ESA satellite finally reveals elusive source of Sun’s solar winds

How wind emerges from dark areas of the Sun known as ‘coronal holes’ has remained a mystery until now

The elusive source of the Sun’s solar wind has been discovered by scientists using data collected by the European Space Agency’s Solar Orbiter satellite.

The advance can lead to better prediction of space weather events like solar flares that are powerful enough to disrupt communication infrastructure on Earth.

The fourth state of matter – plasma – is constantly streaming away from the Sun and forming solar wind – a continuous stream of charged particles flowing outwards from the Sun’s outer atmosphere, the corona.

When particles from the solar wind hit the Earth’s magnetic field, they can create auroras, or northern lights and southern lights, and may also disrupt GPS and communications systems.

While dark areas of the Sun’s atmosphere known as “coronal holes” are known to be the source region of solar wind, how this wind actually emerges from these areas has remained elusive.

The new study, published on Thursday in the journal Science, has found that tiny particle jets on the Sun on the scales of a few hundred kilometres, lasting about 20-100 seconds and reaching speeds of about 100km per second, are likely the energy source of the solar winds.

Researchers, including those from the Max Planck Institute for Solar System Research, said these “picoflare” jets could supply energy and plasma to the solar wind – an important component of space weather impacting planets.

These jets are about trillion times weaker in energy compared to large X-class solar flares that can cause blackouts on Earth, according to scientists.

But the energy content of a single picoflare jet lasting for about one minute, can still be “equal to the average power consumed by about 10,000 households in the UK over an entire year,” study co-author Lakshmi Pradeep Chitta told LiveScience.

In the new study, scientists report observations of a coronal hole using the Extreme Ultraviolet Imager (EUI) instrument on board the Solar Orbiter spacecraft launched by the ESA in 2020.

They identified a variety of small-scale plasma jets within the coronal hole that appear to be powered by short-term changes in the Sun’s magnetic field.

Previous research has shown that these dark holes on the Sun are maintained by “open” magnetic fields, where the star’s magnetic lines of force stretch into space, instead of looping back onto itself.

Due to their relatively low kinetic energies, scientists refer to the plasma particle streams coming from such regions as picoflare jets.

They estimate that the charged plasma particle outflows from numerous and frequent picoflare jets, channelled via the coronal holes, could provide substantial energy to the solar wind.

“We suggest that such picoflare jets 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,” scientists wrote in the study.