exoALMA. X. channel maps reveal complex ${}^{12}$CO abundance distributions and a variety of kinematic structures with evidence for embedded planets

Abstract

We analyze the ${}^{12}$CO $J=3-2$ data cubes of the disks in the exoALMA program. 13/15 disks reveal a variety of kinematic substructures in individual channels: large-scale arcs or spiral arms, localized velocity kinks, and/or multiple faints arcs that appear like filamentary structures on the disk surface. We find kinematic signatures that are consistent with planet wakes in six disks: AA Tau, SY Cha, J1842, J1615, LkCa 15 and HD 143006. Comparison with hydrodynamical and radiative transfer simulations suggests planets with orbital radii between 80 and 310\,au and masses between 1 and 5 M${}_{\mathrm{Jup}}$. Additional kinematic substructures limit our ability to place tight constraints on the planet masses. When the inclination is favorable to separate the upper and lower surfaces (near 45${}^{\mathrm{o}}$, i.e. in 7/15 disks), we always detect the vertical CO snowline and find that the ${}^{12}$CO freeze-out is partial in the disk midplane, with a depletion factor of $\approx 10^{-3}$ - $10^{-2}$ compared to the warm molecular layer. In these same seven disks, we also systematically detect evidence of CO desorption in the outer regions.

16 pages, 8 figures, accepted for publication in the ApJL exoALMA focus issue