Carbon-Bearing Molecules in Oxygen-Rich Circumstellar Envelopes

We are currently conducting a search of oxygen-rich circumstellar envelopes for carbon-bearing molecules with the ISO SWS instrument. CH4 is the molecule in which we are most interested, because it has been shown to be capable of providing the reactive carbon which is needed produce the carbon-bearing molecules in these envelopes (Willacy & Millar 1997). However, CO2 and C2H2 are also possible candidates. The spectral ranges for our observations have been chosen specifically to include ro-vibrational bands in these molecules, but many other molecules, such as HCN, NH3, OH and HO2 have bands in these regions and hopefully there will be a few interesting surprises.