Energy conversion in cometary atmospheres: Hybrid modeling of 67P/Churyumov-GerasimenkoShow others and affiliations
2018 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 616, article id A81Article in journal (Refereed) Published
Abstract [en]
Aims. We wish to investigate the energy conversion between particles and electromagnetic fields and determine the location where it occurs in the plasma environment of comets.
Methods. We used a hybrid plasma model that included photoionization, and we considered two cases of the solar extreme ultraviolet flux. Other parameters corresponded to the conditions of comet 67P/Churyumov-Gerasimenko at a heliocentric distance of 1.5 AU.
Results. We find that a shock-like structure is formed upstream of the comet and acts as an electromagnetic generator, similar to the bow shock at Earth that slows down the solar wind. The Poynting flux transports electromagnetic energy toward the inner coma, where newly born cometary ions are accelerated. Upstream of the shock-like structure, we find local energy transfer from solar wind ions to cometary ions. We show that mass loading can be a local process with a direct transfer of energy, but also part of a dynamo system with electromagnetic generators and loads.
Conclusions. The energization of cometary ions is governed by a dynamo system for weak ionization, but changes into a large conversion region with local transfer of energy directly from solar wind protons for high ionization.
Place, publisher, year, edition, pages
EDP Sciences, 2018. Vol. 616, article id A81
Keywords [en]
comets: individual: 67P/Churyumov-Gerasimenko, Sun: UV radiation, solar wind, methods: numerical, plasmas, acceleration of particles
National Category
Fusion, Plasma and Space Physics
Identifiers
URN: urn:nbn:se:umu:diva-148207DOI: 10.1051/0004-6361/201732353ISI: 000442541100001Scopus ID: 2-s2.0-85056551495OAI: oai:DiVA.org:umu-148207DiVA, id: diva2:1211148
Funder
Swedish National Space Board, 201/15Swedish National Space Board, 112/13Swedish Research Council, 2015-041872018-05-302018-05-302023-03-24Bibliographically approved