Evolution of passive tracers η_i∕o for simulation set A1, following material originated in the outer (top panels)/inner (bottom panels) disk, in polar coordinates. Left panel: initial state (white is 0). All but leftmost column: 1000 orbits after release, for varying values of K_p. We emphasize that color scales are different across rows. For the sake of readability, the disk is here displayed with angular coordinates such that θ_p = π in every frame. Filled lines show the planet’s feeding zone, 0.8R_H in radius; dashed lines are 3R_H large in radius, encompassing a somewhat broader region than the typical HSR.