Question 1

One consequence of nuclear activity in otherwise normal galaxies as well as in quasars are jets of material moving outward at ________ speeds.

Accepted Answer

relativistic

Question 2

Distinguish an E0 from an E7 galaxy.

Accepted Answer

Elliptical galaxies of type E0 show spherical symmetry,like a huge globular cluster; they spin very slowly.E7 spin faster,and are more flattened into a lens shape,but they don't show the disks found in spirals.

Question 3

In active galaxies,their central engines may be temporarily fed by:

Accepted Answer

A)  a sudden surge of star formation. 
B)  a series of supernovae around the core. 
C)  the sudden collapse of the core into a supermassive black hole. 
D)  a close encounter with a neighbor galaxy. 
E)  the fusion of helium into carbon in their cores. 
A)  a sudden surge of star formation. 
B)  a series of supernovae around the core. 
C)  the sudden collapse of the core into a supermassive black hole. 
D)  a close encounter with a neighbor galaxy. 
E)  the fusion of helium into carbon in their cores. D

Question 4

Galaxies are classified into types solely on the basis of their color.

Accepted Answer

A) True 
 B)False

Question 5

The Milky Way is often considered to be an intermediately wound,barred spiral,which would be type ________ according to Hubble.

Accepted Answer

A)  E4 
B)  Sa 
C)  SBb 
D)  SBV 
E)  B2S 
A)  E4 
B)  Sa 
C)  SBb 
D)  SBV 
E)  B2S

Question 6

According to Hubble's Law,the greater a galaxy's redshift,the:

Accepted Answer

A)  closer it is to us. 
B)  younger it is. 
C)  faster it's approaching us. 
D)  farther it is from us. 
E)  greater its mass. 
A)  closer it is to us. 
B)  younger it is. 
C)  faster it's approaching us. 
D)  farther it is from us. 
E)  greater its mass.

Question 7

Active galactic nuclei are usually powered by supermassive black holes.

Accepted Answer

A) True 
 B)False

Question 8

Why do some radio galaxies appear to have lobes while some do not?

Accepted Answer

It's believed that all radio g

Question 9

Why do astronomers speak in terms of redshifts rather than distances to faraway objects?

Accepted Answer

Distance is an uncertain quantity: do yo

Question 10

There is very little interstellar gas or dust in most elliptical galaxies.

Accepted Answer

A) True 
 B)False

Question 11

In what sense are the quasars "quasi-stellar"?

Accepted Answer

A)  Their energy production is hydrogen-helium fusion, like main sequence stars. 
B)  They are upscale versions of O stars, yet hundreds of times more massive. 
C)  Their luminosity comes from the millions of supergiants that compose them. 
D)  Their spectra is like that of ordinary stars. 
E)  In short time exposures, their images looked stellar. 
A)  Their energy production is hydrogen-helium fusion, like main sequence stars. 
B)  They are upscale versions of O stars, yet hundreds of times more massive. 
C)  Their luminosity comes from the millions of supergiants that compose them. 
D)  Their spectra is like that of ordinary stars. 
E)  In short time exposures, their images looked stellar.

Question 12

Which of the following does the intensity of synchrotron radiation NOT depend on?

Accepted Answer

A)  mass of the electron 
B)  temperature 
C)  speed of electrons 
D)  frequency of radiation 
E)  strength of the magnetic field 
A)  mass of the electron 
B)  temperature 
C)  speed of electrons 
D)  frequency of radiation 
E)  strength of the magnetic field

Question 13

Synchrotron radiation produces a(n)________ spectrum.

Accepted Answer

A)  continuous nonthermal 
B)  emission line 
C)  absorption line 
D)  continuous, with some emission lines 
E)  continuous, with some absorption lines 
A)  continuous nonthermal 
B)  emission line 
C)  absorption line 
D)  continuous, with some emission lines 
E)  continuous, with some absorption lines

Question 14

What is true of spiral galaxies?

Accepted Answer

A)  They are much less common at larger redshifts. 
B)  They are relatively rare in regions of high galaxy density. 
C)  They are only found in the center of rich galaxy clusters. 
D)  They have never been seen to have large redshifts. 
E)  They evolve from giant ellipticals. 
A)  They are much less common at larger redshifts. 
B)  They are relatively rare in regions of high galaxy density. 
C)  They are only found in the center of rich galaxy clusters. 
D)  They have never been seen to have large redshifts. 
E)  They evolve from giant ellipticals.

Question 15

What are the Magellanic Clouds? What happened in the LMC in 1987?

Accepted Answer

The Magellanic Clouds are our companion

Question 16

If the redshift is an accurate indication of the distance to that galaxy,then this is considered a cosmological redshift.

Accepted Answer

A) True 
 B)False

Question 17

Why do some quasars have redshifts greater than 1?

Accepted Answer

A)  They are made of different elements than any other objects in the universe. 
B)  They are very distant, with relativistic redshifts that take into account dilation of space-time, as Einstein predicted. 
C)  They are made of tachyons and thus are able to move away from us faster than the speed of light. 
D)  Einstein proved it is impossible to have a redshift greater than 1; these are all due to gravitational lensing tricking us. 
E)  They are moving towards us, which throws off our spectrometers. 
A)  They are made of different elements than any other objects in the universe. 
B)  They are very distant, with relativistic redshifts that take into account dilation of space-time, as Einstein predicted. 
C)  They are made of tachyons and thus are able to move away from us faster than the speed of light. 
D)  Einstein proved it is impossible to have a redshift greater than 1; these are all due to gravitational lensing tricking us. 
E)  They are moving towards us, which throws off our spectrometers.

Question 18

Why is light variability a critical issue with the sizes of active nuclei?

Accepted Answer

The source of the light cannot be any la

Question 19

A galaxy that was once a quasar is likely to:

Accepted Answer

A)  have burned all its fuel by now and be dark. 
B)  now be a dwarf irregular. 
C)  have a black hole at its nucleus. 
D)  still be a quasar. 
E)  be less than 5 billion years old. 
A)  have burned all its fuel by now and be dark. 
B)  now be a dwarf irregular. 
C)  have a black hole at its nucleus. 
D)  still be a quasar. 
E)  be less than 5 billion years old.

Question 20

Why is the energy source for active nuclei like Seyferts thought to be compact?

Accepted Answer

A)  The sources appear to be single stars in photos. 
B)  Their energy appears to be non-stellar synchrotron radiation. 
C)  The light can vary over short time intervals. 
D)  We know the masses of the black holes that lurk there, and can find their radii. 
E)  They are all strong radio sources, with assigned frequencies by their sizes. 
A)  The sources appear to be single stars in photos. 
B)  Their energy appears to be non-stellar synchrotron radiation. 
C)  The light can vary over short time intervals. 
D)  We know the masses of the black holes that lurk there, and can find their radii. 
E)  They are all strong radio sources, with assigned frequencies by their sizes.

Exam 24: Galaxies: Building Blocks of the Universe

One consequence of nuclear activity in otherwise normal galaxies as well as in quasars are jets of material moving outward at ________ speeds.

Distinguish an E0 from an E7 galaxy.

In active galaxies,their central engines may be temporarily fed by:

Galaxies are classified into types solely on the basis of their color.

The Milky Way is often considered to be an intermediately wound,barred spiral,which would be type ________ according to Hubble.

According to Hubble's Law,the greater a galaxy's redshift,the:

Active galactic nuclei are usually powered by supermassive black holes.

Why do some radio galaxies appear to have lobes while some do not?

Why do astronomers speak in terms of redshifts rather than distances to faraway objects?

There is very little interstellar gas or dust in most elliptical galaxies.

In what sense are the quasars "quasi-stellar"?

Which of the following does the intensity of synchrotron radiation NOT depend on?

Synchrotron radiation produces a(n)________ spectrum.

What is true of spiral galaxies?

What are the Magellanic Clouds? What happened in the LMC in 1987?

If the redshift is an accurate indication of the distance to that galaxy,then this is considered a cosmological redshift.

Why do some quasars have redshifts greater than 1?

Why is light variability a critical issue with the sizes of active nuclei?

A galaxy that was once a quasar is likely to:

Why is the energy source for active nuclei like Seyferts thought to be compact?

Charting the Heavens: The Foundations of Astronomy

The Copernican Revolution: The Birth of Modern Science

Radiation: Information from the Cosmos

Spectroscopy: The Inner Workings of Atoms

Telescopes: The Tools of Astronomy

The Solar System: Comparative Planetology and Formation Models

Earth: Our Home in Space

The Moon and Mercury: Scorched and Battered Worlds

Venus: Earth's Sister Planet

Mars: A Near Miss for Life?

Jupiter: Giant of the Solar System

Saturn: Spectacular Rings and Mysterious Moons

Uranus and Neptune: The Outer Worlds of the Solar System

Solar System Debris: Keys to Our Origin

Exoplanets: Planetary Systems Beyond Our Own

The Sun: Our Parent Star

The Stars: Giants,Dwarfs,and the Main Sequence

The Interstellar Medium: Gas and Dust among the Stars

Star Formation: A Traumatic Birth

Stellar Evolution: The Life and Death of a Star

Stellar Explosions: Novae,Supernovae,and the Formation of the Elements

Neutron Stars and Black Holes: Strange States of Matter

The Milky Way Galaxy: A Spiral in Space

Galaxies and Dark Matter: The Large-Scale Structure of the Cosmos

Cosmology: The Big Bang and the Fate of the Universe

The Early Universe: Toward the Beginning of Time

Life in the Universe: Are We Alone?

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