ISO-SWS OBSERVATIONS OF WEAK BANDS OF TRACE COMPONENTS OF ICES TOWARDS THE YOUNG STELLAR OBJECT-W 33A

ISO-SWS observations of the highly obscured young stellar object W 33A reveal two broad absorption features centered at 7.24 and 7.40 mu m T he position and width of these features indicates that they are due to the XH bending mode (X= C, N, or O) of molecules in the solid state. Comparison to interstellar ice analogs shows that the 7.24 mu m band c an be well matched by solid formic acid (HCOOH), while the 7.40 mu m b and can be fitted both by the formate ion (HCOO-) and acetaldehyde (CH 3HCO). The laboratory spectra reveal additional strong features of the se molecules which should make a more definite identification straight forward.