However, the team from The Australian National University, the University of Sydney and the University of Southern Queensland found that close binary stars break this rule, with unexpectedly high magnetic activity given their spin, and in the most extreme cases – where stars spin especially fast – magnetic activity begins to decline.

The researchers say this may be because of tidal forces between closely orbiting stars, affecting their magnetic activity. Understanding these effects could help us identify habitable exoplanets, the researchers conclude.