Lives of Stars

Lives of Stars

Chapter 17 Section 4

Pages 583-589

Chapter 17 Section 4

Pages 583-589

Life Cycle of Stars

• 1. Nebula- A star nursery (gases and dust)– Gravity pulls gas and dust

together.

• 2. Protostar (earliest)– Star is born when nuclear

fusion starts. (combining hydrogen into Helium. Releases large amounts of energy.

Birth of a Star

• Determined By Mass!1.Large Stars- Short lives (10 million)

2.Medium Stars- (10 billion)1. The sun 4.6 Billion Years old

3.Small Stars- Long Lives (200 billion)

Life Time of Stars

1.Occurs when a star begins to run out of fuel.

2.All stars become a giant or a super giant depending on their mass.

3.The final fate of a star is determined by mass.

Death of Stars

• Small Medium Stars

• Were once red giants that lost their atmosphere

• A glowing white core remains– About the size of Earth– 1 million times denser than the

sun

• When it stops glowing, it’s dead, becomes a black dwarf.

White Dwarfs

• When a giant or supergiant star suddenly explodes.

• Must be a massive star.

• Gases expelled can become a new star.

Super Nova

• Left by a Supernova.

• When a giant or super giant star explodes.

• Smaller than white dwarfs

• Extremely Dense

• Pulsar- spinning neutron stars that give off radio waves.

Neutron Stars

• Occurs after the most massive stars explode.

• Gravity PULLS gasses into a small place.

• Gravity becomes so great that nothing not even light can escape.

Black Hole

• Very bright objects, but far away. 12 billion light years

• Very distant galaxies with very massive black holes in the center.

• The gases around the black hole heat up and shine brightly.

Quasars