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| 1 . |
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Which of the following descriptions fits the galaxy type labeled S0 in the Hubble classification? [Hint]
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| 2 . |
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As we progress in the Hubble classification sequence of spiral galaxies from types Sa to Sb to Sc, how do their physical characteristics change? [Hint]
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| 3 . |
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How do the physical characteristics of various elliptical galaxies compare with one another? [Hint]
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| 4 . |
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What are the two objects observable from Earth's southern hemisphere that are known as the Magellanic Clouds? [Hint]
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| 5 . |
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Which of the following is not one of the basic classifications used in Hubble's categorization of galaxy types? [Hint]
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| 6 . |
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How are the orbits of stars within most elliptical galaxies arranged? [Hint]
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| 7 . |
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What method of astronomical distance determination depends on measurement of broadening in a galaxy's spectral lines? [Hint]
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| 8 . |
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Why do astronomers think that the processes that power large active galaxies are basically scaled-up versions of the ones that power neutron-star pulsars or smaller black holes? [Hint]
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| 9 . |
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What characteristic of some radio lobe galaxies contributes to the idea that their energy emission is intermittent? [Hint]
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| 10 . |
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Which of the following is not a characteristic of an active galaxy? [Hint]
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| 11 . |
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What is the effect of the large magnetic field thought to be part of an active galaxy on the material produced by it? [Hint]
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| 12 . |
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What would be the Schwarzschild radius of a black hole with a mass of about 3 billion solar masses, as indicated by studies of data from the region of the core of M87 (Virgo A)? [Hint]
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| 13 . |
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How might lobe radio galaxies and core-dominated radio galaxies be related to each other? [Hint]
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| 14 . |
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At the 18-megaparsec distance from us of M87, what would be the physical size limit that corresponds to the Hubble Space Telescope's angular resolution limit of 0.05 arc seconds? [Hint]
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| 15 . |
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At what rate, in terms of solar masses, would material have to be fed into the accretion disk around a black hole to provide the power radiated by a large active galaxy, typically 1038 Watts, if 10 percent of this mass-energy is radiated away in the form of electromagnetic energy before the rest is captured? [Hint]
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Answer choices in this exercise are randomized and will appear in a different order each time the page is loaded.
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