Work

JWST/NIRSpec Detection of Complex Structures in Saturn's Sub‐Auroral Ionosphere and Stratosphere

Year: 2025

Type: article

Abstract: Past observations of Saturn's sub‐auroral ionosphere have provided no detailed longitudinal information, and variations in underlying stratospheric emission from methane fluorescence have never been resolved spatially. Here, we present the first near‐infrared observations of Saturn using JWST's NIRSpec‐IFU, revealing the 2.8–5.2 micron wavelength region in unprecedented detail. We observe the rotating auroral enhancement associated with planetary‐period currents, the phase of which is re‐discovered for the first time since Cassini. We discover a series of ionospheric dark beads located between 55 and 65N, that appear to be formed by local thermospheric dynamics. In the fluorescing methane, we reveal strange dark arms extending equatorward from a dark polar cap at 60N; four arms from a six‐pointed star, each extend below 45N with the final two arms missing. Neither set of features has any known analog at other planets.

Source: Geophysical Research Letters

DOI: 10.1029/2025gl116491

Authors: Tom S. Stallard, Luke Moore, Henrik Melin, Omakshi Agiwal, M. Nahid Chowdhury, Rosie E. Johnson, Katie L. Knowles, Emma M. Thomas, Paola I. Tiranti, James O’Donoghue, Khalid Mohamed, Ingo Mueller‐Wodarg, Leigh Fletcher, Imke de Pater, Thierry Fouchet, Sarah V. Badman

Institutions: Northumbria University, Boston University, University of Leicester, Aberystwyth University, Imperial College London, University of California, Berkeley, Centre National de la Recherche Scientifique, Université Paris Cité, Université Paris Sciences et Lettres, Observatoire de Paris, Sorbonne Université, LIRA - Laboratoire d'instrumentation et de recherche en astrophysique, Lancaster University

Language: English

Topic: Ionosphere and magnetosphere dynamics

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,190

Funders: National Aeronautics and Space Administration, Northumbria University, European Commission, Agence Nationale de la Recherche, Nuclear Safety and Security Commission, Science and Technology Facilities Council, HORIZON EUROPE European Research Council

Awards: G1231072695, G1576011527, A Consolidated Grant Proposal for Solar and Planetary Science at the University of Leicester, 2022 - 2025, Exploring the Giant Planet Energy Crisis with JWST, G5587474157, G6392633141, PREparing Jupiter's SyStem Exploration with JWST, Fundamental Processes at Giant Planets in the Solar System and Beyond: Global heating and Saturn's Raining Rings

OpenAlex ID: W4413791839

FWCI: 1.364

Cites: 41

Cited by: 3

Related to: 10