Open AccessMultitransition study and new detections of class II methanol masers
Author(s) -
Cragg Dinah M.,
Sobolev Andrej M.,
Ellingsen Simon P.,
Caswell J. L.,
Godfrey Peter D.,
Salii Svetlana V.,
Dodson Richard G.
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2001.04294.x
Subject(s) - maser , physics , astrophysics , methanol , line (geometry) , spectral line , emission spectrum , astronomy , chemistry , geometry , mathematics , organic chemistry
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 ∼10 6 cm −3 and methanol column density ∼ 5×10 17 cm −2 . The substantial differences between the maser spectra in the two sources can be attributed to the geometry of the maser region.