ASTR 220 - Collisions in Space

Homework 4 (12 points)
Due Tuesday May 9 at the beginning of class

  1. What evidence suggests that supermassive black holes exist at the centers of galaxies?

  2. Get on the web. Go to the Galaxy Crash JavaLab, a site which allows you to run your own galaxy collision simulations. Once there, clicking on "APPLET" (at upper left) will bring up a window with 2 spiral galaxies and a bunch of controls. Play around with the applet and its controls to get a feel for what it does.

    ControlThetaPhiPeri Red Galaxy MassNumber of StarsFriction Big Halos
    FunctionInclination Angle of each galaxy Orientation Angle of each galaxy Distance of Closest ApproachIn terms of the Green Galaxy Number of simulated pointsDynamical Drag between Stars Extent of unseen dark matter

    Run 2 simulations which differ ONLY in one control setting. You may choose any of the controls listed above EXCEPT the number of stars. This only affects the quality of the simulation: using more stars looks better, but takes longer to run. For example, you might investigate what happens when you change the mass, or the distance of closest approach.

    Record and report the control settings which you use. Which control did you change? From what to what? Describe the results of your simulations. How did things change when you altered the control setting?

  3. Below is a picture of the spiral galaxy M101.