Comets and Asteroids

Oxygen-bearing Organic Molecules In Comet 67P’s Dusty Coma: First Evidence For Abundant Heterocycles

By Keith Cowing
Status Report
August 3, 2023
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Oxygen-bearing Organic Molecules In Comet 67P’s Dusty Coma: First Evidence For Abundant Heterocycles
Occam’s razor-based deconvolution of the subset of signals associated to CnHmO species as detected by the DFMS on 3 August 2015. The measured signals (ms) are given in arbitrary units (a. u.) with 30% error margins. Color-coded we show the different contributions of the individual molecules to the observed sum fragmentation pattern of CnHmO species, see also details in the main text. The following 36 molecules have been selected: (1) carbon monoxide, (2) formaldehyde, (3) methanol, (4) ketene, (5) acetaldehyde, (6) dimethyl ether, (7) ethanol, (8) 2-propynal, (9) 2-propenal, (10) acetone, (11) propanal, (12) isopropanol, (13) n-propanol, (14) furan, (15) 2,3-dihydrofuran, (16) butanal, (17) tetrahydrofuran, (18) 2-butanol, (19) 2,4-cyclopentadiene-1-one, (20) 2-methylfuran, (21) 2,3-dihydro-4-methylfuran, (22) tetrahydropyran, (23) 1-ethoxypropane, (24) 2-methoxy-2-methylpropane, (25) phenol, (26) 2,5-dimethylfuran, (27) 3-methoxycyclopentene, (28) benzaldehyde, (29) benzyl alcohol, (30) 2,3,5-trimethylfuran, (31) 2-methylcyclohexanol, (32) benzofuran, (33) 4-methylbenzaldehyde, (34) ethoxybenzene, (35) 6-methyl-3,5-heptadien2-one, (36) 2,6-dimethylcyclohexanone, (51) carbon dioxide, (54) acetic acid, (55) glycolaldehyde, (56) methyl formate, (59) propanoic acid, (76) hydroquinone, (77) benzoic acid. For referencing and to distinguish the two populations, selected CnHmO molecules have been given numbers below 50 while CnHmO2 molecules were given numbers above 50. Some of the latter produce relevant CnHmO fragments which show here and are thus listed. — astro-ph.EP

The puzzling complexity of terrestrial biomolecules is driving the search for complex organic molecules in the Interstellar Medium (ISM) and serves as a motivation for many in situ studies of reservoirs of extraterrestrial organics from meteorites and interplanetary dust particles (IDPs) to comets and asteroids.

Comet 67P/Churyumov-Gerasimenko (67P) — the best-studied comet to date — has been visited and accompanied for two years by the European Space Agency’s Rosetta spacecraft. Around 67P’s perihelion and under dusty conditions, the high-resolution mass spectrometer on board provided a spectacular glimpse into this comet’s chemical complexity. For this work, we analyzed in unprecedented detail the O-bearing organic volatiles. In a comparison of 67P’s inventory to molecules detected in the ISM, in other comets, and in Soluble Organic Matter (SOM) extracted from the Murchison meteorite, we also highlight the (pre)biotic relevance of different chemical groups of species.

We report first evidence for abundant extraterrestrial O-bearing heterocycles (with abundances relative to methanol often on the order of 10% with a relative error margin of 30-50%) and various representatives of other molecule classes such as carboxylic acids and esters, aldehydes, ketones, and alcohols. Like with the pure hydrocarbons, some hydrogenated forms seem to be dominant over their dehydrogenated counterparts. An interesting example is tetrahydrofuran (THF) as it might be a more promising candidate for searches in the ISM than the long-sought furan itself.

Our findings not only support and guide future efforts to investigate the origins of chemical complexity in space, but also they strongly encourage studies of, e.g., the ratios of unbranched vs. branched and hydrogenated vs. dehydrogenated species in astrophysical ice analogs in the laboratory as well as by modeling.

N. Hänni, K. Altwegg, D. Baklouti, M. Combi, S. A. Fuselier, J. De Keyser, D. R. Müller, M. Rubin, S. F. Wampfler

Comments: Reproduced with permission from Astronomy & Astrophysics, copyright ESO
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2308.00343 [astro-ph.EP] (or arXiv:2308.00343v1 [astro-ph.EP] for this version)
Submission history
From: Nora Hänni
[v1] Tue, 1 Aug 2023 07:37:45 UTC (5,091 KB)
Astrobiology, Astrochemistry,

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻