VULCAN chemistry results for HAT-P-12 b. The top left panel shows the P − T profile with high intrinsic temperature that results from the optimisation procedure described in Sect. 4.2. The other panels show the VMRs of different molecules detected or expected in the NIRSpec spectrum, for different metallicities, carbon-to-oxygen ratios, and with or without photochemistry. From dark to light grey, the shaded areas indicate respectively the 1, 2, and 3 σ uncertainty intervals of the retrieved atmospheric temperature and of the VMRs for detected species, and the 1, 2, and 3 σ upper limits of the VMRs for non-detected species (inferred from the HST + NIRSpec TEATRO spectra and ARCiS retrieval).