4.2 stars have life cycles
DESCRIPTION
Presented on Monday November 23rd. This follows the textbook- Chapter 4 Section 4.3TRANSCRIPT
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STARS CHANGED OVER THEIR LIFE CYCLES
Space Science:Chapter 4: Section 4.2
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Let’s Begin
Why do stars look like small points of light?
Why don’t they look like in the sky?
Stars are very far away. We only see a few thousand of stars that exist.
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What unit of measurement do we use to measure the distance between stars?
Light-years The distance light travels in one year
Approximately 6 trillion miles
The closest star to Earth is our Sun
The next closest star is 4 light years away
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How do we measure how far stars are away from Earth?
Using parallax The apparent shift in the position of an object when viewed from different locations
Parallax Demonstrations
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Size: the Sun’s diameter is 100x greater than Earth’s
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Some stars are much larger than the Sun. Giant and Super giants are 10-100’s of times larger.
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Betelgeuse: 600 times greater than the Sun
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There are stars much smaller than the Sun as well. These are called white dwarfs.
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What color are the stars we see?
Most stars are white Some appear red Some appear blue
Why is that? Differences in color are due to differences in temperature
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Think of:
The metal coils inside of a toaster
Start off as a dull red Later turn a bright orange
Temperature affects color by heating up the metal
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Stars have life cycles:Length of the cycle and the way a star changes depends on the mass of the star
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Nebula:
All stars form inside a cloud of gas and dust called a nebula
Gravity pulls the dust closer together
The matter contracts and forms a hot dense sphere
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Main Sequence:
Fusion begins if the matter gains enough temperature and density
The birth of main sequence stars
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Low-Mass Stars:
Once fusion begins the star is then classified as a main sequence star Low-mass stars use their fuel slowly Remain in this stage for billions of years
As low-mass stars run out of fuel it expands into a giant star
Once the giant sheds it outer layer it leaves behind a dead core called a white dwarf
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High-Mass Stars:
Once fusion begins the star is then classified as a main sequence star High-mass stars use their fuel quickly Remain in this stage for millions of years
As high- mass stars run out of fuel it expands into a super giant
The super giant explodes when no more fusion can occur- called a supernova
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High-Mass Stars: After supernova May form a dense
body called a neutron star Star squeezes itself
smaller Very DENSE- Example:
pea size sample weighs 100 million tons
Gravitational force collapses atoms
Electrons combined with protons to produce neutrons
May form a black hole More dense than
neutron star Intense surface
gravity lets no light escape
As matter is pulled into the black hole it becomes very hot and emits x-rays
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The Sun is what type of star? Low-Mass Main Sequence Star
What is going to happen to the Sun? Eventually expand into a Red Giant Cool down into a white dwarf Scientist predict that in 4.5 billions years
the Sun will run out of fuel and will form a Red Giant
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