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The first high-resolution observations of 37.7-, 38.3-, and 38.5-GHz methanol masers

journal contribution
posted on 2023-05-19, 21:06 authored by Simon EllingsenSimon Ellingsen, Voronkov, MA, Breen, SL, Caswell, JL, Sobolev, AM
We have used the Australia Telescope Compact Array (ATCA) to undertake the first highangular-resolution observations of 37.7-GHz (7−2 →8−1E) methanol masers towards a sample of 11 high-mass star formation regions which host strong 6.7-GHz methanol masers. The 37.7- GHz methanol sites are coincident to within the astrometric uncertainty (0.4 arcsec) with the 6.7-GHz methanol masers associated with the same star formation region. However, spatial and spectral comparison of the 6.7- and 37.7-GHz maser emission within individual sources shows that the 37.7-GHz masers are less often, or to a lesser degree co-spatial than are the 12.2-GHz and 6.7-GHz masers. We also made sensitive, high-angular-resolution observations of the 38.3- and 38.5-GHz class II methanol transitions (62 → 53A− and 62 → 53A+, respectively) and the 36.2-GHz (4−1 → 30E) class I methanol transition towards the same sample of 11 sources. The 37.7-, 38.3-, and 38.5-GHz methanol masers are unresolved in the current observations, which implies a lower limit on the brightness temperature of the strongest masers of more than 106 K. We detected the 38.3-GHz methanol transition towards seven sources, five of which are new detections and detected the 38.5-GHz transition towards six sources, four of which are new detections. We detected 36.2-GHz class I methanol masers towards all 11 sources, 6 of these are new detections for this transition, of which 4 sources do not have previously reported class I methanol masers from any transition.


Publication title

Monthly Notices of the Royal Astronomical Society








School of Natural Sciences


Blackwell Publishing Ltd

Place of publication

9600 Garsington Rd, Oxford, England, Oxon, Ox4 2Dg

Rights statement

Copyright 2018 The Author(s)

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  • Restricted

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Expanding knowledge in the physical sciences

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