C2 photolytic processes in cometary comae

The authors present observations of C₂ column densities of comets Tuttle 1980h and Meier 1980q. Nonequilibrium chemical models are fitted to the data. It is shown that new rates for the photolytic reactions affecting the creation and destruction of C₂ are necessary. These new rates are: [C₂H+hν→C₂+H] 5×10⁻⁴ s⁻¹ for creation and [C₂+hν→C+C] 4×10⁻⁶ s⁻¹ for destruction. Other possible methods for altering the photometric profiles of C₂ are discussed.