Astro 10 10-20

Astro 10 10-20 - reaction the shell Helium fusion rises...

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Astro 101 10-20-08 Death of stars Thermal Pressure: Depends on heat content The main form of pressure in most stars Degeneracy Pressure: Particles can’t be in the same state in same place Doesn’t depend on heat content How does a star’s mass affect nuclear fusion? High mass stars >8M sun Intermediate Low mass <2M sun Brown dwarfs A star remains on the main sequence as long as It can fuse hydrogen into helium in the core When star no longer fuse hydrogen to helium in core, As core contracts, H begins fusing to He in a shell around the core shrinks and heats up Luminosity increases because the core thermostat is broken, the increasing fusion
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Unformatted text preview: reaction the shell Helium fusion rises very sharply when temperature is hot enough. 3 He -> C Helium Flash Thermostat is broken in low-mass red giant because degeneracy pressure supports core Core temperature rises rapidly when he fusion begins He fusion rate skyrockets until thermal pressure takes over and expands core again Helium burning stars neither shrink nor grow because core thermostat is temporarily fixed The red giant shrinks and become less luminous after helium fusion begins He burning stars are found in a horizontal branch on HR diagram...
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