The study showed that “old” stars rotate faster than the theories of magnetic suppression caused by stellar winds, which had been acceptable until then, predicted. The rotation speed of younger stars can be measured by observing the movement of dark spots on their surface. But determining the rotations of older stars, where spots are rare and less visible, remains complicated.
To overcome this difficulty, researchers have resorted to a new methodology, astrocytology. Using data from the Kepler Space Telescope, they analyzed the oscillations caused by the trapped sound waves in 92 stars of all ages and deduced their rotational velocity.
They discovered that stars at some point in life similar to, or older, the Sun, rotate faster than magnetic suppression theories predicted.
This finding, which confirms a 2016 study, makes it clear that it is of some sort « Weak braking » That works in sun-like stars. In contrast, applying this observational validated model to thousands of other stars previously observed by Kepler or other satellites will make it possible to determine their age more precisely.
The study also sheds new light on the evolution of our Sun and the solar wind it produces. These, being directed by Earth’s magnetosphere, are usually responsible for the auroras. But they could also, during major solar flares, prove particularly dangerous to some satellites, or even electrical installations on Earth.
These results clearly demonstrate that the complex interaction between wind, magnetic field, and star rotation forms one of the cornerstones for understanding stellar dynamics and their evolution. To get a more complete and coherent view of these mechanisms, researchers are relying in particular on the European PLATO Space Telescope, which is scheduled to launch in 2026.