This paper was presented as a poster by Joshua Barnes at the 172nd AAS meeting, in Kansas City, Missouri, and appeared in abstract form in BAAS 20 , 706 (1988).

An Environment for Experiments in Stellar Dynamics

J, Barnes, L.E. Hernquist, P.Hut (The Institute for Advanced Study), P. Teuben (U. of Illinois)

Many important problems in Stellar Dynamics are vulnerable to attack by means of experimental physics when simulated on digital computers. With a collection of interlinked software we can construct synthetic realizations where a wide range of experimental situations can be realized and their dynamical and hydrodynamical evolution directly computed. Topics now under investigation include stellar collisions, few-body scattering cross-sections, evolutions of star clusters, equilibrium galaxy models, and interactions between two or more galaxies.

At the core of our system are a number of N-body integrators, ranging from high-order regularized methods to hierarchical tree-codes. These integrators are complemented by a growing collection of programs for generating and manipulating initial conditions and for reducing the results from numerical calculations. Extensions include software for Smoothed Particle Hydrodynamics and general routines for analytical and numerical modeling of equilibrium systems.

We have implemented this system as a set of extensions to UNIX. A unified command syntax has been defined, providing users with a simple help facility and programmers with a ready-made user interface. Programs can dynamically compile and load user-specified code, supporting very flexible tools for analysis and plotting. A general yet sufficient method for hierarchically structuring binary data files is used to communicate between programs. These software techniques may prove useful in wider contexts.