Scientists have possibly detected new evidence of subtle movements of magnetism deep inside the Sun, which may help them better predict solar storms and space weather.
The new study was conducted by a team of researchers from the Tata Institute of Fundamental Research (TIFR) in Mumbai and New York University, Abu Dhabi, and was originally published in Nature Astronomy.
Scientists used a method called helioseismology to detect the movements inside the Sun. This method is used to study the solar surface to understand the movements inside the Sun, the same way earthquakes are used to study the movements inside the Earth.
They analysed more than a decade of solar observations collected by the Solar Dynamics Observatory, a satellite operated by NASA. In particular, they used measurements from the satellite’s Helioseismic and Magnetic Imager (HMI)– an instrument designed to track oscillations and magnetic activity across the Sun’s surface.
After studying over 5,000 days of data, scientists detected two types of faint waves that travel through the Sun’s outer layers. These waves seem to be related to what scientists call “magneto-Rossby waves”, which are large waves that appear in fluids that rotate, combining magnetic fields and fluid motion.
A glimpse of the Sun’s magnetic structure
The newly detected waves seem to be located just beneath the Sun’s surface, an area known as the convection zone. This is where hot Sun plasma rises and falls in huge waves, helping to transport heat towards space.
The patterns detected in the Sun’s waves seem to reveal the presence of a huge doughnut-shaped magnetic field inside our Sun. This magnetic field, which is weak near the solar surface, might be quite powerful deeper inside, especially since the Sun’s plasma is much denser inside than it is on its surface.
This magnetic structure is quite important since it is closely related to what is known as the solar cycle, which is the 11-year cycle over which our Sun’s activity rises and falls.
Why this matters for Earth
“If what we are seeing are indeed magnetohydrodynamic Rossby waves in the Sun, then they provide a rare, direct window into the large-scale magnetic field hidden beneath the solar surface. In that sense, the waves act almost like tracers of the Sun’s deep magnetic structure, which is one of the key ingredients driving the solar cycle,” said lead researcher Prof Shravan Hanasoge.
Solar activity may impact life and technology on Earth directly. For example, strong solar activity may cause solar flares, which may launch charged particles into space, disrupting satellites, communication systems, navigation signals, and power grids.
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The difficulty in the direct observation of the physics of the solar cycle has made it difficult for scientists to forecast solar activity.
The recently observed magnetic waves could give scientists a new way of tracking what is going on inside the Sun in real time. Scientists could also get a more precise estimate of the intensity and nature of the magnetic field inside the Sun using this method.
A step towards better space weather forecasts
The discovery also closes a gap in the theoretical and observed solar activity. Scientists have theorised for many years that magnetic waves of large scale should exist in the Sun, but directly detecting such activity has been extremely difficult.
With this new evidence, researchers are now starting to see the hidden processes that control the magnetism of the sun. As scientists continue to study the solar data, the findings could help improve the forecasting of solar storms.
They however warn it is too early to say whether this will directly translate into solar-cycle forecasts, and that more work is needed before they can claim predictive power.
“However, if these waves are shaped by the Sun’s internal magnetic field, as we suggest, then tracking them over time could help us monitor how that field evolves during the solar cycle. In principle, that kind of information could improve our ability to anticipate the strength of future cycles,” Hanasoge said.
The ability to more accurately predict solar storms could help space agencies, satellite companies, and energy producers better prepare themselves for the disruptions that occur as a result of the sun’s activities.
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