JWST/NIRSpec observations and atmospheric models. A full wavelength coverage of JWST/NIRSpec observations and model fits for TWA 27A and TWA 28 are shown. (a) The observed spectra (black) and the best-fit model spectra (coloured lines) for TWA 27A (blue) and TWA 28 (orange) across the full wavelength range. (b) The relative residuals ΔF_λ/F_λ = (F_λ,obs – F_λ,model)/F_λ,obs of the best-fit model. (c) The same data in log-scale, with blackbody contribution indicated and the coverage of each grating (G140H, G235H and G395H) shown as shaded regions. The increasing offset between datasets at redder wavelengths reflects distinct blackbody contributions in each system. (d)–(f) Zoomed regions from each grating with key absorption features labelled.