C+ PICKUP IONS IN THE HELIOSPHERE AND THEIR ORIGIN

C+ pickup ions were discovered with the solar wind ion composition spe ctrometer flying on Ulysses. Whereas the other nonlocally occurring pi ckup ions are produced from the interstellar gas penetrating deep into the heliosphere, C+ comes from an ''inner source'' which is located a t a solar distance of a few AU and extends over all heliospheric latit udes investigated so far. The total production of C+, N+, and O+ by th is inner source is of the order of 10(-3) relative to the total produc tion of O+ from the interstellar gas in the heliosphere. Thus the inne r source does not significantly contribute to oxygen or nitrogen in th e anomalous cosmic rays (ACR), but its contribution to ACR carbon may not be negligible. We propose that the inner source material is carbon compounds evaporating from grains. At this time, the evidence points to interstellar as the major source, but we do not want to exclude yet a contribution from grains of solar system origin.