Download Homework #9 (Ch. 21)

Astronomy 120
HOMEWORK - Chapter 21
Stellar Explosions
Use a calculator whenever necessary.
For full credit, always show your work and explain how you got your answer in full, complete
sentences on a separate sheet of paper.
Be careful about units!
Please CIRCLE or put a box around your final answer if it is numerical.
If you wish, you may discuss the questions with friends, but please turn in your own hand-written
solutions, with questions answered in your own way.
1. Chaisson Review and Discussion 21.1
Under what circumstances will a binary star produce a nova?
2. Chaisson Review and Discussion 21.2
What is an accretion disk, and how does one form?
3. Chaisson Review and Discussion 21.3
What is a light curve? How can it be used to identify a nova or supernova?
4. Chaisson Review and Discussion 21.4
Why does the core of a massive star collapse?
5. Chaisson Review and Discussion 21.6
What occurs in a massive star to cause it to explode?
6. Chaisson Review and Discussion 21.7
What are the observational differences between Type I and Type II supernovae?
7. Chaisson Review and Discussion 21.8
What is the Chandrasekhar mass (or limit), and what does it have to do with supernovae?
8. Chaisson Review and Discussion 21.9
How do the mechanisms responsible for Type I and Type II supernovae explain their
observed differences?
9. Chaisson Review and Discussion 21.11
What evidence is there that many supernovae have occurred in our Galaxy?
10. Chaisson Review and Discussion 21.13
What proof do astronomers have that heavy elements are formed in stars?
11. Chaisson Review and Discussion 21.16
How are nuclei heavier than iron formed?
12. Chaisson Review and Discussion 21.18
Why was supernova 1987A so important?
13. Chaisson Problem 21.7
A supernova’s energy is often compared to the total energy output of the sun over its lifetime.
Using the sun’s current energy output, calculate its total energy output, assuming that the sun
has a 1010 year main-sequence lifetime. How does this compare with the energy released by a
supernova?
14. Chaisson Problem 21.9
The Crab Nebula is now about 1 pc in radius. If it was observed to explode in C.E. 1054,
roughly how fast is it expanding? (Assume a constant expansion rate. Is that a reasonable
assumption?)