Download Homework #7 (Ch. 19)

Astronomy 120
HOMEWORK - Chapter 19
Star Formation
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 19.1
Briefly describe the basic chain of events leading to the formation of a star like the Sun.
2. Chaisson Review and Discussion 19.2
What is the role of heat in the process of stellar birth?
3. Chaisson Review and Discussion 19.3
What is the role of rotation in the process of stellar birth?
4. Chaisson Review and Discussion 19.6
Why do stars tend to form in groups?
5. Chaisson Review and Discussion 19.8
In what ways do the formative stages of high-mass stars differ from those of stars like the
Sun?
6. Chaisson Review and Discussion 19.9
What are brown dwarfs?
7. Chaisson Review and Discussion 19.12
At what evolutionary stages must astronomers use radio and infrared radiation to study
prestellar objects? Why can’t they use visible light?
8. Chaisson Review and Discussion 19.14
What is a shock wave? Of what significance are shock waves in star formation?
9. Chaisson Review and Discussion 19.17
What do star clusters and associations have to do with star formation?
10. Chaisson Review and Discussion 19.18
Compare and contrast the observed properties of open star clusters and globular star clusters.
11. Chaisson Review and Discussion 19.19
How can we tell whether a star cluster is young or old?
12. Chaisson Review and Discussion 19.20
In the formation of a star cluster with a wide range of stellar masses, is it possible for some
stars to die out before others have finished forming? Do you think this will have any effect on
the cluster’s formation?
13. Chaisson Problem 19.9
What is the luminosity of a brown dwarf whose radius is 0.1 solar radius and whose surface
temperature is 600 K (0.1 times that of the sun)?
14. A protostar can have a temperature of 600 K and luminosity 1000 times that of the sun.
a) At what wavelength is its peak emission? Use Wien’s Law.
b) What is its radius?
F  Teff 4 and L  4r 2  F .