A102 Review Problems

2003 February 5

These problems are not due as homework. They are here for your own studying purposes. Solutions are availble in PDF format.

(Some of these questions involve topics that will be discussed in class on Wednesday and Friday February 5 and 7.)

1. Chapter 4, Question 12 in the text.

2. Chapter 4, Question 15 in the text.

3. Chapter 4, Question 16 in the text.

4. Stars similar to the Sun, late in their life, turn redder in color; however, they also become much more luminous (emit more total energy per second). From just this information and what you know of thermal (blackbody) radiation, what can you conclude about the nature of these stars late in their life?

5. • (a) The Sun is 93 million miles away. How far back in time are we looking when we observe the sun?
   • (b) The Andromeda Galaxy (a nearby large galaxy) is 0.8 Mpc (that's 0.8 megaparsecs, or 800,000 parsecds) away. How far back in time are we looking when we observe the Andromeda Galaxy?

6. [More challenging] Astronomers use the term absolute magnitude to describe the magnitude of a star as it would be observed from a distance of 10pc, and distance modulus to describe the difference in magnitude between the star as observed and its absolute magnitude. Remembering the definition of magnitude as:

   m = -2.5 log(f/f0)

   where f is the flux of a star, and f0 is a constant, what would be the distance modulus of a star which is 1kpc away?