University Of Tasmania

File(s) under permanent embargo

New class I methanol masers

conference contribution
posted on 2023-05-23, 17:37 authored by Voronkov, MA, Caswell, JL, Simon EllingsenSimon Ellingsen, Breen, SL, Britton, TR, Green, JA, Sobolev, AM, Walsh, AJ
We review properties of all known collisionally pumped (class I) methanol maser series based on observations with the Australia Telescope Compact Array (ATCA) and the Mopra radio telescope. Masers at 36, 84, 44 and 95 GHz are most widespread, while 9.9, 25, 23.4 and 104 GHz masers are much rarer, tracing the most energetic shocks. A survey of many southern masers at 36 and 44 GHz suggests that these two transitions are highly complementary. The 23.4 GHz maser is a new type of rare class I methanol maser, detected only in two high-mass star-forming regions, G357.97-0.16 and G343.12-0.06, and showing a behaviour similar to 9.9, 25 and 104 GHz masers. Interferometric positions suggest that shocks responsible for class I masers could arise from a range of phenomena, not merely an outflow scenario. For example, some masers might be caused by interaction of an expanding Hii region with its surrounding molecular cloud. This has implications for evolutionary sequences incorporating class I methanol masers if they appear more than once during the evolution of the star-forming region. We also make predictions for candidate maser transitions in the ALMA frequency range.


Publication title

Proceedings of the International Astronomical Union Symposium S287


RS Booth, EML Humphreys & WHT Vlemmings






School of Natural Sciences


Cambridge University Press

Place of publication

United Kingdom

Event title

International Astronomical Union Symposium S287

Event Venue

Stellenbosch, South Africa

Date of Event (Start Date)


Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the physical sciences

Usage metrics