The following document lists the file abstract/LDHENDEC_FARICE.abs
from catalogue VI/111.
A plain copy of the file
(without headers/trailers) may be downloaded.
Laboratory spectra have revealed a wealth of molecular spectral features in the wavelength range 20 - 180 microns which may provide information on the physical processes taking place in astrophysical objects especially those in which interactions between gas and grains is important for the global chemical evolution of these objects. Among these features,far infrared H2O ice features at 45, 62 and 165 microns constitute an ideal target for ISO. ISO provides a unique opportunity to investigate the long wavelength continuum of cool emission from molecular clouds surrounding Ultracompact HII regions and thus to determine the nature of the grain components. We propose to use LWS and SWS to obtain IR spectra in the 20 -180 microns domain of selected UC HII regions, predominantly those with strong methanol emission at 6.668 GHz. These spectra will provide information on the far IR opacity law and the nature and structure of water ice, possibly mixed with solid state contaminants such as O2, NH3, CH3OH, N2, in the molecular clouds surrounding the sources. The far IR spectral results will be compared with our own laboratory spectra of analogues of these materials. They will be also correlated with ground based observations of methanol maser emission at 6.668 GHz and continuum emission at 8.4 GHz, near IR images in the 1-3.6 microns region and near and mid IR (10 microns) spectroscopy. Radiative transfer modelling will be carried out and, with the knowledge of the physical state of the ice (amorphous or crystalline) as determined with ISO data, an evaluation of grain temperatures will be possible.