Researchers have directly observed small-scale torsional Alfven waves in the Sun's corona for the first time, a key discovery achieved with the Daniel K. Inouye Solar Telescope in Hawaii. These elusive magnetic waves, theorized since the 1940s, may play a crucial role in explaining why the corona reaches temperatures of millions of degrees while the Sun's surface remains at approximately 5,500oC by Sophie Jenkins
London, UK (SPX) Oct 25, 2025
Researchers have directly observed small-scale torsional Alfven waves in the Sun's corona for the first time, a key discovery achieved with the Daniel K. Inouye Solar Telescope in Hawaii. These elusive magnetic waves, theorized since the 1940s, may play a crucial role in explaining why the corona reaches temperatures of millions of degrees while the Sun's surface remains at approximately 5,500oC.
The study, led by Professor Richard Morton at Northumbria University, used the telescope's advanced Cryogenic Near Infrared Spectropolarimeter (Cryo-NIRSP) to capture unprecedented details in the coronal plasma. This instrument enabled scientists to distinguish the twisting motions of Alfven waves - motions that typically remain hidden behind more familiar swaying plasma movements.
Alfven waves are magnetic disturbances capable of transporting energy through the solar atmosphere. While their larger counterparts have been linked to solar flares, this is the first direct evidence of the constant, small-scale twisting variety. "This discovery ends a protracted search for these waves that has its origins in the 1940s. We've finally been able to directly observe these torsional motions twisting the magnetic field lines back and forth in the corona," said Professor Morton.
The research benefited from new analytical methods developed to isolate and identify the unique spectral signatures produced by these twisting waves. Tracking iron ions heated to 1.6 million degrees Celsius, the team distinguished torsional Alfven waves through red and blue shifts observed on opposite sides of solar magnetic structures.
Understanding Alfven wave behavior holds practical value for forecasting space weather, as magnetic turbulence in the corona can disrupt satellite communications and power systems on Earth. The findings also lend support to theoretical models in which Alfvenic turbulence is responsible for heating the solar corona and driving the solar wind.
The study was an international collaboration funded by the UKRI Future Leaders Fellowship, the National Natural Science Foundation of China, and the European Union's Horizon Europe program. Co-authors represent institutions in the UK, China, Belgium, and the United States.
Research Report:Evidence for small-scale torsional Alfven waves in the solar corona
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