Integrated intensity of ¹²CO (J=3–2) scaled at 100 pc (from Mac Manamon et al. 2026) as a function of the relative offset of the millimetre- and micrometre-sized dust surface densities (positive offset means the micrometre-sized dust peaks further than the millimetre-sized dust). The six discs with a CO detection are shown in blue, while CO non-detections appear in black. The upper limit for AU Mic refers to the ¹²CO (J=2–1) as no (J=3–2) is available (Mac Manamon et al. 2026).