Unidentified Molecular Ions in Comets

S. Wyckoff, R. S. Heyd (Az St Univ)

Several moderately strong emission bands were discovered in plasma tail spectra of comet Halley. These molecular bands have no known laboratory identifications, and have been observed in the plasma tail spectra of several recent comets. Here we report the absence of these bands in the tail spectrum of comet Hale-Bopp. We discuss possible carriers of the unidentifed bands based on correlations of their occurrences in comets with differing carbon monoxide to water abundance ratios.