Download SR Stellar Properties

Name: _______________________
Date: ______________________ Pd: _____
Stellar Properties and the H-R Diagram
Directions: Read pages 127-129 in Prentice Hall Science Explorer, Astronomy.
1. Stars are made mostly of ________________________ and the energy that makes them shine is produced
through _____________________ __________________.
2. List the four characteristics used to classify stars:
a.
c.
b.
d.
3. The color of the coolest stars in the sky is ____________________ with surface temperatures of about
______________ .
4. The color of the hottest stars in the sky is ____________________ with surface temperatures of about
______________ .
5. Arrange the following stars in order from smallest to largest size.
giant
medium-size
white dwarf
neutron
__________________
__________________
__________________
__________________
6. Where would you put our Sun on the “size” spectrum? ________________________
7. Astronomers can determine the __________________ ________________ of a star by observing the star
with a spectrograph.
8. If Rigel and Betelgeuse were the same size, explain why Rigel would appear brighter.
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9. If star Large and star Small were the same temperature, explain why Large would appear brighter.
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10. Apparent Brightness: Explain why the Sun, an average size star with a medium temperature, appears so
much brighter than all other stars in the sky.
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11. Absolute Brightness: A scientist must know a star’s _________________ _____________ and
_________________ . Then the scientist needs to figure out how two stars would compare if they were
equally distant from the Earth.
12. If scientists discovered a star in a distant galaxy, how could they determine what the star is made of?
13. If scientists discover a star in a distant galaxy, how could they infer the temperature of the star?
Name: ________________________________ Date: ___________________ Period: _________
H-R Diagram
Scientists began to learn about stars by observing properties of stars, including brightness and color.
Astronomers tried to make sense of the star data by grouping together stars with similar properties.
The Hertzsprung-Russell diagram provides a way to group similar stars. The H-R diagram is a graph of
absolute magnitude, sometimes called absolute brightness, actual brightness or luminosity, and temperature.
In this activity, students will construct an H-R diagram using data on the 20 stars that are nearest Earth (Table
A) and the 20 stars that appear the brightest in our sky (Table B). Students will use the finished diagram and
your book to compare properties and life cycles. .
Directions:
1. Plot five of the stars in table A on the diagram below. Be sure to label each point with the number label.
-5
0
+5
+10
+15
DIM
Absolute Magnitude (Luminosity)
BRIGHT
2. Plot five of the stars in table B on the diagram below. Be sure to label each point with the number label.
HOT
20,000
14,000
10,000
7,000
Surface Temperature (Kelvin)
5,000
3,000
COOL
Table A: The 20 Stars Nearest to Earth
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
Temperature
(K)
5,800
2,800
2,700
3,200
10,400
2,700
2,800
2,700
4,500
2,800
2,700
2,800
6,800
4,200
3,000
3,200
5,200
3,100
3,000
3,500
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
+7.0
+11.1
+10.3
+5.7
+9.6
+11.9
+8.7
Number Label for
Diagram
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Table B: The 20 Brightest Stars as Seen from Earth
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
Temperature
(K)
10,400
7,400
5,800
4,500
10,700
5,900
11,800
6,800
3,200
14,000
2,000
8,000
21,000
4,200
21,000
3,400
4,900
9,500
9,900
22,000
Absolute
Magnitude
+1.4
-3.1
+4.4
-0.3
+0.5
-0.7
-6.8
+2.7
-5.5
-1.0
-4.1
+2.2
-4.0
-0.2
-3.6
-4.5
+0.8
+2.0
-6.9
-4.6
Number Label for
Diagram
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
Questions
1. A star located in the lower right portion of the H-R diagram is cool and dim.
How would you describe the temperature and brightness of a star in the upper left of the diagram?
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2. Refer to figure 10 on page 132 in Prentice Hall Science Explorer, Astronomy. Use colored pencils to label
the following three regions on your diagram: giants/supergiants, main sequence stars, and white dwarfs.
3. To which group do most of the stars on your diagram belong (Circle one):
giants/supergiants,
main sequence stars
white dwarfs
4. Are any of the stars that you plotted on the H-R diagram white dwarf stars? What is the evidence for your
answer?
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5. Our sun has a surface temperature of 6000 K and an absolute magnitude of + 4.7. Plot the Sun on the H-R
diagram and label it ‘Sun’.
6. Betelgeuse is one of the largest stars in the night sky. It has a surface temperature of 3200 K and an
absolute magnitude of – 5.5. To which group does Betelgeuse belong?
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7. Compare our sun with the supergiant Antares. Which star is in a later stage of its life cycle?
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How do you know?
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8. Black holes are not included on H-R diagrams. We will study them next. Based on what you know, why do
you think they are not included?
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