HR DIAGRAM ACTIVITY



HONORS EARTH SCIENCE

HR DIAGRAM ACTIVITY NAME _________________

DATE _______ HOUR ___

The Hertzsprug- Russel diagram (H-R) is a graph where a star’s temperature is plotted against its brightness. From this diagram you can determine star properties as well as its life stage

Purpose

To classify stars

I. Materials

Star chart, graph, colored pencils

Procedure

1. Determine the color of each star from the temperature-color chart. Record colors on the table.

2. Plot each star on the grid. Use colored pencils to indicate the star’s color. For white stars, use a gray pencil. Notice the graph lines are not evenly spaced. Label each star name.

IV. Observations

|Star |Brightness (L) |

|> 25,000 |Dark Blue |

|11,000-24,999 |Light Blue |

|7,500-10,999 |White |

|6,000-7,499 |Light Yellow |

|5,000-5,999 |Yellow |

|3,500- 4,999 |Orange |

|2,000- 3,499 |Red |

2. Draw a circle around all the white dwarfs and label this enclosed area White Dwarfs.

3. The majority of stars belong to the main sequence group. Draw an ellipse enclosing the points representing main sequence stars. Label this area Main Sequence.

4. Find the Sun on your HR diagram. Draw arrows on the HR diagram showing the various stages the Sun will go through until the end of its life cycle. (page 632)

5. Of the stars you plotted, which is nearest to the end of its life? ________________ (name of star)

Explain how you determined this.

6. The _______________ (longer or shorter) the wavelength, the hotter the star.

7A. Is luminosity more similar to absolute or apparent magnitude? (think about where the sun is) Explain.

7B. If you put Spica and the Sun next to each other at equal distance, which would be brighter? Why?

Use your HR diagram to determine the following: (choose MS, RG or WD)

8. If a star is very hot and very bright, it belongs in this category ___________________

9. If a star is very cool and very dim, it belongs in this category ___________________

10. If a star is very hot and very dim it belongs in this category ______________________

11. If a star is very cool and very bright, it belongs in this category __________________

12. Not all red stars are Red Giants. According to the HR diagram, what also has to be true to be considered a Red Giant?

(use table 23.3 on page 638 to help you)

13. In the main sequence, the most massive stars are what color?

The least massive stars are what color?

14. Look at the main sequence stars on your HR diagram, which main sequence star is the most massive?

15. Complete the sentence. For main sequence stars: The ______ the temperature the _______ the

(higher or lower) (higher or lower)

luminosity the ______ massive the star

(more or less)

16. On the HR diagram to the left, fill in the boxes with the following terms: hot bright, cool bright, hot dim, cool dim

Bonus: Why are there no green stars? (you need to research this)

Here’s a great website (I’ll link it on my website) to help with the HR diagram. Scroll down and click on the Interactive version with questions:

If you can get 12-13 questions correct, you really understand the HR diagram (!

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