This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The sun's magnetic fields are a twisty, curvy, ever-changing mess. In particular, our star's polar regions host areas called polar coronal holes, which contain invisible magnetic highways that stretch into interplanetary space.
But there's a lot we don't know about how those highways actually work, particularly how they give the particles that form the fast solar wind an extra "kick" that sends them zooming at hundreds of kilometers per second. A new paper from a team led by Dr. Yuhang Gao and Professor Hui Tian at Peking University, published recently in the journal National Science Review, suggests they might have found an answer by using high-speed images from the Solar Orbiter to detect never-before-seen rapid, high-frequency magnetic waves in those areas.
Key to this discovery is camera speed. Older instruments, such as NASA's Solar Dynamics Observatory (SDO), took pictures every 12 seconds and had a spatial resolution of around 1,100 km for every pixel. Upgraded equipment offered much faster, higher-resolution imagery.
Solar Orbiter's Extreme Ultraviolet Imager (EUI) captures an image every five seconds, with details down to 420 km per pixel—more than double the precision and twice the speed of earlier instruments. Using data from both instruments from September 2021, the authors subjected the data to an automated magnetic wave-tracking program called the Northumbria University Wave Tracking (NUWT). Taking a close look at solar plumes—ray-like magnetic structures that stick out from the sun's north pole—the authors noted a distinct difference in the number of waves detected by the two observatories.
With the SDO, the algorithm caught 560 wave events, whereas with the EUI, it caught 2,318—more than four times as many. The difference seemed to come down to frequency. Thirty-eight percent of the waves seen by the EUI had wavelengths shorter than 100 seconds, whereas only 9% of the waves detected by the SDO had the same wavelengths.
Another determining factor was speed—how fast the plasma thread moved. The SDO's average speed was around 9.9 km/s, whereas the EUI's averaged 15.4 km/s. And since energy scales with velocity, these faster-moving waves carry much more power.
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