Evidence for planet engulfment by the star HD82943

Current models(1,2) of the evolution of the known extrasolar planetary syst ems need to incorporate orbital migration and/or gravitational interactions among giant planets to explain the presence of large bodies close to their parent stars. These processes could also lead to planets being ingested by their parent stars, which would alter the relative abundances of elements heavier than helium in the stellar atmospheres. In particular, the abundanc e of the rare Li-6 isotope, which is normally destroyed in the early evolut ion of solar-type stars(3) but preserved intact in the atmospheres of giant planets, would be boosted substantially. Li-6 has not hitherto been observ ed reliably in a metal-rich star(4,5), where metallicity refers to the tota l abundance of elements heavier than helium. Here we report the discovery o f Li-6 in the atmosphere of the metal-rich solar-type star HD82943, which i s known to have an orbiting giant planet. The presence of Li-6 can probably be interpreted as evidence for a planet (or planets) having been engulfed by the parent star.