Scientists have uncovered compelling new evidence that some stars may completely engulf and consume their surrounding planets – a phenomenon long predicted by astronomers but never conclusively observed.
The research focused on red dwarf stars, small and relatively cool stars that are among the most common in our galaxy.
Despite their cooler surface temperatures, their interiors are extremely hot and turbulent, meaning they should rapidly destroy all traces of lithium – a chemical element naturally present when stars first form.
But when researchers from the University of Exeter and Keele University analysed data from the Gaia-ESO Spectroscopic Survey, they found something unexpected.
Among thousands of stars studied, six red dwarf stars in three young star clusters showed unusually high levels of lithium in their atmospheres. The team believes the most likely explanation is dramatic: the stars had swallowed their own planets.
Using advanced evolutionary models developed by Professor Isabelle Baraffe from the University of Exeter, the researchers found the stars may have engulfed the equivalent of between three and ten Earth masses of rocky planetary material.
This fresh material would temporarily replenish lithium in the stars' atmospheres, creating the chemical signature observed by the team.
Planet-swallowing events have long been predicted during the chaotic early stages of planetary system formation, when young planets can spiral into their host stars. Scientists believe similar events may even have occurred in the early history of our own Solar System.
If confirmed, the findings could provide a powerful new way to study how planetary systems form and evolve.
Professor Baraffe from the University of Exeter said: "This is exciting because evidence of planet-swallowing events has been long sought for. With my collaborators in Keele, we think that we have finally found the needles in the haystack."
