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

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posted on 2023-05-20, 20:30 authored by Billington, SJ, Urquhart, JS, Konig, C, Beuther, H, Breen, SL, Menten, KM, Campbell-White, J, Simon EllingsenSimon Ellingsen, Thompson, MA, Moore, TJT, Eden, DJ, Kim, WJ, Leurini, S
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.


Publication title

Monthly Notices of the Royal Astronomical Society








School of Natural Sciences


Blackwell Publishing Ltd

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9600 Garsington Rd, Oxford, England, Oxon, Ox4 2Dg

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This article has been accepted for publication in Monthly notices of the Royal Astronomical Society ©: 2020 the authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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