H-R Diagram Lab



Lab: H-R Diagram

Purpose: In this lab we will investigate the relationship between the temperature, brightness and diameter of stars.

Introduction

The H-R Diagram is a tool that astronomers use to classify stars based on their luminosity, magnitude, temperature, spectral class and evolutionary stage. The H-R Diagram was independently discovered in the early 1900’s by the Danish astronomer Ejnar Hertzsprung and the American astronomer Henry Norris Russell. In this activity you will construct an HR Diagram.

Materials: Pencil, graph paper

Procedure

1. Using the graph below, plot the stars from Group 1.

2. Once you have plotted the stars from Group 1, answer the Group 1 Questions.

3. Using the same graph, plot the stars from Group 2.

4. Once you have plotted the stars from Group 2, answer Group 2 Questions.

1. Using the same graph, plot the stars from Group 3.

2. Once you have plotted the stars from Group 3, answer the Group 3 Questions.

3. Refer to your textbook to label the following regions of your diagram- Main Sequence, Red Giants, White Dwarfs.

4. Using the key at the bottom of the graph, color code your diagram.

Questions:

Group 1

1. What would you tell someone who thinks that all stars are very similar (be sure to discuss temperature and brightness)?

2. How does our sun compare to other stars in brightness and temperature?

3. Are the stars scattered randomly on the graph, or is there a pattern?  Explain.

4. Would you expect hotter stars to be dim or bright?  Does the graph agree with this answer?

Group 2

5. Do the Group 2 stars follow the same pattern as the Group 1 stars that you plotted?  Explain.

6. Overall, are the stars in Group 2 very bright or very dim?

7. Are these stars hot or cool compared to other stars?

8. Is the relationship of brightness to temperature for these stars puzzling, or does it make sense?  Explain.

Group 3

9. Compare the areas of the graph where the Group 2 and Group 3 stars are plotted. How are they different?

10. Overall, are the stars in Group 3 very bright or very dim?

11. Are these stars hot or cool compared to other stars?

12. Is the relationship of brightness to temperature for these stars puzzling, or does it make sense?  Explain.

Additional Questions

13. As you can see from the Group 1 stars, the cooler or hotter a star is, the brighter it will be.  The Group 2 and Group 3 stars do not follow this pattern.  Hence, there must be something besides temperature that can affect how bright a star is.  Describe your own theory about these stars (Group 2 and Group 3).  Why would their brightness not be strictly related to their temperature?

14. What is the "Main Sequence?"

15. What percent of all stars are on the Main Sequence?

16. Explain the process of Nuclear Fusion.

17. Why is the process of nuclear fusion important in stars?

18. Why aren’t the Group 2 and Group 3 stars on the Main Sequence?

  |Group 1 |Apparent Magnitude |Distance

(light-years) |Temperature

(Kelvin) |Luminosity

(Sun = 1) | | |Sun |-26.7 |0.00002 |5,800 |1.00 | | |Alpha Centauri A |-0.01 |4.3 |5,800 |1.5 | | |Alpha Centauri B |+1.4 |4.3 |4,200 |0.33 | | |Alpha Centauri C |+11.0 |4.3 |2,800 |0.0001 | | |Wolf 359 |+13.66 |7.7 |2,700 |0.00003 | | |Lalande 21185 |+7.47 |8.1 |3,200 |0.0055 | | |Sirius A |-1.43 |8.7 |10,400 |23.0 | | |Luyten 726-8 A |+12.5 |8.7 |2,700 |0.00006 | | |Luyten 726-8 B |+12.9 |8.7 |2,700 |0.00002 | | |Ross 154 |+10.6 |9.6 |2,800 |0.00041 | | |Ross 248 |+12.24 |10.3 |2,700 |0.00011 | | |Epsilon Eridani |+3.73 |10.8 |4,500 |0.30 | | |Ross 128 |+11.13 |11.0 |2,800 |0.00054 | | |61 Cygni A |+5.19 |11.1 |4,200 |0.084 | | |61 Cygni B |+6.02 |11.1 |3,900 |0.039 | | |Procyon A |+0.38 |11.3 |6,500 |7.3 | | |Epsilon Indi |+4.73 |11.4 |4,200 |0.14 | | |Vega |+0.04 |26.0 |10,700 |55.0 | | |Achernar |+0.51 |65.0 |14,000 |200.0 | | |Beta Centauri |+0.63 |300.0 |21,000 |5,000.0 | | |Altair |+0.77 |16.5 |8,000 |11.0 | | |Spica |+0.91 |260.0 |21,000 |2,800.0 | | |70 Ophiuchi A |+4.3 |17 |5,100 |0.6 | | |Delta Aquarii A |+3.28 |84 |9,400 |24.00 | | |Delta Persei |+3.03 |590 |17,000 |1,300.0 | | |Zeta Persei A |+2.83 |465 |24,000 |16,000.0 | | |Tau Scorpii |+2.82 |233 |25,000 |2,500.0 | | |Barnard's Star |+9.54 |6.0 |2,800 |0.00045 | | |Luyten 789-6 |+12.58 |11.0 |2,700 |0.00009 | | |Alpha Crucis |+1.39 |400.0 |21,000 |4,000.0 | | |Fomalhaut |+1.19 |23.0 |9,500 |14.0 | | |Deneb |+1.26 |1,400.0 |9,900 |60,000.0 | |

  |Group 2 |Apparent Magnitude |Distance

(light-years) |Temperature

(Kelvin) |Luminosity

(Sun = 1) | | |Arcturus |-0.06 |36.0 |4,500 |110.0 | | |Betelgeuse |+0.41 |500.0 |3,200 |17,000.0 | | |Aldebaran |+0.86 |53.0 |4,200 |100.0 | | |Antares |+0.92 |400.0 |3,400 |5,000.0 | |  |Group 3 |Apparent Magnitude |Distance

(light-years) |Temperature

(Kelvin) |Luminosity

(Sun = 1) | | |Sirius B |+8.5 |8.7 |10,700 |0.0024 | | |Procyon B |+10.7 |11.3 |7,400 |0.00055 | | |Grw +70 8247 |+13.19 |49 |9,800 |0.0013 | | |L 879-14 |+14.10 |63? |6,300 |0.00068 | | |Van Maanen's Star |+12.36 |14 |7,500 |0.00016 | | |W 219 |+15.20 |46 |7,400 |0.00021 | |

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