How Giant Planets Collect Their Metals: A New Look at the Mass-Metallicity Relation

Chachan et al. analyze 147 giant exoplanets to refine the mass–metallicity relation. They find that smaller planets are metal-rich, while metallicity decreases with mass but flattens at about seven times solar. This suggests that giant planets continue to accrete heavy elements even during gas accretion, delaying runaway growth until 30–60 Earth masses and challenging classical formation models.