How Did Indian Astrophysicists Uncover the Sun's Subsurface Weather Linked to Its 11-Year Activity Cycle?

New Delhi, April 29 (NationPress) An international collaboration of solar physicists, led by experts from the Indian Institute of Astrophysics (IIA), an autonomous body under the Department of Science and Technology (DST), has unveiled the complexities of the Sun’s subsurface weather, intricately linked to its 11-year solar activity cycle.

The research team, which included scientists from Stanford University (US) and the National Solar Observatory (NSO) (US), investigated massive plasma tides beneath the Sun's surface in a region known as the near-surface shear layer (NSSL). These plasma currents fluctuate in accordance with the Sun’s magnetic rhythm and could significantly impact space weather and terrestrial conditions.

The NSSL, which extends approximately 35,000 km below the Sun’s surface, is essential for understanding solar dynamics. It exhibits unique rotational behaviors that vary with depth, influenced by changes related to the active regions' magnetic fields and the solar cycle.

Published in The Astrophysical Journal Letters, the study explored the dynamic “inner weather” of the Sun, where plasma currents just beneath the surface align with the 11-year sunspot cycle.

The analysis unveiled intriguing patterns, where surface plasma flows converge at active sunspot latitudes but reverse direction halfway through the NSSL, moving outward to create circulation cells. These flows are significantly affected by the Sun’s rotation and the Coriolis force, the same force that drives hurricane spins on Earth, as explained by the team.

“This offers an incredible insight into how the Sun’s internal weather patterns develop and change,” commented Professor S.P. Rajaguru from IIA.

Understanding these hidden phenomena is crucial, as solar activity can disrupt satellites, power grids, and communications on our planet.

“This research brings us closer to developing realistic models for predicting the Sun’s behavior,” Rajaguru added.

The team utilized a method called helioseismology, which monitors sound waves as they traverse the Sun.

They analyzed over a decade’s worth of data from NASA’s Solar Dynamics Observatory/Heloiseismic and Magnetic Imager (SDO/HMI) and the ground-based Global Oscillations Network Group (GONG) of NSO.

“To validate our findings, we focused on a significant sunspot region using 3D velocity maps. The localized flow patterns we observed were consistent with global trends, confirming both surface inflows and deeper outflows,” stated lead author Anisha Sen, a doctoral student at IIA.

These discoveries enhance our comprehension of how the Sun’s magnetic activity correlates with its internal flows, indicating that deeper layers may still hold secrets that drive its global dynamics.