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AST 111 – Space

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Which layer of the Sun is the coolest?
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The photosphere is the coolest.
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Which of these groups of particles has the greatest mass?
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Four individual protons have the most mass.
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Scientists estimate the central temperature of the Sun using…
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…mathematical models of the Sun.
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At the center of the Sun, fusion converts hydrogen into…
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…helium, energy, and neutrinos.
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Solar energy leaves the core of the Sun in the form of…
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…photons.
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How does the number of neutrinos passing through your body at night compare with the number passing through your body during the day?
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They are about the same.
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Why do sunspots appear darker than their surroundings?
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They are cooler than their surroundings.
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Which of these things poses the greatest hazard to communications satellite?
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Particles from the Sun pose the greatest hazard.
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What causes the cycle of solar activity?
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Changes in the organization of the Sun’s magnetic field.
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If the star Alpha Centauri were moved to a distance 10 times farther than it is now, its parallax angle would…
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…get smaller.
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What do we need to measure in order to determine a star’s luminosity?
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Apparent brightness and distance is used.
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What two pieces of information would you need in order to measure the masses of stars in an eclipsing binary system?
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The time between eclipses and the average distance between the stars is needed.
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Which of these stars has the coolest surface temperature?
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A K star has the coolest surface temperature.
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Which of these stars is the most massive?
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A main sequence A star is the most massive.
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Which of these stars has the longest lifetime?
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A main sequence M star has the longest lifetime.
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Which of these stars has the largest radius?
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A supergiant M star has the largest radius.
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Which of these stars has the greatest surface temperature?
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A 30 Msun main sequence star has the greatest surface temperature.
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Which of these star clusters is oldest?
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A cluster whose brightest main sequence stars are yellow is the oldest.
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Stars can form most easily in clouds that are…
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…cold and dense.
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A brown dwarf is…
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…an object not quite massive enough to be a star.
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What happens to a low mass star after a helium flash?
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Its luminosity goes down.
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What would you be most likely to find if you returned to the solar system in 10 billion years?
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The Sun would be a white dwarf.
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Which of these stars does not have fusion occurring in its core?
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A red giant does not have fusion.
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What would stars be like if hydrogen had the smallest mass per nuclear particle?
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Nuclear fusion would not occur in stars of any mass.
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What happens to the core of a high mass star after it runs out of hydrogen?
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It shrinks and heats up.
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Which of these isolated neutron stars must have had a binary companion?
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An isolated pulsar that pulses 600 times per second.
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What would happen to a neutron star with an accretion disk orbiting in a direction opposite to the neutron star’s spin?
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It’s spin would slow down.
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What would happen if the Sun suddenly became a black hole without changing its mass?
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Earth’s orbit would not change.
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Which of these binary systems is most likely to contain a black hole?
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An X-ray binary containing an O star and another object of equal mass.
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How would a flashing red light appear as it fell into a black hole?
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Its flashes would shift to the infrared part of the spectrum.
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Which of these black holes exerts the weakest tidal forces on an object near its event horizon?
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A 106 Msun black hole exerts the weakest tidal force.
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Where do gamma-ray bursts tend to come from?
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Extremely distant galaxies produce gamma-ray bursts.