Spatial distributions of gas, grown dust, and maximum dust size (from top to bottom row) at 7.8 kyr after the launch of the intruder in models C1 and C4 (left and right columns, respectively), illustrating the formation of pre-collisional tails outlined with the black and yellow contour lines. The gas and dust surface densities are in log g cm⁻², the maximum dust size is in log cm.