Modelling Carbon Chain and Complex Organic Molecules in the DR21(OH) Clump

Star-forming regions host a large and evolving suite of molecular species. Molecular transition lines, particularly of complex molecules, can reveal the physical and dynamical environment of star formation. We aim to study the large-scale structure and environment of high-mass star formation through single-dish observations of CH₃CCH, CH₃OH, and H₂CO.

We have conducted a wide-band spectral survey with the IRAM 30-m telescope and the 100-m GBT towards the high-mass star-forming region DR21(OH)/N44. We use a multi-component local thermodynamic equilibrium model to determine the large-scale physical environment near DR21(OH) and the surrounding dense clumps.

We follow up with a radiative transfer code for CH₃OH to look at non-LTE behaviour. We then use a gas-grain chemical model to understand the formation routes of these molecules in their observed environments. We disentangle multiple components of DR21(OH) in each of the three molecules.

We find a warm and cold component each towards the dusty condensations MM1 and MM2, and a fifth broad, outflow component. We also reveal warm and cold components towards other dense clumps in our maps: N40, N36, N41, N38, and N48. We find thermal mechanisms are adequate to produce the observed abundances of H₂CO and CH₃CCH while non-thermal mechanisms are needed to produce CH₃OH.

Through a combination of wide-band mapping observations, LTE and non-LTE model analysis, and chemical modelling, we disentangle the different velocity and temperature components within our clump-scale beam, a scale that links a star-forming core to its parent cloud. We find numerous warm, 20-80 K components corresponding to known cores and outflows in the region. We determine the production routes of these species to be dominated by grain chemistry.

P. Freeman, S. Bottinelli, R. Plume, E. Caux, B. Mookerjea

Comments: Submitted to A&A, 21 pages, 23 figures
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2411.12916 [astro-ph.GA] (or arXiv:2411.12916v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2411.12916
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Submission history
From: Pamela Freeman
[v1] Tue, 19 Nov 2024 22:59:46 UTC (2,255 KB)
https://arxiv.org/abs/2411.12916
Astrobiology,