Download H-R Diagram Lab

H-R Diagram Lab
Note: Remember you are responsible for graphs, charts and other items that form part of
the overall summary of this topic.
Vocabulary
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luminosity: brightness – dependent on a star’s size; temperature and distance
spectral class: classification of stars by their spectrum and luminosity
magnitude: measure of the brightness of a star or other celestial objects
The development of the H-R Diagram began with Danish astronomer Ejnar Hertzsprung
who began plotting the stars around 1911. American astronomer Henry Norris Russell
independently developed his own diagram. These two scientists independently
discovered that comparing magnitudes and spectral class (color) of stars yielded a lot of
information about them. Together, they created a diagram on which they mapped stars
by magnitude and spectral class.
After the astronomers had completed graphing the stars, they noticed that several patterns
appeared. First, they noticed that ninety per cent of the stars fell along a diagonal line
from the top-left corner to the bottom-right corner. These are called main sequence stars,
of which our Sun is a member. Another pattern they noticed was that the Cepheid’s
(class of variable stars that brighten and dim in a regular fashion); giants; super-giants
and dwarfs fell into groupings quite separate from the main sequence stars. The white
dwarfs were on the bottom-left; the red super-giants were in the upper-right; red giants
were on the diagonal that those two made; blue giants were slightly to the right of the
start of the main sequence; Cepheid’s were in the upper middle.
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Objective
Investigate the relationship between stars temperature, brightness and diameter.
Background
The H-R diagram is a graph of star brightness versus star temperature. When many stars
are plotted on an H-R diagram, it is found that they fall into groups. These groupings
indicate star sizes and are clues to how the stars change during their lifetime. The
measure of star brightness used in the H-R diagram is termed absolute magnitude. A
star’s absolute magnitude is not affected by its distance from Earth. The smaller the
absolute magnitude, the brighter the star. The very brightest stars have negative
magnitudes.
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 following questions.
Label this group of questions as “Group 1 Questions.”
a. What would you tell someone who thinks that all stars are very similar (be
sure to discuss temperature and brightness)?
b. How does our sun compare to other stars in brightness and temperature?
c. Are the stars scattered randomly on the graph, or is there a pattern?
Explain.
d. Would you expect hotter stars to be dim or bright? Does the graph agree
with this answer?
3. Using the same graph, plot the stars from Group 2.
4. Once you have plotted the stars from Group 2, answer the following questions.
Label this group of questions as “Group 2 Questions.”
a. Do the Group 2 stars follow the same pattern as the Group 1 stars that you
plotted? Explain.
b. Overall, are the stars in Group 2 very bright or very dim?
c. Are these stars hot or cool compared to other stars?
d. Is the relationship of brightness to temperature for these stars puzzling, or
does it make sense? Explain.
5. Using the same graph, plot the stars from Group 3.
6. Once you have plotted the stars from Group 3, answer the following questions.
Label this group of questions as “Group 3 Questions.”
a. Compare the areas of the graph where the Group 2 and Group 3 stars are
plotted. How are they different?
b. Overall, are the stars in Group 3 very bright or very dim?
c. Are these stars hot or cool compared to other stars?
d. Is the relationship of brightness to temperature for these stars puzzling, or
does it make sense? Explain.
7. Conclusion – you may wish to consult your textbook and use the internet to assist
in answering the following questions.
a. 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?
b. What is the "Main Sequence?"
c. Label the Main Sequence on your H-R Diagram.
d. What percent of all stars are on the Main Sequence?
e. Label “dwarfs" and "giants" on your H-R Diagram.
f. Explain the process of Nuclear Fusion.
g. Why is the process of nuclear fusion important?
h. Summarize the history and probable future of our sun (a main sequence
star). How did it begin and how will it end its life cycle? Be sure to
i.
j.
k.
l.
m.
include the following terms in your discussion: nebula; fusion; gravity;
giant; white dwarf.
Define the following terms: super-giant; supernova; neutron star; black
hole.
What determines if a star will end its life as a white dwarf, a neutron star
or a black hole?
At the beginning of the universe, scientists believe it contained only what
two elements?
Where were all of the other elements formed?
Why aren’t the Group 2 and Group 3 stars not on the Main Sequence?
Group 1
Visual
Magnitude
(Apparent)
Distance
(lightyears)
Temperature
(Kelvin)
Luminosity
(Sun = 1)
(Absolute)
* 1 Sun
-26.7
0.00002
5,800
1.00
* 2 Alpha Centauri A
-0.01
4.3
5,800
1.5
* 3 Alpha Centauri B
+1.4
4.3
4,200
0.33
* 4 Alpha Centauri C
+11.0
4.3
2,800
0.0001
* 5 Wolf 359
+13.66
7.7
2,700
0.00003
* 6 Lalande 21185
+7.47
8.1
3,200
0.0055
* 7 Sirius A
-1.43
8.7
10,400
23.0
* 8 Luyten 726-8 A
+12.5
8.7
2,700
0.00006
* 9 Luyten 726-8 B
+12.9
8.7
2,700
0.00002
* Ross 154
10
+10.6
9.6
2,800
0.00041
* Ross 248
11
+12.24
10.3
2,700
0.00011
* Epsilon Eridani
12
+3.73
10.8
4,500
0.30
* Ross 128
13
+11.13
11.0
2,800
0.00054
* 61 Cygni A
14
+5.19
11.1
4,200
0.084
* 61 Cygni B
15
+6.02
11.1
3,900
0.039
* Procyon A
16
+0.38
11.3
6,500
7.3
* Epsilon Indi
17
+4.73
11.4
4,200
0.14
+0.04
26.0
10,700
55.0
* Vega
18
* Achernar
19
+0.51
65.0
14,000
200.0
* Beta Centauri
20
+0.63
300.0
21,000
5,000.0
* Altair
21
+0.77
16.5
8,000
11.0
* Spica
22
+0.91
260.0
21,000
2,800.0
* Delta Aquarii A
23
+3.28
84
9,400
24.0
* 70 Ophiuchi A
24
+4.3
17
5,100
0.6
* Delta Persei
25
+3.03
590
17,000
1,300.0
* Zeta Persei A
26
+2.83
465
24,000
16,000.0
* Tau Scorpii
27
+2.82
233
25,000
2,500.0
Visual
Magnitude
(Apparent)
Distance
(lightyears)
Temperature
(Kelvin)
Luminosity
(Sun = 1)
(Absolute)
* Arcturus
28
-0.06
36.0
4,500
110.0
* Betelgeuse
29
+0.41
500.0
3,200
17,000.0
* Aldebaran
30
+0.86
53.0
4,200
100.0
* Antares
31
+0.92
400.0
3,400
5,000.0
Group 2
* Delta Aquarii B
32
+2.86
1030
6,000
4,300.0
Visual
Magnitude
(Apparent)
Distance
(lightyears)
Temperature
(Kelvin)
Luminosity
(Sun = 1)
(Absolute)
* Sirius B
33
+8.5
8.7
10,700
0.0024
* Procyon B
34
+10.7
11.3
7,400
0.00055
* Grw +70 8247
35
+13.19
49
9,800
0.0013
* L 879-14
36
+14.10
63?
6,300
0.00068
* Van Maanen's
37 Star
+12.36
14
7,500
0.00016
* W 219
38
+15.20
46
7,400
0.00021
* Barnard's Star
39
+9.54
6.0
2,800
0.00045
* Luyten 789-6
40
+12.58
11.0
2,700
0.00009
* Canopus
41
-0.72
100.0
7,400
1,500.0
* Capella
42
+0.05
47.0
5,900
170.0
* Rigel
43
+0.14
800.0
11,800
40,000.0
* Alpha Crucis
44
+1.39
400.0
21,000
4,000.0
* Fomalhaut
+1.19
23.0
9,500
14.0
Group 3
45
* Deneb
46
+1.26
1,400.0
9,900
60,000.0
* Beta Crucis
47
+1.28
500.0
22,000
6,000.0