depends on the equilibration efficiency of the segregation mechanisms. The scenario typically used in geochemical core formation models involves the impactor’s core equilibration in a deep magma ocean (*cf.* table \[tab:parameters\_magma\] for typical physical parameters) [@rubie_2015]. The metal phase is assumed to fragment into centimetric drops, before separating quickly from the silicates as an *iron rain* and sedimenting to the base of the magma ocean [@ichikawa_2010; @karato_1997; @rubie_2003; @stevenson_1990]. The centimeter scale corresponds to the size at which surface tension prevents further fragmentation of the drops [@rubie_2003]. It is small enough to ensure efficient chemical equilibration between the droplets and the surrounding magma ocean [@rubie_2003]. Iron finally migrates through the solid part of the mantle toward the forming core by diapirism, initiated by Rayleigh-Taylor instabilities within the liquid pond [@karato_1997; @monteux_2009; @samuel_2010; @stevenson_1990], diking [@stevenson_2003] or percolation [@stevenson_1990]. No further equilibration is expected at this stage owing to the solid state of the underlying mantle and the large size of the diapirs.

  ------------------------------------------------ ------------------- ------------------ ----------------------
                            Magma ocean depth, $L$                     m                  
                                      Gravity, $g$                     m.s$^{-2}$         
                                                   Silicate phase      Metal phase        
                                 Density, $\rho_i$ $4\times 10^3$      $7.8\times 10^3$   kg.m$^{-3}$
                     Thermal expansion, $\alpha_i$ $5\times 10^{-5}$   $10^{-5}$          K$^{-1}$
                 Specific heat capacity, $c_{p_i}$ $10^{3}$            $5\times 10^2$     J.kg$^{-1}$.K$^{-1}$
                       