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.
Please note that this resource requires
at least version 1.5 of
Orbits Within Spherical Galaxies Source Code
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… more... download 222kb .zip
Last Modified: January 12, 2011
6-8: 4E/M4. Energy appears in different forms and can be transformed within a system. Motion energy is associated with the speed of an object. Thermal energy is associated with the temperature of an object. Gravitational energy is associated with the height of an object above a reference point. Elastic energy is associated with the stretching or compressing of an elastic object. Chemical energy is associated with the composition of a substance. Electrical energy is associated with an electric current in a circuit. Light energy is associated with the frequency of electromagnetic waves.
AAAS Benchmark Alignments (1993 Version)
4. THE PHYSICAL SETTING
E. Energy Transformations
4E (9-12) #2. Heat energy in a material consists of the disordered motions of its atoms or molecules. In any interactions of atoms or molecules, the statistical odds are that they will end up with less order than they began?that is, with the heat energy spread out more evenly. With huge numbers of atoms and molecules, the greater disorder is almost certain.
Christian, W. (2011). Orbits Within Spherical Galaxies Model (Version 1.0) [Computer software]. Retrieved May 23, 2013, from http://www.compadre.org/Repository/document/ServeFile.cfm?ID=10583&DocID=2074
%0 Computer Program %A Christian, Wolfgang %D January 12, 2011 %T Orbits Within Spherical Galaxies Model %7 1.0 %8 January 12, 2011 %U http://www.compadre.org/Repository/document/ServeFile.cfm?ID=10583&DocID=2074
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