Overview of a large observing campaign of Jupiter's aurora with the Hubble Space Telescope combined with Juno-UVS data

Abstract

Between February and September 2019, Jupiter's ultraviolet aurorae were frequently observed during a large campaign of the Hubble Space Telescope (HST GO-15638). The campaign included approximately 10 visits around each of the perijoves of the Juno spacecraft orbits 18 to 22 around Jupiter. During this time, the solar activity was minimal, giving the opportunity to investigate auroral dynamics minimally driven by the solar wind. The main emission often appeared fainter than usually observed, particularly on the dawn side where the dawn arc was not always present. In contrast, emissions poleward of the main emission were dynamic, exhibiting polar bright spots, extremely bright flares and quasi-periodic flashes. Many other features are observed, such as dawn storms, long-standing secondary arc parallel to the main emission, injection signatures, transpolar arcs and bridges connecting the main emission to the polar emissions. HST high temporal and spatial resolutions enable the investigation of the dynamics of the auroral structures and substructures like beads within the main emission. Juno auroral observations are also combined with HST images to track conjugate auroral features in both hemispheres simultaneously. Finally, a splitting of the main emission into two narrow parallel arcs is highlighted for the first time.