Plasma waves confined to the diamagnetic cavity of comet 67P/Churyumov–Gerasimenko

Gunell, H.; Goetz, C.; Eriksson, A.; Nilsson, H.; Simon Wedlund, C.; Henri, P.; Maggiolo, R.; Hamrin, M.; De Keyser, J.; Rubin, Martin; Stenberg Wieser, G.; Cessateur, G.; Dhooghe, F.; Gibbons, A. (2017). Plasma waves confined to the diamagnetic cavity of comet 67P/Churyumov–Gerasimenko. Monthly notices of the Royal Astronomical Society, 469(Suppl_2), S84-S92. Oxford University Press 10.1093/mnras/stx1134

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Ion acoustic waves were observed in the diamagnetic cavity of comet 67P/Churyumov– Gerasimenko by the Rosetta spacecraft on 2015 August 3, when the comet was 1.25 au from the Sun. Wave spectra recorded by the Langmuir probe (RPC-LAP), peak near 200 Hz, decrease for higher frequencies and reach the noise floor at approximately 1.5 kHz. These waves were observed only when the spacecraft was in the diamagnetic cavity or at its boundary, which is identified as a sharp drop in magnetic field magnitude, measured by RPC-MAG. The plasma, on both sides of the boundary, is dominated by a cold (a few hundred K) water group ion population, one cold (kBTe ~ 0.1 eV) and one warm (kBTe ~ 10 eV) electron population. The observations are interpreted in terms of current-driven ion acoustic waves, generated by currents that flow through bulges on the boundary of the diamagnetic cavity.

Item Type:

Journal Article (Original Article)

Division/Institute:

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

UniBE Contributor:

Rubin, Martin

Subjects:

500 Science > 520 Astronomy
600 Technology > 620 Engineering

ISSN:

0035-8711

Publisher:

Oxford University Press

Language:

English

Submitter:

Dora Ursula Zimmerer

Date Deposited:

15 Nov 2017 10:10

Last Modified:

15 Nov 2017 10:10

Publisher DOI:

10.1093/mnras/stx1134

BORIS DOI:

10.7892/boris.105805

URI:

https://boris.unibe.ch/id/eprint/105805

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