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They were detected a...View Answer
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A) white dwarf
B) neutron star
C) black hole
D) none of the above
F) A) and B)
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A) A massive-star supernova is brighter than a white-dwarf supernova.
B) A massive-star supernova happens only once,while a white-dwarf supernova can repeat periodically.
C) The spectrum of a massive-star supernova shows prominent hydrogen lines,while the spectrum of a white-dwarf supernova does not.
D) The light of a white-dwarf supernova fades steadily,while the light of a massive-star supernova brightens for many weeks.
E) We cannot yet tell the difference between a massive-star supernova and a white-dwarf supernova.
G) A) and D)
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The distribution of gamma-ray bursts is ...View Answer
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No,because no light can escape...View Answer
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A) about the mass of our Sun.
B) limitless;there is no theoretical limit to the maximum mass of a white dwarf.
C) about 3 times the mass of our Sun.
D) about 1.4 times the mass of our Sun.
F) C) and D)
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A) It emits X-rays characteristic of an accretion disk,but the unseen star in the system is too massive to be a neutron star.
B) No light is emitted from this star system,so it must contain a black hole.
C) The fact that we see strong X-ray emission tells us that the system must contain a black hole.
D) Cygnus X-1 is a powerful X-ray burster,so it must contain a black hole.
F) A) and B)
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The extremely dense material could not b...View Answer
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A) X-rays are emitted by the hot gas in the accretion disk.
B) the accretion disk consists of material that spills off the companion star.
C) the central object about which the accretion disk swirls may be either a neutron star or a black hole.
D) several examples of flattened accretion disks being "fed" by a large companion star can be seen clearly in photos from the Hubble Space Telescope.
E) the radiation from an accretion disk may vary rapidly in time.
G) C) and D)
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A) tidal forces due to the black hole
B) X-rays from the accretion disk
C) the crush of gravity at the singularity embedded within the black hole
D) the sucking force from the black hole,which will cause his head to explode
F) A) and C)
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A) a dead star that has faded from view
B) any object made from dark matter
C) an object with gravity so strong that not even light can escape
D) a compact mass that emits no visible light
F) A) and D)
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A) Degeneracy pressure can continue to support an object against gravitational collapse even if the object becomes extremely cold.
B) Degeneracy pressure arises from a quantum mechanical effect that we don't notice in our daily lives.
C) Black holes form when gravity overcomes neutron degeneracy pressure.
D) Degeneracy pressure can arise only from interactions among electrons.
F) None of the above
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A) As a result of traumatic experiences to their evolutionary ancestors,they dislike television.
B) Their immediate ancestors were chimpanzees.
C) They believe that the presence of two stars in their system was critical to their evolution.
D) They evolved from primitive wormlike creatures that had 13 legs,4 eyes,and bald heads,thus explaining why such critters are now considered a spectacular delicacy.
E) They evolved on a different planet in a different star system,and moved to their current location.
G) C) and D)
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B) False
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A) about 50 pounds.
B) as much as the entire Earth.
C) about as much as a truck.
D) about as much as a large mountain.
F) A) and C)
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B) False
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A) The star vibrates.
B) As the star spins,beams of radio radiation sweep through space.If one of the beams crosses Earth,we observe a pulse.
C) The star undergoes periodic explosions of nuclear fusion that generate radio emission.
D) The star's orbiting companion periodically eclipses the radio waves emitted by the main pulsar.
E) A black hole near the star absorbs energy and re-emits it as radio waves.
G) B) and C)
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B) False
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A) the observationally measured radius of the black hole.
B) the way in which the black hole formed.
C) only the mass of the black hole.
D) both the mass and chemical composition of the black hole.
F) A) and C)
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A) because they are so rare
B) because we know they come from pulsating variable stars but don't know how they are created
C) because the current evidence suggests that they are the most powerful bursts of energy that ever occur anywhere in the universe,but we don't know how they are produced
D) because current evidence suggests that they come from our own Milky Way,but we have no idea where in the Milky Way they occur
E) because current evidence suggests that they come from massive black holes in the centers of distant galaxies,adding to the mystery of black holes themselves
G) A) and D)
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