Abstract

High-resolution observations made by the Hubble Space Telescope have developed the modern picture of the Jovian main oval emission as the signature of field-aligned corotation-enforcement currents which keep magnetospheric plasma rotating at the same rate as Jupiter's magnetic field. This model explains the slowly changing behavior and bright emissions of the main oval and allows the magnetosphere to be studied by remote observations, as the auroral oval directly reflects processes in the magnetosphere and properties of the plasma therein. Recent results from the Juno mission have called these results into question, as the strong, field-aligned currents required by the corotation-enforcement current system have not been measured. Where is the corotation-enforcement current-- which must exist to move magnetospheric plasma-- a dominant driver of the main oval emission? Where do other processes drive the main oval aurora instead? We present one of the widest surveys of Jupiter's main oval auroral features to date by combining over 180 hours of Hubble Space Telescope observations to address these questions. This comprehensive survey is the first to measure the corotation rate, an important tool for distinguishing auroral drivers, of all individual auroral features. This analysis is made possible due to the development of automated pipelines to reduce observations, produce keograms, identify discrete auroral emission features, and measure the corotation rates of these features, among other properties. We present the measured properties of emission features as a function of location along the main oval, in terms of longitude, local time, auroral local time, and magnetic local time. These results serve as the foundation for comparison to in-situ measurements from both the Galileo and Juno missions, which will ultimately help reveal which magnetospheric conditions are likely responsible for driving corotating emissions and which are responsible for sub-corotating emissions, such as the dawn storms.