Notes: 3.5 STAR EVOLUTION Name: ________  Part 3: Re-read the highlighted information in your notes. Construct quiz questions using this information. Write the questions next to the paragraph where the answers can be found.  

Part 1: Fill in the blanks during the class discussion. Star Evolution Background

Ø “Evolve” or “Evolution” means to CHANGE. Ø All stars change into different STAGES or phases throughout their

life. Ø What a star ends as depends on its MASS. Ø A low mass star will evolve DIFFERENTLY than a high mass star.

Stages of Star Evolution 1. Nebula:

The BIRTH of a star. Ø A nebula is CLOUD of dust and gas

that is not a star yet. Ø HYDROGEN is most common

gases in a nebula. Ø A nebula is also called a “Stellar

NURSERY”. 2. Protostar: The material in a nebula CONDENSES and the star starts to come together.

Ø CONDENSE means the gases that will form the star begin to collect in the middle.

Ø The bright spots in Nebulas are PROTOSTARS will eventually become STARS.

3. Main Sequence star: Ø This is the stage where the star “

SWITCHES ON”. Ø The gravity in the core of the star is

enough that FUSION begins. Ø Fusion powers the star and turns the

HYDROGEN gas into HELIUM. Ø The equation for fusion is: H1 + H1=

He2 + ENERGY.

Unit    3.5      Star  Evolution    

Nebula  (the  cloud)  

Protostars  (bright  spots)    

4. Giant/SuperGiant Star: Ø Happens when the star runs out of HYDROGEN FUEL. Ø The star INCREASES in size Ø Small to average size stars become GIANT stars Ø Large Mass stars become SUPERGIANT.

5. Star Destruction-Planetary Nebula OR Supernova Once the star runs out of fuel for good it will be destroyed.

Ø A PLANETARY NEBULA is when a Giant star begins to fall apart and the outer layer of gas float out into space.

Ø A supernova is big EXPLOSION that happens when a Supergiant runs out of fuel

6. End of Stars Life. (White Dwarf, Neutron Star, or Black Hole Depending on its MASS a star will end its life as one of three things.

Ø White Dwarf: what SMALL or AVERAGE stars end as. • White Dwarf stars are SMALL, and DIM,

but hot.

Ø Neutron Stars. what MEDIUM LARGE stars end as. • Neutron stars emit RADIO WAVES instead of light.

Ø Black Holes: what the VERY LARGEST

stars end as. • Black holes have so much

GRAVITY that LIGHT cannot escape.

• Black holes may be located in the center of THE GALAXIES and may even hold the galaxies together.

• We could never travel to a black hole because of the distance, but if we could it IS possible it may be a path to another UNIVERSE.

The Life Cycle of our Sun

Ø The sun is currently 4.6 BY old. Ø At 10 BY of age, our sun will become a RED GIANT. Ø Our sun will end its life as a WHITE DWARF after 13 BY.

Part 2. Re-read your notes. Highlight the most important information