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Published byDelphia Carroll Modified over 6 years ago
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The Life of a Star The Life of a Star The Life of a Star
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Interstellar Gas Cloud
General Composition: 71% Hydrogen, 27% Helium, & 2% other How does a cloud start forming a star? Low temperature = low pressure (pushing out) Leads to gravity being able to collapse the cloud into smaller, warmer, dense clumps
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Protostar Stage Clumps to Baby star?
As the gas gets pulled in by gravity, a large flat disk with a dense core at the center starts to form Forms in the infrared & radio Form in groups = similar age Protostar Stage
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Mass Determines Temperature
More mass = more gravity = higher pressure = higher temperatures Mass Determines Temperature
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A star’s life is determined by how much mass it has
Low mass stars = under 10 solar masses High mass stars = over 10 solar masses 1 solar mass = 1 sun Mass is Key
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Structure of High vs. Low Mass Stars
Triple Alpha Process: H He High Mass Stars CNO cycle: Passes the triple alpha process and moves on to heavier elements like CNO Structure of High vs. Low Mass Stars
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You need: 1 cup with 6 marshmallows, a napkin, and 5 pasta noodles
Fusion Demo!
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What is that? Nucleosynthesis: formation of heavy elements by nuclear burning process As temperature increases in the core, heavier elements are fused forming layers of elements Iron – 1 billion K Nucleosynthesis
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Pressure from the formation of new elements presses out while gravity is pushing in
Once gravity wins the star dies Gravity is everything Importance of Gravity
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Once the protostar (baby star) develops H & He fuse forming a main sequence star (yellow dwarf) – like our sun Once most of the H is fused – gravity wins – the star contracts (gets smaller), increasing the temperature, allowing the star to fuse more He – increasing the pressure – making the star expand to a much larger, cooler size – a red giant Once that He is used – fuel runs out – star dissolves into space forming a planetary nebula This leaves behind the bare core – a white dwarf Low Mass Stars
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Once the protostar (baby star) develops H, He, and heavier elements fuse forming a giant star
Once most of the elements are fused – gravity wins – the star contracts (gets smaller), increasing the temperature, allowing the star to fuse even heavier elements – increasing the pressure – making the star expand to a much larger, cooler size – a red super giant Once that fuel runs out – gravity causes the star to collapse on its iron core causing a supernova – leaving behind either a black hole or a neutron star High Mass Star
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Under 10 solar masses Over 10 solar masses
Importance of Gravity Over 10 solar masses
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