Noble Gas Abundance Ratios Indicate the Agglomeration of 67P/Churyumov–Gerasimenko from Warmed-up Ice

Mousis, O.; Ronnet, T.; Lunine, J. I.; Luspay-Kuti, A.; Mandt, K. E.; Danger, G.; Pauzat, F.; Ellinger, Y.; Wurz, P.; Vernazza, P.; Sergeant d’Hendecourt, L. Le (2018). Noble Gas Abundance Ratios Indicate the Agglomeration of 67P/Churyumov–Gerasimenko from Warmed-up Ice. Astrophysical Journal Letters, 865(1), L11. Institute of Physics Publishing IOP 10.3847/2041-8213/aadf89

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The origin of cometary volatiles remains a major open question in planetary science. Comets may have either agglomerated from crystalline ices condensed in the protosolar nebula (PSN) or from amorphous ice originating from the molecular cloud and interstellar medium. Here, based on the recent argon, krypton, and xenon measurements performed by the ROSINA mass spectrometer on board the European Space Agency’s Rosetta spacecraft in the coma of 67P/Churyumov–Gerasimenko, we show that these noble gas relative abundances can be explained if the comet’s building blocks formed from a mixture of gas and H2O grains resulting from the annealing of pristine amorphous ice (i.e., originating from the presolar cloud) in the PSN. In this scenario, the different volatiles released during the amorphous-to-crystalline ice phase transition would have been subsequently trapped at lower temperatures in stoichiometric hydrate or clathrate hydrate forms by the crystalline water ice generated by the transition. Once crystalline water was completely consumed by clathration in the ∼25–80 K temperature range, the volatile species remaining in the gas phase would have formed pure condensates at lower temperatures. The formation of clathrates hydrates and pure condensates to explain the noble gas relative abundances is consistent with a proposed interstellar origin of molecular oxygen detected in 67P/Churyumov–Gerasimenko, and with the measured molecular nitrogen depletion in comets.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences
08 Faculty of Science > Physics Institute

UniBE Contributor:

Wurz, Peter

Subjects:

500 Science > 520 Astronomy
600 Technology > 620 Engineering
500 Science > 530 Physics

ISSN:

2041-8205

Publisher:

Institute of Physics Publishing IOP

Language:

English

Submitter:

Dora Ursula Zimmerer

Date Deposited:

20 Dec 2018 15:30

Last Modified:

20 Dec 2018 15:30

Publisher DOI:

10.3847/2041-8213/aadf89

BORIS DOI:

10.7892/boris.122697

URI:

https://boris.unibe.ch/id/eprint/122697

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