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The Australia Telescope Compact Array has been used to make the first extensive search for the class I methanol masers at 9.9 GHz. In total, 48 regions of high-mass star formation were observed. In addition to masers in W33-Met (G12.80−0.19) and G343.12−0.06 (IRAS 16547−4247) which have already been reported in the literature, two new 9.9-GHz masers have been found towards G331.13−0.24 and G19.61−0.23. We have determined absolute positions (accurate to roughly a second of arc) for all the detected masers and suggest that some class I masers may be associated with shocks driven into molecular clouds by expanding HII regions. Our observations also imply that the evolutionary stage of a high-mass starforming region when the class I masers are present can outlast the stage when the class II masers at 6.7-GHz are detectable, and overlaps significantly with the stage when OH masers are active.

Item Type:	Refereed Article
Keywords:	masers – stars: formation – ISM: HII regions – ISM: molecules.
Research Division:	Physical Sciences
Research Group:	Astronomical and Space Sciences
Research Field:	Galactic Astronomy
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Physical Sciences
Author:	Ellingsen, SP (Professor Simon Ellingsen)
ID Code:	65440
Year Published:	2010
Web of Science® Times Cited:	43
Deposited By:	Physics
Deposited On:	2010-11-16
Last Modified:	2011-03-23
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