2003A&A...399.1009D

We revisit the reported detection and upper limits on HDO in ice mantles present in the molecular cloud environments of the massive young protostars Gl 2136 and W 33A, using independent VLT-ISAAC and UKIRT-CGS4 spectroscopic observations. We also present VLT and UKIRT spectra of RAFGL 7009 near the HDO absorption wavelength and reanalyze the ISO-SWS spectral data for NGC 7538 IRS9, Orion-BN and S140. We demonstrate that the previously reported detections of HDO in W 33A and NGC 7538 IRS9 are incorrect. We present an in-depth analysis that shows that, besides the sensitivity limits, detection of low levels of HDO is difficult in amorphous ice mantles when features from solid methanol, a common grain mantle constituent, are present. We discuss the specific problems arising in the ISO data in this wavelength range for NGC 7538 IRS9. Using VLT-ISAAC observations, we also investigate the HDO/H₂O ratio toward the intermediate mass stars IRAS 05329-0728 and IRAS 08448-4343. Our derived upper limits for the D/H ratio in water ice range from HDO/H₂O<1% to 0.2% in the different sources, and we discuss these limits in comparison with values derived in other environments.