The chemical signatures of planetary engulfment events in binary systems

TL;DR

This study investigates how planetary engulfment events alter stellar chemical compositions, using binary star analysis to identify chemical anomalies indicative of such events, revealing significant inhomogeneities in some systems.

Contribution

It introduces a differential analysis method of twin stars in binaries to detect chemical signatures of planetary engulfment, highlighting the impact on chemical tagging accuracy.

Findings

Discovered the most chemically inhomogeneous binary system to date.

Identified a trend between differential abundances and condensation temperature.

Found five additional systems with chemical anomalies potentially due to planetary engulfment.

Abstract

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.