Question 1

Which of these provides a plausible method to measure the mass of an exoplanet?
A) We use Newton's law of gravity, using the measured distance of the planet from its star and the planet's gravitational pull on the star.
B) We cannot make any firm estimate of the mass of an extrasolar planet with present technology.
C) We use spectra to measure the planet's temperature and photometry to measure its brightness.
D) We measure the planet's angular diameter and hence its size and then use spectra to find its composition and hence density.

Accepted Answer

A) The mass of an exoplanet can be estimated by observing its gravitational effect on its host star, using Newton's law of gravity. This involves measuring the distance of the planet from its star and observing how the planet's gravity influences the star's motion.

Question 2

For an exoplanet to be detected via the astrometric method, it must
A) orbit its star with a component of its motion parallel to the line of sight to from the star to Earth.
B) orbit its star with a component of its motion perpendicular to the line of sight to from the star to Earth.
C) have a low albedo.
D) have a high albedo.

Accepted Answer

The astrometric method detects exoplanets by observing the slight movements (wobbles) of a star around the common center of mass with its planet(s). This movement is most easily observed when the planet's orbit has a component perpendicular to our line of sight, causing the star to move side to side in the sky from our perspective.

Question 3

An astronomer is trying to detect an exoplanet via the radial velocity method. Which of these changes to a particular planet will make it harder to detect, if everything else about the planet is unchanged?
A) decreasing its orbital period
B) decreasing its mass
C) decreasing its radius
D) decreasing its albedo

Accepted Answer

Decreasing the mass of an exoplanet makes it harder to detect using the radial velocity method because the gravitational influence of the planet on its host star is reduced, leading to smaller shifts in the star's velocity that are harder to detect. The radial velocity method relies on detecting variations in the velocity of a star due to the gravitational pull of an orbiting planet, so a less massive planet exerts a weaker force and produces smaller velocity changes.

Question 4

An astronomer is trying to detect an exoplanet via the phase cycle brightness method. Which of these changes to a particular planet will make it easier to detect, if everything else about the planet is unchanged?
A) decreasing its mass
B) increasing its mass
C) decreasing its albedo
D) increasing its albedo

Accepted Answer

Increasing the albedo of a planet makes it easier to detect via the phase cycle brightness method because a higher albedo means the planet reflects more light from its star, making it brighter and more observable from Earth.

Question 5

The transit photometry method for detecting extrasolar planets around distant stars relies on variations in the star's
A) brightness.
B) velocity.
C) position on the sky.
D) spectrum.

Accepted Answer

The transit photometry method detects planets by observing the slight dimming of a star's brightness as a planet passes in front of it.

Question 6

In order to detect multiple planets around a single star using the transit photometry method, the planets must have nearly the same
A) orbital periods.
B) masses.
C) orbital plane.
D) diameters.

Accepted Answer

For the transit photometry method to detect multiple planets around a single star, the planets must pass in front of the star from our point of view. This requires them to have nearly the same orbital plane, so that each planet can transit the star as seen from Earth.

Question 7

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

Accepted Answer

Direct imaging is more successful when an exoplanet has a high albedo, as it reflects more light, making it easier to detect against the glare of its host star.

Question 8

Exoplanets have been detected around binary stars through
A) their effects on the spectra of the stars.
B) the slow increase in the orbital period of the stars, induced by the planet's gravity.
C) the slow decrease in the orbital period of the stars, induced by the planet's gravity.
D) their effects on the timing of eclipses of the stars.

Accepted Answer

The answer of Exoplanets have been detected around binary stars...

Question 9

Which of these methods for detecting exoplanets requires astronomers to take spectra of the stars around which the exoplanets orbit?
A) astrometric method
B) radial velocity method
C) transit photometry method
D) transit timing method

Accepted Answer

The radial velocity method involves measuring the Doppler shifts in the spectrum of a star as it moves towards or away from us due to the gravitational influence of an orbiting exoplanet, which causes slight changes in the star's velocity.

Question 10

In searches for planets orbiting stars other than the Sun, what is the astrometric method?
A) searching for tiny "bumps" on images of a star, due to the light from a planet located close to the star
B) searching for tiny displacements of the infrared image of a star compared with its optical image, caused by the presence of planets that are cool and emit primarily in the infrared
C) searching for tiny wobbles in the position of a star, due to the gravitational pull of a planet orbiting around it
D) searching for tiny wobbles in the positions of absorption lines in a star's spectrum, caused by radial velocity variations of the star as the result of a planet orbiting around it

Accepted Answer

The astrometric method involves searching for tiny wobbles in the position of a star, which are caused by the gravitational pull of a planet orbiting around it. This method relies on the fact that a planet and its host star orbit around their common center of mass, causing the star to move in a small orbit that can be detected through precise measurements of its position in the sky.

Question 11

Astronomers believe that the stellar disk around the star Beta Pictoris contains a Jupiter-size planet. Why do they think this?
A) The planet was imaged directly by the Hubble Space Telescope.
B) Effects of the intense magnetic field of this planet can be detected by powerful radio telescopes.
C) The gravitational effect of this planet has created an off-center disk of dust and gas around the star.
D) The planet causes a measurable decrease in the brightness of Beta Pictoris when it transits across its disk.

Accepted Answer

The gravitational effect of a planet can influence the distribution of material in the disk surrounding its star, leading to observable asymmetries such as an off-center disk of dust and gas. This is why astronomers believe a Jupiter-size planet exists around Beta Pictoris.

Question 12

An exoplanet discovered through the transit photometry method is unlikely to also be detectable with what other method of detecting exoplanets?
A) astrometric method
B) radial velocity method
C) variable transit timing method
D) phase cycle brightness method

Accepted Answer

The astrometric method relies on detecting the tiny wobbles in a star's position caused by the gravitational pull of an orbiting planet, which is independent of the transit photometry method that detects planets by observing the dimming of a star as a planet passes in front of it. The other methods listed (B, C, D) can complement or be related to observations made through transit photometry.

Question 13

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

Accepted Answer

The transit method, which looks for tiny variations in a star's brightness as a planet passes in front of it, has been the most successful technique in discovering exoplanets. This method has been particularly effective when used by space telescopes like Kepler.

Question 14

An astronomer is trying to detect an exoplanet via the radial velocity method. Which of these changes to a particular planet will make it easier to detect, if everything else about the planet is unchanged?
A) increasing its radius
B) increasing its mass
C) increasing its orbital period
D) All of these are correct.

Accepted Answer

Increasing the mass of the planet increases its gravitational pull on the star, causing a larger wobble that is easier to detect with the radial velocity method. Increasing the radius or orbital period does not directly affect the star's motion in a way that enhances detectability by this method.

Question 15

Which of these pairs of exoplanet detection methods are MOST similar in the physical processes underlying the methods?
A) The transit duration time variation and eclipsing binary minima variation methods
B) The astrometric and transit photometry methods
C) The phase cycle brightness and radial velocity methods
D) The distorted disk and radial velocity methods

Accepted Answer

The transit duration time variation and eclipsing binary minima variation methods both rely on the observation of changes in the light curve as a result of objects passing in front of or behind a star, making them similar in the physical processes they utilize for detection.

Question 16

Which of these solar system events is MOST analogous to the phase cycle brightness method for detecting exoplanets?
A) the lunar cycle
B) solar eclipses
C) the gravitational motion of the Sun induced by the planets
D) lunar eclipses

Accepted Answer

The phase cycle brightness method for detecting exoplanets involves observing the changes in brightness of a star as an orbiting planet reflects more or less light at different points in its orbit, similar to how the brightness of the Moon changes during its lunar cycle due to the varying amounts of sunlight it reflects as seen from Earth.

Question 17

Some moons of exoplanets have been detected through
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.

Accepted Answer

Moons of exoplanets, also known as exomoons, can be detected through their effects on the duration of exoplanet transits. When an exoplanet with a moon passes in front of its host star from our point of view, the moon can cause deviations in the timing and duration of the planet's transit across the star. This can provide indirect evidence of the moon's presence.

Question 18

An astronomer is trying to detect an exoplanet via the astrometric method. Which of these changes to a particular planet will make it easier to detect, if everything else about the planet is unchanged?
A) increasing its radius
B) increasing its mass
C) increasing its orbital period
D) All of these are correct.

Accepted Answer

The astrometric method of detecting exoplanets relies on observing the tiny wobbles in a star's position caused by the gravitational pull of an orbiting planet. Increasing the mass of the planet enhances this gravitational effect, making the star's wobble more pronounced and the planet easier to detect. Changes in the planet's radius or orbital period do not directly affect the star's wobble in a way that would make detection easier using this method.

Question 19

After studying an exoplanet system carefully, astronomers determine that the intervals between the transits of a given exoplanet vary in a complex fashion. This most likely indicates that the system
A) has an exoplanet with a thick atmosphere.
B) is actually a binary star.
C) has multiple exoplanets.
D) has an exoplanet with a ring system.

Accepted Answer

The variation in transit intervals suggests the gravitational influence of other exoplanets in the system, causing the observed planet to speed up or slow down in its orbit due to their gravitational interactions.

Question 20

Which of these methods has provided strong evidence for the existence of hundreds of planetary systems around other stars?
A) detection of very regular pulses of radio energy from some stars.
B) spectroscopic evidence of large quantities of molecules such as ammonia and methane, which can exist only in planetary atmospheres.
C) direct photography of actual planets near other stars.
D) periodic wobbling of the positions and spectral line displacements of several nearby stars.

Accepted Answer

The periodic wobbling of the positions and spectral line displacements of several nearby stars, known as the Doppler or radial velocity method, has provided strong evidence for the existence of planets around other stars. This wobbling effect is caused by the gravitational influence of orbiting planets on their host stars.

Quiz 5: Exoplanets and the Formation of Planetary Systems

Which of these provides a plausible method to measure the mass of an exoplanet?

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

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

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

The transit photometry method for detecting extrasolar planets around distant stars relies on variations in the star's

In order to detect multiple planets around a single star using the transit photometry method, the planets must have nearly the same

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

Exoplanets have been detected around binary stars through

Which of these methods for detecting exoplanets requires astronomers to take spectra of the stars around which the exoplanets orbit?

In searches for planets orbiting stars other than the Sun, what is the astrometric method?

Astronomers believe that the stellar disk around the star Beta Pictoris contains a Jupiter-size planet. Why do they think this?

An exoplanet discovered through the transit photometry method is unlikely to also be detectable with what other method of detecting exoplanets?

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

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

Which of these pairs of exoplanet detection methods are MOST similar in the physical processes underlying the methods?

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

Some moons of exoplanets have been detected through

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

After studying an exoplanet system carefully, astronomers determine that the intervals between the transits of a given exoplanet vary in a complex fashion. This most likely indicates that the system

Which of these methods has provided strong evidence for the existence of hundreds of planetary systems around other stars?