N-body Simulations

Click on image for larger version.

The animations presented here are examples of gravitational interactions of stars. The computer program used to generate these simulations is called an N-body code (you can specify "N"umber of bodies). The computer is one of the most important laboratories of an astronomer. Many processes in astronomy are complex and take incredibly long timescales to unfold- we are after all ephemeral creatures, shortlived. Simulations like this can be used to probe the nature of the universe. Astronomers need not visit the center of a star to understand the nuclear fusion that takes place there; nor do they have to wait for billions of years to watch how galaxies collide. Instead, modelling the universe on the computer provides invaluable clues to the inner workings of the cosmos.

These simulations are often shown in our Nightly Observing Program because they offer a perspective that illustrates the kinematics and dynamicism of the universe. This is an idea that is not easily conveyed by looking through the eyepiece of a telescope. The orbits of two stars would be the simplest case- however, this would be rather dull to watch since two orbiting bodies make elliptical and periodic paths about each other. With three stars, the interaction becomes much more complex. On the right an example of three orbiting stars is shown with the trace of their orbits (the paths they follow). The three stars in this example are of slightly different masses. Most people are surprised about how complex and non-repeating this interaction is.

The animation on the left shows the case of one hundred interacting stars. This might be typical of a tight cluster of stars. The stars shown here are of equal mass and hundreds of years pass by each second. Imagine what must be taking place in a globular cluster with one million stars!


N-body code written by Adam Block
1.1 Ghz CPU
Digital Camera
  • Click on the star cluster to see a larger version of the animation.
  • Click on the 3 star example to see a full length version of this animation. Alternatively, click HERE to see largest and full length version of this simulation. WARNING: This is a 7 megabyte file.
  • I originally wrote this program to display under DOS. I have not yet converted it to something that will work under Windows. Thus, there was no easy way to capture the screen and create these animations. To work around this hurdle, I set up a digital camera in front of the computer and took hundreds of frames of my simulations being displayed in slow motion. I then assembled these frames into the animations above. You can even see camera shake and focus faults if you look closely.
  • Minimum credit line: Adam Block

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    Updated: 7/10/2002