New model of Saturn's ionosphere with an influx of water from the rings

The authors propose a model of Saturn's ionosphere in which water plays a major role as a minor constituent present by downward diffusion from a external source. The model Saturn ionosphere is a classical 'F2' type layer resulting from the photodissociative production of H+ from H2 and rapid chemical loss by a series of charge exchange reactions with water. A planet-wide influx of approx. 4 x 107 molecules cm-2 s-1 of water from the rings is consistent with the observed ionospheric electron densities. An enhanced influx of water occurs at latitudes (-380, +440) connected magnetically to the inner edge of Saturn's B ring where an electromagnetic erosion process takes place. (author)