Model parameters and synthetic planets Δσ∕ΔM (see text for further details). A higher value of Δσ∕ΔM indicates that a decrease of the observational uncertainty provides additional information of the internal parameter. The crosses represent the observed planets from Otegi et al. (2020). Composition lines of pure-iron (brown), Earth-like planet (lightbrown), and water ice (blue) are also plotted.