Solar wind interaction with comet 67P: Impacts of corotating interaction regions. Issue 2 (15th February 2016)

• Record Type: Journal Article
• Authors: Edberg, N. J. T.; Eriksson, A. I.; Odelstad, E.; Vigren, E.; Andrews, D. J.; Johansson, F.; Burch, J. L.; Carr, C. M.; Cupido, E.; Glassmeier, K.‐H.; Goldstein, R.; Halekas, J. S.; Henri, P.; Koenders, C.; Mandt, K.; Mokashi, P.; Nemeth, Z.; Nilsson, H.; Ramstad, R.; Richter, I.; Wieser, G. Stenberg
• Is Part Of: Journal of geophysical research. Volume 121:Issue 2(2016:Feb.)
• Page Start: 949
• Page End: 965
• Publication Date: 2016-02-15
• Subjects: Rosetta -- solar wind -- corotating interaction region -- ionosphere -- CME -- RPC; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2015JA022147
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: We present observations from the Rosetta Plasma Consortium of the effects of stormy solar wind on comet 67P/Churyumov‐Gerasimenko. Four corotating interaction regions (CIRs), where the first event has possibly merged with a coronal mass ejection, are traced from Earth via Mars (using Mars Express and Mars Atmosphere and Volatile EvolutioN mission) to comet 67P from October to December 2014. When the comet is 3.1–2.7 AU from the Sun and the neutral outgassing rate ∼10 25 –10 26 s −1, the CIRs significantly influence the cometary plasma environment at altitudes down to 10–30 km. The ionospheric low‐energy (∼5 eV) plasma density increases significantly in all events, by a factor of >2 in events 1 and 2 but less in events 3 and 4. The spacecraft potential drops below −20 V upon impact when the flux of electrons increases. The increased density is likely caused by compression of the plasma environment, increased particle impact ionization, and possibly charge exchange processes and acceleration of mass‐loaded plasma back to the comet ionosphere. During all events, the fluxes of suprathermal (∼10–100 eV) electrons increase significantly, suggesting that the heating mechanism of these electrons is coupled to the solar wind energy input. At impact the magnetic field strength in the coma increases by a factor of 2–5 as more interplanetary magnetic field piles up around the comet. During two CIR impact events, we observe possible plasma boundaries forming, or moving past Rosetta, as the strong solar wind compresses the cometary plasma environment. We also discuss the possibility of seeing some signatures of the ionospheric response to tail disconnection events. Key Points: Rosetta observations of corotating interaction region impacts on comet 67P/C‐G CIR impacts cause, e.g., cold plasma density increase, pileup of B field, and acceleration of comet plasma CIR impact could lead to plasma boundary formation or tail disconnection events