4. In the stages of star formation, what is formed when a prestellar core collapses? a. Protostar c. Planet b. Star-forming core d.

Transcription

1 Name: Astro 101 Test 4 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Which statement best describes a molecular cloud? a. large, thin, and wispy regions of interstllar gas b. large, cold, and dense regions of interstellar gas c. the gas and dust between the stars d. small regions with a dense center that will likely form stars 2. What holds molecular clouds together? a. Pressure c. Static Electricity b. Self-gravity d. Angular Momentum 3. Three stars are found to have been formed from a molecular cloud. How many high density cores must have existed in the cloud prior to star formation? a. three or more c. exactly three b. none d. only one 4. In the stages of star formation, what is formed when a prestellar core collapses? a. Protostar c. Planet b. Star-forming core d. Molecular cloud 5. The increasing temperature of the core of a collapsing cloud of gas is due to: a. increased spin rate of the cloud. b. fragmentation of the core. c. gravitational energy turning into thermal energy. d. radiation. 6. Which of the following is a reason to study star formation with an infrared telescope? a. The dust only emits ultraviolet light. b. Protostars emit infrared light. c. Protostars emit lots of high frequency photons. d. Shorter wavelenths have greater energy. 7. What is the most important thing that must happen for a protostar to officially be a star? a. It must begin Hydrogen fusion. c. It must convert gravitational to thermal energy. b. It must shrink to the proper size. d. It must form a protoplanetary disk. 8. According to the conservation of angular momentum, if an ice skater starts spinning with her arms out wide, then slowly pulls them close to her body, this will cause her to: a. fall over c. spin slower b. spin faster d. maintain a constant rate of spin 9. What gets more massive as a result of accretion in an accretion disk? a. Nothing gets bigger c. Planetesimals only b. The protostar only d. The protostar and planetestimals 1

2 Name: ID: A 10. If a disk spins too fast, it will fly apart. To prevent this from happening and conserve angular momentum, the disk. a. spreads out c. gets fatter b. gets smaller d. contracts to a sphere 11. Which of the following are important in the process of making planets from dust grains in a protoplanetary disk? a. Gravity d. A and B b. Static Electricity e. A and C c. Pressure 12. Was it ever possible (or is it currently possible) for Jupiter to become a star? a. No, its composition is too different from stars for it to become one. b. Yes, it is in the process of becoming a star in the near future. c. Yes, but it cooled off before it could become a star. d. No, it would have to be at least 80 times more massive. 13. Which of the following best describes the outer part of a protoplanetary disk? a. low temperatures, contains only refractory materials b. high temperatures, only metals and rocky materials are solid c. low temperatures, gas and ices are present d. heated by the protostar, find both refractory and volatile materials 14. Why are most of the planets composed of refractory materials found in the inner solar system? a. Refractory material existed only in the inner protoplanetary disk. b. Planetary bodies can only be formed from refractory materials. c. The temperature of the inner protostellar accretion disk was too high for volatile components to remain solid. d. All the bodies composed of refractory materials in the outer disk migrated to the inner disk. 15. An earth-size rocky planet is discovered orbiting a sun-like star at the same distance as Saturn orbits the Sun. Why don t astronomers believe this planet originally formed at its current location? a. The planet s gravity is too small to form that far away. b. There are no rocky materials that far away. c. The temperature is too low at that distance. d. The planet s orbital period is too long. 16. Currently in astronomy we define a planet as different from a star or brown dwarf based on its. a. temperature c. shape b. mass d. radius 17. Detecting a planet around another star using the transit method is difficult because: a. the star must be moving with respect to us b. the planet must pass directly in front of the star c. the planet must have a rocky composition d. the star must be very dim 2

3 Name: ID: A 18. Which method for finding extrasolar planets looks for the total light from a star to increase (brighter) because of a planet? a. Direct Imaging c. Gravitational lensing b. Transit method d. Spectroscopic radial velocity method 19. The most craters are found on: a. Earth c. Venus b. Mercury d. Mars 20. When material from space impacts the surface of a planet, it forms a crater. What other type of landform can it create? a. A rebound peak c. A long crack b. A valley d. A scarp 21. The maria on the moon have fewer craters than the lunar highland areas. What do we infer from this observation? a. Maria crustal rock is softer than highlands crustal rock. b. The maria are younger than the highlands. c. The maria were once covered by oceans of water. d. Maria crustal rock is harder than highlands crustal rock. e. The maria are older than the highlands. 22. Pictures of a newly discovered dwarf planet show that it has a smooth surface. Which of the following is NOT a possible explaination for the smooth surface? a. The dwarf planet has active tectonism. b. The surface was changed by erosion. c. The surface was change by recent lava flows. d. The surface has not changed much since the early days of the solar system. 23. What is the evidence for the Earth s deep interior being composed of regions of different density? a. differences in the speed of seismic waves b. continental drift c. volcanism d. subduction 24. Differentiation of the Earth s interior refers to the fact that the layers separated based on their: a. weight c. mass b. volume d. density 25. What is the primary way we can learn about the interiors of planets other than Earth? a. Making computer models based on density of the planet b. Drilling to the center of the planet c. Studying seismic data d. Sending space probes to the planet s surface 26. Your test is Version A. Please fill in the circle for A for this question on your form. a. Mark this one c. not this one b. not this one d. not this one 3

4 ID: A Astro 101 Test 4 Answer Section MULTIPLE CHOICE 1. ANS: B 2. ANS: B 3. ANS: A DIF: Easy REF: 5.1 OBJ: Describe the process of fragmentation during the collapse of a cloud. 4. ANS: A 5. ANS: C DIF: Easy REF: 5.2 OBJ: Explain why conversion of gravitational to thermal energy heats a collapsing gas. 6. ANS: B 7. ANS: A 8. ANS: B DIF: Easy REF: 5.3 OBJ: Conceptual TOP: IV.C.i.c 9. ANS: D HARD 10. ANS: A 11. ANS: D 12. ANS: D DIF: Medium REF: 5.5 OBJ: Applied TOP: VII.B 1

5 ID: A 13. ANS: C 14. ANS: C DIF: Difficult REF: 5.5 OBJ: Show how temperature differences in our accretion disk led to the formation of terrestrial and giant planets. MSC: Understanding 15. ANS: C 16. ANS: B 17. ANS: B DIF: Medium REF: 5.6 OBJ: Applied TOP: VIII.B.iii 18. ANS: C 19. ANS: B DIF: Medium REF: 6.2 OBJ: Factual TOP: II.E 20. ANS: A 21. ANS: B 22. ANS: D 23. ANS: A DIF: Easy REF: 6.2 OBJ: Explain how seismology is used to probe the inner structure of a planet. 24. ANS: D DIF: Easy REF: 6.3 OBJ: Factual TOP: III.B.i 25. ANS: A CLICKER 26. ANS: A 2