1. Ionospheric plasma of comet 67P probed byRosettaat 3 au from the Sun
- Author
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Martin Rubin, Jean-Pierre Lebreton, Peter Wurz, A. J. Allen, Elias Odelstad, Karl-Heinz Glassmeier, T. W. Broiles, Anders Eriksson, Luc Sagnières, Erik Vigren, Kathleen Mandt, James L. Burch, Xavier Vallières, Chia-Yu Tzou, Chris Carr, K. L. Heritier, Steven J. Schwartz, F. L. Johansson, Arnaud Beth, Thierry Sémon, Emanuele Cupido, Hans Nilsson, Pierre Henri, Marina Galand, Kathrin Altwegg, Ingo Richter, Science and Technology Facilities Council (STFC), Imperial College Trust, Science and Technology Facilities Council [2006-2012], Department of Physics [Imperial College London], Imperial College London, Swedish Institute of Space Physics [Kiruna] (IRF), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Southwest Research Institute [San Antonio] (SwRI), Physikalisches Institut [Bern], Universität Bern [Bern], Swedish Institute of Space Physics [Uppsala] (IRF), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), and Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig]
- Subjects
010504 meteorology & atmospheric sciences ,530 Physics ,Comet ,Coma (optics) ,Astrophysics ,Astronomy & Astrophysics ,ROSINA ,7. Clean energy ,01 natural sciences ,Fusion, plasma och rymdfysik ,comets: individual: 67P ,individual: 67P [comets] ,Ionization ,0201 Astronomical and Space Sciences ,0103 physical sciences ,data analysis [methods] ,WATER ,NUMBER DENSITIES ,ION ,DIAMAGNETIC CAVITY ,NUCLEUS ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences ,Physics ,UV radiation [Sun] ,ENVIRONMENT ,Science & Technology ,[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] ,520 Astronomy ,67P/CHURYUMOV-GERASIMENKO ,Astronomy ,Astronomy and Astrophysics ,Plasma ,Comets: individual: 67P Plasmas Sun: UV radiation Methods: data analysis ,620 Engineering ,plasmas ,Sun: UV radiation ,Fusion, Plasma and Space Physics ,methods: data analysis ,ELECTRON SENSOR ,13. Climate action ,Space and Planetary Science ,Physics::Space Physics ,Physical Sciences ,RPC ,Astrophysics::Earth and Planetary Astrophysics ,Ionosphere - Abstract
We propose to identify the main sources of ionization of the plasma in the coma of comet 67P/Churyumov-Gerasimenko at different locations in the coma and to quantify their relative importance, for the first time, for close cometocentric distances (< 20 km) and large heliocentric distances (> 3 au). The ionospheric model proposed is used as an organizing element of a multi-instrument data set from the Rosetta Plasma Consortium (RPC) plasma and particle sensors, from the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis and from the Microwave Instrument on the Rosetta Orbiter, all on board the ESA/Rosetta spacecraft. The calculated ionospheric density driven by Rosetta observations is compared to the RPC-Langmuir Probe and RPC-Mutual Impedance Probe electron density. The main cometary plasma sources identified are photoionization of solar extreme ultraviolet (EUV) radiation and energetic electron-impact ionization. Over the northern, summer hemisphere, the solar EUV radiation is found to drive the electron density - with occasional periods when energetic electrons are also significant. Over the southern, winter hemisphere, photoionization alone cannot explain the observed electron density, which reaches sometimes higher values than over the summer hemisphere; electron-impact ionization has to be taken into account. The bulk of the electron population is warm with temperature of the order of 7-10 eV. For increased neutral densities, we show evidence of partial energy degradation of the hot electron energy tail and cooling of the full electron population. QC 20200602
- Published
- 2016
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