Astrophysics of Life - The Lives and Deaths of Stars

Solar mass stars cannot squeeze and heat the core

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carbon. Solar mass stars cannot squeeze and heat the core enough to ignite Carbon The increased shell burning causes the outer layers to expand and cool (again) The star moves up the asymptotic branch So what does happen? The Carbon core continues to contract and heat. Shell He burning grows more intense. He flashes occur in the shell. Surface layers pulsate and are finally ejected (slowly, at ~10s of km/s). The hot, tiny core (White Dwarf) is revealed. And a Planetary Nebula appears! (expanding emission line nebula heated by intense radiation from the hot white dwarf) ^ ^ Electron degeneracy pressure || || (up down, up down) Planetary Nebulae have nothing to do with planets
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They emit line radiation (hot gas) but are much smaller than the emission nebulae (HII regions) They are important sources of heavy elements (C, N and O), which will go into the next generation of stars White dwarfs have about ½ the Sun’s mass (the rest was expelled) They are about the size of the Earth! (~0.01 solar radii) Density: ~6600 lbs/cm^3 Very low luminosities, L = 4piR^2 o~ T^4 Electron neutron degeneracy pressure Degeneracy means fitting into the same energy state What eventually happens to a white dwarf? It gets cooler and fainter (at the same radius)
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