A) Although we are not 100% certain that black holes exist,we have strong observational evidence in favor of their existence.
B) If you watch someone else fall into a black hole,you will never see him (or her) cross the event horizon;you'll only see him fade from view as the light he emits or reflects becomes more and more redshifted.
C) A spaceship passing near a 10-solar-mass black hole is much more likely to be destroyed than a spaceship passing at the same distance from the center of a 10-solar-mass main-sequence star.
D) If you fell into a black hole,you would experience time to be running normally as you plunged rapidly across the event horizon.
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Earth's orbit (and those of the other pl...View Answer
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A) as much as a truck.
B) about 5 pounds.
C) as much as the entire Earth.
D) as much as an average person.
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A) There is no upper limit.
B) There is an upper limit,but we do not yet know what it is.
C) 2 solar masses
D) 1.4 solar masses
E) 1 solar mass
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A) If you watch someone else fall into a black hole,you will never see him or her cross the event horizon.However,he or she will fade from view as the light he or she emits (or reflects) becomes more and more redshifted.
B) If we watch a clock fall toward a black hole,we will see it tick slower and slower as it falls nearer to the black hole.
C) A black hole is truly a hole in spacetime,through which we could leave the observable universe.
D) If the Sun magically disappeared and was replaced by a black hole of the same mass,Earth would soon be sucked into the black hole.
E) If you fell into a black hole,you would experience time to be running normally as you plunged rapidly across the event horizon.
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White-dwarf supernovae occur when the ma...View Answer
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A) as large in diameter as the Sun but only about as massive as Earth.
B) as massive as the Sun but only about as large in size as Earth.
C) about the same size and mass as the Sun but much hotter.
D) as massive as the Sun but only about as large in size as Jupiter.
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A) intense X-ray bursts
B) spectral lines from the companion star that alternately shift to shorter and longer wavelengths
C) visible and ultraviolet light from the companion star
D) bright X-ray emission that varies on a time scale of a few hours
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A) about the same as a teaspoonful of Earth-like material.
B) a few tons.
C) more than Mt.Everest.
D) more than the Moon.
E) more than Earth.
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A) the Hubble Space Telescope
B) the Chandra X-Ray Observatory
C) the SOFIA airborne infrared observatory
D) the Arecibo Radio Observatory
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A) It has a larger radius.
B) It has a smaller radius.
C) It has a higher surface temperature.
D) It has a lower surface temperature.
E) It is supported by neutron,rather than electron,degeneracy pressure.
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A massive white dwarf has a stronger gra...View Answer
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A) a brown dwarf.
B) a white dwarf.
C) a neutron star.
D) a very massive main-sequence star.
E) the central core of the Sun after hydrogen fusion ceases but before helium fusion begins.
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A) The accretion disk around a neutron star is made mostly of helium while the accretion disk around a white dwarf is made mostly of hydrogen.
B) The accretion disk around a neutron star is more likely to give birth to planets.
C) The accretion disk around a neutron star is much hotter and emits higher-energy radiation.
D) The accretion disk around a neutron star always contains much more mass.
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A) Black hole binaries are very rare,and wave detection is difficult.
B) The waves disappear into the black hole.
C) The waves must be coming from very far away and haven't reached us yet.
D) Our current theories must be wrong.
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A) Yes,right at the end of its double-shell burning stage of life.
B) Yes,about a million years after it becomes a white dwarf.
C) No,because it is not orbited by another star.
D) No,because the Sun's core will never be hot enough to fuse carbon and other heavier elements into iron.
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A) In a binary system with a black hole,the Schwarzschild radius depends on the distance from the black hole to the companion star.
B) The more massive the black hole,the larger the Schwarzschild radius.
C) Even an object as small as you could become a black hole if there were some way to compress you to a size smaller than your Schwarzschild radius.
D) For black holes produced in massive star supernovae,Schwarzschild radii are typically a few to a few tens of kilometers.
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A) neutron degeneracy pressure
B) electron degeneracy pressure
C) thermal pressure
D) radiation pressure
E) all of the above
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A) they are both very hot and very small.
B) they are the end-products of small,low-mass stars.
C) they are the opposite of black holes.
D) it amplifies the contrast with red giants.
E) they are supported by electron degeneracy pressure.
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