Charge exchange of solar wind ions in the coma of comet P/Halley

Abstract

In addition to solar wind pick-up of cometary ions, charge exchange between solar wind ions and cometary neutrals is, potentially, an important comet-solar wind interaction closer to the nucleus. One monitor of the charge exchange rate is the relative abundances of solar wind He2+ and He+. Radial profiles of these two ions measured by the Giotto IMS/HERS instrument on the inbound trajectory to comet Halley are presented. Results indicate that charge exchange may be an important solar wind loss process in the comet Halley coma at distances ̃ 105 km from the nucleus.