SIMBAD references

We consider the long-term collisional and dynamical evolution of solid material orbiting in a narrow annulus near the Roche limit of a white dwarf. With orbital velocities of 300 km s^–1, systems of solids with initial eccentricity e 10^–3 generate a collisional cascade where objects with radii r  100–300 km are ground to dust. This process converts 1-100 km asteroids into 1 µm particles in 10²-10⁶ yr. Throughout this evolution, the swarm maintains an initially large vertical scale height H. Adding solids at a rate {dot}M enables the system to find an equilibrium where the mass in solids is roughly constant. This equilibrium depends on {dot}M and r₀, the radius of the largest solid added to the swarm. When r₀ <= 10 km, this equilibrium is stable. For larger r₀, the mass oscillates between high and low states; the fraction of time spent in high states ranges from 100% for large {dot}M to much less than 1% for small {dot}M. During high states, the stellar luminosity reprocessed by the solids is comparable to the excess infrared emission observed in many metallic line white dwarfs.