Comets and Asteroids

Recent Chemo-morphological Coma Evolution of Comet 67P/Churyumov-Gerasimenko

By Keith Cowing
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astro-ph.EP
July 21, 2025
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Recent Chemo-morphological Coma Evolution of Comet 67P/Churyumov-Gerasimenko
[LEFT] 6300.304 ˚A [OI] line from 6296.5-6305.8 ˚A, and the 6363.776 ˚A [OI] line from 6361.2-6365.7 ˚A Enhanced red-doublet [OI] maps, from 15 May 2021 to 09 March 2022. Red arrow denotes sky projection of the Northern pole orientation (2016 Rosetta solution). Lime arrow is the velocity vector. Yellow arrow is the Sun angle. North is up and East is left, denoted by white arrows. Concentric dashed rings denote projected cometocentric distance, ρ, as projected onto the sky, in units of 103 kilometres. No rebinning has been applied. [RGHT] Enhanced C2 maps corresponding to the 5125-5167 ˚A wavelength range, from 15 May 2021 to 09 March 2022. Red arrow denotes sky projection of the Northern pole orientation (2016 Rosetta solution). Lime arrow is the velocity vector. Yellow arrow is the Sun angle. North is up and East is left, denoted by white arrows. Concentric dashed rings denote projected cometocentric distance, ρ, as projected onto the sky, in units of 103 kilometres. Binning is 5×5.– astro-ph.EP

We present VLT/MUSE observations of comet 67P/Churyumov-Gerasimenko during its 2021 perihelion passage, from which we generated simultaneous maps of dust, [OI], C2, NH2, and CN comae across 12 pre- and post-perihelion epochs.

These maps reveal the evolutionary and compositional trends of 67P’s coma and further enrich the context and findings of ESA’s Rosetta mission. Dust and gas species displayed distinct structures, where NH2 and CN signals were uniquely associated with known dust fans, raising the question of possible correlation to the dust and contributions of extended sources.

Localised fitted NH2 scale lengths were 1.5-1.9× larger than those fitted for the rest of the coma, which is consistent with an extended source component for northern pre-perihelion emissions. In the southern hemisphere, CN was correlated with a prominent and sharp dust structure, potentially revealing an extended source origin via larger dust particles that preserve the CN parent species, as evidenced by higher spectral slopes in the region.

Gas maps depicted two distinct evolutionary regimes: (1) evolving H2O ([OI]1D) and C2 emissions driven by nucleus sublimation and subsolar insolation, and (2) stable NH2 and CN emissions associated with seasonal dynamics and possible distributed sources. Dust spectral slope maps revealed spectral slope trends consistent with Rosetta findings, while green/red [OI] ratios generally indicate a coma dominated by H2O.

Brian P. Murphy, Cyrielle Opitom, Colin Snodgrass, Sophie E. Deam, Léa Ferellec, Matthew Knight, Bin Yang, Vincent Okoth

Comments: 63 pages, 14 figures, accepted for publication in the Planetary and Space Science journal Special Issue: 10 years of ROSETTA
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2507.13979 [astro-ph.EP] (or arXiv:2507.13979v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2507.13979
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Submission history
From: Brian Murphy
[v1] Fri, 18 Jul 2025 14:43:04 UTC (21,605 KB)
https://arxiv.org/abs/2507.13979
Astrobiology, Astrochemistry, Astrogeology,

Keith Cowing

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) 🖖🏻

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