A) sources of great energy, very large in actual size, and shaped like galaxies. B) sources of intense radio energy only, not visible at other wavelengths, and relatively large but very distant. C) prolific sources of energy, starlike in appearance, and intrinsically small. D) starlike sources of great energy located in the Milky Way Galaxy and intrinsically very small. A) sources of great energy, very large in actual size, and shaped like galaxies. B) sources of intense radio energy only, not visible at other wavelengths, and relatively large but very distant. C) prolific sources of energy, starlike in appearance, and intrinsically small. D) starlike sources of great energy located in the Milky Way Galaxy and intrinsically very small.

A) are more common in nearby clusters of galaxies and less common in distant clusters of galaxies. B) are rare in the Local Group, with only one or two examples. C) increase in number as redshift increases, a relationship that persists to the highest redshifts astronomers can measure. D) peaked in number about 2 billion years after the Big Bang. A) are more common in nearby clusters of galaxies and less common in distant clusters of galaxies. B) are rare in the Local Group, with only one or two examples. C) increase in number as redshift increases, a relationship that persists to the highest redshifts astronomers can measure. D) peaked in number about 2 billion years after the Big Bang.

Exam 18: Quasars and Other Active Galaxies

An astronomer is examining quasars and happens upon two quasars in nearly the same part of the sky that have identical spectra. They cannot see any massive object in the region between the two quasars. What is a reasonable explanation for this discovery?

(Multiple Choice)

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Question 101

The extreme redshifts of quasar spectra are caused by

(Multiple Choice)

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Question 102

The highest recession velocities that have recently been detected for quasars are

(Multiple Choice)

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Question 103

The central "engine" of an active galaxy appears to be

(Multiple Choice)

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Question 104

What is a "peculiar" galaxy?

(Multiple Choice)

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Question 105

The energy output per second of a typical quasar is equal to that emitted by the Sun in 200 years. So, if the luminosity of the Sun is L, what is the luminosity of a typical quasar?

(Multiple Choice)

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Question 106

Quasars are

(Multiple Choice)

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Question 107

The discovery of the peculiar galaxy Cygnus A was a surprise to astronomers because

(Multiple Choice)

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Question 108

Compared with the total output of energy from the Milky Way Galaxy, what is the equivalent output of a typical quasar?

(Multiple Choice)

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Question 109

The mechanism that appears to generate two extensive regions of radio emission near active galaxies is

(Multiple Choice)

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Question 110

"It is starlike in appearance, showing very high redshift and an energy output of at least 100 galaxies from a small region about 1 light-day across." This statement describes which of these astronomical objects?

(Multiple Choice)

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Question 111

Gravitational lensing is caused by the bending of light as it passes a massive object. Why does gravitational lensing so often involve quasars?

(Multiple Choice)

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Question 112

Today, the number density of quasars in the universe is quite small. For how long in the past has this been true?

(Multiple Choice)

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Question 113

An intense radio source is found to coincide with a starlike object whose spectrum contains a pattern of intense emission lines in the visible range that matches that of the Lyman UV hydrogen spectral lines but is very redshifted. What is this object?

(Multiple Choice)

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Question 114

Quasars

(Multiple Choice)

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Question 115

A quasar is observed to have a redshift of about 0.06, with a recessional velocity about 6% of the speed of light. Approximately what distance, in light-years, does the Hubble law give for this object? The Hubble constant is about 70 kilometers per second per megaparsec.

(Multiple Choice)

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(83)

Question 116

The spectrum of a BL Lacertae object shows

(Multiple Choice)

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Question 117

How can astronomers determine the size of an emission region in a very distant and unresolvable source?

(Multiple Choice)

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Question 118

Showing 101 - 118 of 118

An astronomer is examining quasars and happens upon two quasars in nearly the same part of the sky that have identical spectra. They cannot see any massive object in the region between the two quasars. What is a reasonable explanation for this discovery?

The extreme redshifts of quasar spectra are caused by

The highest recession velocities that have recently been detected for quasars are

The central "engine" of an active galaxy appears to be

What is a "peculiar" galaxy?

The energy output per second of a typical quasar is equal to that emitted by the Sun in 200 years. So, if the luminosity of the Sun is L, what is the luminosity of a typical quasar?

Quasars are

The discovery of the peculiar galaxy Cygnus A was a surprise to astronomers because

Compared with the total output of energy from the Milky Way Galaxy, what is the equivalent output of a typical quasar?

The mechanism that appears to generate two extensive regions of radio emission near active galaxies is

"It is starlike in appearance, showing very high redshift and an energy output of at least 100 galaxies from a small region about 1 light-day across." This statement describes which of these astronomical objects?

Gravitational lensing is caused by the bending of light as it passes a massive object. Why does gravitational lensing so often involve quasars?

Today, the number density of quasars in the universe is quite small. For how long in the past has this been true?

An intense radio source is found to coincide with a starlike object whose spectrum contains a pattern of intense emission lines in the visible range that matches that of the Lyman UV hydrogen spectral lines but is very redshifted. What is this object?

Quasars

A quasar is observed to have a redshift of about 0.06, with a recessional velocity about 6% of the speed of light. Approximately what distance, in light-years, does the Hubble law give for this object? The Hubble constant is about 70 kilometers per second per megaparsec.

The spectrum of a BL Lacertae object shows

How can astronomers determine the size of an emission region in a very distant and unresolvable source?

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