Morphology of Jupiter's Polar Auroral Bright Spot Emissions via Juno-UVS Observations

Abstract

Jupiter's very bright ultraviolet (UV) auroras result from the collision between precipitating energetic particles and the atmospheric constituents in the planet's upper atmosphere. The auroras are generally divided into four components: The main emissions, the equatorward emissions, the polar emissions, and the satellites' footprints. The location, morphology and behavior of each component indicates that they are related to specific processes in different parts of the magnetosphere. The ever-present main emissions are the easiest feature to identify. They appear as a discontinuous contour around the magnetic pole. The northern hemisphere is subjected to a magnetic anomaly leading to regions of very strong and very weak magnetic field strength, which distorts the shape of the northern main emissions (Grodent et al., 2008). The main emissions are driven by internal processes in the middle magnetosphere at a radial distance of 20-60 Jovian radii (R J ) in the magnetosphere (Clarke et al., 2004;Vogt et al., 2011). The second component of Jupiter's aurora, the equatorward emissions, appear between the main emissions and Io's footpath and are mostly associated with magnetospheric injections (Dumont et al., 2014;Mauk et al., 2002). The multiple components of the satellite magnetic footprints are connected to the satellites of Jupiter via magnetic field lines (Bonfond, 2012). Lastly, polar auroras are characterized by the large variability of the auroral emissions in the entire region located poleward of the main emissions. The polar auroras are related to the dynamics of the outer magnetosphere, but the detailed mechanisms are still unclear. The UV polar emissions are divided into three subregions, the dark region, the swirl region, and the active region (Grodent et al., 2003). The