Astronomy Chapter 15 ExoPlanets: Planetary Systems Beyond Our Own

The Doppler radial velocity technique works best for: A) planets whose orbits are along our line of sight. B) planets whose orbits are perpendicular to our line of sight. C) planets whose orbits are nearly circular. D) planets whose orbits are very eccentric.

A

What information do we know about the known exoplanets? A) estimates of orbits and masses B) complete composition C) precise masses D) All of the above E) None of the above

A

"Catastrophes" are NOT needed to explain: A) the exceptionally large nickel-iron core of Mercury. B) the asteroid belt. C) our Moon. D) the tilt of Uranus. E) the appearance of Miranda's surface.

B

A late collision with a large planetesimal may have caused what feature on Mars? A) Olympus Mons B) its curious north-south asymmetry C) Hellas Basin D) the Marianas Trench E) its exceptionally large nickel-iron core

B

A planet is located orbiting another star and its radius is about 3 times that of the Earth. It is: A) a brown dwarf. B) a Jupiter. C) a Neptune. D) a super-Earth. E) an Earth.

B

Extrasolar planetary systems are similar to our solar system in all of the following ways, EXCEPT: A) that planetary orbits are relatively coplanar. B) for the presence of hot Jupiters in some systems. C) that planets orbit in the same direction that their parent star rotates. D) that the systems contain interplanetary debris, such as comets or asteroids. E) None of these are dissimilar to our solar system.

B

Hot Jupiters are thought to have moved closer to their parent star than where they originated due to: A) gravitational interactions with the gas disk. B) magnetic attraction to the parent star. C) interactions with another star. D) large impacts. E) many small impacts.

B

Most extrasolar Neptunes and Jupiters found to date have: A) orbits very close to their parent stars, making them hot Neptunes and hot Jupiters. B) orbits that are more eccentric than those of planets in our solar system, with eccentricities greater than 0.1. C) orbits that are less eccentric than those of planets in our solar system, with eccentricities less than 0.01. D) much larger orbits than the jovian planets in our solar system.

B

So far, beyond the solar system the exoplanets found have been mostly: A) large jovians orbiting solar-type stars about where our jovians are found. B) large jovians with terrestrial-type orbits. C) terrestrials very close to their star, and transiting its disk. D) terrestrials with very elongated, distant orbits like comets. E) brown dwarfs much more massive than Jupiter.

B

What is the difference between a hot Jupiter and a cold Jupiter? A) Hot Jupiters have fusion reactions; cold Jupiters do not. B) Hot Jupiters orbit close to the parent stars; cold Jupiters do not. C) Hot Jupiters radiate more energy than they receive from their star; cold Jupiters do not. D) Hot Jupiters have observed volcanoes; cold Jupiters do not. E) Hot Jupiters were an exciting discovery; cold Jupiters were not.

B

What role do the observed irregularities in our solar system play in developing models of planetary formation? A) They are irrelevant to models of planetary formation. B) They help confirm models that lead to random encounters. C) They help reject models that allow for moons to have retrograde orbits. D) They help reject models that allow for hot Jupiters. E) They indicate that the condensation model is the only possible explanation of how solar systems form.

B

When we are lucky enough to see an extra-solar planet transit its star, A) it will cause the star to vanish for several hours. B) we can find the planet's size, mass, and density by the drop in light. C) we can determine what elements are in its atmosphere. D) we can determine its shape. E) we can be certain it is a terrestrial, not a jovian.

B

Why have very few planets with low mass (comparable to Mars or Mercury) been found? A) These small planets are very rare. B) Low mass planets do not produce large enough radial velocity changes in their stars. C) High mass planets are blocking our views of low mass planets. D) Hot Jupiters have ejected most low mass planets from their solar systems. E) Low mass planets are too far from their parent stars to receive enough light to make them visible from Earth.

B

According to the Solar Nebula theory, planets: A) should be randomly oriented to their star's equator. B) will revolve opposite the star's rotation. C) should be a common result of star formation. D) should be extremely rare. E) should orbit perpendicular to their star's equator.

C

Beyond our own solar system, the planets found to date have tended to be: A) Kuiper Belt objects, far from the glare of their suns. B) large jovians far from stars like our Sun. C) large jovians with orbits more like terrestrial planets. D) terrestrials very close to their star, and transiting its disk. E) imaginary, with no present proof that they really exist.

C

Of the first exoplanets found, most were detected by: A) noting the drop in the star's light as the planet transits its disk. B) imaging them with the HST in the infrared, where they are easier to stop. C) noting the Doppler shifts of the star as the planet orbits it from side to side. D) receiving radio transmissions from them, much like Jupiter emits. E) detecting the oxygen in their atmospheres spectroscopically.

C

Planets found in the habitable zone of other stars: A) are all rocky planets, like the terrestrial planets in our solar system. B) are all jovian planets. C) include some Earths and super-Earths. D) include hot Jupiters. E) have been demonstrated to be barren of all life.

C

Space telescopes looking for transiting planets look for small drops in brightness; these drops are: A) less than 10%. B) less than 1%. C) less than 0.01%. D) less than 0.0001%. E) any size.

C

Super-Earths are: A) planets that are most earthlike, likely to harbor life. B) planets that are a few times the mass of the Earth. C) planets that have earthlike masses, but orbit much closer to their star than the Earth does to the Sun. D) any rocky (or terrestrial) planet. E) Earth-mass planets that are much lower in density than the Earth, giving them larger radii.

C

The radius of a super-Earth generally falls in the range: A) above 5 Earth radii. B) between 2 and 5 Earth radii. C) between 1.25 and 2 Earth radii. D) between 0.75 and 1.25 Earth radii. E) below 0.75 Earth radii.

C

When looking for the radial velocity changes or "wobbles" detected due to Doppler shifts, which mass combination is most likely to be detected? A) high mass star, high mass planet B) high mass star, low mass planet C) low mass star, high mass planet D) low mass star, low mass planet E) a high mass planet; the mass of the star is irrelevant

C

Which molecule has not yet been detected in the atmospheres of exoplanets? A) methane B) carbon dioxide C) oxygen D) water

C

As of early 2013, the number of confirmed exoplanets found was: A) 5, all around stars within 20 light years of us. B) 42, all much bigger than Jupiter, but orbiting red dwarf stars. C) over 400, orbiting more than 300 stars. D) about 900, mainly around stars much smaller and fainter than our Sun. E) thousands, around every star we have closely examined to date.

D

In the process of planetary formation, when would the inward migration of Jupiters have most likely occurred? A) shortly after all of the planets had finished forming B) just after the system was cleared of the remaining gas C) before these planets had grown to full size D) after these planets had reached full size, but before terrestrial planets had finished forming E) at least hundreds of millions of years after planetary formation ended

D

The Kepler and CoRoT missions use which technique to detect planet candidates? A) radial velocity measurements B) direct imaging C) measurements of transverse motion D) planetary transits

D

The condensation theory is an example of: A) a catastrophic theory. B) a hot Jupiter theory. C) a collision hypothesis. D) an evolutionary theory. E) a capture theory.

D

To reach the nearest known exoplanet using current technology would take: A) a matter of months. B) 4.4 years. C) about a century. D) about 40,000 years. E) close to a million years.

D

Which of these is NOT a consequence of resonance? A) the Moon's periods of rotation and revolution are equal B) the orbital periods of Neptune and Pluto C) the Kirkwood Gaps in the asteroid belt D) Venus' cloud and surface rotation rates E) Mercury's rotation and revolution around the Sun

D

Why has direct imaging found so few exoplanets? A) Direct imaging is only possible using military satellites. B) Direct imaging only works if the planet is orbiting a brown dwarf. C) Only a few attempts have been made to directly image an extrasolar planet. D) Exoplanets are faint and are usually close to their parent stars.

D

In comparing our own solar system with others found to date, we find: A) most orbits are less circular than the orbits of planets around our Sun. B) jovians often lie much closer to their suns than ours do. C) multiple planets are found in some systems. D) hot Jupiters, even closer to their stars than Mercury is to our Sun. E) All of the above

E

The habitable zone is largest for: A) brown dwarfs. B) red dwarfs. C) white dwarfs. D) red giants. E) blue giants.

E

The habitable zone is the area around a star where: A) planets with life have been found. B) human beings could live. C) the Greenhouse Effect is possible. D) a planet could have an atmosphere. E) temperatures are suitable for planets to have liquid water.

E

When was the first confirmed exoplanet discovered? A) shortly after the invention of the telescope, in the early 1600s B) in prehistoric times C) around 350 BC, by the Ancient Greeks D) early in the 21st century E) near the end of the 20th century

E

Which of the following are irregularities in our solar system that must be explainable in models of planetary formation? A) Venus' low rate of rotation B) Mars' north-south asymmetry C) the tilt of Uranus' rotation axis D) binary Kuiper Belt objects E) All of the above

E

Which statement about extrasolar planets found to date is true? A) All are terrestrials, comparable in size to Earth. B) Few are found by Doppler shifts of their stars, due to their gravity. C) All lie more than 2 A.U. from their star. D) Most have orbital periods of more than a year. E) Some are so close to their stars that their periods are just a few days.

E