The TW Hya Rosetta Stone Project. III.

In this study, we constrain the 2D thermal structure of the protoplanetary disk TW Hya structure utilizing images of seven CO lines. This includes new ALMA observations of ^12^CO J=2-1 and C^18^O J=2-1 as well as archival ALMA observations of ^12^CO J=3-2, ^13^CO J=3-2 and 6-5, and C^18^O J=3-2 and 6-5.

Additionally, we reproduce a Herschel observation of the HD J=1-0 line flux and the spectral energy distribution and utilize a recent quantification of CO radial depletion in TW Hya. These observations were modeled using the thermochemical code RAC2D, and our best-fit model reproduces all spatially resolved CO surface brightness profiles. The resulting thermal profile finds a disk mass of 0.025M_{sun}_ and a thin upper layer of gas depleted of small dust with a thickness of ~1.2% of the corresponding radius.