天文学 TPO38-L4 The Formation of Gas Planets

TPO38-L4

The Formation of Gas Planets



 

  1. What is the main purpose of the lecture?
  • A. To describe two new theories about the formation of rocky planets.
  • B. To discuss competing theories about the formation of gas planets.
  • C. To compare the composition of Jupiter, Saturn, Uranus, and Neptune.
  • D. To explain why young stars are often surrounded by disks of gas and dust.

 

  1. Why does the professor review the formation of rocky planets?
  • A. To contrast it with the formation of the Sun.
  • B. To correct a common misunderstanding about accretion.
  • C. To use the information as the basis for another topic of discussion.
  • D. To introduce recent discoveries about rocky planets in other solar systems.

 

  1. What point does the professor emphasize when he mentions water and ammonia?
  • A. Solid forms of water and ammonia may have contributed to the formation of the gas giants.
  • B. Water and ammonia were not common substances in the outer accretion disk.
  • C. Water and ammonia are pulled in by the gravity of proto-planets more readily than other substances are.
  • D. Most substances found in the core of rocky planets are also found in the core of gas planets.

 

  1. According to the professor, what could have occurred when a proto-planet in the outer accretion disk reached a mass of five to ten Earths?
  • A. It started to shed grains of rock and metal into the solar system.
  • B. Its gravity began to pull in huge amounts of the surrounding gas.
  • C. Its gravity caused clumps to form in the surrounding gas.
  • D. It collided with smaller proto-planets.

 

  1. According to the professor, what are TWO claims of the disk-instability theory?
    [CHOOSE 2 ANSWERS]
  • A. Gas planet formation did not begin with a solid core.
  • B. Gas planets cannot form in extremely cold temperatures.
  • C. Gas planet formation can occur anywhere in the accretion disk.
  • D. Gas planets form over a relatively short time.

 

  1. Which is right about the professor’s opinion about the disk-instability theory?
  • A. It differs from the core-accretion theory in relatively insignificant ways.
  • B. It does not take into account the amount of time needed for gas planets to form.
  • C. It is more applicable to star formation than the core-accretion theory is.
  • D. Solid particles are believed to own a small proportion of the outer accretion disk.


答案:
B C A B AD D

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