stellar evolution

Question 1

Stars hotness to coldness

Answer 1

Blue white—>yellow red

Question 2

What is absolute magnitude

Answer 2

• enables us to compare brightness of stars, same distance from earth

Question 3

Stellar evolution (up to main sequence)

Answer 3

Stellar evolution (up to main sequence)
1. Cloud of dust and gas called a nebula
2. gravitational force pulls the dust and gas together to form a protostar.
→ Temperature high enough H nuclei undergoes nuclear fusion.
→ Lots of energy out, keeps star hot. Star is born
3. Enters a long stable period called a main seq. star. Outward pressure due to thermal expansion balances gravitational force.
4. H nuclei in core runs out, gravitational force larger than thermal expansion. Star is compressed. Outer layers extremely hot. Then the Star expands, becomes red giant

Question 4

Stars similar to the sun

Answer 4

• becomes unstable and ejects its outer layer of dust and gas. Only dense solid core- WHITE DWARF.

Question 5

Stars much bigger than our sun

Answer 5

• bigger stars undergo more fusion. Expand and contract several times. They become red supergiants. Eventually they explode in a supernova
• Either: throws outer nebula, becomes neutron star
• Or: if massive enough, collapses into a black hole

Question 6

Hertzsprung

Answer 6

- remember: 
→ diagonally curved line in middle is main sequence
→ supergiants at the top
→ under is giants
→ bottom left is white dwarfs