Nbody problem, nbody,
manybody problem, astronomy, gravity, gravitational, ordinary
differential equation, ODE, numerical analysis, numerical integration,
integration, source code, calculus, source code


The XStar Nbody Solver
XStar is a Unix program that simulates the movement of stars.
It starts by putting a bunch of stars on the screen, and then it lets
the interbody gravitational forces move the stars around. The result
is a lot of neat wandering paths, as the stars interact and
collide.
Figuring out what paths these stars should take is called the "NBody
Problem", and when there are more than 3 stars involved (N>3), this
can be a very hard problem to solve. XStar is just a "toy" Nbody
solver, but it generates a lot of pretty pictures and gives you an
idea of how stars interact. "Real" Nbody solvers have to work with
many thousands, or even millions of stars, while XStar works with
dozens.
Along with the program, there is a fairly large document that explains
the NBody problem in a fair amount of detail. It doesn't get into
the gory details of the "real" Nbody solvers, but it does give you an
overview of the techniques they use.
Downloads
The source code for XStar (version 2.2) can be obtained as
xstar.tar.gz (231k)
or
xstar.tar (829k)
The introductory text on the Nbody
Problem that comes with the source code to XStar can
be obtained separately as
nbody.ps.gz (157k),
nbody.ps (498k),
nbody.pdf (292k),
or
as web pages (57 pages).
Links
Here are some other useful links that I found while researching
the nbody problem:
Starlab: A Software Environment for Collisional Stellar Dynamics
A Portable
Parallel Particle Program.
Amara's
Recap of Particle Simulation Methods
Scientific Applications for Linux: Physics and Astronomy

