The Rich Molecular Spectrum and the Rapid Outflow of OH 231.8+4.2

The molecular spectrum of the bipolar nebula OH 231.8 + 4.2 was studied with an aim to shed light on its evolution, chemistry, and structure. The observational results on the emission lines of molecules observed in the circumstellar outflow of this nebula, including HCO(+), OCS, HNC, CS, and NH3, are presented. The implications of these data for the structure and composition of OH 231.8 + 4.2 are discussed. The circumstellar chemical processes which may account for the high abundance of the many observed sulfur compounds are considered. 49 references.