Question 1

How do astronomers explain the "superluminal" motions observed in quasars?

Accepted Answer

A) It is an illusion produced when something moves rapidly almost straight at us 
B) No trick,things really do move faster than the speed of light 
C) The black holes in quasars cause a distortion in the rate of passage of time 
D) Quasars are contracting at almost the speed of light 
A) It is an illusion produced when something moves rapidly almost straight at us 
B) No trick,things really do move faster than the speed of light 
C) The black holes in quasars cause a distortion in the rate of passage of time 
D) Quasars are contracting at almost the speed of light A

Question 2

Absorption lines in quasars usually have lower redshifts than the quasars themselves do.This suggests that the absorption lines are caused by gas

Accepted Answer

A) At the same distance as the quasars 
B) Between us and the quasars 
C) That is farther away than the quasars 
D) In the quasar itself 
A) At the same distance as the quasars 
B) Between us and the quasars 
C) That is farther away than the quasars 
D) In the quasar itself B

Question 3

Which of the following is a good description of a Seyfert galaxy?

Accepted Answer

A) A spiral with a small bright nucleus 
B) A giant elliptical 
C) A tidally distorted irregular galaxy 
D) A galaxy in which star formation has ceased 
A) A spiral with a small bright nucleus 
B) A giant elliptical 
C) A tidally distorted irregular galaxy 
D) A galaxy in which star formation has ceased A

Question 4

Quasars all have great distances.Why are there no nearby quasars?

Accepted Answer

A) No quasars have existed in the recent past 
B) Quasars avoid spiral galaxies 
C) Quasars are found only in clusters of galaxies 
D) If quasars are too close to us,they look like pulsars 
A) No quasars have existed in the recent past 
B) Quasars avoid spiral galaxies 
C) Quasars are found only in clusters of galaxies 
D) If quasars are too close to us,they look like pulsars

Question 5

How do we know that the quasars are at large distances?

Accepted Answer

A) They are extremely dim 
B) They have large redshifts 
C) They have large parallaxes 
D) They are greatly obscured by interstellar dust 
A) They are extremely dim 
B) They have large redshifts 
C) They have large parallaxes 
D) They are greatly obscured by interstellar dust

Question 6

Since quasars are thought to be at cosmological distances,we see them as they were when the universe was

Accepted Answer

A) Much older than it is today 
B) Relatively young 
C) Contracting 
D) Much larger than it is today 
A) Much older than it is today 
B) Relatively young 
C) Contracting 
D) Much larger than it is today

Question 7

Why was it difficult for astronomers to identify the spectral lines observed in the spectra of quasars?

Accepted Answer

A) They were formed by elements unknown on Earth 
B) There were too many lines in the spectra 
C) The lines were greatly redshifted 
D) No two quasars have the same spectral lines 
A) They were formed by elements unknown on Earth 
B) There were too many lines in the spectra 
C) The lines were greatly redshifted 
D) No two quasars have the same spectral lines

Question 8

About how large is a 1 million solar mass black hole such as those that may exist at the centers of many galaxies?

Accepted Answer

A) A few km in radius 
B) A few thousand km in radius 
C) A few million km in radius 
D) A few billion km in radius 
A) A few km in radius 
B) A few thousand km in radius 
C) A few million km in radius 
D) A few billion km in radius

Question 9

Some quasars vary in brightness in only a few days.What does this tell us about the quasars?

Accepted Answer

A) They have large magnetic fields 
B) They are quite small 
C) They must be highly luminous 
D) They cannot emit radio waves 
A) They have large magnetic fields 
B) They are quite small 
C) They must be highly luminous 
D) They cannot emit radio waves

Question 10

How do we know that quasars are no larger than the solar system?

Accepted Answer

A) They vary in brightness on a timescale of days or weeks 
B) They appear pointlike when viewed through a telescope 
C) They contain black holes,which must be small 
D) They are too luminous to be very large 
A) They vary in brightness on a timescale of days or weeks 
B) They appear pointlike when viewed through a telescope 
C) They contain black holes,which must be small 
D) They are too luminous to be very large

Question 11

Why do Seyfert Galaxies strengthen the case for quasars being active young galaxies?

Accepted Answer

A) Seyfert galaxies are closer than most quasars,and brighter. 
B) Seyfert galaxies are closer than most quasars,and are less bright. 
C) Seyfert galaxies are farther away than quasars,and are less bright. 
D) Seyfert galaxies are father away than quasars,and are more bright. 
A) Seyfert galaxies are closer than most quasars,and brighter. 
B) Seyfert galaxies are closer than most quasars,and are less bright. 
C) Seyfert galaxies are farther away than quasars,and are less bright. 
D) Seyfert galaxies are father away than quasars,and are more bright.

Question 12

Which of the following is true of Seyfert galaxies?

Accepted Answer

A) They have no spiral arms 
B) They have unusually bright nuclei 
C) They are a form of elliptical galaxy 
D) They are all found in the Local Group of galaxies 
A) They have no spiral arms 
B) They have unusually bright nuclei 
C) They are a form of elliptical galaxy 
D) They are all found in the Local Group of galaxies

Question 13

The spectra of quasars reveal lines of elements such as nitrogen and carbon.These elements are as abundant in quasars as in the Sun.Which of the following is a correct reflection on this fact?

Accepted Answer

A) This is to be expected,since quasars are powered by nucleosynthesis 
B) This observation verifies our ideas on the evolutionary status of quasars 
C) This is odd,since quasars are old and should have Pop.II abundances 
D) This is unexpected,quasars should have large amounts of iron 
A) This is to be expected,since quasars are powered by nucleosynthesis 
B) This observation verifies our ideas on the evolutionary status of quasars 
C) This is odd,since quasars are old and should have Pop.II abundances 
D) This is unexpected,quasars should have large amounts of iron

Question 14

It is thought that most large galaxies probably have black holes at their centers.

Accepted Answer

A) True 
 B)False

Question 15

Quasars were originally discovered as

Accepted Answer

A) Strong radio sources identified with star-like images on photographs 
B) Variable sources of light 
C) Bright galaxies,and only later found to be radio sources 
D) The only type of radio source within our galaxy 
A) Strong radio sources identified with star-like images on photographs 
B) Variable sources of light 
C) Bright galaxies,and only later found to be radio sources 
D) The only type of radio source within our galaxy

Question 16

For a typical luminous radio galaxy,most of the radio emission comes primarily from

Accepted Answer

A) The core of the galaxy 
B) Spiral arms. 
C) Globular clusters. 
D) Two large regions far from the center of the galaxy 
A) The core of the galaxy 
B) Spiral arms. 
C) Globular clusters. 
D) Two large regions far from the center of the galaxy

Question 17

According to current theories,the energy source of radio galaxies and quasars is

Accepted Answer

A) A one thousand solar mass pulsar in each of two radio lobes 
B) A one hundred million solar mass black hole at the center of the object 
C) The conversion of hydrogen to helium via nuclear reactions 
D) Gravitational contraction of massive stars near the spiral arms 
A) A one thousand solar mass pulsar in each of two radio lobes 
B) A one hundred million solar mass black hole at the center of the object 
C) The conversion of hydrogen to helium via nuclear reactions 
D) Gravitational contraction of massive stars near the spiral arms

Question 18

The radio emission from radio galaxies and quasars is due to

Accepted Answer

A) Thermal emission 
B) 21 cm radiation from hydrogen atoms. 
C) Star formation regions. 
D) Synchrotron radiation 
A) Thermal emission 
B) 21 cm radiation from hydrogen atoms. 
C) Star formation regions. 
D) Synchrotron radiation

Question 19

Quasars are currently believed to be

Accepted Answer

A) The brightest elliptical galaxies 
B) The most luminous supernova remnants 
C) An early phase of intense activity in the centers of galaxies 
D) Structures larger than clusters of galaxies 
A) The brightest elliptical galaxies 
B) The most luminous supernova remnants 
C) An early phase of intense activity in the centers of galaxies 
D) Structures larger than clusters of galaxies

Exam 24: Quasars and Other Active Galaxies

How do astronomers explain the "superluminal" motions observed in quasars?

Absorption lines in quasars usually have lower redshifts than the quasars themselves do.This suggests that the absorption lines are caused by gas

Which of the following is a good description of a Seyfert galaxy?

Quasars all have great distances.Why are there no nearby quasars?

How do we know that the quasars are at large distances?

Since quasars are thought to be at cosmological distances,we see them as they were when the universe was

Why was it difficult for astronomers to identify the spectral lines observed in the spectra of quasars?

About how large is a 1 million solar mass black hole such as those that may exist at the centers of many galaxies?

Some quasars vary in brightness in only a few days.What does this tell us about the quasars?

How do we know that quasars are no larger than the solar system?

Why do Seyfert Galaxies strengthen the case for quasars being active young galaxies?

Which of the following is true of Seyfert galaxies?

The spectra of quasars reveal lines of elements such as nitrogen and carbon.These elements are as abundant in quasars as in the Sun.Which of the following is a correct reflection on this fact?

It is thought that most large galaxies probably have black holes at their centers.

Quasars were originally discovered as

For a typical luminous radio galaxy,most of the radio emission comes primarily from

According to current theories,the energy source of radio galaxies and quasars is

The radio emission from radio galaxies and quasars is due to

Quasars are currently believed to be

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