PY 228: STELLAR ASTROPHYSICS

HOMEWORK #2: DUE FEB. 9

This homework involves the use of the program binaries on a REALM workstation. To execute this program follow these simple steps:

  1. Log on to a REALM (Unity, EOS, PAMS...) workstation
  2. Type add py228_info
  3. Type cp /ncsu/py228_info/ucla/Binaries ~/Binaries (This copies the X application defaults file to your root directory.)
  4. Run the program by typing binaries

  1. Verify Kepler's three laws.
  2. Set up the program to simulate the binary star Algol using the following parameters. What is the orbital period? Watch the light curve and the "View from Earth". Is there a bug in this program? (Which star is more luminous?) Forgetting that you know the answers, begin from the observations (radial velocity curves and orbital period) and derive the masses of the two stars.
  3. Adjust the orbital inclination to 0 degrees. Why is such a binary system much less useful in obtaining stellar parameters?
  4. Set up a close binary system with a primary star of spectral type B0V, a secondary star of spectral type G0V, and a separation of 60 solar radii. What is the orbital period? Notice the slight wobble of the primary star. Now change the luminosity class of the primary to a supergiant, choosing a spectral type that gives roughly the same mass as the star had when it was on the main sequence. What will happen to this system when the primary star evolves into a supergiant?