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In order to be able to directly see the Sun's motion due to Jupiter's gravity, an observer at a distance of 30 light- years would need to be able to measure changes in its position of _.


A) 0) 05 arcsecond
B) 0) 5 arcsecond
C) 0) 0005 arcsecond
D) 0) 005 arcsecond

E) A) and B)
F) A) and C)

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How do we think the "hot Jupiters" around other stars were formed?


A) They formed as dense, rocky planets close to the star in the same orbits that they are seen today.
B) They formed as gas giants beyond the frost line and then migrated inwards.
C) Many planets were formed around the star but coalesced into a single planet close in.
D) They formed as gas giants close to the star in the same orbits that they are seen today.

E) All of the above
F) A) and B)

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What type of observation can astronomers use to measure the composition of extrasolar planet atmospheres?


A) measurements of the host star's velocity throughout an orbital cycle
B) comparisons of spectra when planets are in front of or are eclipsed by their host stars
C) combination of a transit observation and a Doppler shift measurement
D) measurement of how frequently the planet blocks the host star's light

E) A) and B)
F) None of the above

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Discoveries force theory revisions: The discovery of "hot Jupiters" forced scientists to revise the nebular theory of solar system formation. Think of a hypothetical discovery that would force further revisions of the theory of planet formation, and explain why this observation would contradict the theory.

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Will vary, but might include ideas such ...

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The majority of planets are estimated to be gas giants.

A) True
B) False

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The reason that most extrasolar planets discovered by the Doppler technique are found close to their parent stars is


A) the wavelength shift of the star's spectrum is larger.
B) they transit more frequently, and have thus been more likely to be detected in the short time we have been searching for them.
C) more of the starlight is blocked by the planet when it transits the star.
D) the closer to a star, the hotter and therefore brighter the planet is.
E) planets that are close to a star are heated up and therefore larger.

F) B) and D)
G) A) and B)

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The star Rho Cancri B has about the same mass as our Sun, and the planet discovered around it orbits somewhat closer than Mercury orbits our Sun. The mass of the planet is estimated to be 1.1 times the mass of Jupiter. Why, according to our theory of solar system formation, is it surprising to find a planet the size of Rho Cancri B's planet orbiting at this distance?

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In the nebular theory, jovian ...

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Which planet search technique is currently best suited to finding Earth- like planets?


A) gravitational lensing
B) transit
C) astrometric
D) Doppler
E) combining all the above

F) B) and C)
G) A) and E)

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Predictions for Extra- solar Planets: What predictions does the solar nebula theory make regarding possible planetary systems surrounding other stars? Discuss at least two such predictions that have been strongly confirmed by observations. Explain how the detection of "hot Jupiter" extrasolar planets seemed to be a striking inconsistency with the solar nebula theory. Do you think astronomers were justified in modifying the solar nebula theory in the face of such evidence as opposed to discarding the theory altogether?

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The solar nebula theory predicts that pl...

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Describe the impact the discovery of extrasolar planets has had for understanding the origin of our own Solar System.

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The discovery of extrasolar planets show...

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A star is seen to have two transiting planets. Planet 1 transits every 3 months, and Planet 2 transits every 15 months. What can we infer about their orbits? (Hint: Review the use of Newton's version of Kepler's Third law from Ch. 4)


A) Planet 2's semimajor axis is about 3 times smaller than Planet 1's.
B) Planet 2's semimajor axis is about 3 times larger than Planet 1's.
C) Planet 2's semimajor axis is about 5 times larger than Planet 1's.
D) Planet 2's semimajor axis is about 5 times smaller than Planet 1's.

E) B) and D)
F) A) and D)

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The astrometric technique of planet detection works best for


A) planets in edge- on orbits.
B) massive planets around nearby stars.
C) large planets around nearby stars.
D) massive planets around distant stars.
E) large planets around distant stars.

F) A) and B)
G) A) and D)

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In essence, the Kepler mission searched for extrasolar planets by .


A) obtaining high- resolution photographs of other star systems
B) observing a star carefully enough to notice that it is experiencing a gravitational tug caused by an unseen planet
C) identifying spectral lines that look like what we expect to see from a planet rather than a star
D) monitoring stars for slight dimming that might occur as unseen planets pass in front of them

E) All of the above
F) A) and B)

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The Doppler technique can be used to measure the eccentricity of a planet's orbit by


A) measuring the time it takes for the star's line- of- sight velocity to cycle from peak to peak, and using Newton's version of Kepler's Third law.
B) measuring the amount by which the starlight is reduced when the planet transits.
C) measuring the asymmetries in the velocity curve.
D) measuring the speed at which the star orbits the mutual center- of- mass of the star and planet, and using Newton's theory of gravity.

E) None of the above
F) B) and C)

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The planet COROT- 14b is only slightly larger than Jupiter, but is several times more massive. Which is the most plausible explanation for its similar size to Jupiter?


A) The hydrogen and helium gas compressed even under their own gravity to a higher density than Jupiter.
B) It is made of elements other than hydrogen and helium which do not compress under their own gravity.
C) Planets that are close to a star are heated up and therefore larger.
D) The mass measurement is mistaken, and it is actually about 10 times more massive than Jupiter.

E) A) and B)
F) A) and C)

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Extrasolar planets have been discovered with average densities similar to


A) water.
B) iron.
C) styrofoam.
D) all of the above
E) none of the above

F) All of the above
G) B) and E)

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You observe a star very similar to our own Sun in size and mass. This star moves very slightly back and forth in the sky once every 4 months, and you attribute this motion to the effect of an orbiting planet. What can you conclude about the orbiting planet?


A) The planet must have a mass about the same as the mass of Jupiter.
B) The planet must be closer to the star than Earth is to the Sun.
C) You do not have enough information to say anything at all about the planet.
D) The planet must be farther from the star than Neptune is from the Sun.

E) A) and C)
F) B) and D)

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You are observing the wobble of a star caused by the orbit of a planet around that star. Which property of this system listed below most significantly affects the period of that wobble?


A) the planet's orbital radius
B) the planet's mass
C) both the planet's orbital radius and its mass
D) neither the planet's orbital radius nor its mass

E) C) and D)
F) A) and C)

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The reason that most extrasolar planets discovered by the transit technique are found close to their parent stars is


A) planets that are close to a star are heated up and therefore larger.
B) more of the starlight is blocked by the planet when it transits the star.
C) they transit more frequently, and have thus been more likely to be detected in the short time we have been searching for them.
D) the closer to a star, the hotter and therefore brighter the planet is.
E) the wavelength shift of the star's spectrum is larger.

F) B) and D)
G) A) and E)

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At least _ % of stars host at least one planet.


A) 1
B) 30
C) 10
D) 70

E) A) and B)
F) A) and C)

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