First detections of methanol maser lines from a rare transition family

2025/12/01 by Johnson, Bradley R., Ellingsen, Simon P., Breen, Shari L. +3
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Stellar, planetary, and galactic studies

paper · doi:10.48550/arxiv.2512.01875

openalex publication_date 2025/12/01 · openalex created_date 2025/12/03 · openalex updated_date 2026/07/28

Abstract

We report the first observations in a rare family of class II methanol maser transitions in both CH₃OH and ¹³CH₃OH toward three southern high-mass star formation regions, along with the first maser detected in the ¹³CH₃OH line. The 8₂ → 9₁ A^- methanol transition was observed in both CH₃OH and ¹³CH₃OH (at 28.9 GHz and 41.9 GHz respectively) toward three sources; G358.93-0.03, NGC6334I and G345.01+1.79, all of which are star formation regions with recent maser flaring events. We report the first maser detection of the 41.9 GHz line in ¹³CH₃OH toward G358.93-0.03 and the first confirmed maser detection of the 28.9 GHz line in CH₃OH toward NGC6334I. Additionally we report a maser detection of the 28.9 GHz line in CH₃OH toward G358.93-0.03, meaning that with our detection of the 41.9 GHz line, this is the first isotopic detection of these lines toward G358.93-0.03. The newly detected maser transitions are associated with the primary millimetre continuum sources (MM1) in both G358.93-0.03 and NGC6334I, within the varying positional uncertainties.

Related

• The Extraordinary Maser Flaring Event in the Massive Protostellar System NGC6334I: Multi-Epoch Milliarcsecond Resolution Investigation of the 6.7-GHz Methanol Masers
• Maser and thermal methanol emission in the millimeter wave range: new masers at 1.3 mm and 2.8 mm
• Discovery of two new methanol masers in NGC 7538
• VLBI observations of 12 GHz methanol masers
• Detection of a 6.7 GHz methanol kilomaser toward NGC4945