The University of Tokyo)
The Galactic Center(GC) 50km/s Molecular Cloud (50MC) is a most remarkable molecular cloud in the SgrA region and appears to include several compact HII regions. In our previous work, the half-shell-like shock structure with a high brightness temperature ratio of TR=TB(SiO)/TB(H13CO+) has been discovered in the 50MC. This cloud is thought to be a candidate for the massive star formation induced by cloud-cloud collision(CCC) from the difference in the slope of the core mass function (CMF) of the identified molecular cloud cores identified the CS(J=1-0) emission line. We observed the whole of the 50MC with a high angular resolution (~1.5”x1.5”) in ALMA cycle1 using the SiO(v=0,J=2-1) and H13CO+(J=1-0) emission lines. As a result, the half-shell-like shock structure of the high TR was confirmed. Since the angular resolution in this work is 10 times or more higher than that in the previous work, the detailed shock structure is also clarified. Additionally, we identified 267 dense molecular cloud cores from the H13CO+ map using the clumpfind algorithm. The number of the identified cores in this data is 7 times larger than that in the previous work. the CMF in the high TR region shows a top-heavy distribution, while the CMF in the low TR region shows a usual power-law distribution as in the Orion A cloud. In addition to these results, we will also present the positional relation with the methanol masers and discuss the massive star formation triggered by the CCC.
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