“Magnetic trees” reveal hidden flows in the Sun’s upper atmosphere
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A study led by ARIES, an autonomous DST institute, has found that the Sun’s slow poleward plasma flow continues nearly 3,000 km above its visible surface, in the upper chromosphere. Using 27 years of radio images from Japan’s Nobeyama Radioheliograph, the team measured speeds of about 5 to 15 metres per second, supporting the “magnetic tree” hypothesis.
- Released
- 17 Jul 2026, Ministry of Science and Technology
- Led by
- ARIES, with PRL, IIT Delhi, IIST and NASA Goddard
- Data
- 27 years of radio observations, Nobeyama Radioheliograph, Japan
- Finding
- poleward flow nearly 3,000 km above the surface, upper chromosphere
- Speed
- about 5 to 15 metres per second
- Published in
- The Astrophysical Journal
The Sun’s meridional flow: what happened?
The Sun has a slow conveyor belt of hot plasma moving from the equator to the poles, called the meridional flow. It carries magnetic fields and helps run the 11-year solar cycle. Until now it had been seen only in the lower layers. This study shows it continues much higher up.
- The team compared thousands of full-disk radio images taken one day apart and measured small shifts in brightness patterns.
- The upper-chromosphere flow moves at speeds similar to those in deeper layers.
- The flow changes over the solar cycle, and the two hemispheres sometimes behave differently.
- Bright radio features moved poleward in step with magnetic fields rooted deep inside the Sun.
What is the “magnetic tree” idea?
- It proposes that magnetic structures high above the Sun’s surface stay connected to deeper layers, like branches to a trunk and roots.
- The study gives strong observational support for it.
- So the upper atmosphere carries information about motions deep inside the Sun, a new tool for studying the solar dynamo.
Why does the Sun’s meridional flow matter?
- Space weather: Solar storms affect satellites, communication, navigation and power grids.
- Science: Radio astronomy can now probe the Sun’s internal dynamics.
What can Prelims ask on the Sun’s meridional flow?
- Meridional flow: equator-to-pole plasma flow on the Sun; part of the 11-year solar cycle.
- Found nearly 3,000 km up, upper chromosphere; 5 to 15 m/s.
- Data: Nobeyama Radioheliograph (Japan), 27 years.
- ARIES: autonomous institute under DST.
How to use this in Mains
- As per PIB (2026-07-17): researchers found a hidden link between the Sun's surface and upper layers using magnetic "tree" structures, aiding space-weather understanding.
- The finding complements what Aditya-L1 is studying.
Quotable data pointResearchers found a hidden link between the Sun's surface and upper layers using magnetic "tree" structures, aiding space-weather understanding.
PIB: S&T: magnetic trees on the Sun, 17 Jul 2026
Exam angle
Prelims: solar layers.
Practice MCQs
Original practice questions (not PYQs).
The ARIES-led study on the Sun's meridional flow used data from which instrument?
Answer (b) & explanation
PIB (S&T), 17 Jul 2026: 27 years of Nobeyama radio observations.
Questions students ask about this
What is the Sun's meridional flow?
A slow flow of plasma from the Sun's equator towards its poles that carries magnetic fields and helps control the 11-year solar cycle.
What did the ARIES-led study find?
That this poleward flow continues nearly 3,000 km above the visible surface, in the upper chromosphere, at about 5 to 15 metres per second.
Why does it matter on Earth?
Plasma and magnetic field motions drive solar storms and space weather, which can affect satellites, navigation and power grids.
Keep studying
Go deeper
Official source: PIB: S&T: magnetic trees on the Sun, 17 Jul 2026
facts from cited sources only; faculty review pending