Binary star's metal boost hints at planet-devouring history

Astronomers studying the HD 81809 binary found that the secondary star HD 81809B has a higher abundance of metals and lithium at its surface than its companion, likely because it swallowed a planet (possibly up to ~75 Earth masses). This chemical difference is the first of its kind in a binary system, with two explanations proposed—the stars formed from different clouds or the engulfment event. The lithium enrichment and a possible debris disk provide evidence for planetary ingestion, though the exact number and makeup of swallowed planets remain uncertain.