  Planetary engulfment events involve the chemical assimilation of a planet
into a star's external layer. This can cause a change in the chemical pattern
of the stellar atmosphere in a way that mirrors the composition of the rocky
object engulfed, with the refractory elements being more abundant than the
volatiles. Due to these stellar chemical changes, planetary engulfment events
can render the process of chemical tagging potentially inaccurate. A
line-by-line differential analysis of twin stars in wide binary systems allows
us to test the chemical homogeneity of these associations with typical
individual stellar Fe I uncertainties of 0.01 dex and eventually unveil
chemical anomalies that could be attributed to planetary engulfment events. Out
of the 14 systems analysed here, we report the discovery of the most chemically
inhomogeneous system to date (HIP34407/HIP34426). The median difference in
abundances of refractory elements within the pair is 0.19 dex and the trend
between the differential abundances and condensation temperature suggests that
the anomaly is likely due to a planetary engulfment event. Within our sample,
five other chemically anomalous systems are found.
