Left: the dust-to-stellar flux ratio at 1 Gyr at 70   μm vs. the innermost giant planet’s eccentricity for the widedisk (grey) and mixed (black) simulations. Filled circles represent stable simulations and open circles unstable ones. The solar system is shown with the grey star. Right: histogram of the fraction of systems that are detectable at 70   μm as a function of the innermost giant planet’s eccentricity; this is essentially a horizontal slice through the left panel.