Graphing Stars with the H/R Diagram
Purpose: The purpose of this activity is to understand the relationships between the luminosity, color,
and temperature of stars.
Part 1: Completing the chart. There are 30 stars. Complete the color and the size part of the chart,
using the information below.
Star Name
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
Achemar
Alcor
Aldebaran
Algol
Alpha Centauri
Alpha Centauri B
Altair
Antares
Barnard’s Star
Betelgeuse
Canopus
Capella A
Deneb
Epsilon
Fomalhaut
HD 224014
Luyten 789-6A
Mira
Mizar
Polaris
Pollux
Procyon
Procyon B
Regulus
Rigel
Sirius
Sirius B
Spica
Sun
Tau Ceti
Van Maanen 2
Vega
ZZ Ceti
Temperature
(oC)
10,000
15,000
5,000
20,000
6,000
5,000
9,000
3,000
3,000
3,000
6,100
4,700
10,000
5,000
8,500
5,000
2,200
3,000
9,000
6,100
4,500
6,500
7,000
20,000
21,000
15,000
10,000
30,000
6,500
6,000
6,500
10,000
10,000
Luminosity
200
10
100
100
1
1
10
10,000
1/1000
20,000
15,000
100
15,000
1/10
10
500,000
1/1000
1,500
100
18,000
10
10
1/1000
100
15,000
10
1/1000
8,000
1
1
1/1000
100
1/1000
Color
Size
Temperature Range (oC)
10,001-30,000
7,501-10,000
5,001-7,500
3,500-5,000
Less than 3,500
Color
Blue
White
Yellow
Orange
Red
Luminosity
Under 1
1-1,000
Above 1,000
Size
Small
Medium
Large
After completing the chart, pick up the circle page and create your stars. In each circle you need to
record the Name of the Star (or its number 1-33). Then color the star the correct color. Make sure
that you are recording the stars on the correct sizes.
Part 2: Constructing the H/R Diagram.
1. Pick up the 11 x 17 inch paper.
2. Using a ruler, draw the X-axis along the longs side of the paper, about 1 inch from the bottom
edge.
3. Using the ruler, draw the Y-axis along the short side of the paper, about 1 inch from the edge.
4. Label the X-axis as “Temperature (oC)”. Dived this axis into 6 increments, each 2.5 inches apart.
Label the increments from left to right: 30,000oC, 20,000oC, 10,000oC, 7,500oC, 6,000oC, 5,000oC,
and 3,000oC.
5. Label the Y-axis as “Luminosity”. Divide this axis into 6 increments, each 1.5 inches apart. Label
the increments from bottom to top: 1/1000, 1/10, 1, 10, 100, 10,000, and 20,000.
6. Title the top of the graph “H/R Diagram”.
Part 3: Graphing the Stars.
1. Glue the 30 stars on the appropriate location on your graph. Graphing the stars will be much like
graphing coordinates in math (X,Y), X is temperature. Y is the star’s luminosity.
2. Label the following on your graph.
a. Main Sequence
d. Super Giants
g. Cool and Dim
b. White Dwarfs
e. Hot and Dim
h. Cool and Bright
c. Red Giants
f. Hot and Bright
Questions: Answer the questions in your ISN in complete sentences.
1. Where do the main sequence stars appear on your diagram?
2. Where do the red giants appear?
3. Where do the white dwarfs appear?
4.
5.
6.
7.
Where is our Sun on the H/R diagram?
What can you tell about the Sun based on its location on the diagram?
Where would you expect a brand new star to appear on your diagram? Why?
Are black holes able to be graphed on an H/R diagram? Why or Why Not?
8. Describe how the color and temperature of stars are related.
9. In main sequence stars, what is the relationship between brightness and temperature?