Orchestra: NBody

Calculate orbits of ensemble of planets orbiting a star

  • Yields accurate gravity field
  • Includes mergers and fragmentation of large planets


  • Essential for ensembles of massive planets
  • Treats gas accretion and migration
  • Infers final planet masses and orbits


  • Fails for planetesimals
  • No interaction with leftover planetesimals or dust grains
  • Cannot model formation of gas giant planets


  • Friends-of-friends for nearest neighbors
  • Hierarchical treatment of timesteps
  • Force-evaluations calculated directly
  • Treecode backup for large numbers of particles
  • Input drag from interactions with gas & small bodies
  • Input accretion from planetesimal swarm
  • Accuracy is machine precision for orbits
  • O(N2) for force-solver

Code is extensively tested

Photo credit: Scott Kenyon & Ben Bromley