Rate of Brownian diffusion K_ij (top-left), coalescence enhancement factor W_ij (top-right), Brownian coagulation rate β_ij (bottom-left) as a function of the collider radius a_i, for forsterite grains and four different values of the target size a_j. The gas temperature is T_gas = 500 K. The Brownian coagulation rate as a function of gas temperature in the ejecta (bottom-right) is shown from 100 to 1300 days for four sets of collider and target sizes given by the (a_i,a_j) parameters.