Azimuthally averaged and normalized intensity profiles of the dust continuum (blue) in combination with the temperature as computed from the stellar luminosity using Eq. A.1 (red). The transparent red bar indicates the 22-30 K temperature range (approximate CO snow line) according to this temperature profile. In some cases the CO snow line has been derived directly from observations (see text), which is indicated with a vertical dashed red line. A blue horizontal bar indicates the beam size. The top row shows the sources without C₂H detection, mostly compact disks (CD), followed by the disks with C₂H detection: first the ring disks (RD), followed by the transition disks (TD), sorted by decreasing stellar luminosity.