The 2140 cm-1 band of frozen CO : laboratory experiments and astrophysical applications.
Abstract
In this paper we present experimental results on the behavior of the 2140/cm band of frozen CO in mixtures with several species such as H2O, CO2, CH3OH. These mixtures have been obtained by depositing both CO with other species and species containing C and O and producing CO by ion irradiation. The obtained results are used to review the identification of the observed interstellar 2140/cm band and we present a new model that, in our opinion, better accounts for the astronomical observations. In particular observations of field stars are well fitted if we assume stratified grain mantles with CO produced by ion irradiation of H2O:CH3OH ices (10 K) in the inner layer which in turn is covered with a layer dominated by irradiated CO (at 10 K). Observations of embedded stars are well fitted by the same model but with grains closer to the source heated up to temperatures which cause the outer CO layer to evaporate and modify the profile of the CO band produced by ion irradiation in the internal mantle. Some predictions on the amount of CO2 expected on those grains, hopefully observable from space, are also given.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- March 1993
- Bibcode:
- 1993A&A...269..568P
- Keywords:
-
- Carbon Monoxide;
- Infrared Astronomy;
- Interstellar Matter;
- Molecular Spectra;
- Carbon Dioxide;
- Line Spectra;
- Methyl Alcohol;
- Astrophysics