Astronomy and astrophysics vol:350 issue:1 pages:163-180
We present infrared spectroscopy and imaging of AFGL 4106. The 2.4-5 mu m ISO-SWS spectrum reveals the presence of a cool, luminous star (T-eff approximate to 3750 K) in addition to an almost equally luminous F star (T-eff approximate to 7250 K). The 5-195 mu m SWS and LWS spectra are dominated by strong emission from circumstellar dust. We find that the dust consists of amorphous silicates, with a minor but significant contribution from crystalline silicates. The amorphous silicates consist of Fe-rich olivines. The presence of amorphous pyroxenes cannot be excluded but if present they contain much less Fe than the amorphous olivines. Comparison with laboratory data shows that the pure Mg-end members of the crystalline olivine and pyroxene solid solution series are present. In addition, we find strong evidence for simple oxides (FeO and Al2O3) as well as crystalline H2O ice. Several narrow emission features remain unidentified.