Exam 18: The Bizarre Stellar Graveyard

A) higher its temperature.
B) smaller its radius.
C) larger its radius.
D) higher its luminosity.

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A) Electron degeneracy pressure is the main source of pressure in white dwarfs,while neutron degeneracy pressure is the main source of pressure in neutron stars.
B) Both electron degeneracy pressure and neutron degeneracy pressure help govern the internal structure of a main-sequence star.
C) The life of a white dwarf is an ongoing battle between electron degeneracy pressure and neutron degeneracy pressure.
D) In a black hole,the pressure coming from neutron degeneracy pressure is slightly greater than that coming from electron degeneracy pressure.

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A) any flattened disk in space,such as the disk of the Milky Way Galaxy
B) a disk of hot gas swirling rapidly around a white dwarf,neutron star,or black hole
C) a stream of gas flowing from one star to its binary companion star
D) a disk of material found around every white dwarf in the Milky Way Galaxy

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A) We now know that gamma-ray bursts come not from neutron stars but from black holes.
B) Theoretical work has proven that gamma rays cannot be produced in accretion disks.
C) Observations from the Compton Gamma-Ray Observatory show that gamma-ray bursts come randomly from all directions in the sky.
D) Observations from the Compton Gamma-Ray Observatory show that gamma-ray bursts occur too frequently to be attributed to neutron stars.
E) Observations from the Compton Gamma-Ray Observatory have allowed us to trace gamma-ray bursts to pulsating variable stars in distant galaxies.

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No,because both events occur o...

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

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A) It will cool down and become a cold black dwarf.
B) As gravity overwhelms the electron degeneracy pressure,it will explode as a nova.
C) As gravity overwhelms the electron degeneracy pressure,it will explode as a supernova.
D) As gravity overwhelms the electron degeneracy pressure,it will become a neutron star.
E) The electron degeneracy pressure will eventually overwhelm gravity and the white dwarf will slowly evaporate.

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A) Light doesn't have mass;therefore,it is not affected by gravity.
B) Light coming from a compact massive object,such as a neutron star,will be redshifted.
C) Light coming from a compact massive object,such as a neutron star,will be blueshifted.
D) Visible light coming 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.
E) 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.

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A) All pulsars are neutron stars,but not all neutron stars are pulsars.
B) Pulsars can form only in close binary systems.
C) A pulsar must have a very strong magnetic field and rotate quite rapidly.
D) Pulsars are kept from collapsing by neutron degeneracy pressure.

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A) The neutron stars will fly apart from one another.
B) It has no effect.
C) The neutron stars will spiral together and merge.
D) The neutron stars will recombine and form a new,young star.

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

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A) They will emit gravitational waves that carry energy and angular momentum away from the system,causing the white dwarfs to gradually spiral inward toward each other and eventually merge.
B) They will emit gravitational waves that carry energy and angular momentum toward the system,causing the white dwarfs to gradually spiral away from one another and eventually fly far apart.
C) They will emit gravitational waves that carry energy and angular momentum away from the system,causing the white dwarfs to quickly spiral away from one another.
D) They will never interact with one another.

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A) The gas in the inner parts of the disk travels faster than the gas in the outer parts of the disk.
B) The gas in the inner parts of the disk is hotter than the gas in the outer parts of the disk.
C) The primary factor determining whether a white dwarf has an accretion disk is the white dwarf's mass.
D) Accretion disks are made primarily of hydrogen and helium gas.

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A) A star system that undergoes a nova may have another nova sometime in the future.
B) A nova involves fusion taking place on the surface of a white dwarf.
C) Our Sun will probably undergo at least one nova when it becomes a white dwarf about 5 billion years from now.
D) When a star system undergoes a nova,it brightens considerably,but not as much as a star system undergoing a supernova.
E) The word nova means "new star" and originally referred to stars that suddenly appeared in the sky,then disappeared again after a few weeks or months.

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A) Both involve explosions on the surface of stellar corpse.
B) Both typically recur every few hours to every few days.
C) Both are thought to involve fusion of hydrogen into helium.
D) Both result in the complete destruction of their host stars.

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A) an O star
B) a star like our Sun
C) a binary M star
D) a white dwarf star with a red giant binary companion
E) a pulsar

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