Life Cycles of Stars

Life Cycles of Stars

THE MAIN FACTOR THAT DETERMINES THE LIFE CYCLE (PATH A STAR WILL

TAKE) IS THE STAR’S

MASS

STAGE 1: FOR ALL STARS NO MATTER WHAT THEIR MASS

Protostars

Protostars All stars form in

nebulas huge clouds of gas (hydrogen) in which stars are made.

Nebula are 1000’s of times bigger than our solar system

As part of the nebula the clouds collapses stars are “born: in them

Pillars of Creation

STAGE 2: FOR ALL STARS NO MATTER WHAT THEIR MASS

Main Sequence Phase

Main Sequence Star Main Sequence

is the longest phase of all stars life

How long a star remains in Main Sequence depends on its MASS.

Our sun is about half way through it’s main sequence of about 10 billion years

Main Sequence & Nuclear Fusion

Nuclear fusion –changes one element into another (one kind of atom into another) this gives off energy in the form of HEAT and LIGHT

A protostar will not enter main sequence if it does not have enough mass and will become a brown dwarf

A proto star must have enough mass, and pressure to begin main sequence and be called a Star

STAGE 3: FOR ALL STARS NO MATTER WHAT THEIR MASSRed Giant Phase or for those very large stars Super Massive Red Giants

Red Giant As the star changes

all of it’s hydrogen into helium the outer layers of the star will become cooler

The layers will expand.

For our Solar System Mercury and Venus will most likely be engulfed with Earth very close to the sun so all living things will be gone.

STAGE 4: FOR LOW/MEDIUM MASS STARS LIKE THE SUN

Planetary Nebula

The end of step 3 – Planetary Nebula

Planetary Nebula

Starts the “Death” of a star like our Sun

Outer layers are expelled by solar winds

Returning materials to interstellar space

STAGE 5: LOW/MEDIUM MASS STARS LIKE SUN

White Dwarf –

White Dwarf

Gravity will cause the red giant to collapse

The star is now much cooler and it collapses into a small white star

It still has the same original mass

STAGE 6: FOR LOW MASS STARS LIKE THE SUNBlack Dwarf

Black Dwarf

The star cools more and more

Eventually it will become a black mass emitting no light

It will then spend the rest of eternity drifting silently through space

STARS AT LEAST 6 X’S BIGGER THAN OUR SUN!

At least six solar masses bigger than our Sun

STAGE 3:FOR GIANT/MASSIVE AND SUPER GIANT/SUPER MASSIVE STARS

Red Supergiant

Super Red Giant

This is the same as with the low mass stars however more elements are changed in the stars core hydrogen to helium, helium to carbon, carbon to iron

STAGE 4:GIANT/MASSIVE AND SUPER GIANT/SUPER MASSIVE STARS

Super Nova

Supernova!

The largest and most powerful explosions in the universe.

The red super giants literally blow themselves apart!

Supernova

All the atoms we are made from came originally from these giant supernova explosions.

STAGE 5: FOR GIANT/MASSIVE STARS

Neutron star

Neutron Star Giant stars at least

6 solar masses ( They are compact

objects that are created in the cores of massive star during supernova The core of the star collapses, and crushes and leaves only the neutrons

STAGE 5: FOR SUPER GIANT/SUPER MASSIVE STAR

Black hole

Black hole

After the supernova a huge mass is left behind.

Formed by stars that are 8 X’s or larger stellar masses than the Sun

Black holes can suck in nearby stars and solar systems.

Hertzsprung-Russell Diagram compares properties of stars

Observe the life stages of stars from birth to death