AST 307 · Introductory Astronomy
Fall 2003


Chapter 23  Nov. 12-14

  1. Describe the method astronomers use to determine the distances to RR Lyrae and Cepheid variable stars from their fluxes and pulsation periods.

  2. Describe how RR Lyrae stars were used to show that the Sun is not at the center of the Milky Way Galaxy.

  3. Draw a sketch of the Milky Way Galaxy showing the disk, halo, bulge, spiral arms, and globular clusters.

  4. Describe the patterns of motion that are seen for the stars in the disk and in the halo of the Milky Way. In particular, describe how orbital speeds of stars depend on distance from the center.

  5. Explain why the density wave theory is needed to explain the persistence of the spiral arms, and how it accomplishes this.

  6. Describe the evidence for dark matter in the outskirts of the Milky Way.

  7. Describe the evidence for a massive black hole at the center of the Milky Way.

14 November 2003
Astronomy Program · The University of Texas at Austin · Austin, Texas 78712
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