Chapter 16 - Space Flashcards
What is a vacuum?
A vacuum is emptiness, a place of no matter
What is a nebula?
A giant cloud of dust and gas
What force brings the dust and gas in a nebula together? What forms in the centre?
Gravity
A protostar is formed
In the protostar phase of the Sun, is the Sun hot enough for nuclear fusion?
No, but it can evaporate ice and push gas away, which leaves rocks behind.
These rocks begin to pull together under gravity, which forms planets.
Gas further out form planets too.
Where did the energy come from that became the protostar’s thermal energy?
As the dust and gas pulls together, it loses GPE, which becomes kinetic energy, which becomes the thermal energy in the star
What happens when the temperature rises in the protostar phase?
Nuclear fusion happens (the star fuses its hydrogen into helium)
What is the phase after the protostar?
Main sequence star
How many kilograms of hydrogen are there on the Sun?
2x10^30 kg
How does a star maintain stability?
The force of gravity counteracts the force of the radiation pressure that is pushing the sun outwards, which makes it stable and able to maintain nuclear fusion for billions of years
When will the main sequence star phase end?
When the star runs out of fuel (hydrogen)
What happens to a main sequence star when it runs out of fuel?
The star begins to swell and cool
At this stage, heavier elements are being fused
This stage is called a red giant
What happens when a red giant runs out of elements it can fuse together?
Due to fusion stopping and no more radiation is released, it will collapse under its own gravity
What happens when a red giant collapses under its own gravity?
It begins to heat again.
It becomes white hot
What is the stage after the red giant?
White dwarf
What happens after a white dwarf?
The small hot dense star gradually cools down, fading and becoming a black dwarf
