2025RNAAS...9..160Z

Carbon Enhanced Metal-Poor (CEMP) stars offer critical insights into the chemical processes of the early universe. Their formation has been attributed to either global enrichment events, like explosions of Population III stars, or local enrichment processes involving close binary interactions. A recently discovered CEMP-r star, GDR3-0928, has a highly carbon-enhanced composition in a dwarf galaxy where other stars are largely unaffected by carbon pollution, likely requiring a local carbon enrichment event. Here we investigate a new local mechanism in which Roche-lobe overflow (RLOF) ejecta from a massive star pollutes a distant third star. We find that reasonable wind velocities, densities, and accretion durations produce accreted masses that are several orders of magnitudes too low to form a CEMP star. These results show that RLOF ejecta alone cannot explain the carbon enhancement observed in GDR3-0928.