P16 Space: The Life Cycle of Stars

Stars and their life cycles produce and distribute all naturally occuring elements.

Protostar

• Stars initially form from nebulas, which are clouds of dust and gas. Gravity pulls the dust and gases together to form a protostar.
• As the temperature rises, the star gets denser and more particles collide with each other. The temperature will eventually get high enough that hydrogen nuclei will begin to undergo nuclear fusion, which gives out huge amounts of energy.
• The energy keeps the core of the star hot.

Main Sequence Star

• The star enters a long stable period, which usually lasts several billion years. (Our sun is in the middle of this.)
• The outward pressure caused by the nuclear fusion which tries to expand the star balances with the gravity pulling inwards.

Red Giant

• Eventually the hydrogen begins to run out, so the star swells into…