Ast Hw12

1. What method has detected the most extrasolar planets (or candidates) so far? -the transit method -Hubble images -the Doppler method

2. What fraction of extrasolar planets could in principle be detected by the transit method? -less than about 1% -about 20% -100%

3. Why are only a small fraction of extrasolar planets detectable by the transit method?

4. Which method could detect a planet in an orbit that is face-on to the Earth? -Doppler method -transit method -astrometric method

5. Which one of the following can the transit method tell us about a planet? -its mass -its size -the eccentricity of its orbit

6. To determine a planet's average density, we can use -the transit method alone. -the astrometric and Doppler methods together. -the transit and Doppler methods together.

7. Based on the model types shown in Figure 13.16 of the textbook, a planet made almost entirely of hydrogen compounds would be considered a -terrestrial planet. -jovian planet. -"water world."

8. What's the best explanation for the location of hot Jupiters? -They formed closer to their stars than Jupiter did. -They formed farther out like Jupiter but then migrated inward. -The strong gravity of their stars pulled them in close.

9. Most of the exoplanets detected to date are found -at about the same distance as the Earth is from the Sun -very close to their parent star -at about the same distance as the planet Jupiter is from the Sun -very far from their parent stars

10. Most of the extrasolar planets detected to date have -masses similar to the Earth -masses smaller than the Earth -masses more similar to Jovian planets -a large range of masses, with no mass range dominating

11. The presence of a hot Jupiter in a planetary system does not bode well for finding a habitable terrestrial planet in that same system. This is -true; a migrating Jupiter will probably remove any habitable terrestrial planet from the Habitable Zone. -true; radiation emanating from a hot Jupiter would lead to excessive heating of the surface of a terrestrial planet. -false; the existence of a hot Jupiter should have no relevance in this situation. (d) false; a hot Jupiter would improve chances because it would protect inner, terrestrial-like planets from impacts -not knowable without additional information.

12. Most of the extrasolar planets detected to date orbit -stars that are hotter than the Sun -stars with temperatures similar to or cooler than the Sun -we do not know the temperatures of most of the central stars

13. Most of the extrasolar planets detected to date have -orbital periods of several years -orbital periods very similar to the Earth's -short orbital periods, in many cases a week or less

14. Relative to the Earth, we expect that Super Terran (Super-Earth) planets will -be more tectonically active than the Earth -be less tectonically active than the Earth -have tectonic activity similar to the Earth -there is no basis to have any expectation of their tectonic activity

15. Which approach to discovering exoplanets is most difficult and has been the least productive? -direct imaging -Doppler shift method -transit method

16. At least one exoplanet with a size equal to or smaller than the Earth has been detected. -True -False

17. The majority of exoplanets discovered before the Kepler mission were hot Jupiters. Is this is because hot Jupiters are the most common type of planet? -yes, later discoveries by Kepler have demonstrated this to be true. -yes. Kepler's discoveries have not found the same results, but that is because Kepler detection method is not sensitive to hot Jupiters. -no. The majority of exoplanets discovered before Kepler were made using a method that is much more likely to find hot Jupiters than other, more common, types of planets.

18. The number of exoplanets discovered to date is a) a few tens -a couple hundred -a few thousand -a few hundred thousand -several million

19. Based on discoveries to date, how many planets do we think exist in our Milky Way galaxy? -more than the number of stars in the Milky Way (hundreds of billions) -we have no idea -a small fraction of the numbers of stars in the Galaxy

20. Based on discoveries to date, how many potentially habitable Earth-like planets do we think exist in our Milky Way galaxy? -more than the number of stars in the Milky Way (hundreds of billions) -around 10 billion -a million or less -we suspect the earth is unique d) we have no idea

21. The astrometric method is best for finding massive planets that orbit -very close to their stars. -farther from their stars. -around extremely distant stars.