Sodium in Comet Tails

K. W. Ogilvie (NASA/Goddard Space Flight Center), M. A. Coplan (University of Maryland)

In September, 1985, the International Cometary Explorer spacecraft, passed through the tail of comet Giacobini-Zinner 7800 km from the nucleus. The relative velocity was 21 km/s. Instruments aboard the spacecraft made magnetic field, energetic particle and ion composition measurements. The composition measurement showed the presence of water group and CO+ ions as well an appreciable but localized flux of ions with M/Q = 24 +/- 1. These observed ions were tentatively identified by Coplan et al. (J. Geophys. Res. 92, 39, 1987) as either C2+ or Na+. In this paper we reinterpret these measurements in light of the recent spectroscopic observations of sodium atoms in tail of the comet Hale-Bopp.