Multitransition study and new detections of class II methanol masers |
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| Authors: | Dinah M Cragg rej M Sobolev Simon P Ellingsen J L Caswell Peter D Godfrey Svetlana V Salii Richard G Dodson |
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| Institution: | Department of Chemistry, Monash University, Clayton, Victoria 3800, Australia;Astronomical Observatory, Ural State University, Lenin Street 51, Ekaterinburg 620083, Russia;School of Mathematics and Physics, University of Tasmania, GPO Box 252-21, Hobart, Tasmania 7001, Australia;Australia Telescope National Facility, CSIRO, PO Box 76, Epping, NSW 2121, Australia |
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| Abstract: | We have used the ATNF Mopra antenna and the SEST antenna to search in the directions of several class II methanol maser sources for emission from six methanol transitions in the frequency range 85–115 GHz. The transitions were selected from excitation studies as potential maser candidates. Methanol emission at one or more frequencies was detected from five of the maser sources, as well as from Orion KL. Although the lines are weak, we find evidence of maser origin for three new lines in G345.01+1.79, and possibly one new line in G9.62+0.20.
The observations, together with published maser observations at other frequencies, are compared with methanol maser modelling for G345.01+1.79 and NGC 6334F. We find that the majority of observations in both sources are consistent with a warm dust (175 K) pumping model at hydrogen density ～106 cm?3 and methanol column density ～ 5×1017 cm?2. The substantial differences between the maser spectra in the two sources can be attributed to the geometry of the maser region. |
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| Keywords: | masers H ii regions ISM: molecules radio lines: ISM |
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