In a fiery breakthrough, scientists from the University of St Andrews have revealed that solar flares, those explosive bursts of energy from the Sun, are packing even more heat than we thought. Their new research shows that particles in these flares can reach temperatures 6.5 times hotter than previously estimated, offering a fresh solution to a mystery that has puzzled solar physicists for nearly half a century.
Published in Astrophysical Journal Letters, the study dives into the intense heating of solar plasma, the soup of charged particles, ions, and electrons that make up the Sun’s outer atmosphere. While it’s long been known that solar flares can heat plasma to over 10 million degrees, this new work suggests that ions alone can soar past 60 million degrees.
Leading the research is Dr Alexander Russell, Senior Lecturer in Solar Theory at the School of Mathematics and Statistics. His team connected dots across different fields of space science to uncover a surprising pattern.
“We were excited by recent discoveries that a process called magnetic reconnection heats ions 6.5 times as much as electrons,” said Dr Russell. “This appears to be a universal law, and it has been confirmed in near-Earth space, the solar wind, and computer simulations. However, nobody had previously connected work in those fields to solar flares.”
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This insight challenges a long-standing assumption in solar physics that ions and electrons must share the same temperature. But when the team revisited calculations using modern data, they found that temperature differences between ions and electrons can persist for tens of minutes in key regions of solar flares.
“Solar physics has historically assumed that ions and electrons must have the same temperature,” Dr Russell explained. “However, redoing calculations with modern data, we found that ion and electron temperature differences can last for as long as tens of minutes in important parts of solar flares, opening the way to consider super-hot ions for the first time.”
And here’s where things get even more exciting: this new understanding may finally explain why flare spectral lines, bright streaks of solar radiation seen in extreme-ultraviolet and X-ray light, have appeared broader than expected since the 1970s. Scientists once blamed turbulence, but that theory has struggled to hold up.
“What’s more,” Dr Russell added, “is that the new ion temperature fits well with the width of flare spectral lines, potentially solving an astrophysics mystery that has stood for nearly half a century.”
This discovery doesn’t just rewrite textbooks; it could reshape how we understand solar activity and its impact on Earth. Solar flares can disrupt satellites, endanger astronauts, and stir up chaos in our planet’s upper atmosphere. Knowing how hot these flares really get helps scientists better predict and prepare for their effects.
So next time the Sun throws a tantrum, remember: it’s not just hot, it’s super-hot, and we’re finally starting to understand why.
Journal Reference:
- Alexander J. B. Russell, Vanessa Polito, Paola Testa, Bart De Pontieu, and Sergey A. Belov. Solar Flare Ion Temperatures. The Astrophysical Journal Letters. DOI: 10.3847/2041-8213/adf74a