Lives of StarsLives of Stars

88thth Grade Science Grade Science

http://hubblesite.org/gallery/tours/

Lives of StarsLives of Stars1.1. Stars begin as gas Stars begin as gas

and dust called a and dust called a nebula.nebula.

http://hubblesite.org/gallery/tours/tour-carina/http://hubblesite.org/gallery/tours/tour-carina/

2.2. 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 A star’s life depends on its massmass. .

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 Cycle1.1. NebulaNebula2.2. ProtostarProtostar3.3. Main Sequence:Main Sequence: 90% of 90% of

stars. Hydrogen continues stars. Hydrogen continues to burn and fuse to make to burn and fuse to make helium.helium.

http://science.nasa.gov/astrophysics/focus-areas/how-do-stars-form-and-evolve/

* Now the star can take 2 * Now the star can take 2 paths, depending on its size.paths, depending on its size.

Small/Medium

Giant Stars

Main Sequence

MAIN SEQUENCE

Small/Medium

Size Stars

Giant and Supergiant Stars

Become red giants and then a planetary nebula.

Can blow up into Supernovas.

When a white dwarf runs out of energy, it turns into a black dwarf.

The remains of a supernova become a neutron star or a black hole.

Planetary Nebula

Planetary nebulae represent the final brief stage in the life of a medium-sized star like our sun. While consuming the last of the fuel in its core, the dying star expels a large portion of its outer envelope. This material then becomes heated by the radiation from the stellar remnant and radiates, producing glowing clouds of gas that can show complex structures, as the ejection of mass from the star is uneven in both time and direction.

http://www.nasa.gov/mission_pages/hubble/science/ngc5189.html

Explore a planetary nebulahttp://hubblesite.org/gallery/tours/tour-catseye/

Small and Medium Small and Medium StarsStarsThese become giants and thenThese become giants and then

Planetary NebulaPlanetary Nebula – a shell of gas – a shell of gas is ejected from the core of the is ejected from the core of the star.star.

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

The White Dwarfs are circledIn the Hubble Space Telescope image below.

The life of Large The life of Large StarsStars

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.

Super NovaThe explosion of a dying giant or supergiant star

SUPERNOVA explosion

Super Giants:Super Giants:When a Super Giant explodes into a When a Super Giant explodes into a

supernova, it can become 2 things:supernova, it can become 2 things:

1. 1. Neutron Star:Neutron Star: Smaller and more Smaller and more dense than a white dwarf. They dense than a white dwarf. They have 3 times as much mass as the have 3 times as much mass as the sun, but are about the size of sun, but are about the size of Houston! Houston!

2.2. Black Hole: Black Hole: This object is so This object is so dense, not even light can escape dense, not even light can escape the gravity field. the gravity field. http://imagine.gsfc.nasa.gov/docs/science/know_l2/black_holes.html

PulsarPulsar

A neutron star that A neutron star that produces radio produces radio waves.waves.

Pulsars appear to Pulsars appear to pulse because they pulse because they rotate!rotate!

http://imagine.gsfc.nasa.gov/docs/science/know_l2/pulsars.html

Nebula Nebula ProtostarProtostar Main Main SequenceSequence

Giant Giant or or SupergiantSupergiant

White DwarfWhite Dwarf SupernovaSupernova

Neutron StarNeutron Star Black DwarfBlack Dwarf OROR

Black HoleBlack Hole

The life cycle of a low mass The life cycle of a low mass star (left oval) and a high mass star (left oval) and a high mass

star (right oval).star (right oval).

http://www.enchantedlearning.com/subjects/astronomy/stars/lifecycle/

Binary Star Binary Star SystemsSystems

A star system with two A star system with two stars.stars.

Stars that revolve around Stars that revolve around each other. 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 and is called a dust and is called a a. Protostara. Protostarb. Nebulab. Nebulac. White dwarfc. White dwarfd. Supernova d. Supernova

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

a. Protostara. Protostar

b. White Dwarfb. White Dwarf

c. Main Sequencec. Main Sequence

d. Neutron Stard. Neutron Star

3. The life of a star depends 3. The life of a star depends on itson its

a. Colora. Color

b. Place in the universeb. Place in the universe

c. Massc. Massd. Temperatured. Temperature

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

a. Truea. True

b. Falseb. False

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

a. Truea. True

b. Falseb. False

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

a. Supernovaa. Supernova

b. Main Sequenceb. Main Sequence

c. Black Holec. Black Hole

d. Nebulad. Nebula

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

a. Protostara. Protostar

b. Neutron Starb. Neutron Star

c. Main Sequencec. Main Sequence

d. Black Holed. Black Hole

8. The most common 8. The most common chemical element in a star ischemical element in a star is

A. HeliumA. Helium

B. HydrogenB. Hydrogen

C. CarbonC. Carbon

D. SodiumD. Sodium

9. The sun formed out of a 9. The sun formed out of a

A. PulsarA. Pulsar

B. Supergiant starB. Supergiant star

C. White DwarfC. White Dwarf

D. NebulaD. Nebula

10. Compared to Rigel, Alpha 10. Compared to Rigel, Alpha Centauri B isCentauri B is

A.A. Cooler and Cooler and brighterbrighter

B.B. Cooler and Cooler and dimmerdimmer

C.C. Hotter and Hotter and brighterbrighter

D.D. Hotter and Hotter and dimmerdimmer