A on the white dwarf sequence b on the giant branch c

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a. On the white dwarf sequence b. On the giant branch c. Below the main sequence  d. On the main sequence e. Among the supergiants Answer: E
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Week 8 Quiz: 1. What are the two primary hydrogen fusion reactions that occur inside stars? a. The Kelvin-Helmholz Mechanism b. The Proton-Proton chain c. The Carrot Cycle d. The CNO Cycle e. The Triple-Alpha Process Answer: B, D 2. Which of the following is NOT a defining feature of all main sequence stars? a. They all have radiative cores and convective envelopes b. They are in hydrostatic equilibrium c. They generate all of their energy by core hydrogen fusion d. They obey a strong mass-luminosity relation e. They are in thermal equilibrium Answer: A 3. Which of the following forms of energy transport is not important in normal stars? a. Conduction b. Radiation c. Convection
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Answer: A 4. Going along the Main Sequence from the upper left (hot, luminous stars) to the  lower right (cool, dim stars) we are also following a sequence of a. Decreasing mass b. Increasing mass c. Increasing radius d. Increasing fraction of metals Answer: A 5. What is the primary way that energy is transported through the outer envelope of  the Sun? a. Convection b. Radiation c. Conduction Answer: A 6. At the same time that nuclear fusion changes from P-P chain to CNO cycle inside  increasingly more massive main-sequence stars, the internal structure changes such  that they have _____ cores and ____ envelopes a. Radiative, radiative b. Convective, radiative c. Radiative, convective d. Convective, convective e. Convective, conductive Answer: B 7. A star is said to be in Thermal Equilibrium if a. It is making more energy than it can radiate away b. Its internal pressure and gravity are in balance c. It is making less energy than it can radiate away d. Its luminosity is balanced by the rate of energy generation Answer: D
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8. The 20 solar mass main-sequence star is about 160,000 times more luminous than  the Sun. The Sun has a main-sequence lifetime of about 10 billion years, what is the  expected main-sequence lifetime of this 20 solar mass star? a. About 20 billion years b. About 160 thousand years c. About 50 million years d. About 1.25 million years  Answer: D 9. The raw materials from which new stars form are a. Hot, low-density clouds of ionized hydrogen b. Hot, low-density clouds of molecular hydrogen c. Cold, dense clouds of neutral atomic hydrogen d. Cold, dense clouds of molecular hydrogen Answer: D 10. Which mass of star forms faster, a high-mass star or a low-mass star? A. A high-mass star B. A low-mass star Answer: A 11. The pre-main sequence phase of star formation ends when it a. Becomes opaque to light and achieve thermal equilibrium b. Stops growing in mass and achieves hydrostatic equilibrium c.
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  • Fall '18
  • hydrostatic equilibrium

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