General Astronomy -
Spring 2013
Homework #11 - due April 17
1. (2 pt) A
galaxy cluster contains: stars, dark matter, and X-ray emitting
gas. Put these three components in order of largest fraction
of cluster mass to smallest.
2. (4 pt) A galaxy cluster at a distance
of 200 Mpc has a velocity dispersion of 600 km/s and a half-light
radius of 0.5 degrees. What is its mass?
3. (2 pt) What is the Copernican
principle?
4. (2 pt) If the Hubble constant were found to be 120 km/s/Mpc,
what
would be
the critical density of the Universe?