University of Michigan - Department of Astronomy

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Version: short


H-R diagram worksheet

the H-R diagram

Part 1: Areas on the H-R diagram

For the following circle the name of the area on the H-R diagram where you would find each type of star. If more than one word describes the area, for example the top right corner, circle both words.

  1. bright stars: top bottom left right center
  2. hot stars: top bottom left right center
  3. hot bright stars: top bottom left right center
  4. cool dim stars: top bottom left right center
  5. sun - like (type G main sequence) stars: top bottom left right center

Part 2: Plotting Stars

Mark each of the following on the H-R diagram and label it as indicated.

  1. A line showing the approximate location of the main sequence (no label).
  2. A blue main sequence star labeled B
  3. A red dwarf main sequence star labeled D
  4. A sun-like star labeled S
  5. A red giant the same color as D and the same brightness as B labeled G
  6. A white dwarf the same color as B and the same brightness as D labeled wd
  7. A large circle indicating the area where you find the biggest diameter stars, labeled supergiants
  8. a large circle indicating where you would find white dwarfs, labeled white dwarfs

Part 3: Getting Information from the H-R Diagram

  1. Stars B and G have the same brightness. Does this mean they are the same temperature? Why or why not?


  2. Stars D and G have the same color. Does this mean they are the same temperature? Why or why not?



  3. What is different about star G that allows it to be the same color as D but as bright as B? Explain.


  4. How can wd be as hot as B, but so dim?


  5. What will happen to wd as it continues to cool off? Why? Draw an arrow on the H-R diagram to show this change.


  6. Which star(s) MUST be bigger in radius than star S? Defend your answer.



  7. Which star(s) MUST be bigger in radius than star D? Defend your answer.



  8. Which star(s) MUST be smaller in radius than star S? Defend your answer.



  9. Which star(s) MUST be smaller in radius than star D? Defend your answer.



  10. Based on your previous four answers, place four dotted lines on the chart to show lines of equal radius. Explain how you decided what orientation the lines shoud go.

updated: 10/19/12 by SAM

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