Artist's concept showing planet KELT-9b orbiting its host star, KELT-9.

The exoplanet KELT-9b is a ‘hot Jupiter’ at risk of destruction by its star (artist’s impression). Credit: NASA/JPL-Caltech

Planetary science

The stars that team up to push planets to their death

One member of a stellar pair nudges planets towards its partner, which rips apart or swallows its victims.

Stars of a certain kind destroy most of their Jupiter-sized planets, simulations suggest.

Stars classified as A-type stars are roughly 1.6–2.4 times the mass of the Sun and are often gravitationally bound to a second star, known as a stellar ‘companion’. Towards the end of their lives, A-type stars swell to form enormous bodies called red giants.

Alexander Stephan at the University of California, Los Angeles, and his colleagues carried out several thousand simulations of systems that included an A-type star, a stellar companion and an orbiting Jupiter-sized planet. In 61% of cases, the companion star’s presence influenced the orbit of Jupiter-sized planets, which moved close enough to the A-type stars to eventually be destroyed — either ripped apart by the star’s gravity, or swallowed up by the star in its bloated later years.

Across the Milky Way, tens of thousands of red giants are probably feasting on such planets at any given time, the authors write.