Electron acceleration at comet 67P/Churyumov-Gerasimenko
| Autor: | Raymond Goldstein, Prachet Mokashi, Kristie LLera, Anders Eriksson, Ingo Richter, Holger Nilsson, Elias Odelstad, James L. Burch, K. Dokgo |
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| Rok vydání: | 2019 |
| Předmět: |
Physics
010504 meteorology & atmospheric sciences Comet Astronomy and Astrophysics Electron Astrophysics Plasma 01 natural sciences Ion Electron acceleration Space and Planetary Science Physics::Space Physics 0103 physical sciences Astrophysics::Earth and Planetary Astrophysics Atomic physics 010303 astronomy & astrophysics 0105 earth and related environmental sciences |
| Zdroj: | Astronomy & Astrophysics. 630:A40 |
| ISSN: | 1432-0746 0004-6361 |
| DOI: | 10.1051/0004-6361/201834701 |
| Popis: | We report the observation by the Ion and Electron Sensor (IES) of energetic (>1 keV) electrons in the plasma environment of comet 67P Churyumov-Gerasimenko (67P). Most of the electrons in the cometary coma are expected to be of solar wind, photoionization, or electron impact origin and are therefore not expected to exceed some hundreds of eV in energy. During the Vega flybys of comet Halley, 1 keV electrons were also observed, and these are explained as having been accelerated by lower hybrid (LH) waves resulting from the two-stream instability involving the solar wind and pickup-ion flows. These waves resonate with the cyclotron motion of the ions and the longitudinal motion of electrons and are on the order of several Hz, at least in the case of 67P. We postulate that the energetic electrons we have observed intermittently during December 2015 through January 2016 are also the result of such a process and that Landau damping causes the acceleration and subsequent abrupt decrease in this energy (also seen at Halley). We show from this study an event on 19 January 2016 when IES simultaneously observed accelerated electrons, solar wind protons, water ions, and LH waves. A dispersion analysis shows that the ion–ion two-stream instability has positive growth rates for such waves during the observation period. |
| Databáze: | OpenAIRE |
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