Near-Surface Shear Layer:
An international team of solar physicists, including scientists from the Indian Institute of Astrophysics (IIA), has mapped dynamic plasma currents in the Sun’s Near-Surface Shear Layer (NSSL), revealing patterns that correlate with the Sun’s 11-year magnetic activity (sunspot) cycle.
- The Near-Surface Shear Layer (NSSL) is a crucial region located just beneath the Sun’s visible surface, extending to a depth of about 35,000 km.
- In the NSSL, the Sun’s angular velocity (rotation speed) decreases rapidly with radius, creating a rotational shear that varies with depth, latitude, and solar magnetic activity.
- The study revealed surface plasma flows converge towards sunspot latitudes but reverse midway in the NSSL and flow outward, forming large circulation cells.
- These flows are shaped by the Sun’s rotation and the Coriolis force, which also influences Earth’s hurricanes. This connection helps explain how the Sun’s spin behaviour varies with depth.
- Despite being dynamic, these localised flows do not drive the Sun’s large-scale zonal flows, known as torsional oscillations, implying the presence of deeper unknown forces in the Sun’s interior.
