This lab uses a Java-based simulation to study the orbits of binary stars, and how this motion affects spectral lines through the Doppler Shift.

You may work in pairs. At least one of you must have your laptop with you, with a browser that can render Java programs. (Any current version of Internet Explorer should do, for example. I used Safari on a Macintosh.) You will also need to connect to the internet, so bring an ethernet cable with you as well.

This lab is made possible by the University of Washington Astronomy Clearinghouse. The binary star lab is from Cornell University. You should print out the lab and the worksheet before coming to class. You will want to keep open a window on the actual simulation program.

Play around with the program a little bit so you can get used to it. Confirm that you get the correct result for "Model 0" on the worksheet. Then, follow the instructions on the lab and turn it in with your worksheet.

Here are some special notes:

• The lab says that the "Separation a" is the distance between the stars in solar radii, but this is wrong. The units for the separation is astronomical units (AU).
• For estimating the radial velocity range, just do the best you can. The little scale you are given is not so good that you can make very precise determinations.
• For Model 6, I was only able to set the eccentricity to 0.8, not 0.9, but that's enough to make the point.
• You need not work the "Extra exercises as time allows".