The latest research from Andrews University shows that the temperature of particles in solar flares far exceeds previous scientific estimates, and the temperature of some ions is even 6.5 times higher than originally thought. The discovery provides an explanation for a solar flare mystery that has puzzled the astronomical community for half a century.
Solar edge flares are as large as Earth's. Image source: Alexander Russell (Andrews University) was produced using the open source Python software package SunPy and NASA Solar Dynamics Observatory space telescope data. The data was provided by the NASA EPIC team.
A solar flare is a violent explosion of energy in the sun's outer atmosphere, causing local temperatures to rise to more than 10 million degrees Celsius. These violent activities will significantly increase solar X-rays and radiation, affecting the safety of spacecraft, astronauts, and the Earth's upper atmosphere on Earth.
According to the study, conventional wisdom holds that when solar flares heat plasma, the temperatures of electrons and ions are consistent. However, the research team introduced recent discoveries in different fields and confirmed that solar flares heat ions much more strongly than electrons, and the actual temperature of ions can be as high as more than 60 million degrees.
Dr. Alexander Russell, the main leader of the study and senior lecturer in solar theory at the School of Mathematics and Statistics at the University of St. Andrews, said: "Recently, a physical process called magnetic reconnection has been found to make the heating efficiency of ions 6.5 times that of electrons. This rule has been confirmed many times in near-Earth space, solar wind and computer simulations, but has never been applied to solar flare research before."
Solar flare. Image credit: Produced by Alexander Russell (Andrews University) using the open source SunPy Python package, with data from the NASA Solar Dynamics Observatory Space Telescope (acquired via the NASA EPIC team).
It was previously believed that the temperatures of electrons and ions in a flare should be the same. However, after recalculating with modern data, the researchers found that the huge difference in temperature can last for tens of minutes, giving scientists the first opportunity to re-examine the impact of ultra-high-temperature ions on the physical processes of flares.
This latest ion temperature data well explains the broadening phenomenon of solar flare spectral lines and promotes a breakthrough in nearly 50 years of confusion in the astrophysics community. Since the 1970s, academic circles have suspected that spectral line broadening could only be caused by turbulence, but the specific turbulence mechanism has always been difficult to define. Now researchers propose that the significant increase in ion temperature itself can become an important reason for spectral line broadening, which will trigger changes in observational and theoretical research paradigms.
The results have been published in the "Astrophysical Journal Letters" magazine on September 3, 2025. Authors include Alexander J.B. Russell, Vanessa Polito, Paola Testa, Bart De Pontieu, and Sergey A. Belov.
Compiled from /ScitechDaily