Stallard, Tom S. and Moore, Luke and Melin, Henrik and Agiwal, Omakshi and Chowdhury, M. Nahid and Johnson, Rosie E. and Knowles, Katie L. and Thomas, Emma M. and Tiranti, Paola I. and O’Donoghue, James and Mohamed, Khalid and Mueller‐Wodarg, Ingo and Fletcher, Leigh and de Pater, Imke and Fouchet, Thierry and Badman, Sarah V. (2025) JWST/NIRSpec Detection of Complex Structures in Saturn's Sub‐Auroral Ionosphere and Stratosphere. Geophysical Research Letters, 52 (17): e2025GL116. ISSN 0094-8276
Full text not available from this repository.Abstract
Plain Language Summary: Saturn's upper atmosphere is very poorly understood. Despite decades of ground‐based observations and a decade of measurements from Cassini, the incredibly weak emission from both ions and neutrals in the top of Saturn's atmosphere have proven highly illusive. Here, we describe revolutionary observations made by the JWST telescope. The incredible sensitivity of JWST/NIRSpec allows us to measure both the ionosphere and stratosphere enhanced by orders of magnitude compared to past observations. We have discovered a series of ionospheric dark ’beads', forming across a range of longitudes, away from the region with brightest aurora. We suggest it is unlikely that they are driven by underlying atmospheric processes, or infalling material from the surrounding space environment, and speculate they are forming as a result of shears between ionospheric winds. Underlying this, the upper stratosphere appears to have an atmospheric formation unlike anything previously known. A dark polar cap appears to be extending arms down into the sub‐equatorial region, with spokes reaching out as a six‐pointed star. However, two of these six arms are missing, resulting in a strangely asymmetric structure. We cannot explain how this structure has formed, but it may be associated with changes seen in the underlying atmosphere.