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Astronomy Week 6-9 Quiz.docx

Explosive hydrogen fusion e photodisintegration of

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d. Explosive hydrogen fusion e. Photodisintegration of nuclei Answer: B, E 3. During the red giant phase of a low-mass star’s life, it has a ____ core surrounded  by a _____ shell a. Inert carbon-oxygen, hydrogen-helium fusion b. Inert helium, hydrogen fusion c. Helium fusion, inert hydrogen d. Helium fusion, hydrogen fusion Answer: B 4. A low-mass horizontal branch star gets most of its energy from ____ and is in ____ a. Core helium fusion, thermal but not hydrostatic equilibrium b. Shell helium fusion, hydrostatic but not thermal equilibrium c. Shell hydrogen fusion, hydrostatic but not thermal equilibrium d. Core helium fusion, hydrostatic and thermal equilibrium e. Kelvin-Helmholz contraction, hydrostatic equilibrium Answer: D 5. A typical core-collapse supernova explosion is a bright as a. 10 thousand suns b. 10 trillion suns c. 10 billion suns d. 10 million suns Answer: C 6. What is the final evolutionary phase of an intermediate mass (48Msun) star? a. Thermal pulsations eject the envelope, leaving behind on O-Ne-Mg white dwarf b. Thermal pulsations eject the envelope, leaving behind a C-O white dwarf c. The O-Ne-Mg core collapses, turning the star into a black hole
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d. The O-Ne-Mg core collapses, destroying the star in a kilonova explosion Answer: A 7. The primary stages in the life of a low-mass star like the Sun in order are a. Main sequence, sub-giant, red giant, horizontal branch, asymptotic giant, envelope  ejection, white dwarf b. Main sequence, sub-giant, horizontal branch, red giant, red supergiant, white dwarf  c. Main sequence, sub-giant, red giant, horizontal branch, asymptotic giant, nova, white  dwarf d. Main sequence, blue supergiant, red supergiant, supernova, neutron star e. Main sequence, red giant, blue giant, supergiant, supernova, black hole Answer: A 8. What distinguishes stars more massive than about 8 solar masses from lower-mass  stars? a. They become red giants instead of red supergiants b. Their cores never get hot enough to ignite carbon fusion c. They can generate energy from fusion of elements heavier than carbon d. They have longer main-sequence lifetimes e. They can fuse iron into heavier elements to gain energy Answer: C 9. When the shockwave initiated by the bouncing iron/nickel core stalls after a few  milliseconds, what do we think revives the shockwave? a. Violent heating by neutrinos pouring out of the post-bounce core b. Explosive nuclear fusion in the wake of the initial shockwave c. Sudden detonation of the post-bounce core d. Ignition of oxygen fusion as the shockwave passes through the inner envelope Answer: A 10. As a high-mass (greater than 4 solar mass) main-sequence star ages it a. It builds up an inert oxygen-neon-magnesium core
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b. The amount of helium at the surface increases as fusion proceeds c.
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  • Fall '18
  • hydrostatic equilibrium

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