STCE seminar
Title: Magnetosphere-Ionosphere Coupling in the Auroral Zones of Earth and Jupiter
by Robert L. Lysak, University of Minnesota
Abstract: The Juno satellite, in polar orbit around Jupiter, has allowed for the first comparison of auroral particles and fields between the Earth and Jupiter. These two auroral zones have many similarities but are distinct in other ways. Both auroral zones show monoenergetic acceleration of electrons as well as broadband acceleration; however, at Jupiter the broadband acceleration is dominant, while monoenergetic acceleration dominates at Earth. In addition, the downward current region at Jupiter is a region of bright aurora due to the bidirectional, broadband acceleration of electrons, while downward current regions at Earth are generally dark. In both magnetospheres, coupling to the ionosphere is important in the evolution of auroral currents and fields. Somewhat surprisingly, the density and temperature of the Jovian ionosphere is similar to that of Earth; however, the composition is quite different, with Jupiter’s ionosphere largely consisting of protons with the second most common ion being H3+. In both magnetospheres, the rapid drop in plasma density in the topside ionosphere leads to an Ionospheric Alfven Resonator that can structure the currents in the 1 Hz range. These regions can be investigated with a combination of fluid and test particle simulations. Of particular interest at Jupiter is the coupling of the moon Io to the magnetosphere and ionosphere, leading to an extended auroral tail consisting of multiple subspots. In addition, Jupiter’s polar cap is a region of strong particle acceleration, with upward moving electrons and downward moving heavy ions accelerated to the MeV range and auroral “swirl” regions being present.
When: August 3, 2PM,
Where: Meridian room at the Royal Observatory of Belgium and online (zoom-link will be provided on time)
Contact: Hervé Lamy (BIRA-IASB)
