Life Cycle of Stars

by Cheyenne Eldridge

Interstellar Medium

Material that fills space between stars

Gas and Dust

Betweens the stars

First Stage of Star Life Cycle

hydrogen (97%) and helium (3%)

Nebula is a cloud of dust and gas. There are a bunch of different regions that use gravity to make little “clumps” of gas and dust. Those little clump things are called proto-stars.

Equilibrium Established

“a state in which opposing forces or influences

are balanced.”

Gravity and Gas Pressure

Nuclear Energy and Gravity


Gas Pressure

Birth of a Star

Nuclear Fusion

The process in which a protostar releases thermal energy, photons, supports the star, and stops contraction

When a protostar builds up enough mass to achieve a critical temperature

protostar+heat=nuclear fusion

nuclear fusion-(thermal energy x photons)= star

Second Phase of Life Cycle

Main Sequence Phase

Hydrogen and Helium

Star radiates energy into space

Size of the star

Hydrogen fuel runs out, so the star has to start burning helium in order to maintain stability

Third Phase of Life Cycle

Red Giant

Helium and Hydrogen

Star expands and core contracts due to gravity, and temperature increases until nuclear fusion is possible again (burning helium this time instead of hydrogen)

Nuclear Fusion

Temperature increases and size increased, but core shrinks

Final Phase of Star Life Cycle

When it runs out of helium fuel. The star needs to burn helium when it runs out of hydrogen.
The star will either collapse and become a white dwarf and then a black dwarf, or become a
supernova,or become a black hole.
When a blue giant gets very hot and bright and collapses then explodes
A supernova is a big explosion of star stuff
Planetary nebula forms when a star can't support itself with fusion in the core
Planetary nebula is a nebula with a shell made from the gas from old red giants