A search for interstellar gas-phase CO2 gas: Solid state abundance ratios
vanDishoeck, EF × Helmich, FP deGraauw, T Black, JH Boogert, ACA Ehrenfreund, P Gerakines, PA Lacy, JH Millar, TJ Schutte, WA Tielens, AGGM Whittet, DCB Boxhoorn, DR Kester, DJM Leech, K Roelfsema, PR Salama, A Vandenbussche, Bart #
Astronomy and astrophysics vol:315 issue:2 pages:L349-L352
We present searches for gas-phase CO2 features in the ISO-SWS infrared spectra of four deeply embedded massive young stars, which all show strong solid CO2 absorption. The abundance of gas-phase CO2 is at most 2. 10(-7) with respect to H-2, and is less than 5% of that in the solid phase. This is in strong contrast to CO, which is a factor of 10-100 more abundant in the gas than in solid form in these objects. The gas/solid state ratios of CO2, CO and H2O are discussed in terms of the physical and chemical state of the clouds.