We have used the Australia Telescope Compact Array to search for a number of centimetre wavelength methanol transitions which are predicted to show weak maser emission towards star formation regions. Sensitive, high spatial, and spectral resolution observations towards four high-mass star formation regions which show emission in a large number of class II methanol maser transitions did not result in any detections. From these observations, we are able to place an upper limit of ≲ 1300 K on the brightness temperature of any emission from the 3₁A⁺–3₁A^-, 17_-2–18_-3 E (v_t = 1), 12₄–13₃ A^-, 12₄–13₃ A⁺, and 4₁A⁺–4₁A^- transitions of methanol in these sources on angular scales of 2 arcsec. This upper limit is consistent with current models for class II methanol masers in high-mass star formation regions and better constraints than those provided here will likely require observations with next-generation radio telescopes.

Item Type:	Refereed Article
Keywords:	ISM, molecules, masers, radio lines, 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:	Chipman, A (Mr Antony Chipman)
UTAS Author:	Ellingsen, SP (Professor Simon Ellingsen)
ID Code:	112496
Year Published:	2016
Web of Science® Times Cited:	2
Deposited By:	Mathematics and Physics
Deposited On:	2016-11-14
Last Modified:	2017-11-01
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