Observations could help predict large explosions in the future
The Solar Dynamics Observatory detected a record solar flare on October 3, 2024.
Like a toddler about to throw a tantrum, the sun might change its face just before it erupts.
Observations leading up to massive solar flare revealed changes near the solar surface beginning three hours before the flash, the scientists report in a paper submitted May 8 to arXiv.org. The findings could help experts develop methods to predict future solar flares, potentially giving us time to protect Earth’s power grid, satellites in orbit, and astronauts in space.
“That’s always kind of the goal when we talk about pre-torage,” says solar physicist Louis Seyfritz of the New Jersey Institute of Technology in Newark. “If we can predict when a huge solar flare… is going to happen, that means we can protect [astronauts] from any harmful radiation.
Seyfritz and his colleagues examined space observations of an active region of the sun that emitted a class X solar flarethe most intense type of eruption, on October 3, 2024.
“Pre-torching isn’t very well documented because people like to see things explode,” says Seyfritz. But the flares come in groups. He and his colleagues knew that the same region had already emitted a strong flare a few days earlier. On October 3, other scientists trained NASA’s Interface Region Imaging Spectrograph space telescope on a single point in the active region to see if they could capture a flare in action.
The telescope tracked changes in the light emitted by the silicon IV ion, which traces the plasma in the transition region between the sun’s surface and the corona.
“One of the biggest questions about rashes is what triggers them. In nature, most systems like to remain stable, so what causes the sun’s magnetic field to destabilize to the point where an uncontrolled release of energy is the next step?” asks solar physicist Emily Mason of Predictive Science Inc. in San Diego, who was not involved in the new work. “Observations like this, which show what happens before this enormous release of energy, are essential to understanding this trigger.”
Seyfritz and his colleagues analyzed features of light that probe the temperature, turbulence and movement of plasma toward or away from the sun’s surface. They found that all three parameters gradually increased three hours before the eruption, as the region accumulated energy. About 20 minutes before the flare, the temperature and turbulence jumped, as did the speed of the plasma as it moves away from the sun.
The team found that the parameters varied periodically over the three hours before the eruption, with constant highs and lows every 8 minutes and 20 minutes. During the last hour before the eruption, the temperature and turbulence tracers changed in synchrony.
Both oscillations appeared to vary depending on the wavelength of the measured light, with shorter wavelengths indicating the 8-minute period and longer wavelengths indicating the 15-minute period, Mason notes. This suggests that two different physical mechanisms could be occurring in the plasma, she says.
The work is interesting and important, she says, but there are many steps between here and forecasting solar flares that could be useful. It would be good to check if similar oscillations appear in an active region which isn’t it on the verge of bursting, on the one hand.
And there are practical obstacles too.
“I am confident that the oscillations reported here have the ability to predict major flares, but we would need a mission capable of observing the entire sun at once (and probably performing the analysis on board) in order to be useful predictively,” she says. “The technology exists. It’s a question of financing.”
