Ion composition at comet 67P near perihelion: Rosetta observations and model-based interpretation

Heritier, K. L.; Altwegg, Kathrin; Balsiger, Hans; Berthelier, J.-J.; Beth, A.; Bieler, André; Biver, N.; Calmonte, Ursina Maria; Combi, M. R.; De Keyser, J.; Eriksson, A. I.; Fiethe, B.; Fougere, N.; Fuselier, S. A.; Galand, M.; Gasc, Sébastien; Gombosi, T. I.; Hansen, K. C.; Hassig, M.; Kopp, Ernest; ... (2017). Ion composition at comet 67P near perihelion: Rosetta observations and model-based interpretation. Monthly notices of the Royal Astronomical Society, 469(Suppl_2), S427-S442. Oxford University Press 10.1093/mnras/stx1912

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We present the ion composition in the coma of comet 67P with newly detected ion species over the 28–37 u mass range, probed by Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA)/Double Focusing Mass Spectrometer (DFMS). In summer 2015, the nucleus reached its highest outgassing rate and ion-neutral reactions started to take place at low cometocentric distances. Minor neutrals can efficiently capture protons from the ion population, making the protonated version of these neutrals a major ion species. So far, only NH+₄ has been reported at comet 67P. However, there are additional neutral species with proton affinities higher than that of water (besides NH₃) that have been detected in the coma of comet 67P: CH₃OH, HCN, H₂CO and H₂S. Their protonated versions have all been detected. Statistics showing the number of detections with respect to the number of scans are presented. The effect of the negative spacecraft potential probed by the Rosetta Plasma Consortium/LAngmuir Probe on ion detection is assessed. An ionospheric model has been developed to assess the different ion density profiles and compare them to the ROSINA/DFMS measurements. It is also used to interpret the ROSINA/DFMS observations when different ion species have similar masses, and their respective densities are not high enough to disentangle them using the ROSINA/DFMS high-resolution mode. The different ion species that have been reported in the coma of 67P are summarized and compared with the ions detected at comet 1P/Halley during the Giotto mission.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences
08 Faculty of Science > Other Institutions > Emeriti, Faculty of Science
08 Faculty of Science > Physics Institute

UniBE Contributor:

Altwegg, Kathrin; Balsiger, Hans; Bieler, André; Calmonte, Ursina Maria; Gasc, Sébastien; Kopp, Ernest; Rubin, Martin and Tzou, Chia-Yu

Subjects:

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

ISSN:

0035-8711

Publisher:

Oxford University Press

Language:

English

Submitter:

Dora Ursula Zimmerer

Date Deposited:

15 Nov 2017 11:10

Last Modified:

15 Nov 2017 11:10

Publisher DOI:

10.1093/mnras/stx1912

BORIS DOI:

10.7892/boris.105838

URI:

https://boris.unibe.ch/id/eprint/105838

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