Solar scientists confirm 70 year magnetic wave prediction

Magnetic loops on the Sun, captured by NASA's Solar Dynamics Observatory (SDO). The latest research has confirmed the presence of torsional magnetic plasma waves on the surface of the Sun, as predicted by over 70 years ago. Image credit: NASA

Researchers have confirmed the existence of magnetic waves on the surface of the Sun that were predicted by a Swedish scientist over 70 years ago.

Physicist Hannes Alfvén presented the theoretical case for the torsional magnetic plasma waves in 1947, work that was rewarded with the Nobel Prize for Physics in 1970.

Writing in Nature Astronomy, a team led by Dr Marco Stangalini from the Italian Space Agency and Professor Róbertus Erdélyi from the University of Sheffield, and including scientists from the Department of Physics at Aberystwyth University, report the first direct recording of the phenomenon now known as Alfvén waves.

Soon after their mathematical prediction, Alfvén waves were recognized for their potential impact in many research areas, including neutrino physics, the physics of interstellar medium, and industrial applications in metallurgy.

Their key attribute is their ability to transport energy and information over very large distances due to their purely magnetic nature.

Until now, the waves have eluded scientists as it has not possible to detect their direct signature, and they have remained ‘hidden’ in the solar photosphere, the Sun’s outer shell.

Alfvén’s prediction has now been confirmed using data collected by the Interferometric BIdimensional Spectropolarimeter (IBIS), which is based at the US National Solar Observatory in New Mexico.

In addition to confirming their presence, the team has identified the waves as an efficient mechanism for the extraction of vast amounts of energy from the solar photosphere to the upper layers of the Sun and potentially into interplanetary space.

Dr Marianna Brigitta Korsós is a Post-Doctoral Research Assistant in the Solar System Physics Group at the Department of Physics at Aberystwyth University, and a member of the team that made the discovery.

Dr Korsós said: “This research was about finding direct evidence for the presence of these purely magnetic waves which earned Alfvén the Nobel Prize for Physics more than 50 years ago. This is a fantastic area of astronomy that is developing rapidly thanks to the availability of better and better detectors. I am very proud to be part of this collaboration as a young female researcher at Aberystwyth University and I have learnt a lot about this fascinating area of science.”

Dr Huw Morgan, from the Solar System Physics Group at Aberystwyth University, added: “In solar physics we are continuously seeking clues to reveal the presence of phenomenon in observation. We know that magnetic waves occur in the solar atmosphere, and must play an important role. Yet they are extremely difficult to observe directly - we depend on indirect and often ambiguous signatures in data. This study is exciting. It shows the culmination of several decades of improvements in observing technology and computer modelling in the field which is finally opening a window to the processes that power the solar atmosphere.”

According to the team, the direct discovery of torsional Alfvén waves in the solar photosphere is just a first step towards exploiting the capabilities and capacities of these magnetic waves.

There are now superb additional opportunities to research their relevance, thanks to the opportunities offered by the Solar Orbiter satellite, the 4 metre aperture ground-based Daniel K. Inouye Solar Telescope (DKIST) and the European Solar Telescope (EST Project)

Dr Korsós is also an active leading member of SAMNet which is dedicated to understanding the interaction of solar activity with the Earth’s upper atmosphere, including solar magentism.

The paper Torsional oscillations within a magnetic pore in the solar photosphere was published in Nature Astronomy on Monday 10 May 2021.

The Solar System Physics Group at Aberystwyth University

The Solar System Physics Group at Aberystwyth studies this single system from the development of eruptive features on the Sun, through the evolution and structure of material in the solar wind, and the impact of this flow on the environments of the inner planets. The group is involved in several current or planned missions, and has a programme of developing novel optical systems and robotic components for space exploration.

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