New study solves the sun’s spinning mystery

Credit: MPS / Y. Bekki.

For a long time, the way the sun spins has been a bit of a head-scratcher for scientists.

Unlike a spinning ball that turns at the same rate everywhere, the sun has a peculiar pattern: its equator zips around much faster, completing a rotation in about 24 days, while the poles take their time, spinning once every 34 days.

This strange behavior extends from the sun’s surface deep into its heart, a turbulent layer known as the convection zone.

This zone, filled with rolling storms of hot plasma, is a key player in generating the sun’s magnetic field and all the solar activity that affects Earth.

Scientists have theorized that a slight temperature difference between the sun’s poles and its equator could be responsible for this odd spinning pattern.

But pinning down such a tiny difference has been incredibly tricky, especially when you’re trying to see through the sun’s super-hot interior, which can get up to a million degrees.

However, a team from the Max Planck Institute for Solar System Research has made a breakthrough. Using data from NASA’s Solar Dynamics Observatory, they’ve cracked the case by studying the sun’s long-period oscillations.

These are essentially large, swirling motions on the sun’s surface, discovered by the same team three years prior. Particularly, oscillations near the poles, moving at speeds of up to 70 km/h, have shed new light on this mystery.

By conducting complex 3D simulations, the researchers showed that these poleward oscillations help to redistribute heat from the poles to the equator.

This process evens out the temperature across the sun’s surface to a surprisingly narrow margin – the poles are less than seven degrees warmer than the equator.

This minimal temperature difference might seem insignificant, but it’s actually a critical piece of the puzzle. It balances the sun’s angular momentum, acting as a feedback mechanism that shapes the entire star’s dynamics.

Until now, attempts to model these processes were stuck in 2D and couldn’t capture the full picture.

The findings not only deepen our understanding of the sun’s differential rotation but also highlight the role of these oscillations in the star’s overall behavior.

It turns out that the temperature gradient driving these oscillations is similar to the forces that power Earth’s cyclones, though the sun’s version involves a smaller temperature difference causing massive flows of plasma at high speeds.

This study opens up new avenues for exploring the sun’s internal mechanisms. By better understanding these oscillations, scientists hope to unlock more secrets about the sun’s interior and how its dynamic processes impact solar activity.

Future research will aim to further decode the oscillations’ diagnostic potential, offering more insights into our closest star’s complex workings.

The research findings can be found in Science Advances.

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