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The “Life” of Non-living
Stars
By Erin Belluomini
Why do stars look different colors in
the night sky?
Stars are different colors
 Colors indicates the temperature of the
star
 Red stars are the coolest
 Blue stars are the hottest
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Fascinating Examples
Orion is a well-known winter constellation
 Orion contains a large red star known as
Betelgeuse
 Orion also contains a blue star known as
Rigel
 Betelgeuse and Rigel differ in their
temperatures too
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From what elements are stars
created?
Studying light from a star can tell us what
elements are in stars
 A continuous spectrum shows all the
colors when white light passes through a
prism
 Elements emitted from stars do not show
all the colors of the spectrum
 The colors that get absorbed tell scientists
from what elements the star is made

Common Elements of Stars
Hydrogen and Helium are the most
abundant elements in stars
 Stars contain other trace elements
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Carbon, nitrogen and oxygen are the most
common
How do scientists classify stars?
Originally stars were classified by the
elements they contained
 Astronomers created system based on
brightness…absolute magnitude
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Positive #s are dim, negative #s are bright
Stars are classified by temperature
Why do we see different constellations
throughout the year?
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Earth revolves around sun
Earth’s tilt and revolution cause season’s
Earth faces a different part of sky each season
A different constellation is seen at different times
of the year
Motion of and Distance to Stars
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Stars closer to Earth seem to move
Stars further away seem to stay in one place
Known as parallax
Parallax used to calculate actual distances to
stars
Distance measured in light-years
A light-year is the distance light travels in one
year….very fast!
Our Sun’s Color and Classification
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Our sun is Earth’s closest star
Our sun’s color is yellow
Our sun’s temperature is 6000 C
Hydrogen, Helium, Calcium and other
heavier elements make up our sun
• Our sun is a class G star
• Our sun is about +4.8 in absolute
magnitude
Do stars “live” forever?
Stars do not live forever
 Stars can exist for billions of years
 Stars get different classifications as they
age
 To stay alive, stars must generate energy
through nuclear fusion

Nuclear Fusion
How the sun generates energy
 Process where two hydrogen nuclei fuse
to form helium
 The beginning of a stars life
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Click to view
video clip!
The Life Cycle of Stars
Stars begin life as a ball of gas and dust
 Temperatures reach 10,000,000 C
 Nuclear Fusion begins
 This stage known as a Protostar
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Main Sequence

Main Sequence is the second and longest
stage of a star’s life
Hydrogen continues to fuse into helium
 Size of star changes very little during this
stage

Giants and Supergiants
Giants and Supergiants result when a star
uses all the hydrogen in its core
 Star grows very large and cools

The H-R Diagram
• An H-R Diagram
Shows relationship between surface
temperature and absolute magnitude
Massive Stars
• Use their hydrogen much more
quickly than stars like our sun.
• Generate more energy but have
shorter lives.
• Meet dramatic deaths as
Supernova explosions!
• Become neutron stars, pulsars
and maybe black holes.
Our Sun’s Age
• Our Sun was born from a solar nebula.
• Our Sun is about half way through it’s life
cycle.
• Our Sun will not live forever!
• How will our Sun die?
The Click of
Death
Why We Study Stars
The structure and composition of the
universe can be learned by studying stars
and galaxies and their evolution.
 Understanding the properties of stars
provides us with an understanding of our
sun, which is a star!
 The properties of the sun affect Earth
directly, so it is important to know them.
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Fun Facts
• The brightest star discovered is at least
150 times as large and probably 40 million
times as bright as our sun! (Break out
those sunglasses)!
• Sir Isaac Newton was the first to discover
that white light is composed of different
colors!
Comprehension Question
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1) What are the two elements that commonly
make up stars?
a) Hydrogen (H) and Oxygen (O)
b) Hydrogen (H) and Helium (He)
c) Helium (He) and Nitrogen (N)
d) Hydrogen (H) and Nitrogen (N)
Correct!
b) Hydrogen and Helium are the most
common and abundant elements in
stars!
Congratulations you are a Sun God or
Goddess!
Incorrect!
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Try again! Remember that stars undergo
nuclear fusion which means one element
fuses to become another! Much energy
is released in the process!
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Hint: What two elements are close
enough to each other on the periodic
table to be able to undergo nuclear
fusion.
Comprehension Question
2) What will be the next stage of our sun’s life
cycle?
a)
b)
c)
d)
A white dwarf
A pulsar
A red giant
A protostar
Correct Again!
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Our star will become a red giant once all
of it’s hydrogen in its core is used, its
helium has begun to fuse and the center
of the star shrinks. The Sun will grow
very large and will cool down!
You are definitely a “STAR” student!
Incorrect!
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Remember that currently our star is a
main-sequence, average size, yellow
star!
Works Cited
My vacation
• Look at this sunset!