Exploring Key Characteristics in Saturn's Infrared Auroral Emissions Using VLT‐CRIRES: Intensities, Ion Line‐of‐Sight Velocities, and Rotational Temperatures

We present a study of Saturn's northern auroral emission using data from 19 May 2013 from the Very Large Telescope's long‐slit spectrometer Cryogenic Infrared Echelle Spectrograph (VLT‐CRIRES). Adaptive optics, combined with the spectral resolution of VLT‐CRIRES ( 100,000), offers unprecedented spectrally resolved views of Saturn's infrared aurora. Discrete emission lines—used to derive dawn‐to‐dusk profiles of auroral intensity, ion line‐of‐sight velocity, and thermospheric temperature—reveal a dawn‐enhanced aurora with an average temperature of 361 (±48) K and a localized dark region in the emission co‐located with a noon‐to‐midnight (and vice versa) flow in the ion velocity on the scale of ∼1 km/s, resembling an ionospheric polar vortex. A temperature hotspot of 379 (±66) K may be driving an emission region, corresponding to a location where is failing to cool the thermosphere. Results presented here have implications for current understanding on the complex nature of Saturn's thermosphere‐ionosphere‐magnetosphere interaction.