12CO gas structures of protoplanetary disks

We derived gas-disk radii, integrated fluxes, optically thick emission layers, and brightness temperature profiles for the disk population of the old (4-14Myr) Upper Scorpius star-forming region. We measured CO emission sizes for 37 disks with bright CO J=3-2 emission (S/N>10 on the integrated flux; out of the 83 disks with CO detections), finding that the median radius containing 90% of the flux is ~82au, with radii spanning from 22 up to 247au.

We report a correlation between the ^12^CO brightness temperatures and stellar luminosities, with a Pearson coefficient of 0.6, which we used to prove that the ^12^CO optically thick emission layer primarily emanates from a region below the superheated dust, which is optically thin to the stellar irradiation. Moreover, we derive 33 CO emission-surface height profiles, finding a median aspect ratio of <z/r>~0.16 in a range from ~0.01 up to ~0.45 over the sample.