Mass fractions of FeO in the mantle in the planetary sample versus their respective semimajor axes using disk conditions around Kepler-102 – whose metallicity is closest to the Sun’s – at three different formation times, with varying shades of blue indicating the progression of time. The blue dashed lines correspond to the polynomial fit of degree 3. In contrast, the purple squares denote the FeO mass fractions of terrestrial Solar System bodies (Trønnes et al. (2019), Table 2) as a function of their distances from the Sun. The purple dashed line represents the best fit for better visualization.