Why solar flares are way hotter than researchers thought

"Beautiful yet dangerous solar flares that erupt from the sun could be as hot as 180 million degrees Fahrenheit, researchers say. That's more than six times hotter than solar physicists previously believed, according to a new report in Astrophysical Journal Letters. Alexander Russell, a physicist with the University of St. Andrews in Scotland, called that temperature "a crazy number" that he and his colleagues found "incredible.""

"Previously, researchers used telescopes to measure the temperature of electrons in solar flares. "And we've kind of just assumed, well, the ion temperature would be the same as the electron temperature," says Russell. But recent computer simulations and measurements in near-Earth space suggest that this assumption is wrong: They show that ions heat up way more. Russell and his colleagues did some calculations and found that solar flares could actually be over 100 million degrees Fahrenheit, and quite possibly hotter."

"James Drake, a physicist at the University of Maryland who wasn't part of this research team, has been studying how magnetic processes heat and speed up electrons and ions for some time. He says until now, the difference between the two has been overlooked when it comes to solar flares. "We've been confronting the solar physicists," says Drake, "telling them that even though they've measured in a lot of detail what's going on with the electrons, they're missing something big.""

Solar flare temperatures may reach about 180 million°F, over six times previous estimates. Ions in flares heat to far higher temperatures than electrons, contrary to prior assumptions based on telescope electron measurements. Computer simulations and near-Earth measurements indicate significant ion heating. Calculations show flares could exceed 100 million°F and possibly reach 180 million°F. The ion/electron temperature difference could change understanding of flare heating and particle acceleration. Previous telescope-based measurements captured only electron temperatures, not ion temperatures, causing underestimation of flare energy and associated risks to space hardware and humans.

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