The U.S. Department of Energy announced this week that it can now more accurately predict when a solar eruption might happen, and protect people and technology from its effects.
Solar eruptions are bad news: they propel millions of tons of plasma gas and radiation outward from the sun, straight through space. The radiation is certainly enough to kill a rogue astronaut or destroy an unsuspecting rocket. And they can spell problems here on our little planet, as well: interrupting cell phone service, ruining satellites, and shutting down power grids. For the record, solar eruptions are different from solar flares, although they frequently occur together.
Knowing when a solar eruption will happen would mitigate these fears, because we could properly prepare for them. For space explorers, that would mean keeping astronauts and unmanned voyagers safely on Earth until the explosion and its effects had dissipated.
The key finding involves a mechanism that may stop eruptions from happening before they ever leave the massive star. Researchers at the Princeton Plasma Physics Laboratory (PPPL), an agency of the U.S. Department of Energy, discovered that a phenomenon called "toroidal field tension force" seems to fight the eruptions, calming the forces down and bringing the sun back to stasis. Here's how it works:
The sun's outermost layer, the corona (yum), is full of magnetic energy that is constantly twisting and turning on the surface of the sun, delicately dancing between strands, like jump ropes on a playground. These are called "magnetic flux ropes," and they are always in motion. Sometimes, however, they twist to a point where they destabilize and begin to break apart. When that happens, they either explode out into space in the form of a solar eruption, or they collapse back toward the sun and take up their jump-roping duties again.
Until now, we didn't know why the solar jump ropes sometimes succeeded in hurling gas and radiation outward, and sometimes didn't. This made it difficult to safely plan space missions, especially when there was a hint of an eruption.
The researchers found that along each magnetic jump rope runs a guide — a special magnetic field that serves as a quality control checkpoint, keeping the jump ropes in line. This magnetic field is stronger than the others, and basically keeps them from losing their cool. When the ropes begin to destabilize, the guide-field interrupts the process, creating a "toroidal field tension force," which is essentially a dynamic force that prevents the eruption. When the guide falls asleep on the job, and doesn't produce enough counter-energy to get the toroidal field tension force going, there is no check on the magnetic jump ropes, and they erupt.
The researchers made the discovery using the laboratory's Magnetic Reconnection Experiment, which is, according to the agency, "the world's leading device for studying how magnetic fields in plasma converge and violently snap apart." I bet it is, because how many devices are competing for that title? Anyway, congrats, guys.
The researchers were able to recreate the same conditions present on the sun inside the device, and give the quality control field more or less power to control the other ropes. They were then able to see how a weak quality controller resulted in an eruption. So the presence of guide fields should help scientists recognize whether an eruption is likely.
