On the occurence of carbon dioxide in interstellar grain mantles.
Abstract
The detection of solid CO on dust grains in dense molecular clouds leads to the prediction that CO2 is also present in solid form, and a detection of the expected CO2 feature at 15.2 microns in IRAS low-resolution spectra (LRS) of the protostellar object AFGL 961 was recently reported. This paper presents the results of a search of the LRS database for sources selected on the basis of strong water-ice absorption at 3 microns in ground-based spectra. It is found that, surprisingly, several sources with optical depths greater than 1, indicative of large column densities of molecular material, show no detectable 15.2-micron absorption, suggesting that CO2 is not a widespread abundant constituent of grain mantles in molecular clouds. The detection of CO2 absorption in AFGL 961 and its absence in several superficially similar sources may reflect local differences in the ultraviolet radiation field which drives CO to CO2 conversion.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- September 1991
- DOI:
- 10.1093/mnras/252.1.63
- Bibcode:
- 1991MNRAS.252...63W
- Keywords:
-
- Abundance;
- Carbon Dioxide;
- Interstellar Matter;
- Molecular Clouds;
- Absorption Spectra;
- Astronomical Spectroscopy;
- Infrared Astronomy Satellite;
- Protostars;
- Ultraviolet Radiation;
- Astrophysics