Deck 11: Extrasolar Planets: Their Nature and Potential Habitability

Question 1

O-type stars in our galaxy are

A) very common, making up about 50% of the total
B) fairly common (several percent)
C) very rare (less than 1%)
D) the most common type of stars in our galaxy (75% or more)

Answer 1

very rare (less than 1%)

Question 2

Solar-type stars in our galaxy are

A) very common, making up about 50% of the total
B) very rare (less than 1%)
C) fairly common (several percent)
D) the most common type of stars in our galaxy (75% or more)

Answer 2

fairly common (several percent)

Question 3

High mass stars are much less common than low mass stars because they

A) are born in much smaller numbers
B) have much shorter lifetimes
C) have much longer lifetimes
D) two of these

Answer 3

two of these

Question 4

When a star finally runs out of hydrogen to fuse in its central core

A) it grows smaller and dimmer, becoming a brown dwarf
B) it grows larger and brighter, becoming a giant or supergiant star
C) it grows smaller and dimmer becoming a white dwarf
D) it remains the same size but grows brighter

Question 5

The intrinsic brightness of a star is referred to as its

A) radiance
B) luminosity
C) surface temperature
D) apparent brightness

Question 6

M-type stars in our galaxy are

A) fairly common (several percent)
B) the most common type of stars in our galaxy (75% or more)
C) very common, making up about 50% of the total
D) very rare (less than 1%)

Question 7

A star less massive than our Sun

A) will have a longer lifetime
B) will have a shorter lifetime
C) will have the same lifetime as the Sun
D) could have either a longer lifetime or a shorter lifetime depending on its chemical composition

Question 8

Stars are mostly made of

A) hydrogen and helium
B) pure hydrogen
C) carbon, hydrogen, oxygen and nitrogen
D) an equal mixture of all elements

Question 9

The presence of elements heavier than helium in stars is very important because

A) they provide the raw materials for the formation of planets and life
B) without them they could not form
C) they help stabilize their interiors
D) they are responsible for the fusion reactions at their centers

Question 10

What is the most common class of star in our galaxy?

A) G-type
B) O-type
C) M-type
D) A-type

Question 11

What is the minimum possible mass for a star?

A) 0.01 solar masses
B) 0.008 solar masses
C) 0.1 solar masses
D) 0.08 solar masses

Question 12

The most important property of a star which determines its evolution is its

A) chemical composition
B) surface temperature
C) mass
D) radius

Question 13

The color of a star is a measure of its

A) surface temperature
B) chemical composition
C) mass
D) size

Question 14

What proportion of their lives do stars spend fusing hydrogen to helium in their cores?

A) 90%
B) 70%
C) 50%
D) 10%

Question 15

Compared to young stars, very old stars have

A) exactly the same chemical composition
B) a lower proportion of elements heavier than helium
C) a higher proportion of elements heavier than helium
D) no elements heavier than helium at all

Question 16

What is the least common class of star in our galaxy?

A) A-type
B) M-type
C) O-type
D) G-type

Question 17

One of the fundamental principles of stellar evolution is that the more massive a star is

A) the more heavy elements it contains
B) the more planets it has around it
C) the faster it evolves
D) the slower it evolves

Question 18

Stars spend most of their lives

A) fusing hydrogen into helium in their cores
B) slowly dimming as they die with no fusion occurring in their cores
C) as slowly brightening protostars
D) fusing helium into carbon in their cores

Question 19

A star more massive than our Sun

A) will have a longer lifetime
B) will have a shorter lifetime
C) will have the same lifetime as the Sun
D) could have either a longer lifetime or a shorter lifetime depending on its chemical composition

Question 20

Approximately what proportion of stars have masses lower than the Sun?

A) 90%
B) 10%
C) 50%
D) 70%

Question 21

Which of the following could be a stable planetary orbit in a binary system?

A) a large orbit around both stars in a wide binary system
B) an orbit close to one of the stars in a wide binary system
C) a "figure-of-eight" orbit about both stars in a close binary system
D) an orbit close to one of the stars in a close binary system

Question 22

Multiple star systems in our galaxy

A) are extremely rare, making up less than 1% of the total
B) are very common, making up about 50% of the total
C) are fairly common, making up around 30% of the total
D) do not exist

Question 23

G-, K-, and M-type stars

A) do not contain enough heavy elements to form planets
B) have lifetimes long enough for planets to form and for simple life to appear, but not long enough for advanced life to develop
C) have lifetimes too short for planet formation
D) have lifetimes long enough for advanced life to evolve

Question 24

The center of mass of the solar system is

A) midway between the Sun and Jupiter
B) exactly at the center of the Sun
C) just outside the orbit of Mercury
D) close to but not exactly at the center of the Sun

Question 25

When a low mass star like our Sun dies, it leaves behind a

A) white dwarf
B) brown dwarf
C) neutron star
D) black hole

Question 26

Even though K- and M-type stars are suitable for life, why might they not have many habitable planets around them?

A) because their habitable zones are very wide
B) because their habitable zones are very narrow
C) because their lifetimes are too short
D) because they contain too few heavy elements to form planets

Question 27

B-type stars have lifetimes

A) long enough for advanced life to evolve
B) too short for planet formation
C) long enough for planets to form but not for life to appear
D) long enough for planets to form and for simple life to appear, but not long enough for advanced life to develop

Question 28

Brown dwarfs have

A) very narrow habitable zones
B) no habitable zones
C) very wide habitable zones
D) habitable zones similar to the Sun

Question 29

O-type stars

A) have lifetimes long enough for advanced life to evolve
B) have lifetimes long enough for planets to form and for life to appear, but not long enough for advanced life
C) do not contain enough heavy elements to form planets
D) have lifetimes too short for planet formation

Question 30

Life will most likely be able to appear and evolve on a planet around which stage of a star's life?

A) core hydrogen-fusion
B) shell helium-fusion
C) core helium-fusion
D) shell hydrogen-fusion

Question 31

Which of the following types of stars are NOT suitable for advanced life?

A) K-type
B) M-type
C) G-type
D) F-type

Question 32

In most extrasolar planetary systems the center of mass is likely to be located

A) midway between the star and its most massive planet
B) close to the center of the parent star
C) exactly at the center of the parent star
D) close to the center of the most massive planet

Question 33

Life may be less likely around A- and F-type stars because

A) they emit large quantities of ultraviolet radiation
B) they experience violent surface activity
C) their habitable zones are very narrow
D) rocky planets are unlikely to form around them

Question 34

Brown dwarfs are

A) stars in the process of forming
B) very cool, low mass stars of spectral type M
C) the burnt out cores of dead stars
D) objects with insufficient mass to sustain nuclear fusion in their cores

Question 35

A- and F-type stars

A) do not contain enough heavy elements to form planets
B) have lifetimes long enough for advanced life to evolve
C) have lifetimes too short for planet formation
D) have lifetimes long enough for planets to form and for simple life to appear, but not long enough for advanced life to develop

Question 36

Which of the following types of stars are suitable for advanced life?

A) A-type
B) F-type
C) O-type
D) K-type

Question 37

Which of the following could be a stable planetary orbit in a binary system?

A) a large orbit around both stars in a close binary system
B) a "figure-of-eight" orbit about both stars in a close binary system
C) an orbit close to one of the stars in a close binary system
D) a large orbit around both stars in a wide binary system

Question 38

Which of the following methods has been the MOST successful in detecting extrasolar planets around other star systems?

A) regular changes in the positions of the parent stars with respect to more distant stars as they move across the sky
B) detection of brightness changes in a star as a planet passes in front of it
C) detection of Doppler shifts in the spectra of the parent stars
D) detection of reflected starlight

Question 39

Which type of stable planetary orbit would be best in a wide binary system?

A) a large elliptical orbit around both components
B) a large circular orbit around both components
C) a "figure-of-eight" orbit around both components
D) an orbit close to one of the components

Question 40

When high-mass stars dies, they explode as supernovae, leaving behind a

A) white dwarf
B) neutron star or black hole
C) brown dwarf
D) red dwarf

Question 41

Which space mission is searching for extrasolar planets using the astrometric method?

A) Kepler
B) GAIA
C) CoRoT
D) Spitzer

Question 42

What is a major limitation in the Doppler method for detecting extrasolar planets?

A) it is better at finding massive planets like Jupiter rather than small planets like the Earth
B) it is best suited to finding planets which orbit relatively close to their star
C) it requires the use of fairly large telescopes and long exposures which limits the number of star that can be studied
D) all of these are major limitations

Question 43

Which of the following methods describes the transit method for detecting extrasolar planets?

A) regular changes in the positions of the parent stars with respect to more distant stars as they move across the sky
B) detection of Doppler shifts in the spectra of the parent stars
C) detection of brightness changes in a star as a planet passes in front of it
D) detection of reflected starlight

Question 44

For the transit of an extrasolar planet to be observed, the

A) orbital plane of the planet has to be aligned along our line of sight
B) planet has to be very large
C) orbital plane has to be perpendicular to our line of sight
D) parent star has to be very small

Question 45

The wavelengths of radiation from a star that is moving toward us

A) can be longer or shorter depending on the distance to the star
B) are shorter than if the star were not moving
C) are longer than if the star were not moving
D) are the same as if the star were not moving

Question 46

Gravitational lensing is the process by which

A) a massive object magnifies and distorts the light from an object behind it
B) the wavelengths of light from a star are shifted as it moves about its center of mass
C) a planet passes in front of its parent star and blocks part of its light
D) a massive object accelerates another object that passes close to it

Question 47

If a star has an extrasolar planet, the amplitude of its radial velocity curve is related to the planet's

A) mass
B) orbital shape
C) orbital period
D) radius

Question 48

Stars only exhibit a Doppler shift if they are moving

A) away from us along the line of sight
B) perpendicular to our line of sight
C) in a circular motion about us
D) toward or away from us along the line of sight

Question 49

When Mercury or Venus passes in front of the disk of the Sun, we call this

A) an eclipse
B) a shadow event
C) a transit
D) an occultation

Question 50

Which of the following extrasolar planets would be the most difficult to detect using the Doppler shift method?

A) a low mass planet far from its parent star
B) a massive planet close to its parent star
C) a low mass planet close to its parent star
D) a massive planet far from its parent star

Question 51

If a star has an extrasolar planet, the wavelength of its radial velocity curve is related to the planet's

A) orbital shape
B) radius
C) mass
D) orbital period

Question 52

The radial velocity curve of a star with an extrasolar planet is a plot of

A) radial velocity against luminosity
B) radial velocity against brightness
C) radial velocity against distance
D) radial velocity against time

Question 53

Which of the following extrasolar planets would be easiest to detect using the Doppler shift method?

A) a massive planet far from its parent star
B) a low mass planet far from its parent star
C) a low mass planet close to its parent star
D) a massive planet close to its parent star

Question 54

Which of the following methods uses astrometry to detect extrasolar planets around other star systems?

A) detection of Doppler shifts in the spectra of the parent stars
B) detection of reflected starlight
C) detection of brightness changes in a star as a planet passes in front of it
D) regular changes in the positions of the parent stars with respect to more distant stars as they move across the sky

Question 55

Which of the following methods has been the LEAST successful in detecting extrasolar planets around other star systems?

A) regular changes in the positions of the parent stars with respect to more distant stars as they move across the sky
B) detection of Doppler shifts in the spectra of the parent stars
C) detection of brightness changes in a star as a planet passes in front of it
D) detection of reflected starlight

Question 56

The wavelengths of radiation from a star that is moving perpendicular to us

A) can be longer or shorter depending on the distance to the star
B) are shorter than if the star were not moving
C) are longer than if the star were not moving
D) are the same as if the star were not moving

Question 57

A nearby star is discovered to have a high mass planet at a very small distance from it. What would its radial velocity curve look like?

A) large amplitude, short wavelength
B) small amplitude, long wavelength
C) small amplitude, short wavelength
D) large amplitude, long wavelength

Question 58

The wavelengths of radiation from a star that is moving away from us

A) can be longer or shorter depending on the distance to the star
B) are shorter than if the star were not moving
C) are the same as if the star were not moving
D) are longer than if the star were not moving

Question 59

Which method of exoplanet detection is based on Einstein's General Theory of Relativity?

A) Doppler
B) transit
C) microlensing
D) astrometric

Question 60

In an extrasolar planetary system containing a single planet, the parent star is measured to move about its center of mass every 24 years. Given this, what is the orbital period of the planet?

A) 48 years
B) 12 years
C) 24 years
D) this cannot be determined from this observation

Question 61

The habitable zones for stars may be considerably larger if they have planetary systems containing

A) super-Earths with thick hydrogen atmospheres
B) Earth-sized planets with thick carbon dioxide atmospheres
C) super-Earths with thin hydrogen atmospheres
D) Earth-sized planets with thick methane atmospheres

Question 62

If a star has an extrasolar planet, the shape of its radial velocity curve is related to the planet's

A) orbital eccentricity
B) mass
C) radius
D) orbital period

Question 63

Many of the known extrasolar planets orbit their stars

A) more closely than Mercury orbits the Sun
B) at about the same distance as the Earth orbits the Sun
C) at about the same distance as the planet Jupiter orbits the Sun
D) much further than the distance the planet Jupiter orbits the Sun

Question 64

Studies of multiplanet exoplanet systems have shown us that other planetary systems can sometimes differ from ours by

A) having their planets packed much closer to each other than our solar system's planets
B) exist in binary star systems
C) containing planets with much lower masses
D) two of these

Question 65

The results of statistical studies of the exoplanet systems discovered to date suggests that what proportion of stars are likely to have a planet less than half the size of the Earth and in an orbit within a star's habitable zone?

A) 10 to 20%
B) 50%
C) much less than 10%
D) more than 90%

Question 66

The average density of a planet can be obtained from

A) the Doppler method only
B) a combination of the Doppler and transit methods
C) the transit method only
D) a combination of the astrometric and Doppler methods

Question 67

If we are eventually able to detect Earth-like extrasolar planets directly, they will be seen very

A) close to their parent stars and will be very dim in comparison
B) far from their parent stars and will be very dim in comparison
C) far from their parent stars and will be bright in comparison
D) close to their parent stars and will be bright in comparison

Question 68

Why does the Doppler shift method of detecting extrasolar planets only give us the minimum mass of a planet?

A) because we don't necessarily know the density of the planet
B) because we don't necessarily know the angle the planet's orbit makes with our line of sight
C) because we don't necessarily know the diameter (size) of the planet
D) because we don't necessarily know the mass of the parent star very

Question 69

Imagine we have a planet identical to Jupiter around another star, with the exception that its orbit is much closer. How would its density compare to Jupiter?

A) it would be slightly higher
B) it would be much higher
C) it would be lower
D) it would be the same

Question 70

Imagine we have a planet identical to Jupiter around another star, with the exception that its orbit is much closer. How would its size compare to Jupiter?

A) it would be the same size
B) it would be larger
C) it would be much smaller
D) it would be slightly smaller

Question 71

When we measure the mass of a planet using the Doppler shift method, we know that it is mass

A) could well be smaller
B) could be larger or smaller
C) is exactly as measured
D) could well be larger

Question 72

Compared to the planets in our own solar system, exoplanets have

A) a much narrow range of composition
B) a much wider range of compositions
C) an almost identical range of compositions
D) completely different compositions

Question 73

Which method of extrasolar planet detection is able to measure the compositions of extrasolar planet atmopsheres?

A) gravitational lensing
B) Doppler technique
C) transit technique
D) astrometric technique

Question 74

The orbits of many extrasolar planets detected to date are

A) parabolic
B) highly elliptical
C) perfectly circular
D) slightly elliptical

Question 75

The results of statistical studies of the exoplanet systems discovered to date suggest that

A) planets are common
B) small planets outnumber large plates by a significant margin
C) Earth-size planets are very common
D) all of these are true

Question 76

How can we explain the presence of extrasolar planetary systems with Jovian-sized planets at distances at which we normally find terrestrial planets?

A) they are brown dwarfs that were captured by their parent stars
B) these are massive terrestrial planets that formed close to their parent stars
C) they are Jovian planets that were spun out from their rapidly spinning parent stars
D) the Jovian planets formed farther out and then migrated inward

Question 77

Which of the following methods allows us to determine the size of an extrasolar planet around another star?

A) detection of brightness changes in a star as a planet passes in front of it
B) detection of reflected starlight
C) regular changes in the positions of the parent stars with respect to more distant stars as they move across the sky
D) detection of Doppler shifts in the spectra of the parent stars

Question 78

A planet with a density comparable to the Earth but several times more massive is described as a

A) mini-Neptune
B) super-Earth
C) mega-Earth
D) super-Jovian

Question 79

Why is it better to search for extrasolar planets directly using infrared (IR) rather than visible radiation?

A) the planet doesn't reflect any visible radiation, only IR radiation
B) the star doesn't emit any IR radiation because it is too hot
C) the visible light from planets will be blocked by interstellar dust along our line of sight while the IR radiation will not
D) the planet emits more IR radiation than it reflects in the visible

Question 80

Many of the extrasolar planets that have been detected directly to date are

A) very large and at great distances from their parent star
B) small and at great distances from their parent star
C) small and close to their parent star
D) very large and close to their parent star