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Life Cycle of a Star. Based on Mass of Star. All Stars – Stage 1-Nebula. Gravity main force, pulls cloud INWARD. Temperature = INCREASES Gravity based on MASS OF CLOUD. Orion’s Nebula. All Stars – Stage 1 - PROTOSTAR. Size DECREASES Mass becomes more DENSE
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Life Cycle of a Star Based on Mass of Star
All Stars – Stage 1-Nebula • Gravity main force, pulls cloud INWARD. • Temperature = INCREASES • Gravity based on MASS OF CLOUD.
All Stars – Stage 1 - PROTOSTAR • Size DECREASES • Mass becomes more DENSE • Temperature hot enough to give off light.
All Stars – Stage 2 – Main Sequence • Nuclear Fusion begins in core. • Heat pushes OUTWARD • Star becomes STABLE • Now a MAIN SEQUENCE STAR
Nuclear Fusion • Hydrogen fuses into Helium in the Core. • 4 H 1 He Creates great heat! E = mc2
Medium Mass Star (Sun)-Stage 3 • Red Giant • Runs out of hydrogen fuel • Fusion occurs in outer shell causing expansion • Outward pressure GREATER than inward pressure. • Sun will expand out to Mars. • Cools and turns Red.
Medium Mass Star – Final Stage • White Dwarf = Hot but Dim • Red Giant core collapses • Inward pressure GREATER than outward pressure • Outer shell escapes into space = Planetary Nebula
White Dwarf with Planetary Nebula Foofing
High Mass Star Stages • First stages the same but more MASSIVE! • Nebula • Protostar • Main sequence
H-R Diagram • Where would High-Mass main sequence stars be?
High Mass Star Stages • Super Giant • Higher heat and mass allows fusion of heavier elements. • H He C O Fe • Outward pressure GREATER than inward pressure • Expands, runs out of fuel and cools = turns Red
High Mass Star – The End • Super Giant runs out of fuel = Core collapses • Inward pressure GREATER than outward pressure • Core collapse triggers EXPLOSION! • Explosion = SUPER NOVA
High Mass Star – The End • Core continues to collapse • Gravitational force HUGE! • Turns into a NEUTRON STAR • Gives off pulsing radio waves (called Pulsar)
High Mass Star – The End • Black Hole • If massive enough: • Continues to collapse into a Black Hole • Inward pressure GREATER than outward pressure • Gravity so great, light cannot travel fast enough to escape them. • Detected by X-rays emitted by things being pulled in.
Life Expectancy of a Star • The Mass of a star determines the length of • it’s life. • More Mass = Higher energy used = shorter life. • Low Mass Star • 100 Billion years • Medium Mass Star (our Sun) • 10 Billion years • High Mass Star • 10 Million years
Solar Nebula Theory • Nebula • Main sequence – accretion disk formed • Collision of particles formed clumps • Clumps formed asteroids • Asteroids became planets • https://www.youtube.com/watch?v=VW9FJb1HkDU (2:04 min)