The degree of differentiation is shown as a function of the formation time t₀ (assuming instantaneous accretion) and the terminal radius D. The light grey area indicates the parameter range for which no melting occurs. This region is separated (dashed line) to the small region where melting occurs but only partial differentiation, i.e. no core forms. The dark grey region indicates the parameter range for which the planetesimals is differentiated into an iron core and silicate mantle. The sizes of the core and the mantle increase with increasing terminal radius and decreasing accretion time (white arrow).