Stellar evolution

Question 1

State life cycle of a star with same mass as the sun

Answer 1

Nebula
Protostar
Main sequence
Red giant
White dwarf

Question 2

State life cycle of a star with larger mass than sun

Answer 2

Nebula
Protostar
Main sequence
Red super giant
Supernova
Neutron star/black hole

Question 3

Describe nebula stage

Answer 3

Stars form a cloud of dust and gas which is eventually pulled together by the force of gravity, forming a protostar

Question 4

Describe protostar stage

Answer 4

Force of gravity within nebula pulls it together. Temperature rises as the star gets denser and more particles collide. When temperature gets high enough hydrogen nuclei undergo nuclear fusion

Question 5

Describe main sequence star stage

Answer 5

Star enters a long stable period as soon as fusion begins. Outward pressure caused by thermal expansion balances force of gravity pulling everything inwards

Question 6

Describe red giant star stage

Answer 6

Hydrogen in core begins to run out and force due to gravity is larger than pressure of thermal expansion. Helium fusion begins. Star is compressed until is is dense and hot enough that the energy created makes the outer layers of the star expand, becoming a red giant (cooler surface)

Question 7

Describe white giant stage (solar mass star)

Answer 7

Becomes unstable, ejecting outer layer of dust and gas, leaving behind a hot, dense solid core, a white dwarf

Question 8

Describe supernova stage (larger than sun)

Answer 8

Start to glow brightly as they undergo more fusion making heavier elements. When fusion reactions can’t continue, core of star collapses and explodes as supernova

Question 9

Describe neutron star/black hole stage (larger than sun)

Answer 9

Supernova throws outer layers of dust and gas into space, leaving dense core (neutron star). If this star is big enough it collapses and forms a black hole.