Fomalhaut and its "Dust Disk"

Caption NASA originale:"The NASA SST has obtained the first infrared images of the dust disc surrounding Fomalhaut, the 17th brightest star in the sky. Planets are believed to form from such a flattened disc-like cloud of gas and dust orbiting a star very early in its life. The Spitzer telescope was designed in part to study these circumstellar discs, where the dust particles are so cold that they radiate primarily at infrared wavelengths. Located in the constellation Piscis Austrinus, the parent star and its putative planetary system is found at a distance of 25 light-years. The 70-micron image (lower left) clearly shows an asymmetry in the dust distribution, with the southern lobe one-third brighter than the northern. Such an unbalanced structure could be produced by a collision between moderate-sized asteroids in the recent past (releasing a localized cloud of dust) or by the steering effects of ring particles by the gravitational influence of an unseen planet".