Comparison of the continuum-subtracted spectrum of HK Tau A (top panel, dark grey) and B (bottom panel) in the 13.5–16.2 μm range. The primary shows emission lines from several molecular components (H₂O, ¹²CO₂, HCN, and OH), to which we show the total fit (light grey) and the single molecular components (coloured lines). On the other hand, the noise level in HK Tau B is too high for any confident claim of molecular emission, and only the bright [Ne III] line is visible.