Hajra, Rajkumar; Henri, Pierre; Vallières, Xavier; Moré, Jerome; Gilet, Nicolas; Wattieaux, Gaetan; Goetz, Charlotte; Richter, Ingo; Tsurutani, Bruce T; Gunell, Herbert; Nilsson, Hans; Eriksson, Anders I; Nemeth, Zoltan; Burch, James L; Rubin, Martin (2018). Dynamic unmagnetized plasma in the diamagnetic cavity around comet 67P/Churyumov–Gerasimenko. Monthly notices of the Royal Astronomical Society, 475(3), pp. 4140-4147. Oxford University Press 10.1093/mnras/sty094
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sty094.pdf - Published Version Available under License Publisher holds Copyright. This article has been accepted for publication in Monthly notices of the Royal Astronomical Society ©: 2018 the Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. Download (1MB) | Preview |
The Rosetta orbiter witnessed several hundred diamagnetic cavity crossings (unmagnetized regions) around comet 67P/Churyumov–Gerasimenko during its two year survey of the comet. The characteristics of the plasma environment inside these diamagnetic regions are studied using in situ measurements by the Rosetta Plasma Consortium instruments. Although the unmagnetized plasma density has been observed to exhibit little dynamics compared to the very dynamical magnetized cometary plasma, we detected several localized dynamic plasma structures inside those diamagnetic regions. These plasma structures are not related to the direct ionization of local cometary neutrals. The structures are found to be steepened, asymmetric plasma enhancements with typical rising-to-descending slope ratio of ~2.8 (±1.9), skewness ~0.43 (±0.36), mean duration of ~2.7 (±0.9) min and relative density variation ΔN/N of ~0.5 (±0.2), observed close to the electron exobase. Similar steepened plasma density enhancements were detected at the magnetized boundaries of the diamagnetic cavity as well as outside the diamagnetic region. The plausible scalelength and propagation direction of the structures are estimated from simple plasma dynamics considerations. It is suggested that they are large-scale unmagnetized plasma enhancements, transmitted from the very dynamical
outer magnetized region to the inner magnetic field-free cavity region.
Item Type: |
Journal Article (Original Article) |
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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 500 Science > 530 Physics |
ISSN: |
0035-8711 |
Publisher: |
Oxford University Press |
Language: |
English |
Submitter: |
Dora Ursula Zimmerer |
Date Deposited: |
16 May 2018 11:50 |
Last Modified: |
05 Dec 2022 15:14 |
Publisher DOI: |
10.1093/mnras/sty094 |
BORIS DOI: |
10.7892/boris.116516 |
URI: |
https://boris.unibe.ch/id/eprint/116516 |
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