Term
| Dust + gas are drawn together by what? |
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Definition
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Term
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Definition
| Cloud of gas or dust in space |
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Term
| What did Hubble discover? |
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Definition
That the 'Big Bang' was the beginning of the universe.
14,000 million years ago |
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Term
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Definition
The speed at which a galaxy moves away from us is proportional to its distance from us.
With increasing distance, the speed increases.
Proves that the universe is expanding |
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Term
| What causes the clouds of gas and dust to form a protostar (shining)? |
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Definition
| As it gets denser, it gets hotter, then it has enough energy to start nuclear fusion and emit radiation which is the shining part of the star |
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Term
| What do nebula mainly contain? |
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Definition
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Term
| Why does fusion stop at Fe? |
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Definition
| Because the energy taken to fuse the Fe is greater than the energy released |
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Term
| How are elements larger than Fe formed? |
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Definition
| Supernova (lots of heat produced in the supernova providing the energy to fuse the Fe etc into heavier elements) |
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Term
| What is the evidence that planets like the Earth were formed by a Supernova? |
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Definition
| Heavy elements like Uranium are located in the Earth |
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Term
| What stops the stars from collapsing? |
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Definition
| The gravity compressing the star is balanced by the radiation pressure emitted by nuclear fusion |
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Term
| What determines the length of the life of a star as a protostar? |
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Definition
| Depends on the size of the star, as this will depend how much hydrogen is available to fuse and radiate. |
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Term
| Why is the surface of a red giant red? |
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Definition
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Term
| How does a red giant form? |
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Definition
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Term
| How is a white dwarf formed? |
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Definition
| The (small) red giant loses some of it's gas into space, and the core contracts, gets brighter again. |
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Term
| Give three properties of a white dwarf |
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Definition
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Term
| How is a black dwarf formed? |
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Definition
| White dwarf cools down as it loses enegry called "dark matter" |
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Term
| Why does a supernova occur? |
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Definition
| A (large) red giant becomes highly unstable at the end of it's red giant phase. Contracts rapidly. Violent explosion. |
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Term
| How is a neutron star formed? |
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Definition
| The core of a star is condensed into the very dense. Core made of many neutrons squashed together. |
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Term
| What causes a neutron star to form a black hole? |
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Definition
As it's very dense it has a high gravity
if the core is very big then the gravity becomes too great for the star, and it becomes infinitely squished.
Now so small it hardly exists, gravity so large not even light can escape it. |
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Term
| Name the different stages of the cycle of a star. |
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Definition
Nebula - protostar - red giant
/ \
white dwarf supernova
/ \
black dwarf neutron star |
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