Mass-loading, pile-up, and mirror-mode waves at comet 67P/Churyumov-Gerasimenko

M. Volwerk (1) , Ingo Richter (2) , B. Tsurutani (3) , C. Götz (2) , Kathrin Altwegg (4) , T. Broiles (5) , J. Burch (5) , C. Carr (6) , Emanuele Cupido (6) , M. Delva (1) , M. Dósa (7) , Niklas Jt Edberg (8) , A. Eriksson (8) , Pierre Henri (9) , Christoph Koenders (2) , Jean-Pierre Lebreton (9) , K. E. Mandt (5) , Hans Nilsson (8) , A. Opitz (10) , M. Rubin (4) , K. Schwingenschuh (11) , G. Stenberg Wieser (8) , K. Szegö (7) , C. Vallat (12) , X. Vallieres (9) , Karl-Heinz Glassmeier (2)

1 IWF - Space Research Institute of Austrian Academy of Sciences
2 Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig]
3 JPL - Jet Propulsion Laboratory
4 Physikalisches Institut [Bern]
5 Space Science Division [San Antonio]
6 Blackett Laboratory
7 Wigner Research Centre for Physics [Budapest]
8 IRF - Swedish Institute of Space Physics [Uppsala]
9 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
10 IRAP - Institut de recherche en astrophysique et planétologie
11 IWF - Institut für Weltraumforschung = Space Research institute [Graz]
12 Octogone - Octogone Unité de Recherche Interdisciplinaire

The data from all Rosetta plasma consortium instruments and from the ROSINA COPS instrument are used to study the interaction of the solar wind with the outgassing cometary nucleus of 67P/Churyumov-Gerasimenko. During 6 and 7 June 2015, the interaction was first dominated by an increase in the solar wind dynamic pressure, caused by a higher solar wind ion density. This pressure compressed the draped magnetic field around the comet, and the increase in solar wind electrons enhanced the ionization of the outflow gas through collisional ionization. The new ions are picked up by the solar wind magnetic field, and create a ring/ring-beam distribution, which, in a high-β plasma, is unstable for mirror mode wave generation. Two different kinds of mirror modes are observed: one of small size generated by locally ionized water and one of large size generated by ionization and pickup farther away from the comet.

Keywords: Space plasma physics (charged particle motion and acceleration); nonlinear phenomena; waves and instabili-ties)

Domains: Sciences of the Universe [physics]

M. Volwerk, Ingo Richter, B. Tsurutani, C. Götz, Kathrin Altwegg, et al.. Mass-loading, pile-up, and mirror-mode waves at comet 67P/Churyumov-Gerasimenko. Annales Geophysicae, 2016, 34, pp.1-15. ⟨10.5194/angeo-34-1-2016⟩. ⟨insu-01320578⟩