HST UV High Resolution Spectra of Jupiter's Aurora: Thermospheric Temperature and Search for Proton Aurora

The auroral current systems in Jupiter’s thermosphere result in tremendous amounts of heating through a combination of incident electron collisions and Joule heating from ionospheric currents. The deposited energy is 20-50 times the absorbed solar UV flux, so that this energy dominates the global energetics of the upper atmosphere. We have measured the H2 temperature in auroral regions at Jupiter through high resolution spectra of the H2 emission bands. The ratio of band intensities is modeled to reveal the ro-vibrational temperature of the emitting H2. Recent (Jan. 2024 and Fall 2025) observations of the northern auroral region with HST / STIS and a high resolution grating were obtained with a slow scan of a long, narrow aperture across the emitting area. The field of view passed across most of the auroral region, including the magnetic footprint of Io and the downstream tail emission regions, with observations to date on 3 different days. The observations and subsequent modeling of the spectra will be presented.