IIA-led study charts flows in the Sun's near-surface shear layer tied to the 11-year cycle
A study led by the Bengaluru-based Indian Institute of Astrophysics traced plasma flows in the Sun's near-surface shear layer that change with the 11-year sunspot cycle, DST said on 29 April 2025.
Summary
A study led by astronomers of the Indian Institute of Astrophysics (IIA), an autonomous institute of the Department of Science and Technology, traced plasma flows in the Sun's near-surface shear layer (NSSL), a region extending to about 35,000 km below the surface, that pulse in step with the 11-year sunspot cycle, according to a PIB release of 29 April 2025. Researchers from IIA, Stanford University and the US National Solar Observatory used helioseismology and over a decade of data from NASA's Solar Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI) and the ground-based GONG network. The study, published in The Astrophysical Journal Letters, found that surface flows converge toward active sunspot latitudes but reverse direction midway through the NSSL. IIA's Prof. S.P. Rajaguru and PhD student Anisha Sen were among the researchers.
Key facts
- Lead institute
- Indian Institute of Astrophysics (autonomous institute of DST), Bengaluru
- Region studied
- Near-surface shear layer, about 35,000 km deep
- Link
- Flows change with the 11-year sunspot cycle
- Partners
- Stanford University; National Solar Observatory (USA)
- Data
- NASA SDO/HMI and GONG; helioseismology
- Journal
- The Astrophysical Journal Letters
Practice MCQs 3 questions
The Sun's near-surface shear layer (NSSL), studied by an IIA-led team (PIB, 29 April 2025), extends to about what depth below the surface?
Show answer
Correct answer: D — 35,000 km
The NSSL extends to about 35,000 km in depth beneath the Sun's surface.
Consider the following about the IIA-led solar study reported on 29 April 2025: 1. The Indian Institute of Astrophysics is an autonomous institute of the Department of Science and Technology. 2. The study was published in The Astrophysical Journal Letters. Which of the statements given above is/are correct?
Show answer
Correct answer: C — Both 1 and 2
Both are correct. IIA is an autonomous institute of DST, and the study appeared in The Astrophysical Journal Letters.
The IIA-led study of the Sun's near-surface shear layer used a technique that tracks sound waves as they travel through the Sun. What is this technique called?
Show answer
Correct answer: A — Helioseismology
The team employed helioseismology, which tracks sound waves travelling through the Sun, using SDO/HMI and GONG data.