2004/07/13 by S. P. Ellingsen, D. M. Cragg, J. E. J. Lovell +4 · 1 citation
Chemistry · Physics and Astronomy · #Advanced Chemical Physics Studies #Astrophysics and Star Formation Studies #Molecular Spectroscopy and Structure #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2004.08200.x
14 pages, 12 figures, landscape table in additional file, Accepted for publication in MNRAS
arxiv created 2004/07/13 · openalex publication_date 2004/10/01 · arxiv updated 2009/12/01 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/04
We 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.