Presentation #133.05 in the session Planetary Nebulae, Supernova Remnants.
Protoplanetary nebulae (PPNe) bridge the asymptotic giant branch (AGB) and planetary nebulae (PNe) phases in stellar evolution. The molecular content in PNe varies considerably from that of the AGB phase such that significant changes must occur in the interim PPNe stage. To further investigate this evolution, we have been examining the molecular content of M1-92 (IRAS 19343+2926), the Cotton Candy Nebula (IRAS 17150+3224), and IRAS 22036+5306, using the 12-meter antenna and the Sub-millimeter Telescope (SMT) of the Arizona Radio Observatory (ARO), in addition to the IRAM 30-meter facility. All three sources are known to contain CO and have either bipolar or quadrupolar morphologies. Our current measurements have extended the molecular identifications to include CN, HCO+, H13CO+, H2CO, HCN, HNC, H2S, SO2, and SiO and towards M1-92. Here the 12C/13C ratio is ~ 3. We also have found CN, HCN, and HNC in the Cotton Candy Nebula, as well as H2S, SO, and SO2 in IRAS22036+5306. Despite the oxygen-rich nature of these objects, carbon-bearing molecules are clearly present, and sulfur is prominent as well. The current set of observations, and their chemical interpretation, will be presented.