Heavy-element content of giant planets from Thorngren et al. (2016). Plotted here is the enrichment a 15 Earth mass core could have that grows by gas enriched with either dust (red) or vapour (blue). The purple line shows the combined heavy-element content of the planet if it accretes dust and vapour, while the dashed purple line shows the maximum enrichment a planet could have growing in a disc with a metallicity of 3%.