Europa's FUV auroral tail on Jupiter -: art. no. L06201

Ultraviolet images of Jupiter's northern aurora obtained in 2005 confirm the existence of an electromagnetic interaction between Europa and the Jovian ionosphere. The auroral signature shows a two-component structure: a quasi-circular Europa spot, followed by a previously undetected faint tail emission trailing in the direction of corotation flow. The characteristic brightness for the auroral spot is similar to 14 +/- 1 kR above background, and approximately 7 +/- 1 kR for the tail. The spot's size is similar to 1100 km, magnetically mapping to an interaction region <= 15 Europa diameters. The auroral tail extends over similar to 5000 km, which maps along a region of at least 70 Europa diameters. The ultraviolet power emitted by both components varies from a fraction to several GW. The present study suggests auroral interaction at Europa similar to that at Io, but scaled-down by an order of magnitude, including a sub-corotating plasma plume in the geometrical wake of Europa.