Overview

• Researchers report in The Astrophysical Journal Letters that ions in flare plasma can exceed 60 million kelvin, far above electron temperatures.
• The team argues ion–electron temperature differences can persist for tens of minutes in key flare regions, challenging the long‑held equal‑temperature assumption.
• Preferential ion heating could account for unusually broad extreme‑ultraviolet and X‑ray spectral lines that were previously attributed mainly to strong turbulence.
• Evidence cited includes reconnection measurements in near‑Earth space and the solar wind, plus supporting computer simulations indicating a 6.5× ion‑heating factor.
• The authors call for targeted tests using NASA’s upcoming MUSE mission and the EUVST telescope and for updated flare models that revise turbulence energy estimates.