HNBody: Integration of Hierarchical N-Body Systems

Authors: Kevin P. Rauch with Douglas P. Hamilton.

The HNBody (Hierarchical N-Body) package integrates the motion of particles in self-gravitating systems where the total mass is dominated by a single object; it is based primarily on symplectic integration techniques in which two-body Keplerian motion is integrated exactly, but also includes ODE integrators (Bulirsch-Stoer and Runge-Kutta) for comparison or special applications. Options include choices of coordinate system, division of particles into classes based on mass scales, order of accuracy, and others.

Download HNBody (latest version is 1.2.1). To be apprised of new HNBody releases, e-mail your request to or

To get started, peruse the online reference manual and sample integration. Note that the manual is included in the download packages; it is also available as a separate download (ZIP archive format).

And check out Rogue Star, an interactive animation utilizing HNBody.

HNBody is freely available! If you use our code in your work, we simply ask that you clearly state this in your publication, and cite the Rauch & Hamilton 2002 DDA proceedings (a journal article is in progress). We would also appreciate it if you send us a reference to your paper.

HNBody References:

The symplectic algorithms that we employ are based on the following papers: