期刊
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
卷 121, 期 2, 页码 949-965出版社
AMER GEOPHYSICAL UNION
DOI: 10.1002/2015JA022147
关键词
Rosetta; solar wind; corotating interaction region; ionosphere; CME; RPC
资金
- Swedish National Space Board [109/02, 135/13, 166/14, 114/13]
- Vetenskapsradet [621-2013-4191, 621-2014-5526]
- CNRS
- CNES
- Observatoire de Paris
- Universite Paul Sabatier, Toulouse
- UK Science and Technology Facilities Council
- STFC [ST/H002383/1] Funding Source: UKRI
- Swedish National Space Agency (SNSA) [114/13] Funding Source: Swedish National Space Agency (SNSA)
- Science and Technology Facilities Council [ST/H002383/1] Funding Source: researchfish
- UK Space Agency [ST/H004262/1, ST/P002250/1, ST/K001698/1] Funding Source: researchfish
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 3.1-2.7AU from the Sun and the neutral outgassing rate approximate to 10(25)-10(26)s(-1), the CIRs significantly influence the cometary plasma environment at altitudes down to 10-30km. The ionospheric low-energy (approximate to 5eV) 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 -20V 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 (approximate to 10-100eV) 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.
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