Astronomy Final exam. (13)

18) Which planet can we see occasionally transit across the face of the Sun? A) Mercury B) Mars C) Jupiter D) Uranus E) all of the above

A) Mercury

5) The density of a planet can be determined by combining Doppler and astrometric measurements. FALSE/TRUE

Answer: FALSE

31) Which of the following is a consequence of the discovery of hot Jupiters for understanding our own Solar System? A) It shows that our Solar System is very unusual. B) It shows that our Solar System is very typical. C) It shows that we do not fully understand the formation of our Solar System. D) It shows that life in the Universe is rare. E) It shows that Jupiter is unusually cold.

C) It shows that we do not fully understand the formation of our Solar System.

2) Approximately how many other planetary systems have been discovered to date? A) ten B) a hundred C) a thousand D) ten thousand E) a million

C) a thousand

12) The composition of a planet can be determined by A) the Doppler technique. B) astrometric measurements. C) transit observations. D) spectra. E) all of the above

D) spectra.

10) Current techniques can measure stellar motion to less than A) walking speed. B) running speed. C) freeway speed. D) cruising speed of an airplane. E) orbital speed of Jupiter.

A) walking speed.

7) What is astrometry? A) measuring distances to stars B) searching for planets around stars C) measuring the positions of stars on the sky D) measuring the velocities of stars via the Doppler effect E) using metric units for distance (e.g. meters rather than light years)

C) measuring the positions of stars on the sky

24) The depth of the dip in a star's brightness due to the transit of a planet depends most directly on A) the planet's mass. B) the planet's density. C) the planet's size. D) the size of the planet's orbit. E) the eccentricity of the planet's orbit.

C) the planet's size.

27) What do models suggest make up the clouds on "hot Jupiters"? A) ammonia B) methane C) water D) rock dust E) sodium

D) rock dust

6) A planet's size can be determined by observing its transit across a star. FALSE/TRUE

Answer: TRUE

28) How do we think the "hot Jupiters" around other stars were formed? A) They formed as gas giants close to the star in the same orbits that they are seen today. B) They formed as dense, rocky planets close to the star in the same orbits that they are seen today. C) They formed as gas giants beyond the frost line and then migrated inwards. D) Many planets were formed around the star but coalesced into a single planet close in. E) They spun off from the young star when it was rapidly rotating.

C) They formed as gas giants beyond the frost line and then migrated inwards.

19) Which planet search technique is currently best suited to finding Earth-like planets? A) Doppler B) astrometric C) transit D) gravitational lensing E) combining all the above

C) transit

15) The transit method of planet detection works best for A) big planets in edge-on orbits around small stars. B) big planets in face-on orbits around small stars. C) small planets in edge-on orbits around big stars. D) small planets in face-on orbits around big stars. E) Earth-like planets in any orbit.

A) big planets in edge-on orbits around small stars.

4) Which of the following methods has not yet detected planets around other stars? A) detection of reflected light by the planet B) detecting periodic Doppler shifts in a star's spectrum C) detecting periodic shifts in the position of a star on the sky D) detecting the decrease in light as a planet transits a star E) All of the above have succeeded.

A) detection of reflected light by the planet

13) The size and shape of a planet's orbit can be determined by A) the Doppler technique. B) transit observations. C) spectral measurements. D) knowing the planet's mass by any technique and applying Newton's version of Kepler's third law. E) gravitational microlensing.

A) the Doppler technique.

26) The composition of a planet's atmosphere be measured during a transit by analyzing A) the excess absorption of starlight at specific wavelengths. B) the excess emission of starlight at specific wavelengths. C) the length and depth of the dip in light during the transit. D) the amplitude and period of the star's motion. E) the wobble in a star's position on the sky.

A) the excess absorption of starlight at specific wavelengths.

10) Once a planet forms in a disk-like nebula around a star, its orbit is fixed and will never change. FALSE/TRUE

Answer: FALSE

3) The Doppler technique for planet detection has found Earth-like planets around nearby Sun-like stars. FALSE/TRUE

Answer: FALSE

9) Because we have not found another planetary system like our own, we can conclude that our Solar System must be quite unusual. FALSE/TRUE

Answer: FALSE

1) Astronomers have discovered more planets around other stars than in our Solar System. FALSE/TRUE

Answer: TRUE

11) Multiple planets have been identified around other stars via the transit technique. FALSE/TRUE

Answer: TRUE

12) The signature of a planet is largest in radial velocity measurements when the planet and star are lined up along the line of sight to the telescope. FALSE/TRUE

Answer: TRUE

13) The signature of a planet is largest in transit measurements when the planet and star are lined up along the line of sight to the telescope. FALSE/TRUE

Answer: TRUE

14) The total amount of light from a star-planet system drops when the planet goes behind the star. FALSE/TRUE

Answer: TRUE

2) Most of the planets discovered around other stars are more massive than Jupiter. FALSE/TRUE

Answer: TRUE

4) Planetary orbits that are face-on to our line of sight produce no Doppler shift in the stellar spectrum. FALSE/TRUE

Answer: TRUE

7) Transits of multiple planet systems can be analyzed to infer planetary masses. FALSE/TRUE

Answer: TRUE

8) Multiple-planet systems have been identified around other stars via the Doppler technique. FALSE/TRUE

Answer: TRUE

11) A planet's density can be measured by combining A) Doppler and astrometric observations. B) Doppler and transit observations. C) spectral observations of the planet's atmosphere. D) any method that measures the gravitational tug of the planet on the star. E) direct imaging from the new generation of space telescopes.

B) Doppler and transit observations.

5) Most of the planets discovered around other stars A) are more massive than Earth and orbit very far from the star. B) are more massive than Earth and orbit very close to the star. C) are less massive than Earth and orbit very far from the star. D) are less massive than Earth and orbit very close to the star. E) are found around neutron stars.

B) are more massive than Earth and orbit very close to the star.

14) The astrometric technique of planet detection works best for A) large planets around nearby stars. B) massive planets around nearby stars. C) large planets around distant stars. D) massive planets around distant stars. E) planets in edge-on orbits.

B) massive planets around nearby stars.

21) A planet is detected via the Doppler technique. The velocity change of the star is a measure of A) the planet's size and density. B) the planet's mass and orbital distance. C) the planet's mass and composition. D) the planet's orbital period and eccentricity. E) the planet's size and orbital distance.

B) the planet's mass and orbital distance.

33) If every star had an Earth-like planet in an Earth-like orbit, how many could be detected by a transit? A) 1 in 2 B) 1 in 20 C) 1 in 200 D) 1 in 2,000 E) 1 in 20,000

C) 1 in 200

32) Viewed from afar, the transit of Earth would cause the Sun's brightness to dim by approximately one part in A) 100. B) 1,000. C) 10,000. D) 100,000. E) a million.

C) 10,000.

30) Which of the following is a consequence of the discovery of hot Jupiters for the nebular theory of solar system formation? A) It has been discarded. B) It has been modified to allow for the formation of gas giants within the frost line. C) It has been modified to allow for planets to migrate inwards or outwards due to gravitational interactions. D) Its status is unclear and awaits further observations that will determine whether hot Jupiters are dense Earth like planets or gas giants. E) It remains unchanged as it only needs to explain our Solar System.

C) It has been modified to allow for planets to migrate inwards or outwards due to gravitational interactions.

9) Planets detected via the Doppler technique have been mostly A) Earth-mass, in Earth-like orbits. B) Jupiter-mass, in Jupiter-like orbits. C) Jupiter-mass, in very close orbits. D) Earth-mass, in very close orbits. E) a wide range of masses, in edge-on orbits.

C) Jupiter-mass, in very close orbits.

29) What would happen to the planets in a solar system where the central star did not have a strong wind? A) One planet would grow to dominate all the others and gravitationally eject them out of the system. B) All planets would continue to grow to large sizes but their orbits would be unchanged. C) The gas in the solar nebula would create a drag on the planets and their orbits would migrate inwards. D) The gas in the solar nebula would create a drag on the planets and their orbits would migrate outwards. E) Nothing, the star does not affect the process of planet formation.

C) The gas in the solar nebula would create a drag on the planets and their orbits would migrate inwards.

25) Why are many of the newly detected extrasolar planets called "hot Jupiters"? A) Their masses and composition are similar to what we would expect if Jupiter were hotter. B) The planets tend to be detected around more massive, hotter stars than our Sun. C) Their masses are similar to Jupiter but they are very close to the central star and therefore hot. D) Their masses are similar to Jupiter but their composition is similar to Mercury. E) The discovery of other planets is very exciting.

C) Their masses are similar to Jupiter but they are very close to the central star and therefore hot.

3) Which of the following methods has led to the most discoveries of massive planets orbiting near their parent stars? A) detecting the starlight reflected off the planet B) detecting the infrared light emitted by the planet C) detecting the gravitational effect of an orbiting planet by looking for the Doppler shifts in the star's spectrum D) detecting the shift of the star's position against the sky due to the planet's gravitational pull E) detecting a planet ejected from a binary star system

C) detecting the gravitational effect of an orbiting planet by looking for the Doppler shifts in the star's spectrum

20) What are the two main differences between extrasolar planetary systems discovered to date and our Solar System? A) extrasolar planets tend to be more massive and dense than Jupiter B) extrasolar planet orbits tend to be more eccentric and inclined than in our Solar System C) extrasolar planet orbits tend to be closer and more eccentric than in our Solar System D) extrasolar planet orbits tend to be closer and more circular than in our Solar System E) extrasolar planets tend to be bigger and denser than Jupiter

C) extrasolar planet orbits tend to be closer and more eccentric than in our Solar System

16) The reason that most extrasolar planets are found close to their parent stars is A) the planets reflect more light the closer they are to the star. B) more of the starlight is blocked by the planet when it transits the star. C) the amount and frequency of the star's motion are both higher. 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.

C) the amount and frequency of the star's motion are both higher.

1) The first planets around other Sun-like stars were discovered A) by Huygens, following his realization that other stars are Suns. B) by Galileo following the invention of the telescope. C) at the turn of last century. D) about a decade ago. E) at the turn of this century.

D) about a decade ago.

8) By itself, the Doppler technique provides a measure of a planet's A) minimum mass. B) orbital radius. C) orbital eccentricity. D) all of the above

D) all of the above

17) The Doppler technique only provides a measure of the minimum mass of a planet because A) only a small part of the planet's motion is measured. B) without a transit observation, the size and therefore density of the planet is unknown. C) we do not know the exact composition of the planet. D) only the motion of star toward the observer is measured, not the full motion. E) we do not have the technology to make a direct image of a planet yet.

D) only the motion of star toward the observer is measured, not the full motion.

22) A planet is detected via the Doppler technique. The repeating pattern of the stellar motion tells us A) the planet's size. B) the planet's mass. C) the planet's density. D) the orbital period of the planet. E) the orbital eccentricity of the planet.

D) the orbital period of the planet.

6) How much brighter is a Sun-like star than the reflected light from a planet orbiting around it? A) a hundred times brighter B) a thousand times brighter C) ten thousand times brighter D) a million times brighter E) a billion times brighter

E) a billion times brighter

23) A planet is detected via the Doppler technique. The shape of the periodic velocity pattern tells us A) the planet's size. B) the planet's mass. C) the planet's density. D) the orbital period of the planet. E) the orbital eccentricity of the planet.

E) the orbital eccentricity of the planet.