astronomy chapter 18 – Flashcards
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Which of the following best summarizes what we mean by dark matter?
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matter that we have identified from its gravitational effects but that we cannot see in any wavelength of light
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Which of the following best summarizes what we mean by dark energy?
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It is a name given to whatever is causing the expansion of the universe to accelerate with time.
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What is a rotation curve?
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a graph showing how orbital velocity depends on distance from the center for a spiral galaxy
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Which of the following is NOT one of the three main strategies used to measure the mass of galaxy clusters?
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measuring the temperatures of stars in the halos of the galaxies
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What do we mean when we say that particles such as neutrinos or WIMPs are weakly interacting?
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They respond to the weak force but not to the electromagnetic force, which means they cannot emit light.
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Measuring the amount of deuterium in the universe allows us to set a limit on _________.
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the density of ordinary (baryonic) matter in the universe
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What is the primary form of evidence that has led astronomers to conclude that the expansion of the universe is accelerating?
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observations of white dwarf supernovae
