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Discovery of new 19.9-GHz methanol masers in star-forming regions
journal contribution
posted on 2023-05-16, 15:17 authored by Simon EllingsenSimon Ellingsen, Cragg, DM, James LovellJames Lovell, Sobolev, AM, Ramsdale, PD, Godfrey, PDWe have used the NASA Tidbinbilla 70-m antenna to search for emission from the 21-30 E (19.9-GHz) transition of methanol. The search was targeted towards 22 star formation regions that exhibit maser emission in the 107.0-GHz 31-40 A+ methanol transition, and in the 6.6-GHz 51-60 A+ transition characteristic of class II methanol maser sources. A total of seven sources were detected in the 21-30 E transition, six of these being new detections. Many of the new detections are weak (≳0.5 Jy), however, they appear to be weak masers rather than thermal or quasi-thermal emission. We find a strong correlation between sources that exhibit 19.9-GHz methanol masers and those that both have the class II methanol masers projected against radio continuum emission and have associated 6035-MHz OH masers. This suggests that the 19.9-GHz methanol masers arise in very specific physical conditions, probably associated with a particular evolutionary phase. In the model of Cragg, Sobolev & Godfrey these observations are consistent with gas temperatures of 50 K, dust temperatures of 150-200 K and gas densities of 106.5-107.5 cm-3.
History
Publication title
Monthly Notices of the Royal Astronomical SocietyVolume
354Pagination
401-413ISSN
0035-8711Department/School
School of Natural SciencesPublisher
Blackwell Publishing LtdPlace of publication
Oxford, UKRepository Status
- Restricted