Dynamic Plasma Interaction at Io: Multispecies Hybrid Simulations. Issue 1 (25th January 2019)

• Record Type: Journal Article
• Authors: Šebek, Ondřej; Trávníček, Pavel M.; Walker, Raymond J.; Hellinger, Petr
• Is Part Of: Journal of geophysical research. Volume 124:Issue 1(2019)
• Page Start: 313
• Page End: 341
• Publication Date: 2019-01-25
• Subjects: Io -- plasma interaction -- hybrid model; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2018JA026153
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: The interaction between the Io plasma torus and Io exhibits significant dynamics resulting from temporal variations of both external conditions in the plasma torus and local conditions in Io's environment. We present analysis of an extensive simulation campaign of the Io plasma interaction under varying interaction conditions performed by using a hybrid multispecies simulation model. We test two models of electron impact ionization, one resulting in plasma production constrained to the upstream hemisphere of Io and the other producing a more symmetric distribution of the plasma with nonnegligible plasma production on the downstream side of Io. In the latter case, the simulation model provides high level of agreement with Galileo measurements of magnetic field obtained during the I0 flyby, where the model captures even smaller‐scale features of the magnetic field profile. Our simulated results provide strong support for the existence of Io's induced dipole field. In this model we assume that induced dipole field moment is antiparallel to the direction of the inducing magnetic field, equivalent to induction in a highly conductive Io. Our results further support the idea that Io's atmosphere collapsed during the Galileo I27 flyby, which manifests itself in the lack of ion heating due to pickup processes in the extended atmosphere. Our results show that the dominant torus species, O + and S ++, are depleted around Io and may exhibit temperature anisotropy, T ⊥ / T ‖ < 1, resulting from merging of ion populations coming from opposite sides of Io along the magnetic field. Key Points: A nonnegligible ion source on the downstream side of Io is required to explain Galileo observations Simulated results provide strong support for the existence of Io's induced dipole field Dominant torus species have parallel temperature exceeding the perpendicular temperature close to Io