Chapter 13 home work 9 Other Planetary Systems

Question 1

Which of the following properties can be inferred from the star’s orbital period?

the planet’s orbital radius
the planet’s mass
both the planet’s orbital radius and its mass
neither the planet’s orbital radius nor its mass

Answer 1

the planet’s orbital radius

Question 2

Is it possible to determine the planet’s mass from the star’s velocity curve?

yes, by measuring the star's orbital period only
yes, by measuring only the change in the star's orbital velocity over the orbit
yes, by measuring both the star's orbital period and its change in velocity over the orbit
no, because the star's spectrum cannot tell us about the planet

Answer 2

yes, by measuring both the star’s orbital period and its change in velocity over the orbit

Question 3

Consider the planet that causes the stellar motion shown in Plot 2 (be sure you have clicked the “Plot 2” button in the lower window of the animation). What can be said about a different planet orbiting the same star with an orbital period of 500 days?

The planet must be farther from the star.
The planet must be more massive.
The planet must be less massive.
The planet must be closer to the star.

Answer 3

The planet must be closer to the star.

Question 4

The ______ was used to find a jupiter sized planet through careful measurements of the changing position of a star

Answer 4

Astrometric technique

Question 5

Discovering planets through the _________ requires obtaining and studying many spectra of the same star.

Answer 5

Doppler technique

Question 6

The _____ is currently searching for planet transits around some 100,000 stars.

Answer 6

Kepler mission

Question 7

The ________ is used to find extrasolar planets by carefully monitoring chnages in a star’s brightness with time.

Answer 7

transit technique

Question 8

The _________ is being designed to measure very small changes in stellar positions, which should allow it to discover many extrasolar planets.

Answer 8

GAIA Astrometry Mission

Question 9

Proposed plans for the _______ would someday provide us with the first actual images and spectra of terrestrial worlds orbiting other stars.

Answer 9

Terrestrial Planet Finder mission

Question 10

Each item describes a characteristic that applies to one of the three planet-detection methods shown following. Match the items to the correct planet-finding method. Doppler Method:

Used for most of the first 200 extrasolar planets detections
Current best-suited to find Jupiter sized extrasolar planets orbiting close to their stars
Planet detection strategy of Nasa’s Kepler Mission
Allows for the extrasolar planets radius to be determined
Can potentially detect planets in only a few percent of all planetary systems
Looks for very slight, periodic dimming of a star
This method was first to identify Earth-sized extrasolar planets.
Measures precise changes in a star’s position in the sky, fractions of acrseconds.

Answer 10

Used for most of the first 200 extrasolar planets detections

Current best-suited to find Jupiter sized extrasolar planets orbiting close to their stars

Question 11

Each item describes a characteristic that applies to one of the three planet-detection methods shown following. Match the items to the correct planet-finding method. Transit Method:

Used for most of the first 200 extrasolar planets detections
Current best-suited to find Jupiter sized extrasolar planets orbiting close to their stars
Planet detection strategy of Nasa’s Kepler Mission
Allows for the extrasolar planets radius to be determined
Can potentially detect planets in only a few percent of all planetary systems
Looks for very slight, periodic dimming of a star
This method was first to identify Earth-sized extrasolar planets.
Measures precise changes in a star’s position in the sky, fractions of acrseconds.

Answer 11

Planet detection strategy of Nasa’s Kepler Mission
Allows for the extrasolar planets radius to be determined
Can potentially detect planets in only a few percent of all planetary systems
Looks for very slight, periodic dimming of a star
This method was first to identify Earth-sized extrasolar planets.

Question 12

Each item describes a characteristic that applies to one of the three planet-detection methods shown following. Match the items to the correct planet-finding method. Astrometric Method:

Used for most of the first 200 extrasolar planets detections
Current best-suited to find Jupiter sized extrasolar planets orbiting close to their stars
Planet detection strategy of Nasa’s Kepler Mission
Allows for the extrasolar planets radius to be determined
Can potentially detect planets in only a few percent of all planetary systems
Looks for very slight, periodic dimming of a star
This method was first to identify Earth-sized extrasolar planets.
Measures precise changes in a star’s position in the sky, fractions of acrseconds.

Answer 12

Measures precise changes in a star’s position in the sky, fractions of acrseconds.

Question 13

The graph above shows how a star’s orbital speed varies with time due to the gravitational tug of an orbiting planet. These data were obtained by measuring __________.

the precise wavelengths of spectral lines in the spectrum of the orbiting planet
the precise brightness of the star divided by the precise brightness of the planet
the precise wavelengths of spectral lines in the spectrum of the star
the orbital period of the planet that is orbiting the star

Answer 13

the precise wavelengths of spectral lines in the spectrum of the star

Question 14

The graph above shows how a star’s orbital speed varies with time due to the gravitational tug of an orbiting planet. Based on these data, the planet’s orbital period is about:

2 days.
4 days.
6 days.
50 days.

Answer 14

4 days.

Question 15

This diagram shows the orbital path of the Sun around the center of mass of our solar system as it would appear from a distance of 30 light-years for the period 1960-2025. If aliens had constructed this graph at their home star system, they could learn all of the following except:

the fact that large, icy objects orbit the Sun in the Kuiper belt.
the fact that the Sun has more than two planets.
the mass and orbital period of Jupiter.
the orbital distance of Saturn.

Answer 15

the fact that large, icy objects orbit the Sun in the Kuiper belt.

Question 16

This painting shows what “hot Jupiter” might look like as it orbits its star at a distance of about 0.02 AU. Which of the following best interprets what is shown?

We are seeing the planet in gibbous phase.
It is glowing on its night side because its cloudtops are hot enough to emit visible light.
The planet has a striped appearance because different cloud layers reflect different amounts of light from the star.
The planet is rotating so rapidly that light from the day side is bent around to the night side.

Answer 16

It is glowing on its night side because its cloudtops are hot enough to emit visible light.

Question 17

What is an extrasolar planet?

         A planet that is considered an "extra," in that it was not needed for the formation of its solar system        
         A planet that is extra large compared to what we'd expect        
         A planet that orbits a star that is not our own Sun        
         A planet that is larger than the Sun

Answer 17

A planet that orbits a star that is not our own Sun

Question 18

Before the Kepler Mission began, most known extrasolar planets had been discovered by ____________.

the Doppler technique
the astrometric technique
the transit technique.
the Hubble Space Telescope

Answer 18

the Doppler technique

Question 19

How does the Kepler mission look for planets around other stars?

It is sufficiently powerful to take low-resolution photographs of planets orbiting nearby stars.
It looks for slight changes in a star's brightness that repeat at regular intervals.
It looks for slight back and forth shifts in a star's position in our sky.
It looks for Doppler shifts in stellar spectra.

Answer 19

It looks for slight changes in a star’s brightness that repeat at regular intervals.

Question 20

What information does the Doppler technique give about an extrasolar planet?

         the planet's density        
         the planet's minimum mass        
         the planet's radius        
         all of the above

Answer 20

the planet’s minimum mass

Question 21

Which detection techniques can find the planet’s orbital distance (assuming we know the mass of the star)?

         only the transit technique        
         only the Doppler technique        
         only the astrometric technique        
         all of these techniques

Answer 21

all of these techniques

Question 22

What is the closest that extrasolar planets have been found to their stars?

         nearer to their stars than Mercury to our Sun        
         unknown: we do not know the distance with enough accuracy to say        
         nearer to their stars than Earth to the Sun        
         nearer to their stars than Saturn to the Sun

Answer 22

nearer to their stars than Mercury to our Sun

Question 23

Based on available data, what kind of objects in our solar system do most of the known extrasolar planets resemble?

         Kuiper belt objects        
         terrestrial planets        
         jovian planets        
         none of the above: most extrasolar planets apparently belong to some new category of object

Answer 23

jovian planets

Question 24

Which new idea has been added into our theory of solar system formation as a result of the discoveries of extrasolar planets?

         In some star systems, it is possible for jovian planets to form in the inner solar system and terrestrial planets to form in the outer solar system.        
         Some of the "exceptions to the rules" in our own solar system are likely to have been the result of giant impacts.        
         Jovian planets can migrate from the orbits in which they are born.        
         In addition to the categories of terrestrial and jovian, there must be an "in-between" category of planet that has the mass of a jovian planet but the composition of a terrestrial planet.

Answer 24

Jovian planets can migrate from the orbits in which they are born.

Question 25

Why is it so difficult to take pictures of extrasolar planets?

No telescope is powerful enough to detect the faint light from a distant planet.
Telescopes are too busy with other projects.
Extrasolar planets give off light at different wavelengths than planets in our solar system.
Their light is overwhelmed by the light from their star.

Answer 25

Their light is overwhelmed by the light from their star.

Question 26

The astrometric technique looks for planets with careful measurements of a star’s _________.

brightness
velocity towards or away from us
position in the sky
all of the above

Answer 26

position in the sky

Question 27

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?

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

Answer 27

The planet must be closer to the star than Earth is to the Sun.

Question 28

In general, which type of planet would you expect to cause the largest Doppler shift in the spectrum of its star?

a massive planet that is close to its star
a massive planet that is far from its star
a low-mass planet that is far from its star
a low-mass planet that is close to its star

Answer 28

a massive planet that is close to its star

Question 29

Which of the following discoveries relating to extrasolar planets came as a surprise to scientists who expected other solar systems to be like ours?

There are planets ranging in size from smaller than Earth to much larger than Jupiter.
Some planets more massive than Jupiter orbit their star more closely than Mercury orbits the Sun.
In some star systems, we've found more than one planet orbiting the same star.
Many of the planets orbit stars similar to our sun.

Answer 29

Some planets more massive than Jupiter orbit their star more closely than Mercury orbits the Sun.

Question 30

To date, we’ve found very few planets orbiting their stars at distances comparable to the distances of the jovian planets in our solar system. Why do astronomers think this is the case?

Planets at such distances are extremely rare.
Planets at such distances are probably very low in mass.
It takes longer to detect a planet with a long orbital period, and we have only started our search relatively recently.
No known technique can detect planets at such large distances.

Answer 30

It takes longer to detect a planet with a long orbital period, and we have only started our search relatively recently.

Question 31

Current evidence suggests that some massive jovian planets orbit at very close orbital distances to their stars (called ‘Hot Jupiters’). How do we think these planets ended up on these close orbits?

These planets are jovian in nature and were able to form close to their stars because their solar nebulas were very cold in temperature.
Despite their large masses, these planets are terrestrial in nature and therefore could form in their inner solar systems.
These planets migrated inward after being born on orbits much farther from their stars.
These planets were captured from other solar systems.

Answer 31

These planets migrated inward after being born on orbits much farther from their stars.

Question 32

To date (as of March 2013), what is the current number of all extrasolar planets detected, including all planet candidates from the Kepler Mission?

15
over 3,000
0
350

Answer 32

over 3,000