Lives of Stars

Lives of StarsLives of StarsStars begin as gas and Stars begin as gas and dust called a dust called a nebula.nebula. Gravity pulls the gas Gravity pulls the gas

and dust in and fusion and dust in and fusion begins. This forms a begins. This forms a

ProtostarProtostar or ‘new star’ or ‘new star’

Protostar

Lifetimes of StarsLifetimes of StarsA star’s life depends on its mass. A star’s life depends on its mass. Stars smaller than the sun live up Stars smaller than the sun live up

to 200 billion years.to 200 billion years.Medium sized stars like the sun Medium sized stars like the sun

live around 10 billion years.live around 10 billion years.Stars 15 times more massive Stars 15 times more massive

than the sun live about 10 million than the sun live about 10 million years.years.

Star Life CycleStar Life CycleNebulaNebulaProtostarProtostarMain Sequence:Main Sequence: 90% 90% of stars. Hydrogen of stars. Hydrogen continues to burn and continues to burn and fuse to make helium.fuse to make helium.

MAIN SEQUENCE

Giant/Super Giant:Giant/Super Giant: The The star begins to run out of star begins to run out of fuel. The star expands.fuel. The star expands.

Supernova:Supernova: Massive Massive stars can blow up to an stars can blow up to an enormous size.enormous size.

mass

RED GIANT

Small and Medium Small and Medium StarsStarsThese become giants and then These become giants and then

White Dwarfs:White Dwarfs: blue-white core blue-white core of a star that is left behind.of a star that is left behind.

These have no fuel, but glow These have no fuel, but glow faintly from left over energy. faintly from left over energy.

When a white dwarf burns out, When a white dwarf burns out, it is dead. Then it is a it is dead. Then it is a Black Black Dwarf.Dwarf.

fusion

WHITE DWARF

PULSAR

Super Giants:Super Giants:When a Super Giant explodes When a Super Giant explodes into a supernova, it can into a supernova, it can become 2 things:become 2 things:A. A. Neutron Star:Neutron Star: Smaller and Smaller and more dense than a white more dense than a white dwarf. They have 3 times as dwarf. They have 3 times as much mass as the sun, but much mass as the sun, but are about the size of are about the size of Houston! Houston!

Black Hole:Black Hole: This object is so This object is so dense, not even light can dense, not even light can escape the gravity field.escape the gravity field.

Super NovaSUPERNOVA explosion

: BLACK HOLE

http://chandra.harvard.edu/photo/2004/rxj1242/index.html

Nebula Nebula ProtostarProtostar Main SequenceMain Sequence

Giant Giant or or SupergiantSupergiant

White DwarfWhite Dwarf SupernovaSupernova

Neutron StarNeutron Star Black DwarfBlack Dwarf

OROR

Black HoleBlack Hole

Binary Star Binary Star SystemsSystems

Stars that revolve Stars that revolve around each other. around each other.

Sometimes this causes Sometimes this causes stars to appear as if they stars to appear as if they are blinkingare blinking

Let’s Review!Let’s Review!

1. All stars begin as gas and 1. All stars begin as gas and dust calleddust called

a.a. ProtostarProtostarb.b. NebulaNebulac.c. White dwarfWhite dwarf

2. Most stars are in this 2. Most stars are in this stagestage

a. Protostara. Protostarb. White Dwarfb. White Dwarfc. Main Sequencec. Main Sequence

3. The life of a star depends 3. The life of a star depends on itson itsa. Colora. Colorb. Place in the universeb. Place in the universec. Massc. Mass

4. If the star is super 4. If the star is super massive, it will live massive, it will live longer.longer.

a. Truea. Trueb. Falseb. False

5. Low mass stars will 5. Low mass stars will become black holesbecome black holes

a. Truea. Trueb. Falseb. False

6. An object so dense, not 6. An object so dense, not even light can escape.even light can escape.

a. Supernovaa. Supernovab. Main Sequenceb. Main Sequencec. Black Holec. Black Holed. Nebulad. Nebula

7. A new star where fusion 7. A new star where fusion begins.begins.

a. Protostara. Protostarb. Neutron Starb. Neutron Starc. Main Sequencec. Main Sequence