Belfast scientists crack 70-year-old mystery of the Sun

"This theory was predicted some 75 years ago but we now have the proof"

Belfast scientists crack 70-year-old mystery of the Sun

A sunspot located towards the edge of the sun, visible here as a dark collection of plasma with magnetic field strengths similar to those found in modern hospital MRI machines. However, it is the size of the sunspot, which is comparable to that of our own Earth that gives these structures immense power and energy | Image: Queen's University Belfast

Scientists at Queen's University in Belfast have made a ground-breaking discovery that may be key to how the sun heats its atmosphere.

They found that magnetic waves crashing through the sun could be responsible.

In 1942, Swedish physicist and engineer Hannes Alfvén predicted the existence of a new type of wave due to magnetism acting on a plasma, which led him to win the Nobel Prize for Physics in 1970.

Since his prediction, Alfvén waves have been associated with a variety of sources, - including nuclear reactors, the gas cloud that envelops comets, laboratory experiments, medical MRI imaging and in the atmosphere of our nearest star, the sun.

Scientists have suggested for many years that these waves may play an important role in maintaining the Sun's extremely high temperatures, but until now had not been able to prove it.

Dr David Jess from the School of Mathematics and Physics at Queen’s University explained: "For a long time scientists across the globe have predicted that Alfvén waves travel upwards from the solar surface to break in the higher layers, releasing enormous amounts of energy in the form of heat.

"Over the last decade scientists have been able to prove that the waves exist but until now there was no direct evidence that they had the capability to convert their movement into heat.

"At Queen’s, we have now led a team to detect and pinpoint the heat produced by Alfvén waves in a sunspot.

"This theory was predicted some 75 years ago but we now have the proof for the very first time.

"Our research opens up a new window to understanding how this phenomenon could potentially work in other areas such as energy reactors and medical devices."

Dr David Jess, Queen's University Belfast | Image: Queen's University Belfast

The international team included Queen’s University Belfast, the Space Research Institute, Austria, Ilia State University, Georgia, the National Solar Observatory, USA and Instituto de Astrofísica de Canarias in Spain.

The study used advanced high-resolution observations from the Dunn Solar Telescope in New Mexico - alongside observations from NASA's Solar Dynamics Observatory - to analyse the strongest magnetic fields that appear in sunspots.

These sunspots have intense fields, similar to modern MRI machines in hospitals, and are much bigger than our own planet.

A view of a sunspot on the solar surface, visible here as a dark collection of plasma with magnetic field strengths similar to those found in modern hospital MRI machines | Image: Queen's University Belfast

Dr Samuel Grant from Queen's said: "By breaking the sun’s light up into its constituent colours, our international team of researchers were able to examine the behaviour of certain elements from the periodic table within the Sun’s atmosphere, including calcium and iron.

"Once these elements had been extracted, intense flashes of light were detected in the image sequences.

"These intense flashes had all the hallmarks of the Alfvén waves converting their energy into shock waves, in a similar way to a supersonic aircraft creating a boom as it exceeds the speed of sound.

"The shock waves then ripple through the surrounding plasma, producing extreme heat.

"Using supercomputers, we were able to analyse the data and show for the first time in history that the Alfvén waves were capable of increasing plasma temperatures violently above their calm background."

The research paper has been published in Nature Physics.