Astronomy Final M/C and Vocab – Flashcards
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The universe is said to be closed if
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gravity is strong enough to stop the expansion in a finite time
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The cosmological principle states that the universe is
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homogeneous isotropic
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The resolution of Olber's paradox suggests that it gets dark at night because
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the universe is not infinite in age
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The average star spends ___ of its lifetime on the main sequence
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90%
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Comets falling into the inner solar system from the ___ become long-period comets
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Oort cloud
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the center of our galaxy lies in the direction of the constellation of
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Sagittarius
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____ first noticed that for Cepheid variable stars, there was a direct relation between the luminosity and the period of the variation in their brightness
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Henrietta Leavitta
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The first pulsar was discover by ___ in Nov of 1967.
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Jocelyn Bell
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Why don't all supernova remnants contain pulsars?
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the pulsar may be tipped so that the beams do not sweep past earth or the pulsar is eject from the remnant because of recoil momentum is an asymmetric explosion
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The event horizon
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has a radius equal to the Schwarzschild radius
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pulsars are believed to slow down because
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they are converting energy of rotation into radiation
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the slowing of clocks in strongly curved space time is known as
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time dilation
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a ___ has a radius of about 10 km and is supported by the pressure associated with degenerate neutrons
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neutron star
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a type 1 supernova is believed to occur when
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carbon detonation occurs in a white dwarf
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a planetary nebula is
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the expelled outer envelope of a medium mass star
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an ___ is a collection of 10^5 to 10^6 stars in a region 10 to 30 pc in diameter. the stars in the collection tend to be more than 10^9 years old and be mostly yellow and red stars
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globular cluster
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What is the lifetime in years of a 10 solar mass star on the main sequence? t=1/(M^2.5); 1 solar lifetime=10^10 years
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3.2 x 10^7 years
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The crab nebula is:
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a supernova remnant
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__ are small dark nebulae about 1 light-year in diameter that contain 10 to 1000 solar masses
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Bok globules
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iron meteorites
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appear to have formed in the interiors of molten planetesimals
