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Statistical properties of 12.2 GHz methanol masers associated with a complete sample of 6.7 GHz methanol masers


Breen, SL and Ellingsen, SP and Caswell, JL and Green, JA and Fuller, GA and Voronkov, MA and Quinn, LJ and Avison, A, Statistical properties of 12.2 GHz methanol masers associated with a complete sample of 6.7 GHz methanol masers, The Astrophysical Journal, 733, (2) Article 80. ISSN 1538-4357 (2011) [Refereed Article]


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Copyright © 2011 IOS Press and the The American Astronomical Society

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DOI: doi:10.1088/0004-637X/733/2/80


We present definitive detection statistics for 12.2 GHz methanol masers toward a complete sample of 6.7 GHz methanol masers detected in the Methanol Multibeam survey south of declination −20◦. In total, we detect 250 12.2 GHz methanol masers toward 580 6.7 GHz methanol masers. This equates to a detection rate of 43.1%, which is lower than that of previous significant searches of comparable sensitivity. Both the velocity ranges and the flux densities of the target 6.7 GHz sources surpass that of their 12.2 GHz companion in almost all cases. Eighty percent of the detected 12.2 GHz methanol maser peaks are coincident in velocity with the 6.7 GHz maser peak. Our data support an evolutionary scenario whereby the 12.2 GHz sources are associated with a somewhat later evolutionary stage than the 6.7 GHz sources devoid of this transition. Furthermore, we find that the 6.7 GHz and 12.2 GHz methanol sources increase in luminosity as they evolve. In addition to this, evidence for an increase in velocity range with evolution is presented. This implies that it is not only the luminosity but also the volume of gas conducive to the different maser transitions that increases as the sources evolve. Comparison with GLIMPSE mid-infrared sources has revealed a coincidence rate between the locations of the 6.7 GHz methanol masers and GLIMPSE point sources similar to that achieved in previous studies. Overall, the properties of the GLIMPSE sources with and without 12.2 GHz counterparts are similar. There is a higher 12.2 GHz detection rate toward those 6.7 GHz methanol masers that are coincident with extended green objects.

Item Details

Item Type:Refereed Article
Keywords:ISM: molecules – masers – radio lines: ISM – stars: formation
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Galactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Breen, SL (Dr Shari Breen)
UTAS Author:Ellingsen, SP (Professor Simon Ellingsen)
ID Code:69743
Year Published:2011
Web of Science® Times Cited:43
Deposited By:Mathematics and Physics
Deposited On:2011-05-17
Last Modified:2017-11-01
Downloads:368 View Download Statistics

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