NEATH IV: An Early Onset of Complex Organic Chemistry in Molecular Clouds

Complex organic molecules (COMs) are widely detected in protostellar and protoplanetary systems, where they are thought to have been inherited in large part from earlier evolutionary phases.
The chemistry of COMs in these earlier phases, namely starless and prestellar cores, remains poorly understood, as models often struggle to reproduce the observed gas-phase abundances of these species. We simulate the formation of a molecular cloud, and the cores within it, out of the diffuse interstellar medium, and follow the chemical evolution of the cloud material starting from purely-atomic initial conditions.
We find that the formation of both gas- and ice-phase COMs precedes the formation of cores as distinct objects, beginning at gas densities of a few 103cm−3. Much of this COM-enriched material remains at these relatively modest densities for several Myr, which may provide a reservoir for accretion onto planet-forming discs in later evolutionary stages.
We suggest that models of core and disc chemistry should not ignore the complex dynamical evolution which precedes these structures, even when studying supposedly late-forming molecules such as CH3OH and CH3CN.

Column density maps at 5.53 Myr of total hydrogen nuclei, and of CO, CH3OH and CH3CN in gas and ice phases. The colour bars correspond to total hydrogen nuclei (left) and the gas- and ice-phase columns of CO (centre) and of both COM species (right). — astro-ph.SR
F. D. Priestley, P. C. Clark, S. E. Ragan, S. Scibelli, M. T. Cusack, S. C. O. Glover, O. Fehér, L. R. Prole, R. S. Klessen
Comments: 10 pages, 8 figures. MNRAS accepted
Subjects: Astrophysics of Galaxies (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2501.17955 [astro-ph.GA] (or arXiv:2501.17955v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2501.17955
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Submission history
From: Felix Priestley
[v1] Wed, 29 Jan 2025 19:30:10 UTC (4,119 KB)
https://arxiv.org/abs/2501.17955
Astrobiology, Astrochemistry,