Solar eruptions may not have slinky-like shapes as commonly believed, according to a study that may help protect satellites in space as well as the electrical grid on Earth in the future. Revisiting older data, researchers from the University of New Hampshire in the US found new information about the shape of coronal mass ejections (CMEs) -- large-scale eruptions of plasma and magnetic field from the Sun.
"Since the late 1970s, coronal mass ejections have been assumed to resemble a large slinky -- one of those spring toys -- with both ends anchored at the Sun, even when they reach Earth about one to three days after they erupt," said Noe Lugaz, an associate professor at the University of New Hampshire. "But our research suggests their shapes are possibly different," Lugaz said. Knowing the shape and size of CMEs is important because it can help better forecast when and how they will impact Earth, according to the research published in the Astrophysical Journal Letters.
CMEs are one of the main sources for creating beautiful and intense auroras, like the Northern and Southern Lights. However, they can also damage satellites, disrupt radio communications and wreak havoc on the electrical transmission system causing massive and long-lasting power outages. Right now, only single point measurements exist for CMEs making it hard for scientists to judge their shapes, researchers said.
These measurements have been helpful to space forecasters, allowing them a 30 to 60 minute warning before impact, they said. The goal is to lengthen that notice time to hours -- ideally 24 hours -- to make more informed decisions on whether to power down satellites or the grid. The researchers took a closer look at data from two NASA spacecraft, Wind and ACE, typically orbiting upstream of Earth.
They analysed the data of 21 CMEs over a two-year period between 2000 and 2002 when Wind had separated from ACE. "Because they are usually so close to one another, very few people compare the data from both Wind and ACE," said Lugaz. "But 15 years ago, they were apart and in the right place for us to go back and notice the difference in measurements, and the differences became larger with increasing separations, making us question the Slinky shape," said Lugaz.
The data points towards a few other shape possibilities, researchers said. Either CMEs are not simple slinky shaped -- they might be deformed ones or something else entirely -- or they are slinky-shaped but on a much smaller scale, roughly four times smaller, than previously thought.
