Star Life Cycle Webquest: http://aspire.cosmic-ray.org/labs/star_life/starlife_main.html

Work your way through the pages of this website, carefully reading and studying the information here. Answer the questions below as you go.

Protostars
1. What is accretion?
2. What is meant by “equilibrium”?
3. What happens if a protostar reaches the critical temperature? What happens if it does not?

Main Sequence Stars
4. So, what is a star?
5. What do stars use for fuel?
6. How are heavier elements made?
7. Try the interactive lab. Print or summarize your results.
8. Which hypothesis is correct, and why?
1) The bigger a star is, the longer it will live.
2) The smaller a star is, the longer it will live.

Equilibrium
9. When does a star achieve equilibrium?
10. Do the equilibrium cycle interactive lab. Summarize your results in the table below (use increases, decreases, or stays the same to fill in what happens to pressure, gravity, and temperature):

STAGE	PRESSURE	GRAVITY	TEMPERATURE
1. Nuclear fusion
2. Out of fuel
3. Fusion stops
4. Core contracts
5. Nuclear fusion reinitiates

11. Take the practice quiz (true/false questions about equilibrium) and after carefully reading the information about what happens to a star after the main sequence stage, take Star Quiz part 1.

The Beginning of the End: Helium Burning
12. Do the helium burning interactive lab. Summarize your results in the table below (use increases, decreases, or stays the same to fill in what happens to pressure, gravity, and temperature):

STAGE	PRESSURE	GRAVITY	TEMPERATURE
1. Nuclear fusion
2. Out of fuel
3. Fusion stops
4. Core contracts
5. Outer layer blown off

13. Take the star quiz part 2
14. What is the name of the stage of most helium-burning stars, like the star Mira?

The End of a Star
15. What do low mass stars become at the end of their existence? Medium mass stars? Massive stars?
16. Do the carbon-burning interactive lab. Summarize your results in the table below (use increases, decreases, or stays the same to fill in what happens to pressure, gravity, and temperature):

STAGE	PRESSURE	GRAVITY	TEMPERATURE
1. Nuclear fusion
2. Out of fuel
3. Fusion stops
4. Core contracts
5. Supernova

17. Do the interactive lab that shows what happens to different sized stars at the end of their lives.
18. From the results of your lab, record the sequence of life cycle stages each type of star goes through:
small:
low:
medium:
massive:

Hertzsprung-Russell Diagram
19. What stage would you be in if you were a star?
20. Read the information, then try the interactive Hertzsprung-Russell diagram and check your work carefully.

Applications of the Hertzsprung-Russell Diagram
21. Do the interactive lab. At the end, click display written answers and copy and paste your work into your webquest, or print it and attach it.
22. Summarize the relationships among the brightness, size and temperature of a star.

Interactive Hertzsprung-Russell Diagram
23. Complete the following chart:

Stage	Temperature	Luminosity

24. Do the interactive Hertzsprung Russell diagram with questions.