A) Rapid observations in other wavelengths show that some gamma ray bursts coincide with points showing typical supernova light curves.
B) Some gamma ray bursts have been found to originate with galaxies that are actively forming stars, and would thus have a few very massive (but short lived) stars.
C) The locations of gamma ray bursts suddenly begin blocking light from more distant stars.
D) A and B
E) B and C
G) A) and D)
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A) a newborn star.
B) a white dwarf.
C) nothing.
D) a neutron star or black hole.
F) A) and C)
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A) The 1.2 solar mass white dwarf has a higher surface temperature.
B) The 1.2 solar mass white dwarf is supported by neutron degeneracy pressure; the 1 solar mass white dwarf is supported by electron degeneracy pressure.
C) The 1.2 solar mass white dwarf has a smaller radius.
D) The 1.2 solar mass white dwarf has a lower surface temperature.
E) The 1.2 solar mass white dwarf has a larger radius.
G) A) and B)
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A) A black hole forms when two massive main- sequence stars collide.
B) If enough mass is accreted by a white dwarf star that it exceeds the 1.4 solar mass limit, it will undergo a supernova explosion and leave behind a black- hole remnant.
C) If enough mass is accreted by a neutron star, it will undergo a supernova explosion and leave behind a black- hole remnant.
D) Any star that is more massive than 8 solar masses will undergo a supernova explosion and leave behind a black hole remnant.
E) During a supernova, if a star is massive enough for its gravity to overcome neutron degeneracy pressure in the core, the core will collapse to a black hole.
G) B) and E)
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A) It is the "point of no return" of the black hole; anything closer than this point will not be able to escape the gravitational force of the black hole.
B) The term is intended to emphasize the fact that an object can become a black hole only once, and a black hole cannot evolve into anything else.
C) It is the edge of the black hole, where one could leave the observable universe.
D) It is the center of the black hole, a place of infinite density where the known laws of physics cannot describe the conditions.
F) None of the above
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B) False
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As he approached the black hole, he woul...View Answer
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A) the Earth
B) the Sun
C) the Moon
D) Jupiter
F) A) and C)
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There is overwhelming evidence that puls...View Answer
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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) 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.
C) The more massive the black hole, the larger the Schwarzschild radius.
D) For black holes produced in massive star supernovae, Schwarzschild radii are typically a few to a few tens of kilometers.
F) A) and C)
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A) As gravity overwhelms the electron degeneracy pressure, it will explode as a nova.
B) It will cool down and become a cold black dwarf.
C) As gravity overwhelms the electron degeneracy pressure, it will explode as a supernova.
D) The electron degeneracy pressure slowly overwhelms gravity and the white dwarf evaporates.
E) As gravity overwhelms the electron degeneracy pressure, it will become a neutron star.
G) All of the above
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The extremely dense material could not b...View Answer
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Gamma- ray bursts are distributed unifor...View Answer
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A) a star that is burning iron in its core
B) a binary system that happens to be aligned so that one star periodically eclipses the other
C) a neutron star or black hole that happens to be in a binary system
D) a rapidly rotating neutron star
E) a star that alternately expands and contracts in size
G) A) and E)
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A) White dwarfs are made only from stars that have masses less than the 1.4- solar- mass limit.
B) Electron degeneracy pressure depends on the speeds of electrons, which approach the speed of light as a white dwarf's mass approaches the 1.4- solar- mass limit.
C) The upper limit to a white dwarf's mass is something we have learned from observations, but no one knows why this limit exists.
D) White dwarfs get hotter with increasing mass, and above the 1.4- solar- mass limit they would be so hot that even their electrons would melt.
F) B) and C)
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A) a rapidly spinning neutron star
B) the sudden formation of a new star in the sky
C) an explosion on the surface of a white dwarf in a close binary system
D) the explosion of a massive star at the end of its life
F) A) and B)
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A) a basketball
B) the Earth
C) a city
D) the Sun
E) a football stadium
G) B) and D)
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A) any flattened disk in space, such as the disk of the Milky Way Galaxy
B) a disk of material found around every white dwarf in the Milky Way Galaxy
C) a disk of hot gas swirling rapidly around a white dwarf, neutron star, or black hole
D) a stream of gas flowing from one star to its binary companion star
F) B) and D)
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A) neutron star
B) black hole
C) white dwarf
D) none of the above
F) B) and C)
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A) Theoretical work has proven that gamma rays cannot be produced in accretion disks.
B) Observations from the Compton Gamma- Ray Observatory showed that gamma- ray bursts occur too frequently to be attributed to neutron stars.
C) Observations from the Compton Gamma- Ray Observatory showed that gamma- ray bursts come randomly from all directions in the sky.
D) We now know that gamma- ray bursts come not from neutron stars but from black holes.
E) Observations from the Compton Gamma- Ray Observatory allowed us to trace gamma- ray bursts to pulsating variable stars in distant galaxies.
G) B) and E)
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