The sun’s magnetic field, which drives sunspots and flares, has long been assumed to be generated deep within the star through a process called dynamo action. However, a recent study by researchers at MIT, the University of Edinburgh, and other institutions has found that the sun’s magnetic field may actually arise from instabilities in its outermost layers. By simulating perturbations in the flow of plasma within the top 5 to 10 percent of the sun’s surface, the team was able to generate realistic magnetic field patterns that matched observations of the sun, while deeper simulations produced less realistic results. This suggests that sunspots and flares may be a product of a shallow magnetic field, challenging previous assumptions about the sun’s magnetic activity.
The findings of this study could have implications for the forecasting of solar flares and geomagnetic storms, which have the potential to damage satellites and telecommunication systems. By identifying the origins of the sun’s magnetic field, scientists may be better equipped to understand and predict solar activity. The study’s co-authors emphasize the importance of understanding the complex interactions that drive the solar dynamo in order to improve forecasting capabilities.
The researchers utilized data from helioseismology, a field in which observed vibrations on the sun’s surface are used to infer the average structure and flow of plasma beneath the surface. By developing a precise model of the sun’s surface and implementing algorithms into the Dedalus Project, the team was able to identify patterns in the surface flows that could potentially lead to the sun’s magnetic field. The simulations produced patterns that resembled observed sunspots, which have been known to occur in cyclical patterns every 11 years and generally gravitate around the equator.
The team’s discovery of self-reinforcing changes in the sun’s average surface flows suggests a new mechanism for the generation of the sun’s magnetic field, one that may be more closely aligned with observed solar activity. By focusing on flow patterns near the surface, the researchers were able to identify similarities between the sun’s plasma flows and those found in accretion disks around black holes, which are driven by magnetorotational instability. This new understanding challenges existing theories about the origin of the sun’s magnetic field and points to a different mechanism that may better explain solar phenomena.
While the idea that the sun’s magnetic field originates from its outermost layers may be controversial within the scientific community, the study provides compelling evidence that a shallow magnetic field could be responsible for the sun’s activity. The team is continuing to investigate whether the new surface field patterns can generate individual sunspots and the full 11-year solar cycle. This research has been supported in part by NASA, and the findings have the potential to significantly advance our understanding of solar dynamics and improve forecasting capabilities for space weather events.