ALMA CO observations of a giant molecular cloud in M 33: Evidence for high-mass star formation triggered by cloud-cloud collisions
Abstract
We report the first evidence for high-mass star formation triggered by collisions of molecular clouds in M 33. Using the Atacama Large Millimeter/submillimeter Array, we spatially resolved filamentary structures of giant molecular cloud 37 in M 33 using 12CO(J = 2-1), 13CO(J = 2-1), and C18O(J = 2-1) line emission at a spatial resolution of ∼2 pc. There are two individual molecular clouds with a systematic velocity difference of ∼6 km s-1. Three continuum sources representing up to ∼10 high-mass stars with spectral types of B0V-O7.5V are embedded within the densest parts of molecular clouds bright in the C18O(J = 2-1) line emission. The two molecular clouds show a complementary spatial distribution with a spatial displacement of ∼6.2 pc, and show a V-shaped structure in the position-velocity diagram. These observational features traced by CO and its isotopes are consistent with those in high-mass star-forming regions created by cloud-cloud collisions in the Galactic and Magellanic Cloud H II regions. Our new finding in M 33 indicates that cloud-cloud collision is a promising process for triggering high-mass star formation in the Local Group.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- January 2021
- DOI:
- 10.1093/pasj/psaa045
- arXiv:
- arXiv:1908.08404
- Bibcode:
- 2021PASJ...73S..62S
- Keywords:
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- ISM: H ii regions;
- ISM: individual objects (M 33;
- M 33GMC 37);
- stars: formation;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 13 pages, 10 figures, 1 table, accepted for publication in PASJ