Sketch illustrating the pebble-planet encounter in a local frame where the pebble is co-moving with the central planet. The approach velocity is given by the relative velocity between these two objects (Δv). The perturbed and unperturbed trajectories are represented in the blue solid and dashed lines. The important timescales are the pebble-planet encounter time t_enc = b∕Δv, and the settling time t_set = b∕v_set, where v_set is the sedimentation velocity when the planet’s gravity equals to the gas drag.