http://arxiv.org/abs/1403.5268
We consider the ability of three models – impacts, captures, and collisional cascades – to account for a bright cloud of dust in Fomalhaut b. Our analysis is based on a novel approach to the power-law size distribution of solid particles central to each model. When impacts produce debris with (i) little material in the largest remnant and (ii) a steep size distribution, the debris has enough cross-sectional area to match observations of Fomalhaut b. However, published numerical experiments of impacts between 100 km objects suggest this outcome is unlikely. If collisional processes maintain a steep size distribution over a broad range of particle sizes (300 microns to 10 km), Earth-mass planets can capture enough material over 1-100 Myr to produce a detectable cloud of dust. Otherwise, capture fails. When young planets are surrounded by massive clouds or disks of satellites, a collisional cascade is the simplest mechanism for dust production in Fomalhaut b. Several tests using HST or JWST data – including measuring the expansion/elongation of Fomalhaut b, looking for trails of small particles along Fomalhaut b’s orbit, and obtaining low resolution spectroscopy – can discriminate among these models.
S. Kenyon, T. Currie and B. Bromley
Mon, 24 Mar 14
47/50