Dynamics of the CO+ coma of comet 29P/Schwasmann-Wachmann 1

Comet-centaur 29P/Schwassmann-Wachmann 1 was observed in CO+ emission and contin-uum during 2007-2009 using the 6-m Big Telescope Alt-azimuth at the Special Astrophysical Observatory of the Russian Academy of Sciences. We analysed the morphology of the CO+ and dust coma. The distributions of dust and CO+ ions in the coma are not similar and vary depending on the level of comet activity. CO+ ions are more concentrated towards the nucleus than the dust continuum. The column density of the CO+ was derived and found to vary from 3.7*10^9 to 4.3*10^10 ions cm^-2. The production rate of CO+ was estimated to be from (7.01)*10^24 to (1.15)*10^26 ions s^-1. We discuss possible mechanisms for the ionization of cometary material and show that impact ionization by solar wind particles is probably the main ionization mechanism at large heliocentric distances.
7 pages, 5 figures