1. How much more energy per cm2 per second would a 4000 K black body emit than a 2000 K black body?
2. Approximate how much more energy per cm2 per second a blue star would emit more than a yellow star.
If we assume that stars are spherical, the total area of the star would be 4Πr2, where R is the radius of the star and Π is delicious no just kidding Π x is 3.1416. Since Stephen's Law gives us the energy emitted by each square centimeter of the star per second, the total energy emitted by the entire star will be:
L = Wein's constant * 4ΠR2*T4 the units being energy per second. L is called the intrinsic luminosity. Notice that it depends on the radius of the star & the star's temperature.
3. A Star, Sirius A, has a temperature and radius twice that of our Sun. How much greater is the intrinsic luminosity of Sirius A as compared to our Sun? (Show your work!)
4. Why does Sirius A appear so much fainter than the Sun?
5. Sirius A has a companion star, Sirius B, which is also twice as hot as our Sun but which has an intrinsic luminosity only 0.0025 that of our Sun. What is the diameter of Sirius B compared to that of our Sun?
6. Another star, Betelgeuse, has a temperature only one-half as great as our Sun, but it is 10,000 times brighter. Explain why this star is so much brighter than our Sun.