— Researchers report that solar flares may heat ions to as much as 180 million degrees Fahrenheit, many times higher than previous estimates, based on new calculations and supporting space measurements.
Key Takeaways
- New analysis indicates ion temperatures in solar flares can exceed 100 million°F and may reach about 180 million°F.
- That peak is more than six times higher than earlier electron-based temperature estimates.
- The finding comes from calculations published in Astrophysical Journal Letters and is led by Alexander Russell (University of St. Andrews).
- Near-Earth measurements and computer simulations show ions can heat much more strongly than electrons during flares.
- Understanding ion heating changes flare models and has implications for satellite hardware and astronaut safety.
Verified Facts
The study in Astrophysical Journal Letters reports ion temperatures in some solar flares could approach 180 million °F (roughly 100 million °C is not used here to avoid unit mixing in the original report), a value the authors describe as far above prior expectations. Previous flare temperature estimates typically relied on telescope measurements of electron temperatures; those electron values are substantially lower than the new ion estimates.
Alexander Russell, a physicist at the University of St. Andrews, led the analysis. The team combined theoretical calculations with insights from recent particle measurements made in near-Earth space and large-scale plasma simulations. They conclude that energy released by magnetic reconnection can preferentially heat ions, producing much higher ion temperatures than electron temperatures.
Independent expert James Drake of the University of Maryland, who was not part of the new paper, has long studied how magnetic processes partition energy between electrons and ions. He told reporters the difference between ion and electron heating in flare environments has been underappreciated and that the new analysis helps close that gap.
Context & Impact
Solar flares occur when magnetic energy stored in the Sun’s atmosphere is released suddenly; that energy accelerates particles and heats plasma. If ions reach tens or hundreds of millions of degrees Fahrenheit, the dynamics of flare evolution, particle escape, and radiation output can differ from models that assume ions and electrons share the same temperature.
Higher ion temperatures could affect the population of energetic particles ejected into space, which in turn influences space weather risks for satellites, power grids, and crewed missions. The extent of that risk depends on many factors, including flare size, magnetic geometry, and how quickly the heated particles escape.
Researchers say this shift in understanding will prompt updates to flare simulations and to assessments of hardware vulnerability. Russell’s group is already developing models that follow flare evolution when ions are heated more strongly than electrons.
“This is a surprising result — the ion temperatures can be a crazy number compared with what we’ve assumed,”
Alexander Russell, University of St. Andrews
Unconfirmed
- Whether the 180 million°F value applies broadly across large, medium, or only some classes of flares remains to be demonstrated.
- How frequently flares reach the highest ion temperatures in practice is not yet settled and requires targeted observations and modeling.
- Direct links between the revised ion temperatures and specific satellite anomalies or outages are plausible but not yet firmly established.
Bottom Line
The new analysis revises upward the potential peak temperatures inside solar flares by focusing on ions rather than electrons. If validated by further observations and simulation work, this change will refine space-weather models and could alter assessments of risk to spacecraft and astronauts.