Spectra of CO and [CI] in protoplanetary disks

The principal gas-phase carbon carriers CO, C^0^, and C^+6 can now be observed regularly in disks. The gas-phase carbon abundance in disks has thus far not been well characterized observationally.

We obtain new constraints on the [C]/[H] ratio in a large sample of disks, and compile an overview of the strength of [CI] and warm CO emission. We carried out a survey of the CO 6-5 line and the [CI] 1-0 and 2-1 lines towards 37 disks with the APEX telescope, and supplemented it with [CII] data from the literature. The data are interpreted using a grid of models produced with the DALI disk code.