Name __________________________________________________
Period________
Lab # ______
Properties of Stars Lab
The Hertzsprung-Russell diagram (or H-R diagram) is a graph in which a star’s temperature is
plotted against its absolute magnitude. From such a diagram, other information about the star’s
properties and life cycle can be determined. A simplified H-R diagram appears in your textbook
(p626). In this laboratory, you will construct an H-R diagram using the data from the 20 stars that
are nearest to our sun (Table 1) and the 20 stars that appear brightest in our sky (Table 2). Then
you will use the finished diagram to describe the properties and life cycles of stars.
In Tables 1 and 2, the unit for distance is a parsec. And the Kelvin (K) or absolute temperature scale
is used.
Define parsec ____________________________________________________________
Define absolute magnitude ________________________________________________
Objectives:
 To graph a H-R diagram
 To identify the characteristics of a star using the H-R diagram
 To classify a star by its position on the H-R diagram
 To compare the life cycles of stars based on their position on the H-R diagram.
You will need:
 2 colored pencils (COLORS MUST BE EASY TO SEE AND DIFFERENT)
 Graph
 Sample HR diagram (p626 in book)
Procedure:
1. Look over the 2 Tables. Answer Analysis and Conclusion Questions 1-4
2. Graph: The following tips will be helpful!
 Temperature is the x axis
 Absolute Magnitude is the y axis
 Absolute magnitude decreases as the value is more positive. (a +15 is less bright
than a +1 or a –3)
 Therefore when you graph this +4.4 plots below the +4
3. Graph: Table 1:
 Use one of your colored pencils and mark each point as a ●
4. Graph: Table 2:
 Use the other colored pencil and mark each point as an X
5. Answer the Analysis and Conclusion questions
Name __________________________________________________
______
Table 1
The 20 Nearest Stars
Name
Alpha Centauri
Barnard’s Star
Wolf 359
Lalnde 21185
Sirius
Luyten 726-8
Ross 154
Ross 248
Epsilon Eridani
Ross 128
Luyten 789-6
61 Cygni
Procyon
Epsilon Indi
Sigma 2398
BD +43º44
Tau Ceti
CD -36º15693
BD +5º1668
CD-39º14192
Period________
Lab #
Table 2
The 20 Brightest Stars as Seen from Earth
Distance
(parsec)
Temperature
(K)
Absolute
Magnitude
1.31
1.83
2.35
2.49
2.67
2.67
2.94
3.16
3.30
3.37
3.37
3.4
3.47
3.51
3.60
3.60
3.64
3.66
3.76
3.92
5800
2800
2700
3200
10,400
2700
2800
2700
4500
2800
2700
2800
6800
4200
3000
3200
5200
3100
3000
3500
+4.4
+13.2
+16.8
+10.5
+1.4
+15.4
+13.3
+14.7
+6.1
+13.5
+14.9
+7.5
+2.7
+7.0
+11.1
+10.3
+5.7
+9.6
+11.9
+8.7
Name
Alpha Centauri
Sirius
Procyon
Altair
Formalhaut
Vega
Arcturus
Pollux
Capella
Aldebaran
Achernar
Canopus
Spica
Beta Centauri
Alpha Crucis
Antares
Betelgeuse
Beta Crucis
Rigel
Deneb
Distance
(parsec)
Temperature
(K)
Absolute
Magnitude
1.31
2.67
3.47
5.1
7.0
8.0
11.0
12.0
14.0
16.0
20.0
30.0
80.0
90.0
120.0
120.0
150.0
150.0
250.0
430.0
5800
10,400
6800
8000
9500
10,700
4500
4900
5900
4200
14,000
7400
21,000
21,000
21,000
3400
3200
22,000
11,800
9900
+4.4
+1.4
+2.7
+2.2
+2.0
+0.5
-0.3
+0.8
-0.7
-0.2
-1.0
-3.1
-3.6
-4.1
-4.0
-4.5
-5.5
-4.6
-6.8
-6.9
1. Compare the two star lists, in Tables 1 & 2. How many stars appear on both the Nearest
Stars list and the Brightest Stars as Seen from Earth? Name them.
__________________________________________________________________________
2. Are the nearest stars also the brightest stars as seen from Earth?
__________________________________________________________________________
__________________________________________________________________________
3. Name and give the absolute magnitude of the 3 brightest stars.
________________________________
________________________________
________________________________
4. Name and give the distances for the 3 closest stars.
________________________________
________________________________
Name __________________________________________________
Period________
Lab # ______
________________________________
Finish 5-12 after you have completed your graph
5. What are the main groups of stars? Refer to the H-R diagram on p626 in your book for
the names of the groups of stars.
__________________________________________________________________________
**Label the groups on the graph**
6. What is the name of the group that most of the stars on the graph belong?
__________________________________________________________________
7. A star located in the lower right portion of the graph is cool and dim. What are the
characteristics of a star in the upper left portion of the diagram?
__________________________________________________________________
8. According to the graph and the H-R diagram in your book, are any of the 20 nearest or 20
brightest stars white dwarfs? Give evidence for your answer.
__________________________________________________________________
9. Our sun has a temperature of 6000 K and has an absolute magnitude of +4.7 Use a sun
symbol (☼) to show the location of our sun on your graph. What group of stars does the
sun belong in?
__________________________________________________________________
10.Betelgeuse is 150 parsecs away and has a surface temperature of only 3200 K. What
does this indicate about the size of Betelgeuse?
__________________________________________________________________
11.On your diagram there is another star plotted near Betelgeuse. What is the name of that
star? What kind of star is it?
__________________________________________________________________
12.Which star is farther along in its life cycle, the sun or the red super giant Antares? How
can you tell?
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________