1999A&A...342L..32D

We present ground-based L-band spectra of the high-mass protostars RAFGL 7009S and W 33A. Absorption bands at 3.54, 3.84 and 3.94µm arise in both lines of sight. We attribute these bands to the methanol ν₃ CH₃ symmetric stretch and combination modes. The CH₃OH abundance relative to water ice is about 30% for RAFGL 7009S and 5-22% for W 33A, making CH₃OH the most abundant solid state molecule after H₂O toward these two sources. The profiles of the absorption features toward these objects are very similar, showing that the methanol is located in similar ice environments. Detailed spectral comparison with laboratory data implies that the methanol is not mixed uniformly with the water ice. The similarities in the spectra of these two protostars are discussed within the context of chemical differences along other lines of sight. Methanol appears to be more efficiently produced on grain mantles in the vicinity of high-mass protostars than in other locations.