Giant 'BEASTie' planets may have been stolen from their parent stars – Physics World - physicsworld.com

Two astronomers in the UK have shown that some giant planets orbiting far from their host stars have likely been captured from the planetary systems of other stars.

Using computer simulations, Richard Parker and Emma Daffern-Powell at the University of Sheffield have showed that giant planets recently discovered by the BEAST mission — and dubbed “BEASTies” — were probably ejected from their original systems shortly after their formation, and were then captured by other stars.

In systems like TRAPPIST-1, several, small, rocky planets can be tightly packed together in orbits close to their host stars.

In contrast, Jupiter-sized planets have been discovered in orbits hundreds of astronomical units (au, the distance from Earth to the Sun) from their hosts – often challenging astronomers’ preconceptions about how planetary systems form.

In 2021, the B-star Exoplanet Abundance Study (BEAST) discovered two Jupiter-sized planets orbiting OB type stars.

This discovery strengthens the idea that planets orbiting at distances greater than 100 au from their host stars are no longer occupying the systems where they originally formed.