STATISTICAL PROPERTIES OF 12.2 GHz METHANOL MASERS ASSOCIATED WITH A COMPLETE SAMPLE OF 6.7 GHz METHANOL MASERS

Journal Article · Wed Jun 01 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/733/2/80· OSTI ID:21576760

Breen, S L; Caswell, J L; Green, J A; Voronkov, M A ^[1]; Ellingsen, S P ^[2]; Fuller, G A; Quinn, L J; Avison, A ^[3]

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1. CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia)
2. School of Mathematics and Physics, University of Tasmania, Private Bag 37, Hobart, Tasmania 7001 (Australia)
3. Jodrell Bank Centre for Astrophysics, Alan Turing Building, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom)

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{sup 0}. 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.

• OSTI ID: 21576760
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 733; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ALCOHOLS
AMPLIFIERS
DETECTION
ELECTRONIC EQUIPMENT
EQUIPMENT
FLUX DENSITY
HYDROXY COMPOUNDS
LUMINOSITY
MASERS
MATHEMATICS
METHANOL
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
OPTICAL PROPERTIES
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
STARS
STATISTICS
VELOCITY