Particle-in-cell modelling of comet 67P/Churyumov-Gerasimenko: spatial structures of densities and electric fields
2023 (Engelska)Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 674, artikel-id A65Artikel i tidskrift (Refereegranskat) Published
Abstract [en]
Context: Sufficiently far from the Sun, all comets go through a phase of low activity. Rosetta observations at large heliocentric distances of approximately 3 au showed that the plasma at a low-activity comet is affected by both steady state electric fields and low-frequency waves.
Aims: Our goal is to provide a model for the electric fields in the inner coma at a low-activity comet and to simulate waves and field structures farther away from the nucleus.
Methods: We compare analytical models for the convective, ambipolar, and polarisation electric fields to the results of an electrostatic particle-in-cell simulation of a scaled-down low-activity comet.
Results: We find good agreement between the steady state field model and the simulation results close to the nucleus. At larger cometocentric distances, waves dominate the electric field. These waves are interpreted as the scaled-down electrostatic limit of the previously observed singing comet waves. The comet ion density is not spherically symmetric.
Conclusions: Low-activity comets can be modelled using electrostatic particle-in-cell simulations of a scaled-down system. Outside the innermost part of the coma (r ≥ 40 km), the plasma is not spherically symmetric and the electric field is dominated by waves.
Ort, förlag, år, upplaga, sidor
EDP Sciences, 2023. Vol. 674, artikel-id A65
Nyckelord [en]
Comets: general, Comets: individual: 67P/Churyumov-Gerasimenko, Methods: numerical, Plasmas, Waves
Nationell ämneskategori
Fusion, plasma och rymdfysik Astronomi, astrofysik och kosmologi
Identifikatorer
URN: urn:nbn:se:umu:diva-211156DOI: 10.1051/0004-6361/202245197ISI: 001000673900011Scopus ID: 2-s2.0-85162086249OAI: oai:DiVA.org:umu-211156DiVA, id: diva2:1781058
Forskningsfinansiär
Rymdstyrelsen, 108/18The European Space Agency (ESA)Vetenskapsrådet, 2018-05973Swedish National Infrastructure for Computing (SNIC)
Anmärkning
The software used in this work was developed by J. Lindkvist and H. Gunell and is available for download at: https://doi.org/10.5281/zenodo.7664037
2023-07-072023-07-072023-07-07Bibliografiskt granskad