SO 5₆ − 4₅ emission towards AB Aur. Top: Integrated spectrum (histogram), with best fit rotationally symmetric Keplerian disk model superimposed (greenish curve). Bottom: Integrated emission over the indicated velocity ranges, from blueshifted to redshifted (from left to right). Contour levels are 2.5 σ and 5 σ. The beam size is displayed in the left panel. The cross indicates the AB Aur star position and the disk orientation (PA 126°) and inclination (22°) and the ellipse marks the approximate peak radius of the dust ring. The red triangle is the approximate position of the putative protoplanet traced by CO and near-IR emission.