written by Wolfgang Christian

The Orbits Within Spherical Galaxies model displays the two-dimensional trajectories of particles (stars) within a galaxy having a spherically symmetric mass distribution that heuristically approximates the distributions found in galaxies and bulges.  The model uses a mass density proposed by Walter Dehnen to describe spatial distributions that vary as r^-4 and  r^-g in galactic envelopes and cores where g is an adjustable power-law parameter.  Units are chosen such that a typical galaxy has total mass M=1 and that the gravitational constant G=1.

The Orbits Within Spherical Galaxies model is a supplemental simulation for the article "Radial motion in a central potential for singular mass densities" by Ulrich Zürcher and Miron Kaufman in the American Journal of Physics 79(5), 521-526 (2011) and has been approved by the authors and the American Journal of Physics (AJP) editor.  The simulation was developed using the Easy Java Simulations (EJS) modeling tool.  It is distributed as a ready-to-run (compiled) Java archive.  Double clicking the  ejs_mech_orbits_OrbitsWithinSphericalGalaxies.jar file will run the program if Java is installed.

• Download ejs_mech_orbits_OrbitsWithinSphericalGalaxies.jar - 1932kb Java Archive File

Last Modified June 11, 2014

This file has previous versions.

The source code zip archive contains an XML representation of the Orbits Within Spherical Galaxies model.   Unzip this archive in your EJS workspace to compile and run this model using EJS.

• Download ejs_mech_orbits_OrbitsWithinSphericalGalaxies.zip - 222kb Compressed File

Last Modified January 12, 2011