Spatial variation of energy transport mechanisms within solar flare ribbons
Solar flares release a tremendous amount of magnetic energy that subsequently manifests in several forms; the bulk of this energy is transported through the Sun's atmosphere and explosively heats the chromosphere. While hard X-ray observations have pointed to flare-accelerated electrons as a primary means by which energy is transported following flares, alternative processes undoubtedly act alongside, or even instead of, those energetic electrons. To shed light on this we analysed flare-optimized, high-cadence Solar Orbiter observations. Footpoints from two flare ribbons were observed by the Spectral Imaging of the Coronal Environment (SPICE) instrument. Curiously, those footpoints exhibited contrasting behaviour: one had short-lived yet strong decreases in the Lyman β/Lyman γ line intensity ratio, whereas the other exhibited a more prolonged, moderate dip in that ratio. These observations were compared to synthetic spectra from radiation hydrodynamic simulations of flares driven by various energy transport mechanisms. This revealed that one footpoint was driven by energetic particle precipitation, while the other was driven by enhanced thermal heat flux. The implication is that energetic particles do not dominate along the entirety of flare ribbons. Critically, we must now focus on understanding where, when and why different mechanisms dominate in solar flare energy transport.
Authors
- Joel C. Allred (ORCID: https://orcid.org/0000-0003-4227-6809)
- Graham S. Kerr (ORCID: https://orcid.org/0000-0001-5316-914X)
- Joseph Plowman (ORCID: https://orcid.org/0000-0001-7016-7226)
- Adam F. Kowalski (ORCID: https://orcid.org/0000-0001-7458-1176)
- S. Krucker
- T. A. Kucera (ORCID: https://orcid.org/0000-0001-9632-447X)
- Jenny Marcela Rodriguez-Gomez
- Andrew Inglis (ORCID: https://orcid.org/0000-0003-0656-2437)
- Laura A. Hayes (ORCID: https://orcid.org/0000-0002-6835-2390)
- Daniel F. Ryan (ORCID: https://orcid.org/0000-0001-8661-3825)
- J. W. Brosius (ORCID: https://orcid.org/0000-0001-7475-6693)
- Ryan O. Milligan (ORCID: https://orcid.org/0000-0001-5031-1892)
- Peter R. Young (ORCID: https://orcid.org/0000-0001-9034-2925)
Institutions
- Queen's University Belfast (GB)
- Southwest Research Institute (US)
- Planetary Science Institute (US)
- Dublin Institute For Advanced Studies (IE)
- Joint Institute for Laboratory Astrophysics (US)
- University of America (US)
- FHNW University of Applied Sciences and Arts Northwestern Switzerland (CH)
- Department of Space (IN)
- Northumbria University (GB)
- National Solar Observatory (US)
- Heliophysics (US)
- University College London (GB)
- University of Glasgow (GB)
- University of California, Berkeley (US)
Publication Details
- Journal
- Nature Astronomy
- Published
- 2026-01-06
- DOI
- https://doi.org/10.1038/s41550-025-02747-9
- Primary Topic
- Solar and Space Plasma Dynamics
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- National Aeronautics and Space Administration
- UK Space Agency
- Belgian Federal Science Policy Office
- Centre National d’Etudes Spatiales
- Nuclear Safety and Security Commission
- Bundesministerium für Wirtschaft und Energie
- Norsk Romsenter
- Goddard Space Flight Center
- Science and Technology Facilities Council