Soft X-Ray Emission from Saturn's Magnetosheath II: Solar Wind Driving
By Dan Naylor (Lancaster University)
Saturn’s magnetosphere is dominated by Enceladus-sourced, water-group neutrals that form a torus and extend into the magnetosheath. Soft X-ray emission can be generated in the magnetosheath due to charge exchange between highly charged solar wind ions and the neutrals. Imaging of the soft X-rays is an emerging technology that aims to provide a more global and dynamic view of the magnetosheath and, for example, give insights into the driving of the magnetosphere by the solar wind. The ESA/CAS SMILE mission has now launched and aims to image the terrestrial magnetosheath. We, along with Rogan et al. (2026, https://doi.org/10.1029/2025JA034462), explore the viability of soft X-ray imaging at Saturn. We consider charge exchange between Enceladus-sourced H, O and OH and solar wind ions O7+ and O8+ to estimate the emission rates from the system and the flux detected by a soft X-ray imager (SXI) at the system. We also vary solar wind dynamic pressure to test the effect of changing solar wind conditions on X-ray production. X-ray volumetric emission rate is on the order of 10-11 to 10-10 photon cm-3 s-1 for slow and fast solar winds. For a SMILE-like SXI imaging the system from around 50 RS, >100 photons could be detected within a quarter of a planetary rotation. A hypothetical future instrument with increased FOV and effective area significantly increases photon count rate, highlighting that X-ray imaging may be a useful technique to better understand Saturn’s magnetosphere and neutral environment on a potential future mission.
See publication for more details:
Naylor, D., Ray, L. C., Rogan, P. C., Dunn, W. R., & Smith, H. T. (2026). Soft X-ray emission from Saturn's magnetosheath II: Solar wind driving. Journal of Geophysical Research: Space Physics, 131, e2025JA034461. https://doi.org/10.1029/2025JA034461

Emission rate slices (a, b, c) in the y-z, x-y and x-z planes and modelled intensity maps (d, e, f) for a nose-on, top-down and side-on view of the system, for a SMILE-like soft X-ray imager at ~50 RS from Saturn.