Study of the Io footprint short timescale variability

The electromagnetic interaction between Io and Jupiter leads to single or multiple auroral UV spots in both jovian hemispheres. This study concentrates on short timescale (~1 min) morphological changes of the footprints. In order to achieve a sufficient time resolution, we use the time-tag mode of the HST/STIS instrument. This allows us to account for the spots blurring due to the rapid evolution of the jovian magnetic field lines. In addition to the spots motion, our analysis focuses on the spots brightness variations and on the correlation between these variations. The characterization of the parameters herein gives rise to both clues and new questions on the mechanisms that induce the precipitation of energetic electrons.