{
  "id": "1706.08579",
  "version": "v1",
  "published": "2017-06-26T20:13:31.000Z",
  "updated": "2017-06-26T20:13:31.000Z",
  "title": "Numerical Simulations of Collisional Cascades at the Roche Limits of White Dwarf Stars",
  "authors": [
    "Scott J. Kenyon",
    "Benjamin C. Bromley"
  ],
  "comment": "37 pages of text, 12 figures, ApJ, accepted",
  "categories": [
    "astro-ph.SR",
    "astro-ph.EP"
  ],
  "abstract": "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/sec, systems of solids with initial eccentricity $e \\gtrsim 10^{-3}$ generate a collisional cascade where objects with radii $r \\lesssim$ 100--300 km are ground to dust. This process converts 1-100 km asteroids into 1 $\\mu$m particles in $10^2 - 10^6$ 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 $r_0$, the radius of the largest solid added to the swarm. When $r_0 \\lesssim$ 10 km, this equilibrium is stable. For larger $r_0$, 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.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-06-26T20:13:31.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "white dwarf stars",
      "roche limit",
      "collisional cascade",
      "numerical simulations",
      "metallic line white dwarfs"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 37,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}