# Astronomy 300: Homework Assignment #8

Due: FRIDAY, April 21

1. Consider the energy production in the Sun via the Proton Proton Chain. If all other factors remained the same, how would the Sun's energy production increase if its core temperature increased by 5%?

2. The temperature of the core of the Sun (where its nuclear fusion reactions take place) is about 15 million K. At this temperature, the average speed of particles is insufficient for two protons to overcome the Coulomb Barrier and come within 1 femtometer (=10-15 m =1 fermi) of each other. Since fusion requires the protons to come this close (where the strong nuclear force can take over), how does the Sun manage to generate energy?

3. What is the Triple Alpha Process and why does it require much higher temperatures to initiate than the Proton-Proton Chain? Does the Sun use the Triple Alpha Process? Will it ever?

4. Consider a star undergoing the Triple Alpha Process. How would a 5% increase in core temperature affect this star's energy production? Compared to the P-P Chain what would you say about the temperature sensitivity of the Triple Alpha Process?

5. Carrol & Ostlie, Problem 10.13 (2 points)

6. Carrol & Ostlie, Problem 10.14

7. Life as we know it requires complex molecules using atoms such as Carbon, Oxygen & Iron, which exist on a solid planet made of Nickel, Magnesium, Aluminum, etc. Population II were formed much earlier in the history of the universe than Population I stars. Which Population would you consider more likely to support planets with life, and why?

8. What was being measured in the Homestake Mine experiment created by Raymond Davis? Write down the reaction that the experiment used for detection. What problem was found?

9. Intitially many scientists thought the problem lay with Davis' experimental method, or with solar models proposed by John Bahcall. But in the early 2000's this problem was solved. How? Hint: The solution to this problem resulted in a Nobel Prize for Davis.