New Delhi– A team of solar physicists, led by researchers from the Indian Institute of Astrophysics (IIA), has uncovered new insights into the Sun’s subsurface weather, shedding light on how it connects to the star’s 11-year solar activity cycle.
Working in collaboration with scientists from Stanford University and the U.S. National Solar Observatory (NSO), the researchers have traced vast plasma currents beneath the Sun’s surface, within a region known as the near-surface shear layer (NSSL). These currents appear to fluctuate in tandem with the Sun’s magnetic activity cycle and may play a key role in driving space weather that affects Earth.
The NSSL extends roughly 35,000 kilometers below the Sun’s surface and is characterized by complex rotational dynamics that shift with depth, location, and time — often corresponding to the solar cycle and the emergence of magnetic sunspot regions.
The findings, published in The Astrophysical Journal Letters, provide a deeper understanding of the Sun’s internal dynamics. The study revealed that surface plasma flows tend to converge toward sunspot-active latitudes. However, midway through the NSSL, the direction of these flows reverses, moving outward and forming large-scale circulation cells. These patterns are strongly influenced by the Sun’s rotation and the Coriolis force — the same force that causes hurricanes to spin on Earth.
“This is a stunning look into how the Sun’s inner weather patterns form and evolve,” said Professor S.P. Rajaguru of the IIA, which operates under India’s Department of Science and Technology.
Understanding these subsurface flow patterns isn’t just an academic exercise — it has practical importance, as solar activity can trigger geomagnetic storms that disrupt satellites, communication networks, and power infrastructure on Earth.
“This work brings us a step closer to building realistic models that can predict solar behavior,” Rajaguru added.
The researchers used a technique called helioseismology, which analyzes sound waves traveling through the Sun to study its interior. By examining more than a decade of data from NASA’s Solar Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI) and the NSO’s Global Oscillations Network Group (GONG), the team was able to map the Sun’s internal plasma motion over time.
“To validate the findings, we zoomed in on a massive sunspot region using 3D velocity maps,” said Anisha Sen, a doctoral researcher at IIA and lead author of the study. “The local flow patterns matched the global trends — confirming both the surface inflows and deeper outflows.”
The discovery marks a major step forward in understanding how the Sun’s magnetic field interacts with its internal plasma flows. It also raises new questions about the deeper layers of the Sun that may ultimately drive its global magnetic behavior. (Source: IANS)
