NYU, Princeton, the Max Planck Institute, and NASA have all teamed up to uncover the nature of the Sun’s plasma motions. By creating an MRI of the plasma motions, they have taken a step towards understanding the nature of heat transfer in the Sun, a topic that has remained largely theoretical until now.
Nuclear fusion in the core of the Sun generates heat that is transported to the surface by way of convection. However the Sun is opaque leaving direct observation of this phenomenon out of our reach. To date, our understanding of heat transfer has been theoretical, applying our understanding of fluid mechanics to the Sun.
“Our current theoretical understanding of magnetic field generation in the Sun relies on these motions being of a certain magnitude,” explained Shravan Hanasoge, associate research scholar in geosciences at Princeton University and a visiting scholar at NYU’s Courant Institute of Mathematical Sciences. “These convective motions are currently believed to prop up large-scale circulations in the outer third of the Sun that generate magnetic fields.”
Internal plasma motions are responsible for solar phenomena such as sunspots on the Sun’s surface and the Sun’s magnetic field. By uncovering the nature of plasma motions, the research team aims to understand these occurrences using empirical data rather than theoretical applications.
Scientists used a whopping 16-million pixel camera on board NASA’s Solar Dynamics Observatory. The Helioseismic and Magnetic Imager (HMI) allowed researchers to measure the motions of the Sun’s surface. Observing the surface waves allowed them to infer the underlying plasma motions that are otherwise impossible to see. The calculations were similar to that of measuring water currents based surface patterns in the water.
Results differed wildly from previously held notions of the Sun’s plasma motions. Observations revealed they were approximately 100 times slower than that of previously projected estimates.
“Our results suggest that convective motions in the Sun are nearly 100 times smaller than these current theoretical expectations,” said Hanasoge, also a postdoctoral fellow at the Max Plank Institute in Katlenburg-Lindau, Germany. “If these motions are indeed that slow in the Sun, then the most widely accepted theory concerning the generation of solar magnetic field is broken, leaving us with no compelling theory to explain its generation of magnetic fields and the need to overhaul our understanding of the physics of the Sun’s interior.”
The current research is extremely valuable to the astronomical community because it is the first empirically evaluated data to help explain the nature of heat transfer in the sun, setting the foundation for a better understanding of solar phenomena.