Detection of CO₂ ice and gas. The overplotted black curve shows the JWST/MIRI spectrum at the position indicated by the dot in Fig. A.1. The uncertainties on the surface brightness are ∼ ± 40 MJy sr⁻¹. The best-fit gas-phase model (T_gas = 30 K and log N = 16.8 cm⁻²) is shown in blue. We divided out this model, resulting in the brown curve. The orange curve shows a single-temperature model for clinoenstatite emission. The dashed gray line shows the continuum we adopted to analyze the ice band. The green curve shows the normalized spectrum using that continuum. The red curve shows a laboratory spectrum for CO₂ ice (CO:CO₂ 2:1 ice mixture at 80 K); and the bottom panel shows the residuals between the normalized spectrum (green) and the ice model (red).