Download Stars - Haag

Stars
Chapter 2 Section 1
What does the color of a star tell you?
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The color of a star will tell you it’s temperature
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Colors such as red and
yellow = cooler temperature
stars
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Blue and white stars = hotter temperature stars
All stars are different, but how are they classified?
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Stars are classified by brightness and
temperature.
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Stars are classified in order of highest to lowest
temperatures.(OBAFGKM)
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hottest stars being classified as O
coolest stars being classified as M.
Star’s are also classified according to their
brightness.
Luminosity is the amount of energy emitted
by a star each second
How do we tell what stars are made of?
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Each star is made up of specific gases.
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Astronomers can tell what elements a star is made
up of by observing the light given off.
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The inner layers of a star are very dense and hot.
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The outer layers are made up of cool gases.
How do they observe the light?
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Astronomers use a tool called a spectrograph,
which breaks down light into its different
wavelengths.
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The different wavelengths create what is called
a spectrum.
How do different elements look?
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If you look at gases such as: nitrogen, oxygen,
hydrogen…. through a spectrograph it will
create emission lines.
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Gases only give off certain colors of light or
certain wavelengths, these are emission lines.
Why don’t stars give off bright line emissions?
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The cool atmosphere of a star absorbs certain
colors of light or wavelengths.
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This creates dark line emissions.
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These types of spectrums are known as
absorption spectrums.
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They help scientists to identify the elements that
make up a star’s atmosphere
Spectroscope Lab
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Fluorescent light
krypton
Sunlight
Neon
Helium
Nitrogen
How do we determine the brightness of a star?
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The brightness of stars from earth is known as its
apparent magnitude. This depends on size and
energy output
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This is not it’s true brightness
In order to find a star’s absolute magnitude
(how bright it actually is) astronomers use the
star’s apparent magnitude and it’s distance from
earth.
Distances and Motion of Stars.

Distance can be measured in either light years or
Kilometers.
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In order to determine this number astronomers
use a star’s parallax and simple trigonometry.
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Parallax is the apparent shift of a star’s
position when viewed at different locations.
The North star is
431 light years
away
Motion of Stars

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Star’s seem to move at night due to the
rotation of earth on it’s axis.
Know as a stars Apparent Motion
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Because of this all the stars appear to rotate around
Polaris (North Star)
Star Trails
Orion star
trails
Big Dipper
star trails
Orion star
trails
North Pole
star trails
Apparent motion
But stars actually do move in space, this can
be seen by the movement of stars over a
time period of thousands of years.
 This is called Actual Motion
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Actual Motion
Focus Questions
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How is color related to star temperature?
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What produces an absorption spectrum?
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Explain two ways in which stars are classified.
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What the difference between apparent magnitude and
absolute magnitude?
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Why do stars seem to revolve around Polaris?
Doppler effect- as a car
approaches it sounds higher in
frequency (pitch). The same thing
occurs with light.
Moving Away - redshift
Moving Towards - blueshift
Doppler Effect