Question 1

Which of the following is a good description of a Seyfert galaxy?&#10;A)A spiral with a small bright nucleus&#10;B)A giant elliptical&#10;C)A tidally distorted irregular galaxy&#10;D)A galaxy in which star formation has ceased

Accepted Answer

Seyfert galaxies are a type of active galaxy that have a small, bright nucleus. They are typically classified as spirals with a characteristic narrow emission line spectrum.

Question 2

How do we know that quasars are no larger than the solar system?&#10;A)They vary in brightness on a timescale of days or weeks&#10;B)They appear pointlike when viewed through a telescope&#10;C)They contain black holes,which must be small&#10;D)They are too luminous to be very large

Accepted Answer

The rapid variability in brightness of quasars on a timescale of days or weeks indicates that they must be relatively small, as larger objects would not be able to change brightness so quickly due to the light travel time across the object.

Question 3

Since quasars are thought to be at cosmological distances,we see them as they were when the universe was&#10;A)Much older than it is today&#10;B)Relatively young&#10;C)Contracting&#10;D)Much larger than it is today

Accepted Answer

Quasars are believed to be at very far distances, meaning that the light we receive from them has been traveling for a very long time. Therefore, we see them as they were in the past. The farther away a quasar is, the younger it appears because we are seeing it as it was when it emitted the light that is now reaching us. Therefore, the correct answer is B, relatively young.

Question 4

About how large is a 1 million solar mass black hole such as those that may exist at the centers of many galaxies?&#10;A)A few km in radius&#10;B)A few thousand km in radius&#10;C)A few million km in radius&#10;D)A few billion km in radius

Accepted Answer

The answer of About how large is a 1 million...

Question 5

Some quasars vary in brightness in only a few days.What does this tell us about the quasars?&#10;A)They have large magnetic fields&#10;B)They are quite small&#10;C)They must be highly luminous&#10;D)They cannot emit radio waves

Accepted Answer

The fact that some quasars vary in brightness in only a few days suggests that they must be quite small. This is because the light variations cannot be caused by changes in the overall brightness of a large object, but rather by variations in the emission from a small region within the quasar.

Question 6

Why do Seyfert Galaxies strengthen the case for quasars being active young galaxies?&#10;A)Seyfert galaxies are closer than most quasars,and brighter.&#10;B)Seyfert galaxies are closer than most quasars,and are less bright.&#10;C)Seyfert galaxies are farther away than quasars,and are less bright.&#10;D)Seyfert galaxies are father away than quasars,and are more bright.

Accepted Answer

Seyfert galaxies, which are closer than most quasars and less bright, serve as a sort of intermediate class of active galaxies. Their properties suggest that quasars, which are more distant and more luminous, could be an earlier, more active phase of galaxies like Seyferts. This supports the idea that quasars are active young galaxies, with Seyfert galaxies possibly representing a later, less active stage in the evolution of galactic nuclei.

Question 7

Quasars are currently believed to be&#10;A)The brightest elliptical galaxies&#10;B)The most luminous supernova remnants&#10;C)An early phase of intense activity in the centers of galaxies&#10;D)Structures larger than clusters of galaxies

Accepted Answer

Quasars are currently believed to be an early phase of intense activity in the centers of galaxies. They are powered by supermassive black holes and are among the most luminous objects in the universe.

Question 8

Quasars were originally discovered as&#10;A)Strong radio sources identified with star-like images on photographs&#10;B)Variable sources of light&#10;C)Bright galaxies,and only later found to be radio sources&#10;D)The only type of radio source within our galaxy

Accepted Answer

Quasars were first discovered as strong radio sources, which were identified with star-like images on photographs. Later, they were found to exhibit variability in their brightness.

Question 9

Which of the following is true of Seyfert galaxies?&#10;A)They have no spiral arms&#10;B)They have unusually bright nuclei&#10;C)They are a form of elliptical galaxy&#10;D)They are all found in the Local Group of galaxies

Accepted Answer

Seyfert galaxies are a type of spiral galaxy with unusually bright nuclei, which are caused by the activity of a supermassive black hole at the center of the galaxy. Seyfert galaxies can have spiral arms or not, so A and C are incorrect. Seyfert galaxies can be found both within and outside the Local Group, so D is also incorrect.

Question 10

Quasars all have great distances.Why are there no nearby quasars?&#10;A)No quasars have existed in the recent past&#10;B)Quasars avoid spiral galaxies&#10;C)Quasars are found only in clusters of galaxies&#10;D)If quasars are too close to us,they look like pulsars

Accepted Answer

Quasars are extremely luminous active galactic nuclei, powered by supermassive black holes at their centers. They were much more common in the early universe, during a period known as the "quasar epoch," which occurred billions of years ago. The reason we don't see nearby quasars is that they are remnants of an earlier phase in the universe's evolution, and no new quasars have formed in the recent past.

Question 11

How do we know that the quasars are at large distances?&#10;A)They are extremely dim&#10;B)They have large redshifts&#10;C)They have large parallaxes&#10;D)They are greatly obscured by interstellar dust

Accepted Answer

The answer of How do we know that the quasars...

Question 12

For a typical luminous radio galaxy,most of the radio emission comes primarily from&#10;A)The core of the galaxy&#10;B)Spiral arms.&#10;C)Globular clusters.&#10;D)Two large regions far from the center of the galaxy

Accepted Answer

The answer of For a typical luminous radio galaxy,most of...

Question 13

Why was it difficult for astronomers to identify the spectral lines observed in the spectra of quasars?&#10;A)They were formed by elements unknown on Earth&#10;B)There were too many lines in the spectra&#10;C)The lines were greatly redshifted&#10;D)No two quasars have the same spectral lines

Accepted Answer

The answer of Why was it difficult for astronomers to...

Question 14

How do astronomers explain the &#34;superluminal&#34; motions observed in quasars?&#10;A)It is an illusion produced when something moves rapidly almost straight at us&#10;B)No trick,things really do move faster than the speed of light&#10;C)The black holes in quasars cause a distortion in the rate of passage of time&#10;D)Quasars are contracting at almost the speed of light

Accepted Answer

The answer of How do astronomers explain the &#34;superluminal&#34; motions...

Question 15

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

Accepted Answer

The answer of It is thought that most large galaxies...

Question 16

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?&#10;A)This is to be expected,since quasars are powered by nucleosynthesis&#10;B)This observation verifies our ideas on the evolutionary status of quasars&#10;C)This is odd,since quasars are old and should have Pop.II abundances&#10;D)This is unexpected,quasars should have large amounts of iron

Accepted Answer

The answer of The spectra of quasars reveal lines of...

Question 17

The radio emission from radio galaxies and quasars is due to&#10;A)Thermal emission&#10;B)21 cm radiation from hydrogen atoms.&#10;C)Star formation regions.&#10;D)Synchrotron radiation

Accepted Answer

The answer of The radio emission from radio galaxies and...

Question 18

According to current theories,the energy source of radio galaxies and quasars is&#10;A)A one thousand solar mass pulsar in each of two radio lobes&#10;B)A one hundred million solar mass black hole at the center of the object&#10;C)The conversion of hydrogen to helium via nuclear reactions&#10;D)Gravitational contraction of massive stars near the spiral arms

Accepted Answer

The answer of According to current theories,the energy source of...

Question 19

Absorption lines in quasars usually have lower redshifts than the quasars themselves do.This suggests that the absorption lines are caused by gas&#10;A)At the same distance as the quasars&#10;B)Between us and the quasars&#10;C)That is farther away than the quasars&#10;D)In the quasar itself

Accepted Answer

The answer of Absorption lines in quasars usually have lower...

Deck 24: Quasars and Other Active Galaxies