Stellar Evolution

Question 1

What are the hottest and coldest stars?

Answer 1

Red stars are the coldest and blue stars are the hottest

Question 2

Describe how a main sequence star is formed

Answer 2

1) All stars are initially a giant cloud of dust and gas called a nebula
2) Forces of gravity within a nebula pull the gas together to form a protostar
3) As the protostar heats up it will undergo nuclear reactions in the core, forming a main sequence star

Question 3

Describe the lifecycle of a low mass star after the main sequence

Answer 3

1) The main sequence star eventually reaches a state where the hydrogen in the core runs out, causing the outer layers to swell up and expand, and a red giant to be formed
2) The core would then collapse completely and leave behind a white dwarf

Question 4

Describe the lifecycle of a high mass star after the main sequence

Answer 4

1) When the hydrogen gas in the core runs out it causes the outer layers of the star to swell up and expand. This causes a red supergiant to be formed.
2) When the core of the star collapses a huge explosion occurs leaving behind a supernova.
3) At the centre of the explosion a neutron star would be left behind and if the star is big enough the centre of the star would continue to collapse until it leaves behind a black hole

Question 5

How does the brightness of a star affect the magnitude?

Answer 5

The brighter the star, the smaller the magnitude

Question 6

What is absolute magnitude?

Answer 6

The absolute magnitude of stars is a measure of how bright they would be if they were all the same distance away from us