The outer region of the jovian system between
50 and 300 jovian radii from the planet is found to be the host of a previously unknown dust population. We used the data from the dust detector aboard the Galileo spacecraft collected from December 1995 to April 2001 during Galileo's numerous traverses of the outer jovian system. Analyzing the ion amplitudes, calibrated masses and speeds of
grains, and impact directions, we found about 100 individual events fully compatible with impacts of
grains moving around Jupiter in bound orbits. These
grains have moderate eccentricities and a wide range of inclinations—from pro
grade to retro
grade ones. The radial number density profile of the micrometer-sized dust is nearly flat between about 50 and 300 jovian radii. The absolute number density level (
10 km
−3 with a factor of 2 or 3 uncertainty) surpasses by an order of magnitude that of the interplanetary back
ground. We identify the sources of the bound
grains with outer irregular satellites of Jupiter. Six outer tiny moons are orbiting the planet in pro
grade and fourteen in retro
grade orbits. These moons are subject to continuous bombardment by interplanetary micrometeoroids. Hypervelocity impacts create ejecta, nearly all of which get injected into circumjovian space. Our analytic and numerical study of the ejecta dynamics shows that micrometer-sized particles from both satellite families, although strongly perturbed by solar tidal
gravity and radiation pressure, would stay in bound orbits for hundreds of thousands of years as do a fraction of smaller
grains, several tenths of a micrometer in radius, ejected from the pro
grade moons. Different-sized ejecta remain confined to spheroidal clouds embracing the orbits of the parent moons, with appreciable asymmetries created by the radiation pressure and solar
gravity perturbations. Spatial location of the impacts, mass distribution, speeds, orbital inclinations, and number density of dust derived from the data are all consistent with the dynamical model.