BBC Sky at Night Magazine
Distant binary stars have wonky planets
A new study investigating the strange orbits of so-called ‘Tatooine’ worlds – those orbiting a binary pair of stars, with two suns in their skies – has revealed the further apart a pair is, the wonkier their planets are.
The study used the Atacama Large Millimeter/Submillimeter array (ALMA) to look at circumbinary discs, the planet-forming rings of dust around young binaries.
“With our study, we wanted to learn more about the typical geometries of circumbinary discs,” says Ian Czekala from the University of California at Berkeley, who took part in the study. “The high-resolution ALMA data was critical for studying some of the smallest and faintest circumbinary discs yet.”
This found the discs around stars orbiting each other are quickly aligned with the plane of the stars. Pairs with longer orbital times
– usually meaning they’re further apart – have more off-kilter discs. Testing whether this misalignment extends to the planets created is
difficult, however. Previous exoplanet surveys such as Kepler have struggled to observe planets around wide binaries, meaning there could be an entirely new population of Tatooine worlds waiting to be discovered. www.almaobservatory.org