Radial dependence of CO gas (red) and dust (black) temperature. The gas temperature is derived from the ¹²CO(3–2) analysis. Beyond 400 au, CO temperature is extrapolated from the fitted law in the range of 300− 400 au. The power-law exponents are indicated in each range. The uncertainty on the exponent is about 0.15 for the best constrained values (−1.2 and −1.8), and 0.3 for the others. The primary beam attenuation introduces a bias of 8% at 400 au. The dust temperature is taken from Dutrey et al. (2014). Beyond a radius of 285 au, the dust temperature corresponds to an extrapolation.