Example of the formation of a planetary system from initially 100 lunar-mass embryos in low gas mass initial mass 0.023 M_⊙), low metallicity ([Fe/H] = −0.13) disc. The initial mass of planetesimals is 65.1 M_⊕. Four moments in time (in years) are shown. Lines shows the growth tracks in the semi-major axis-mass plane. Black points show (proto)planets existing at a given epoch. Grey open circles show the last position of protoplanets that were accreted by another more massive body in a giant impact. The colours of the lines are |τ_mig ∕τ_grow| = |d lnm∕d lna|.