At least one in a dozen stars exhibits evidence of planetary ingestion

Stellar chemical compositions can be altered by ingestion of planetary material and/or by planet formation that removes refractory material from the proto-stellar disc. These planet signatures appear as correlations between elemental abundance differences and condensation temperature (Tcond). Detecting such signatures is challenging due to unknown occurrence rates, small amplitudes, and heterogeneous samples with large age differences; co-natal stars with identical initial compositions enable clearer detections. Leveraging Gaia to identify co-moving, co-natal pairs, we present high-precision abundances for a homogeneous sample of 91 co-natal pairs (plus 34 far, control pairs) and identify at least seven new instances of planetary ingestion, implying an occurrence rate of 8%. An independent Bayesian indicator disentangles planet signatures from random abundance variation and atomic diffusion. These results provide new evidence of planet signatures and observational constraints on mechanisms of planet engulfment, formation, and evolution.

Fan Liu, Yuan-Sen Ting, David Yong, Bertram Bitsch, Amanda Karakas, Michael T. Murphy, Meridith Joyce, Aaron Dotter, Fei Dai