Name_______________________________ Period ________
Properties of Stars
Background: YES YOU HAVE TO READ THIS PART!!
All stars are different. Some are small. Some are large. Every star is at a different stage in its life
journey. Some have died and gone supernova, others are just dwindling white dwarfs that are cooling.
Some stars are just being born in their nebulas. Some have turned into black holes or supergiants, etc.
If you graph all of the stars in our universe according to their brightness (absolute magnitude) and
their temperature, they all fit into specific places on the graph based on what type of star they are. [For
example, all of the supergiants would plot in the top right section while the regular young stars that are like
our Sun (called “main sequence stars”) plot in the center along a diagonal line based on their sizes.] This
graph is given the name “Hertzsprung-Russell diagram,” or “H-R diagram.” Using this diagram/graph, you
can analyze a star’s properties and you can figure out what stage of life a star is in based on where it plots on
the graph. Its color depends on its temperature. Blue ones are hotter and red stars are cooler.
Larger Main
Sequence Stars
Smaller Main
Sequence Stars
violet
blue
green
yellow
orange
red
In this exercise, you will construct an H-R diagram using data on 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 and answer the
questions on the next page.
Name_______________________________ Period ________
1. Compare the two star lists (Tables 1 and 2). How many stars happen to appear on BOTH the Nearest
Stars list (Table 1) and the Brightest Stars as Seen from Earth list (Table 2)? Name all of the stars that
happen to be on both lists. (don’t list every star…just the ones that are written twice…once in each list)
2. Analyzing your answer for question number 1, are the nearest stars also the brightest stars as seen
from Earth? ________ Why do you think that is?
3. On the graph attached, plot every one of the “nearest stars” using an “”
4. On the same graph, plot every one of the “brightest stars as seen from Earth” using a “”
a. If the stars appear on both lists, just circle the star “  ” to represent both symbols
AFTER YOU HAVE FINISHED GRAPHING ALL OF THE STARS, answer these questions…don’t forget to come
back to them and answer them…worth lots of points!
5. The stars located in the lower right portion of your chart are cool and dim. What are the characteristics
of a star in the upper left portion of the diagram?
6. What are the characteristics of a star located in the upper right portion of the diagram?
7. Compare your graph with the H-R diagram on the first page of this packet. Label each type of stars on
your graph. (example: label the white dwarf section, the main sequence section, etc.)
8. What group do most of the stars you graphed belong to? (white dwarf, red giant, main sequence, etc.)
9. Comparing both your chart and the chart on the first page, are any of the 20 nearest or 20 brightest
stars “white dwarfs”?
10. Our Sun has a temperature of 5800 K (which is 6073°Celsius) and an absolute magnitude of +4.7. Use
a “” symbol to plot the location of the Sun on your diagram. To which group does the Sun belong?
(label it “Sun” on your graph also)
11. Compare the absolute magnitude and temperature of the Sun with those of other stars in its group.
How are they the same/different?
12. Betelgeuse is 150 parsecs away (480 light years) and has a surface temperature of only 3200 K
(3473°Celsius). Yet Betelgeuse is one of the brightest stars as seen from Earth. Why do you think it is
so bright? (hint: it has to do with its size and location on the diagram)
13. On your diagram, there is another star that is plotted near Betelgeuse. What is the name of the
star?____________________ What kind of star is it?
14. Compare our Sun with the red supergiant, Antares. Which star is further along in its life cycle?
__________ How do you know?
Name_______________________________ Period ________
FYI: In Tables 1 and 2, the unit used for distance is the parsec. A parsec is equal to 3.26
light-years. The Kelvin (K) is the unit used in the tables for temperature. (Kelvin uses the
same scale as °Celsius but it starts at -27 °Celsius. 273 Kelvins equals 0°Celsius)
( Absolute magnitude means “brightness” or “LUMINOSITY."
The negative numbers are the brightest stars)
BRIGHTEST STARS AS SEEN FROM EARTH
NEAREST STARS
Name
Alpha Centauri
Barnard's Star
Wolf 359
Lalande 21185
Sirius
Luyten 726-8
Ross 154
Ross 248
Epsilon Eridani
Ross 128
Luyten 789-6
61 Cygni
Procyon
Epsilon Indi
Sigma 2398
BD +43.44
Tau Ceti
CD -36.15693
BD +5.1668
CD -39.14192
Distance
(parsecs)
1.31
1.83
2.35
2.49
2.67
2.67
2.94
3.16
3.3
3.37
3.37
3.4
3.47
3.51
3.6
3.6
3.64
3.66
3.76
3.92
Temperature
(K)
5800
2800
2700
3200
10400
2700
2800
2700
4500
2800
2700
2800
6800
4200
3000
3200
5200
3100
3000
3500
Absolute
Magnitude
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
11.1
10.3
5.7
9.6
11.9
8.7
Name
Sirius
Canopus
Alpha Centauri
Arcturus
Vega
Capella
Rigel
Procyon
Betelgeuse
Achernar
Beta Centauri
Altair
Alpha Crucis
Aldebaran
Spica
Antares
Pollux
Fomalhaut
Deneb
Beta Crucis
Distance
(parsecs)
Temperature
(K)
Absolute
Magnitude
2.7
30
1.3
11
8
14
250
3.5
150
20
90
5.1
120
16
80
120
12
7
430
150
10400
7400
5800
4500
10700
5900
11800
6800
3200
14000
21000
8000
21000
4200
21000
3400
4900
9500
9900
22000
4.4
-3.1
4.4
-0.3
0.5
-0.7
-6.8
2.7
-5.5
-1
-4.1
2.2
-4
-0.2
-3.6
-4.5
0.8
2
-6.9
-2.6
IMPORTANT HINTS FOR THE GRAPH ON THE NEXT PAGE
FYI:
 Temperature is on the bottom. The numbers get bigger as you go to the left (opposite of a normal graph).
 The Absolute Magnitude (or brightness/luminosity) is on the left. The numbers get bigger as you go down
(again…this is opposite of a normal graph)
FYI (also):
 The graph you will use has uneven lines and the numbers aren’t spaced apart evenly (called a logarithmic graph).
 It works the same as a normal graph still…just count the lines in between each number and fit the numbers in
between.
Name_______________________________ Period ________
Name_______________________________ Period ________
-7
-6
-5
-4
-3
-1
0
+1
+2
+3
+4
+5
+6
+7
+8
+9
+10
+11
+12
+13
+14
+15
Temperature (K)
(Note:  numbers get bigger this way)
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
10,000
9,000
+17
20,000
+16
30,000
Absolute Magnitude (Brightness/Luminosity)
(Note:  numbers get bigger this way)
-2