AFGL 989 vs. LIDA model. LIDA model using the SPECFY online tool (orange) superposed to the ISO spectrum of the protostar AFGL 989 (black) in the optical depth scale taken from Gibb et al. (2004). The synthetic spectrum in the optical depth scale is composed of the linear combination of three ice spectra (pure H₂O, H₂O:CO₂ (10:1), and CO:CO₂ (2:1)) and silicate template from the GCS 3 source. The dominant ice spectrum is H₂O:CO₂ (10:1), shown by the gray dashed line. The assignments of a few bands are indicated. The red hatched area highlights an infrared absorption excess attributed to ammonia hydrates and large grains (see text).