Extreme ultraviolet images of the Sun obtained by the Extreme Ultraviolet Imager (EUI) instrument onboard the ESA/NASA Solar Orbiter spacecraft have revealed numerous small-scale jets within a coronal hole. These so-called picoflare jets, only a few hundred kilometers across, have been observed to last only 20 to 100 seconds and reach speeds of approximately 100 km/sec. They could produce enough high-temperature plasma to sustain the solar wind and that the wind emerges from coronal holes as a highly intermittent outflow at small scales.
“We could only detect these tiny jets because of the unprecedented high-resolution, high-cadence images produced by EUI,” said Dr. Lakshmi Pradeep Chitta, an astronomer at the Max Planck Institute for Solar System Research.
“In particular, the images were taken in the extreme ultraviolet channel of EUI’s high resolution imager, which observes million-degree solar plasma at a wavelength of 17.4 nm.”
“Of particular importance is the fact that the analysis shows that these features are caused by the expulsion of plasma from the solar atmosphere.”
Solar astronomers have known for decades that a significant fraction of the solar wind is associated with magnetic structures called coronal holes — regions where the Sun’s magnetic field does not turn back down into the Sun. Instead, the magnetic field stretches deep into the Solar System.
Plasma can flow along these ‘open’ magnetic field lines, heading into the Solar System, creating the solar wind.
But the question was: how did the plasma get launched?
The traditional assumption was that because the corona is hot, it will naturally expand and a portion of it will escape along the field lines.
But the new results look into the coronal hole that was situated at the Sun’s south pole, and the individual jets that were revealed challenge the assumption that the solar wind is produced only in a steady continuous flow.
“One of the results here is that to a large…
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