Despite several decades of space exploration and research, fundamental questions about solar dynamics remain unanswered. Researchers have questioned if convective motions in the Sun’s interior, which refers to movement of fluid that transports heat outwards, are actually vigorous enough to drive the rotation of the Sun. Studying convective movement involves complications as the fluid movement occurs below the surface of the Sun, invisible to us. Laboratory experiments cannot simulate the extreme conditions of the Sun.
To overcome these limitations, a team of researchers at NYU Abu Dhabi Center for Space Science, led by Assistant Research Professor Shravan Hanasoge, has utilized sound waves, which are generated at the solar surface, propagate in the interior, then re-emerge at the surface where they can be observed. The process of imaging the solar interior with sound waves is called helioseismology. The team’s imaging showed unusual and unexpected patterns which challenged theoretical and computational models of convection in the Sun.
In the study, Turbulence in the Sun is suppressed on large scales and confined to equatorial regions, published in the journal Science Advances, Hanasoge and his team present a novel method of helioseismology to study the internal dynamics of the Sun. The observed fluid motions were then compared to existing numerical simulations of how the sun transports heat in the internal convection zone.
The results of the helioseismology technique showed different patterns from the previously determined calculations. The comparison showed that the Sun has a preference for generating small-scale fluid motions that are confined to its equator, while the numerical simulation appeared to generate large-scale motions away from the equator. This has important implications for our appreciation of how fundamental processes in the Sun work.
“Our current understanding of the Sun, derived from numerical simulations, show qualitatively different fluid motions from those obtained from seismic studies of the Sun,” said Hanasoge. “The Sun, despite being so highly observed, holds many mysteries as to how it operates. These differences highlight gaps in our understanding of solar convection and point to challenges ahead.”
Image caption:
These images show flows in the north-south (left panels) and the east-west directions (right panels). Upper panels are obtained from analyses of seismic observations of the Sun, recorded by the HMI instrument onboard the Solar Dynamics Observatory, a space-based satellite. The lower panels are from numerical calculations of how convection might look in the Sun. The comparison shows that the Sun has a preference for generating small-scale fluid motions that are confined to the equatorial regions, while the numerical simulation appeared to generate large-scale motions away from the equator. This has important implications for our appreciation of how fundamental processes in the Sun work. Courtesy of NYU Abu Dhabi Center for Space Science.