Evidence of rocky planet engulfment in the wide binary system HIP 71726/HIP 71737

Binary stars are supposed to be chemically homogeneous, as they are born from the same molecular cloud. However, high precision chemical abundances show that some binary systems display chemical differences between the components, which could be due to planet accretion. In this work, we determine precise fundamental parameters and chemical abundances for the binary system HIP 71726/ HIP 71737. Our results show that the component HIP 71726 is more metal-rich than HIP 71737 in the refractory elements such as iron, with Δ[Fe/H] = 0,11 ±0,01 dex. Also, it has a lithium abundance ~1 dex higher than HIP 71737. The ingestion of ~10  Earth masses fully explains both the enhancement in refractory elements and the high lithium content observed in HIP 71726, reinforcing the planet engulfment scenario in some binary systems.