Scientists have worked out how fast our Sun spins compared to other similar stars, and found that it’s a bit of a slowcoach.
In a study published in the journal Science, researchers from New York University in Abu Dhabi looked at 40 stars similar in mass to our Sun, 13 of which they could measure the rotation of using observations from NASA’s Kepler space telescope.
Our Sun rotates about 11 percent faster at its equator than at its mid-latitudes, about halfway from the equator to the poles, known as latitudinal differential rotation. The former takes about 25 days to rotate, while the latter takes about 31 days. The effect is even more apparent at the poles, which spin 30 percent slower than the equator.
But they found this difference was more pronounced in other stars, spinning up to two and a half times faster at their equators than their mid-latitude regions, something theories had not predicted.
"This is very unexpected, and challenges current numerical simulations, which suggest that stars like these should not be able to sustain differential rotation of this magnitude," lead author Othman Benomar said in a statement.
While we can’t watch these other stars rotate as our images aren’t good enough, we can learn about their rotation from how much they wobble – their oscillations. The team were able to measure these wobbles, a field known as asteroseismology, to see how fast these distant stars were rotating at different points on their surface.
Working out how fast a star spins is important, as it can tell us more about how its magnetic field works, which drives solar storms. On our Sun, we know its rotation plays a key role in how it generates magnetic fields, but there’s a lot we still don’t know.
“[L]earning more about how stars rotate and generate their own magnetic fields could help us gain further insight into the solar dynamo, the physical process that generates the Sun's magnetic field," Katepalli Sreenivasan, a co-author on the study, said in the statement.
Magnetic fields on our Sun are responsible for generating solar storms, which can cause problems back on Earth for satellites in orbit and for power grids. If we can understand how this process works, then we can better predict when a solar storm might be heading our way.
At the moment we don’t have enough information to work out what drives magnetic activity on stars. But using upcoming telescopes like ESA’s PLATO telescope, due to launch in 2026, it will be possible to monitor tens of thousands of Sun-like stars using asteroseismology, and learn more about how this process takes place.