Lifecycle Of A Star Flashcards
What is a protostar?
> cloud of dust and gas ( hydrogen and helium) that is slowly coming together with increasing gravity
How does a protostar develop into a main sequence star?
The dust and gas gradually gains gravity
> some gravity is converted to heat energy, when the temperature is high enough, H will begin to fuse into He, releasing vast amounts of heat and light.
- a star is born
What happens in a main sequence star?
> the outward pressure caused by the nuclear fusion is equal to the inward forces of gravity. The star enters a long stable period
> size is maintained.
How is a red giant formed?
> eventually the H runs out, the star begins to form heavier elements such as iron
> swells into a red giant
How is planetary nebula formed?
The unstable red giant ejects its outer layer of dust and gas, forming a planetary nebula.
Why is the red giant red?
> because the outer surface is beginning to cool.
How is the white dwarf formed?
> after the red giant ejects its outer layer as a planetary nebula, a dense white hot solid core is left
-this is the white dwarf.
What does the white dwarf form when it cools?
A black dwarf.
What it the life cycle of a small star?
> protostar
> main sequence star
> red giant
-planetary nebula
> white dwarf
> black dwarf
What is the lifecycle of a star larger than the sun?
> planetary nebula
> main sequence star
> red super giant
> supernova
> neutron star/ black hole
How are elements heavier than iron produced?
> a red supergiant undergoes more fusion, expanding and contracting to form elements as heavy as iron
> eventually they explode, forming elements heavier than iron, and ejecting them into the universe.
Describe the formation of a supernova.
> the red supergiant undergoes fusion again, expanding and contracting to produce elements as heavy as iron.
> eventually it explodes with vast amounts of heat and light energy, releasing elements as heavy as gold into the universe.
How is a neutron star formed?
The supernova ejects layers of dust and gas until all that remains is a very dense core= neutron star.
