The color of a pure photosphere with no circumstellar dust would be off the diagram below. The trajectories trace colors of disks structurally identical to the ones around b Pic and a PsA but with varying total amounts of dust in contrast to the stellar photospheres.
False color represents surface brightness.
There is no obvious correlation within the present small-number statistics between stellar type and average amount of dust. It is crucial to note that some models of the construction of the planets in our solar system indicate that the presence of an asteroid belt is not guaranteed . This is counter to the common intuition that an asteroid belt must form just inside the orbit of the first ice giant due to gravitational disturbances by that planet. These model systems otherwise resemble ours, with a set of terrestrial planets and a set of Jovian planets. Of course such systems will show up first and most easily in radial velocity searches, so their true prevalence is unknown.