The Lyman alpha bulge of Jupiter: Effects of non‐thermal velocity field

In this preliminary study, we outline for the first time the effect of non‐thermal line broadening processes (turbulence, random waves, convection ,...) on the shape and intensity of the H Ly‐α line resonance scattered from the atmosphere of Jupiter and we show how a non‐thermal velocity field, confined to the bulge region, in the upper atmosphere of Jupiter, may account for most of the H Ly‐α bulge features. Both the shape and the brightness of the Ly‐α line from the bulge region as reported by the IUE instrument and the Voyager UV Spectrometer can be recovered assuming resonant scattering with a total atomic hydrogen [H]∼ 4 × 10 17 cm −2 , and a non‐thermal component [H]∼ 2 × 10 15 cm −2 above the thermopause.