Exam 14: The Bizarre Stellar Graveyard

A) an object that will ultimately become a black hole
B) the remains of a star that died by expelling its outer layers in a planetary nebula
C) a star made mostly of elements with high atomic mass numbers, so that they have lots of neutrons
D) the remains of a star that died in a massive star supernova (if no black hole were created)

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A) the Sun
B) a small city
C) a basketball
D) the Earth
E) a football stadium

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No. X- ray bursts occur when a...

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A) No, because the Sun's core will never be hot enough to fuse carbon and other heavier elements into iron.
B) Yes, right at the end of its double- shell burning stage of life.
C) Yes, about a million years after it becomes a white dwarf.
D) No, because it is not orbited by another star.

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A) The spectrum of a massive- star supernova shows prominent hydrogen lines, while the spectrum of a white- dwarf supernova does not.
B) A massive- star supernova happens only once, while a white- dwarf supernova can repeat periodically.
C) A massive- star supernova is brighter than a white- dwarf supernova.
D) The light of a white- dwarf supernova fades steadily, while the light of a massive- star supernova continues to brighten for many weeks.
E) We cannot yet tell the difference between a massive- star supernova and a white- dwarf supernova.

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White- dwarf supernovae occur when the m...

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A) Light escaping from a compact massive object, such as a neutron star, will be redshifted.
B) Visible light escaping from a compact massive object, such as a neutron star, will be redshifted, but higher frequencies, such as X- rays and gamma rays, will not be affected.
C) Light escaping from a compact massive object, such as a neutron star, will be blueshifted.
D) Less energetic light will not be able to escape from a compact massive object, such as a neutron star, but more energetic light will be able to.
E) Light doesn't have mass; therefore, it is not affected by gravity.

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A) main- sequence star, white dwarf, neutron star, black hole singularity
B) main- sequence star, neutron star, white dwarf, black hole singularity
C) main- sequence star, black hole singularity, neutron star, white dwarf
D) black hole singularity, main- sequence star, white dwarf, neutron star

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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

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A) always a black hole
B) always a white dwarf
C) always a neutron star
D) either a white dwarf or a neutron star
E) either a neutron star or a black hole

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A) limitless; there is no theoretical limit to the maximum mass of a white dwarf
B) about the mass of our Sun
C) about 1.4 times the mass of our Sun
D) about 3 times the mass of our Sun

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A) Degeneracy pressure can arise only from interactions among electrons.
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 continue to support an object against gravitational collapse even if the object becomes extremely cold.

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A) 10 solar masses
B) 3 solar masses
C) 1) 4 solar masses
D) 0) 5 solar masses

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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 always contains much more mass.
D) The accretion disk around a neutron star is much hotter and emits higher- energy radiation.

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A) The events responsible for gamma ray bursts apparently produce only gamma rays, and no other light that we can hope to detect.
B) Gamma ray bursts are among the most luminous events that ever occur in the universe.
C) Based on their distribution in the sky, we can rule out a connection between gamma ray bursts and X- ray binaries in the Milky Way Galaxy.
D) Gamma ray bursts were originally discovered by satellites designed to look for signs of nuclear bomb tests on Earth.

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A) The mystery companion has a mass of over 3 solar masses.
B) The mystery companion gives off periodic X- ray bursts.
C) The mystery companion has an X- ray emitting accretion disk.
D) The mystery companion has a mass of over 1.4 solar masses.

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A) jets of material shot out of the accretion disk will shoot down their planet
B) tidal forces from the black hole will rip the planet apart
C) the red giant star, which provides most of energy the civilization needs to exist, will soon be destroyed in the accretion disk
D) the planet's orbit gradually will decay, as it is sucked in by the black hole
E) the red giant will probably supernova within the next million years

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