NASA’s Solar Dynamics Observatory captured this image of an M7.3 class solar flare on 2 October 2014. The solar flare is the bright flash of light on the right limb of the sun. A burst of solar material erupting out into space can be seen just below it. Credit: NASA/Goddard/SDO
Solar flares are sudden, massive explosions of electromagnetic radiation released from the Sun’s outer atmosphere and can last anywhere from minutes to hours.
These events heat solar plasma, made of electrons and positively charged ions, to temperatures of more than 10 million degrees Celsius.
But new research suggests the process might affect the types of charged particles differently, with positive ions reaching temperatures of more than 60 million degrees.
As the Sun rotates, its magnetic fields get tangled up, stretching and twisting until they break and rejoin to form new lines in a process called magnetic reconnection, This converts magnetic energy into kinetic, thermal and particle acceleration energy.
“We were excited by recent discoveries that a process called ‘magnetic reconnection’ heats ions 6.5 times as much as electrons,” says Dr Alexander Russel who co-led the research at the University of St Andrews, UK.
“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.
“Solar physics has historically assumed that ions and electrons must have the same temperature. However, redoing calculations with modern data, we found that ion and electron temperature differences can last for as long as 10s of minutes in important parts of solar flares, opening the way to consider super-hot ions for the first time.”
The research has been published in The Astrophysical Journal Letters.