stellar evolution. ngc 3603 bok globules and giant gaseous pillars (evidence of embryonic stars),...
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Stellar EvolutionStellar Evolution
Stellar EvolutionNGC 3603
Bok globules and giant gaseous pillars (evidence of embryonic stars),
circumstellar disks around young stars
progressing to aging, massive stars in a young starburst cluster
blue super-giant with its ring and bipolar outflowmarks the end of the life cycle.
STAGE ONESTAGE ONE
Stars begin as a NEBULA - a dark cloud of gas and dust
Made mostly of hydrogen and helium with small amounts of heavier elements
Eagle NebulaM16
Horse Head Nebula Horse Head Nebula
Veil Nebula Trifid Nebula
The nebula begins to contract and gravitational attraction increases
It continues shrinking and starts to spin.
Eventually it forms a flat disk with a PROTOSTAR in the middle
Planetary Disks Forming
STAGE TWO - Main STAGE TWO - Main SequenceSequence
Longest part Energy is produced as fusion take place in
the core of the star The energy from fusion balances the force
of gravity and makes it a very stable stage
Stage ThreeStage Three
Happens when almost all of the hydrogen atoms have fused into helium atoms
The core contracts due to the force of gravity
This increases the temp and causes the helium to fuse into carbon
This gives off a lot of energy and the star swells up to a giant or supergiant star
Stage FourStage Four
Helium fusion ends The star loses its outer
gases and reveals a core
An expanding shell of gases shed by this dying star forms a PLANETARY NEBULA
Ant Nebula
Stingray nebula (Hen-1357), the youngest Stingray nebula (Hen-1357), the youngest known planetary nebula. known planetary nebula.
The "Spirograph" NebulaThe "Spirograph" Nebula
Cat’s Eye Nebula
The star collapses inward and forms a hot dense core of matter called a WHITE DWARF
Some white dwarfs may explode into a NOVA while they are cooling
What about really BIG What about really BIG stars??stars??
Stars with masses 10 -100 times greater than the sun can produce a huge explosion called a SUPERNOVA
SN1987A
What happens after the What happens after the explosion?explosion?
The core may contract into a very small, dense ball of neutrons called a NEUTRON STAR –
If it rotates it is called a PULSAR
Really large stars contract with greater force and become a BLACK HOLE
Centaurus A (Hidden Black Hole)Centaurus A (Hidden Black Hole)
Classifying StarsClassifying Stars
Hertzsprung-Russell (HR) Diagram
Plots temp. v. luminosity
Most stars are main sequence
