Download The Hertzsprung-Russell Diagram

The Hertzsprung-Russell Diagram
Today you will use the H-R diagram to compare other stars to our sun and to study the life cycle of a
star. The Hertzspung-Russell diagram is often called the H-R diagram for short. Its purpose is to
compare the brightness, temperature, and size of other stars to our sun. It also shows the stages in
the life cycle of stars.
The chart below describes the color and temperature range of stars:
Color
Temperature Range (ºC)
Indigo (purple)
26,000 – 50,000
Blue
12,000 – 25,000
White
7,600 – 11,000
Yellow-white
6,100 – 7,500
Yellow
5,100 – 6,000
Orange
3,600 – 5,000
Red
1,500 – 3,500
Figure 1
Materials
H-R diagram
Colored pencils – indigo (purple), blue, white, yellow, orange, and red
Chapter 28 of McDougal Littell Earth Science
Procedure
1. Use the chart above to determine the color of the stars on the H-R diagram.
2. Use the colored pencils to color each of the stars the color that represents its temperature.
3. Circle the long line of stars running diagonally through the middle of the diagram.
4. Label these stars as the “main sequence stars.”
5. Circle the group of ten stars above the main sequence.
6. Label these stars as the “red giant stars.”
7. Circle the group of five stars below the main sequence.
8. Label these stars as the “white dwarf stars.”
9. Label the following steps on your H-R diagram to show the series of changes that our sun has
undergone since its formation 4.6 billion years ago.
a. Originally, a big cloud of gas and dust called a nebula condensed to form a young, cool
star called a red dwarf. In this first stage of life, our sun was a dim red star. Circle an
area and put a 1 on your H-R diagram to show the first stage of the sun’s formation.
b. As the sun grew older and fusion continued, it became a stable star and entered the
main sequence stage of its life cycle. This is where the sun is today in its life cycle.
Circle an area and put a number 2 on your H-R diagram to show the sun’s present
stage in its life.
c. When our sun begins to die out, it will grow 100 times in size to form a red giant. Circle
an area and put a number 3 on your H-R diagram to indicate the third stage of the
sun’s life.
d. Finally, the red giant Sun will expand and then collapse to form a small, remnant star
called a white dwarf.
10. Circle an area and put a number 4 to indicate this last stage of the sun’s life.
11. Connect the numbers which indicate the life cycle of our sun with a dotted line.
12. Draw an arrow on the dotted line to show which way the sun’s life cycle goes.
13. Label the dotted line as the Sun’s Life Cycle.
Name: ________________________
Analysis and Conclusion
1. What is absolute magnitude?
2. What happens to the absolute magnitude of the stars as one moves up the y-axis?
3. What does the color of a star depend on?
4. What happens to the temperature of the stars as one moves from left to right along the xaxis?
5. Describe the following characteristics of our sun:
a. Temperature=
b. absolute magnitude=
c. color=
d. group=
6. Describe the following characteristics of the star Sirius B:
a. Temperature=
b. absolute magnitude=
c. color=
d. group=
7. Describe the following characteristics of the star Betelguese:
a. Temperature=
b. absolute magnitude=
c. color=
d. group=
8. Which group contains the most stars?
9. As the temperature of the stars in the main sequence increases, what happens to their
absolute magnitude?
10. Explain why white dwarfs are dim even though they have a higher temperature.
11. Explain why the red giants are so bright even though they are cool stars.
12. From what did our sun form?
13. In what stage of its life cycle is the sun today?
14. What will happen to our sun when it begins to die out?
15. After the sun goes through its red giant stage, what will happen to it?