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Abstract

The University of Tasmania Mt Pleasant 26-m and Ceduna 30-m radio telescopes
have been used to search for 6.7-GHz class II methanol masers towards two hundred
GLIMPSE sources. The target regions were selected on the basis of their mid-infrared
colours as being likely to be young high-mass star formation regions and are either
bright at 8.0 μm, or have extreme [3.6]-[4.5] colour. Methanol masers were detected
towards 38 sites, nine of these being new detections. The prediction was that approximately
20 new 6.7-GHz methanol masers would be detected within 3.5 arcmin of
the target GLIMPSE sources, but this is the case for only six of the new detections.
A number of possible reasons for the discrepancy between the predicted and actual
number of new detections have been investigated. It was not possible to draw any
firm conclusions as to the cause, but it may be because many of the target sources
are at an evolutionary phase prior to that associated with 6.7-GHz methanol masers.
Through comparison of the spectra collected as part of this search with those in the
literature, the average lifetime of individual 6.7-GHz methanol maser spectral features
is estimated to be around 150 years, much longer than is observed for 22-GHz water
masers.

Item Type:	Article
Authors/Creators:	Ellingsen, SP
Keywords:	words: masers – stars:formation – ISM: molecules – radio lines : ISM
Journal or Publication Title:	Monthly Notices of the Royal Astronomical Society
Publisher:	Blackwell Publishing
ISSN:	0035-8711
DOI / ID Number:	https://doi.org/10.1111/j.1365-2966.2007.11615.x
Additional Information:	The definitive version is available at www.blackwell-synergy.com
Item Statistics:	View statistics for this item

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