1. Estimate the mass of a main-sequence star that is 10,000 times as luminous as the Sun. What is the luminosity (in terms of the Suns luminosity) of a main-sequence star whose mass is one-tenth that of the Sun? You can refer to the Mass-Luminosity table in your text on p 371.

2. Why do you think more massive stars are more luminous?

3. In this lab you studied the HR diagram of a star cluster. Discuss the properties of stars at different places on the main sequence. Which end is older? Which end is hotter? Which end is brighter? etc... Discuss the differences in stars in different parts of the HR diagram. Which are larger? Which are older? Which are oldest? etc....

4. Explain the difference between absolute and apparent magnitudes. Why might we want a quantity like absolute magnitude? How might our classification of stars be different without it? Now also think about how the idea and definition of an absolute magnitude, along with stellar spectral types, relate to the distances to stars.

5. Suppose you know that apparent magnitude of the star is 1.7, and you also know its distance is 200 pc. Determine the absolute magnitude of that star, and discuss what type of stars it belongs to.

6. The bright star Capella has a spectral type of G8 and an absolute magnitude of 0.7. What are the star's approximate surface temperature, luminosity, and radius? (Use the HR diagram on the back).

Updated: 2001.10.29 (Monday) 09:50:16 EST