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90764
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907640
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Level 2 Science, 2011
90764 Describe the nature and life cycle of stars
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November 2011
Credits: Two
Check that the National Student Number (NSN) on your admission slip is the same as the number at the
top of this page.
You should attempt ALL the questions in this booklet.
If you need more room for any answer, use the extra space provided at the back of this booklet.
Check that this booklet has pages 2 – 10 in the correct order and that none of these pages is blank.
YOU MUST HAND THIS BOOKLET TO THE SUPERVISOR AT THE END OF THE EXAMINATION.
ASSESSOR’S USE ONLY
Achievement
Describe the nature and life cycle
of stars.
Achievement Criteria
Achievement with Merit
Explain the nature of stars and
their life cycle.
Achievement with Excellence
Discuss the nature of stars and
their life cycle.
Overall level of performance
© New Zealand Qualifications Authority, 2011. All rights reserved.
No part of this publication may be reproduced by any means without the prior permission of the New Zealand Qualifications Authority.
2
You are advised to spend 25 minutes answering the questions in this booklet.
RESOURCE
The Hertzsprung-Russell (H-R) Diagram compares the real brightness of stars (in terms of their Absolute
Magnitude: –8 very bright, +16 very faint) with their colour (Spectral Type).
Hertzsprung-Russell Diagram
Surface Temperature (Kelvin)
10 000
50 000
4 000
Blue Supergiants
–8
–4
–2
Red
Giants Betelgeuse
Canopus
ß Centauri
α Crucis
ß Crucis
Spica
μ Cephei
ε Aurigae
Deneb
Rigel
–6
Absolute Magnitude
6 000
Antares
Alphard
Arcturus
Pollux
Regulus
0
Vega
Sirius A
2
Fomalhaut
Altair
Aldebaran
Procyon A
4
Sun
α Centauri A
40 Eridani A
6
8
10
Sirius B
12
Procyon B
14
16
40 Eridani B
Barnard’s Star
proxima Centauri
1
5
O
9
1
5
B
9
1
5
A
9
1
5
F
9
1
Spectral Type
5
G
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K
9
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M
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This page has been deliberately left blank.
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QUESTION ONE
ASSESSOR’S
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In April 2010, a group of astronomers reported the discovery of a brown dwarf only 10 light years
from our sun.
A brown dwarf has a similar composition of gases as our Sun, but it is a failed star.
For copyright reasons,
this resource cannot be
reproduced here.
The Sun
For copyright reasons,
this resource cannot be
reproduced here.
http://upload.wikimedia.org/wikipedia/commons/b/b4/
The_Sun_by_the_Atmospheric_Imaging_Assembly_of_
NASA%27s_Solar_Dynamics_Observatory_-_20100819.
jpg
Brown Dwarf
http://2.bp.blogspot.com/_NsNjn35go9Y/TCeBgHcszRI/
AAAAAAAAA8A/8BkkLsdd7FE/s1600/browndwarf.jpg
Discuss why the brown dwarf has not developed into a star like our Sun.
In your answer you should refer to:
•
•
•
•
•
star formation
size
mass
luminosity
fuel usage.
You may wish to use a labelled diagram in your answer.
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QUESTION TWO
ASSESSOR’S
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The brightest star in the night sky is Sirius A. This star is 8.7 light years from Earth. It is 40 times
more luminous and twice the size of our sun.
For copyright reasons,
this resource cannot be
reproduced here.
X-ray image of Sirius A and Sirius B
http://destinationterre2.files.wordpress.com/2010/03/siriusb_cxo_big.jpg
Sirius A has a companion star know as the “Pup” or Sirius B. This star cannot be seen by the naked
eye.
As Sirius B orbits around Sirius A, it makes Sirius A wobble.
Using the H-R diagram, discuss the characteristics of Sirius A and Sirius B.
Contrast the two stars and explain why Sirius B causes Sirius A to wobble.
Points you may consider are:
•
•
•
•
•
star types
star size
fuel use
gravitational forces
star composition.
You may wish to use a labelled diagram in your answer.
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QUESTION THREE
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The Large Magellanic Cloud (LMC) is a globular galaxy that forms a companion to our galaxy, the
Milky Way. It is 168 000 light years away from our galaxy.
In 1967 a Supernova was observed in the LMC.
For copyright reasons,
this resource cannot be
reproduced here.
Image of the supernova in the LMC
http://www.eso.org/public/images/eso0437c/
Discuss what happens when a supernova occurs.
In your answer you should refer to:
•
•
•
•
original star type and size
steps that lead to the supernova
explanation of the appearance of supernova
what happens during and after a supernova.
You may wish to use a labelled diagram in your answer.
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QUESTION
NUMBER
Extra space if required.
Write the question number(s) if applicable.
Science 90764, 2011
ASSESSOR’S
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90764