The sun’s powerful magnetic field, responsible for creating sunspots and unleashing solar storms, has long puzzled astronomers. This magnetic field generates stunning auroras and can disrupt GPS and communication satellites. Despite centuries of study, the exact source of the sun’s magnetic field has remained elusive since Italian astronomer Galileo first observed sunspots in the early 1600s.
New Theory Challenges Previous Assumptions
Researchers behind a recent interdisciplinary study have proposed a new theory published in the journal Nature. Contrary to previous beliefs that the sun’s magnetic field originates deep within the star, the new theory suggests the source is much closer to the surface.
The model developed by the team could help scientists better understand the 11-year solar cycle and improve forecasting of space weather, which affects both technological systems and night sky phenomena.
“This work proposes a new hypothesis for how the sun’s magnetic field is generated that better matches solar observations and, we hope, could be used to make better predictions of solar activity,” said Daniel Lecoanet, an assistant professor at Northwestern University’s McCormick School of Engineering.
Importance of Accurate Solar Cycle Predictions
Accurate forecasting of the solar cycle’s strength is crucial for anticipating solar activity. Previous models, which assumed the magnetic field was generated deep within the sun, have not been able to make accurate forecasts. Lecoanet emphasized the need for a model that could predict whether the next solar cycle would be particularly strong or weak.
Sunspots, which are the origin points for explosive solar flares and ejections, help scientists track the sun’s activity. The recent solar storm, indicative of the sun approaching its “solar maximum,” underscores the importance of understanding these cycles.
Advanced Modeling Techniques
To study the sun’s magnetic field, scientists rely on mathematical models. The new model by Lecoanet and his colleagues is groundbreaking because it incorporates torsional oscillation, which are magnetically driven flows of gas and plasma that contribute to sunspot formation.
Their calculations revealed that magnetic fields can be generated about 20,000 miles (32,100 kilometers) below the sun’s surface, much closer than the previously assumed depth of 130,000 miles (209,200 kilometers).
Computational Breakthrough
Developing new numerical algorithms was key to this discovery. Geoff Vasil, a professor at the University of Edinburgh and the study’s lead author, conceived the idea two decades ago. It took over ten years to develop the necessary algorithms, and the simulations required the power of a NASA supercomputer, using around 15 million CPU-hours.
Impact and Future Research
Ellen Zweibel, a professor of astronomy and physics at the University of Wisconsin-Madison, praised the study in a commentary published alongside it. Although not involved in the research, Zweibel noted that the team had added “a provocative ingredient to the theoretical mix that could prove key to unraveling this astrophysical enigma.”
The new hypothesis offers a natural explanation for torsional oscillations, missing from previous models, and promises to enhance our understanding of the sun’s magnetic field and solar activity.