exoALMA. X. Channel Maps Reveal Complex 12CO Abundance Distributions and a Variety of Kinematic Structures with Evidence for Embedded Planets

Abstract

We analyze the 12CO 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 MJup. 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°, i.e., in 7/15 disks), we always detect the vertical CO snowline and find that the 12CO freeze-out is partial in the disk midplane, with a depletion factor of ≈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.