At Least One in a Dozen Stars Exhibits Evidence of Planetary Ingestion

Stellar chemical compositions can be altered by ingestion of planetarymaterial and/or planet formation which removes refractory material from theproto-stellar disc. These "planet signatures" appear as correlations betweenelemental abundance differences and the dust condensation temperature.Detecting these planet signatures, however, is challenging due to unknownoccurrence rates, small amplitudes, and heterogeneous star samples with largedifferences in stellar ages, and therefore stars born together (i.e., co-natal)with identical compositions can facilitate such detections. While previousspectroscopic studies were limited to small number of binary stars, the Gaiasatellite provides new opportunities for detecting stellar chemical signaturesof planets among co-moving pairs of stars confirmed to be co-natal. Here wereport high-precision chemical abundances for a homogeneous sample of 91co-natal pairs of stars with a well-defined selection function and identify atleast seven new instances of planetary ingestion, corresponding to anoccurrence rate of 8effectively disentangle the planet signatures from other factors, such asrandom abundance variation and atomic diffusion. Our study provides newevidence of planet signatures and facilitates a deeper understanding of thestar-planet-chemistry connection by providing new observational constraints onthe mechanisms of planet engulfment, formation and evolution.