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ATLASGAL - Relationship between dense star-forming clumps and interstellar masers

Citation

Billington, SJ and Urquhart, JS and Konig, C and Beuther, H and Breen, SL and Menten, KM and Campbell-White, J and Ellingsen, SP and Thompson, MA and Moore, TJT and Eden, DJ and Kim, WJ and Leurini, S, ATLASGAL - Relationship between dense star-forming clumps and interstellar masers, Monthly Notices of the Royal Astronomical Society, 499, (2) pp. 2744-2759. ISSN 0035-8711 (2020) [Refereed Article]


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DOI: doi:10.1093/mnras/staa2936

Abstract

We have used catalogues from several Galactic plane surveys and dedicated observations to investigate the relationship between various maser species and Galactic star-forming clumps, as identified by the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) survey. The maser transitions of interest are the 6.7 and 12.2-GHz methanol masers, 22.2-GHz water masers, and the masers emitting in the four ground-state hyperfine structure transitions of hydroxyl. We find clump association rates for the water, hydroxyl and methanol masers to be 56, 39, and 82 per cent, respectively, within the Galactic longitude range of 60 > ℓ > -60. We investigate the differences in physical parameters between maser associated clumps and the full ATLASGAL sample, and find that clumps coincident with maser emission are more compact with increased densities and luminosities. However, we find the physical conditions within the clumps are similar for the different maser species. A volume density threshold of n(H2) > 104.1 cm-3 for the 6.7-GHz methanol maser found in our previous study is shown to be consistent across for all maser species investigated. We find limits that are required for the production of maser emission to be 500 L and 6 M, respectively. The evolutionary phase of maser associated clumps is investigated using the L/M ratio of clumps coincident with maser emission, and these have similar L/M ranges (∼100.2-102.7 L/M) regardless of the associated transitions. This implies that the conditions required for the production of maser emission only occur during a relatively narrow period during a star’s evolution. Lower limits of the statistical lifetimes for each maser species are derived, ranging from ∼0.4-2 × 104 yr and are in good agreement with the ‘straw man’ evolutionary model previously presented.

Item Details

Item Type:Refereed Article
Keywords:Stars: formation – Stars: massive – ISM: molecules – submillimetre: ISM.
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:Ellingsen, SP (Professor Simon Ellingsen)
ID Code:142556
Year Published:2020
Deposited By:Physics
Deposited On:2021-01-25
Last Modified:2021-07-06
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