Astronomy Chapter 13 Vocabulary – Flashcards
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Electron Degeneracy Pressure
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degeneracy pressure exerted by electrons, as in brown dwarfs and white dwarfs
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White dwarf limit
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the maximum possible mass for a white dwarf, which is about 1.4Msun
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Accretion disk
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a rapidly rotating disk of material that gradually falls inward as it orbits a starlike object (e.g. white dwarf, neutron star, or black hole).
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Nova
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The dramatic brightening of a star that lasts for a few weeks and then subsides; it occurs when a burst of hydrogen fusion ignites ina shell on the surface of an accreting white dwarf in a binary star system
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White dwarf supernova
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A supernova that occurs when an accreting white dwarf reaches the white-dwarf limit, ignites runaway carbon fusion, and explodes like a bomb.
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Massive star supernova
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A supernova that occurs when a massive star dies, initiated by the catastrophic collapse of its iron core
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Neutron degeneracy pressure
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Degeneracy pressure exerted by neutrons, as in neutron stars
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Pulsars
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A neutron star from which we see rapid pulses of radiation as it rotates.
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X-ray binaries
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A binary star system that emits substantial amounts of X rays. thought to be from an accretion disk around a neutron star or black hole
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X-ray bursters
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An object that emits a burst of X rays every few hours to every few days; each burst lasts a few seconds and is thought to be caused by helium fusion on the surface of an accreting neutron star in a binary system
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Space time
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The inseperable, four-dimensional combination of space and time
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Event horizon
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The boundary that marks the "point of no return" between a black hole and the outside universe; events that occur within the event horizon can have no influence on our observable unviverse
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Schwarzschild radius
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A measure of the size of the event horizon of a black hole
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Singularity
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The place at the center of a black hole where, in principle, gravity crushes all matter to an infinitely tiny and dense point
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Gamma ray bursts
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A sudden burst of gamma rays from deep space; such bursts apparently come from distant galaxies, but their precise mechanism is unknown
