Question 1

In what way are many of the extrasolar planetary systems that have been discovered so far fundamentally different from our own solar system?

Accepted Answer

A)   The relative positions of where the planets formed are inverted, with the Jovian-type planets forming close to the stars and the terrestrial-type planets forming farther out.
B)   Many terrestrial planets discovered so far have masses intermediate between the terrestrial planets of our system and the ice giants.
C)   The massive Jovian-type planets appear to have formed at large distances, like our own Jovian planets, and then spiraled in close to their stars.
D)   There are no Jovian-mass planets. B

Question 2

A gas and dust cloud will not necessarily collapse because it normally experiences a balance between its internal gas pressure and

Accepted Answer

A)   kinetic energy.
B)   friction.
C)   gravity.
D)   electrostatic repulsion. C

Question 3

The observation of hot dust around nearby stars implies that those stars have

Accepted Answer

A)   asteroids.
B)   a solar wind.
C)   much higher luminosity than the Sun.
D)   Kuiper belts. A

Question 4

Exoplanets that do NOT orbit any star are believed to have

Accepted Answer

A)   been ejected from their host stars during supernova explosions.
B)   formed in binary systems.
C)   formed without any nearby stars in molecular clouds.
D)   been ejected from their host stars through collisions with planetesimals.

Question 5

What kind of orbits can exoplanets in binary star systems have?

Accepted Answer

A)   Astronomers do not know, because none have been detected so far.
B)   They orbit only one of the stars.
C)   They have an orbit around the center of mass of both stars.
D)   Some orbit one of the stars, while some have an orbit around the center of mass of both stars.

Question 6

An astronomer is trying to detect an exoplanet via the microlensing method. Which of these changes to a particular planet will make it easier to detect, if everything else about the planet is unchanged?

Accepted Answer

A)   increasing its radius
B)   increasing its mass
C)   increasing its orbital period
D)   All of these are correct.

Question 7

For an exoplanet to be detected via the direct imaging method, it must

Accepted Answer

A)   have a large mass.
B)   orbit its star with a component of its motion perpendicular to the line of sight to from the star to Earth.
C)   be the only exoplanet in the system.
D)   have a high albedo.

Question 8

Astronomers studying a transiting exoplanet can detect other nontransiting planets in the same system by

Accepted Answer

A)   timing the interval between transits.
B)   taking spectra of the star as the planet transits.
C)   measuring microlensing of the transiting planet.
D)   Directly imaging the planet during a transit.

Question 9

What fraction of the mass of the universe is in the form of atoms other than hydrogen and helium?

Accepted Answer

A)   10%
B)   much less than 1%
C)   2%
D)   50%

Question 10

If one wants to find an exoplanet capable of sustaining life, he would look for each one of these situations EXCEPT

Accepted Answer

A)   a planet far enough from its star that liquid water would not boil away
B)   a planet close enough to its star that liquid water would not be permanently frozen
C)   a star without an extremely large wind
D)   a solar system containing a giant planet in a highly eccentric orbit

Question 11

The MOST abundant material in the universe is

Accepted Answer

A)   nitrogen.
B)   carbon dioxide.
C)   water.
D)   hydrogen.

Question 12

Most of the mass of the universe-98%-is in the form of

Accepted Answer

A)   hydrogen and helium.
B)   nitrogen and oxygen.
C)   iron and silicon.
D)   hydrogen.

Question 13

What fraction of the mass of Earth is made up of the elements hydrogen and helium?

Accepted Answer

A)   about 70%
B)   2%
C)   much less than 1%
D)   98%

Question 14

Which of these solar system events is MOST analogous to the phase cycle brightness method for detecting exoplanets?

Accepted Answer

A)   the lunar cycle
B)   solar eclipses
C)   the gravitational motion of the Sun induced by the planets
D)   lunar eclipses

Question 15

What type of search technique has discovered the largest number of planets around stars other than the Sun?

Accepted Answer

A)   looking for tiny variations in the star's position in the sky, caused by the gravitational pull of one or more planets orbiting the star
B)   looking for tiny variations in the star's radial velocity, caused by the gravitational pull of one or more planets orbiting the star
C)   looking for tiny variations in the star's brightness, caused by the planet moving in front of the star
D)   using space-based telescopes to search for tiny pinpoints of light that follow circular or elliptical paths around the star

Question 16

The oldest extrasolar planets have been found in

Accepted Answer

A)   open clusters.
B)   black holes.
C)   globular clusters.
D)   the nucleus of our Galaxy.

Question 17

Some moons of exoplanets have been detected through

Accepted Answer

A)   their effects on the measured radial velocities of exoplanets.
B)   their effects on the duration of exoplanet transits.
C)   their infrared emission.
D)   the light they reflect from their star.

Question 18

In astronomy, a dense core is a region in the process of forming a

Accepted Answer

A)   star.
B)   black hole.
C)   white dwarf.
D)   galactic bulge.

Question 19

The very first exoplanets to be discovered were found through

Accepted Answer

A)   distorted protoplanetary disks.
B)   variations in the stars radial velocity.
C)   pulsar timing.
D)   transits of the exoplanet in front of its star.

Question 20

Which of these characteristics of the extrasolar planets that have so far been discovered surprised astronomers?

Accepted Answer

A)   More than half of the extrasolar planets have strong lines of molecular oxygen in their spectra, a possible indication of life on these planets.
B)   The majority of the extrasolar planets rotate much faster than the planets in our solar system.
C)   Many of the extrasolar planets are giant planets like Jupiter, orbiting at distances characteristic of terrestrial planets like Earth, where giant planets were not believed to be able to form.
D)   Many of the extrasolar planets are terrestrial planets like Earth, orbiting at distances characteristic of giant planets like Jupiter, where terrestrial planets were not believed to be able to form.

Exam 5: Exoplanets and the Formation of Planetary Systems