What causes solar eruptions? Scientists find new clues to help us understand how they affect Earth

Eruptions on the sun, whether large or small, are all triggered by a single mechanism, scientists have shown. The research aims to improve our understanding of the Sun's activity and how it affects us down on Earth.

There are many types of solar eruptions, involving big explosions of energy. These include eruptions known as 'coronal jets' and 'coronal mass ejections' (CMEs).

While coronal jets are relatively small bursts of plasma from the Sun, CMEs are larger and refer to giant clouds of magnetised particles and plasma blown into space.

Astronomers long believed very different processes were behind these two phenomena.

"Coronal jets and CMEs have very different sizes and they look a bit different. Scientists believed that due to these large differences in scale and slightly different shapes these eruptions were driven by different mechanisms," Dr Peter Wyper, Royal Astronomical Society Fellow and lead author of the study, told IBTimes UK.

The theory was that in coronal mass ejections, the initial release of energy did not change the magnetic topology (the structure of the magnetic flux) – but that this was not the case when it came to coronal jets. Coronal jets seem to involve a process known as magnetic reconnection, whereby magnetic topology is rearranged.

However, recent observations of coronal jets have cast doubt on this theory. Scientists say that both types of solar eruptions may be caused by the same processes. Indeed, they have seen that coronal jets appear to be driven by snake-like filaments of dense plasma low in the Sun's atmosphere, just like CMEs.

Snake-like-filaments

In the study now published in the journal Nature, a team of scientists hypothesised that both types of solar eruptions don't actually emerge from different kinds of processes. Rather, coronal jets are miniature versions of coronal mass ejections.

The scientists, from Durham University and NASA's Goddard Space Flight Center, developed 3D computer simulation models to draw a theoretical link between large- and small-scale eruptions.

The models suggest that coronal mass ejections and coronal jets may have physically identical origin and that all coronal jets may be driven by snake-like filament ejection, just like large mass ejections. What then determines the size of an eruption is the size of the filament and the strength and structure of the magnetic field around it.

These findings improve scientists' understanding of solar eruptions, which can have a number of important consequences for Earth.

"When the largest coronal mass ejections occur, where huge amounts of solar plasma, radiation and high energy particles are being released towards Earth, the impact on our planet can be significant," Wyper concluded.

"It can be something quite cool as these eruptions are responsible for auroras. But they can also cause problems to our satellites, and magnetic oscillations can create electrical currents in utility grids that can lead to our electrical systems becoming dysfunctional. Learning about solar eruptions can help us prepare for their impacts."