Thanks Jeremy,

Looking at this paper, I would say that the most significant finding is that the molecular oxygen (O2) that was detected at 67P was primordial and not derived from water or other O-containing simple molecules. It is good that a firm statement can be made about this - that's one good thing about isotope ratios in that if a big difference (compared to solar/terrestrial) is found, it can lead to a definitive conclusion.

That O2 was found in 67P in plentiful amounts (and retrospectively in 1P/Halley data) was also one of the most remarkable findings from Rosetta. Some 1-10% relative to water was present in the coma, which is an enormous amount for such a hypervolatile molecule, especially since 67P has been in the 'warmer' inner Solar System for a fair amount of time.

Richard

----- Original Message -----

From: Jeremy Shears

To: baa-comet@simplelists.com

Sent: Friday, December 11, 2020 9:36 AM

Subject: [BAA Comets] Molecule dependent oxygen isotopic ratios in the coma of comet 67P/Churyumov-Gerasimenko

MNRAS paper on ArXiv by K. Altwegg, H. Balsiger, M. Combi, J. De Keyser, M. N. Drozdovskaya, S. A. Fuselier, T. I. Gombosi, N. Hänni, M. Rubin, M. Schuhmann, I. Schroeder, S. Wampfler

https://arxiv.org/abs/2012.05788

Considers isotopic enrichment ratios in various volatile species in 67P, including CO, CO2, water, methanol and formaldehyde, and their underlying chemical origin.

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