Cyanide Chemistry in Comet Hale-Bopp (C/1995 O1)

Abstract

Observations of comet Hale-Bopp (C/1995 O1) have been carried out near perihelion (1997 March) at millimeter wavelengths using the NRAO 12 m telescope. The , , and lines of HCN at 88, 177, and J = 1 r 0 2 r 1 3r2 265 GHz were measured in the comet as well as the lines of H CN, HC N, and HNC. The 13 15 J = 3 r 2 N = transition of CN near 226 GHz was also detected, and an upper limit was obtained for the line 2 r 1 J = 2 r 1 of HCNH. From the measurements, column densities and production rates have been estimated. A column density ratio of [HCN]/[HNC] = was observed near perihelion, while it was found that [HCN]/[HCNH ] 7 1 1. The production rates at perihelion for HCN and CN were estimated to be Q(HCN) ∼ s and 28 1