8.1.2 - The Life Cycle of a Star

What type of reactions take place at the start of a star’s life cycle as dust and gas is drawn together?

Fusion reactions.

What factor determines the type of lifecycle a star undergoes?

The size of the star.

Which two phases do all stars of the same or greater size than the sun undergo?

1. Protostar phase.

2. Main sequence phase.

What do stars of a similar magnitude to the sun become at the end of their life-cycle?

A black dwarf.

What two things can stars much bigger than the sun become at the end of their lifecycle?

1. Neutron star.

2. Black hole.

What two phases do stars of similar size to the sun go through between being a main sequence star and a black dwarf?

1. Red giant.

2. White dwarf.

What two phases do stars of greater size than the sun go through between being a main sequence star and a neutron star/black hole?

1. Red super giant.

2. Supernova.

What are produced during the fusion processes in a star?

All of the naturally occurring elements.

What condition is required for fusion reactions to occur in a star?

Very high temperatures.

How are elements heavier than iron produced?

In a supernova.

What type of nuclei fuse together to form heavier elements in a star?

Hydrogen nuclei fuse to form heavier elements.

How are elements distributed throughout the universe?

Through the explosion of a massive star (supernova).