Question 1

In the 1780s,Sir William Herschel tried to measure the Sun's position in the Milky Way Galaxy by:

Accepted Answer

A)   counting the density of stars in different directions along the Milky Way.
B)   measuring distances to star clusters and H II regions in the disk of the Galaxy.
C)   measuring the locations of globular clusters around the Galaxy.
D)   comparing the Milky Way with the Andromeda Galaxy. A

Question 2

The famous nineteenth-century observational astronomer Lord Rosse built the largest telescope of his time (and discovered the spiral nature of many so-called "nebulae")in which country?

Accepted Answer

A)   England
B)   the United States
C)   Ireland
D)   Germany C

Question 3

In which case does gravity,a long-range force,NOT result in a bound system?

Accepted Answer

A)   the orbital movements of globular clusters about the center of the Milky Way
B)   disruption by tidal forces from the Milky Way of the most recently discovered member of the Local Group, Canis Major Dwarf, a close companion of the Milky Way Galaxy
C)   the motions of galaxies within clusters
D)   the motions of clusters within superclusters D

Question 4

Collisions between galaxies:

Accepted Answer

A)   do not occur because the distances between galaxies are so vast.
B)   are relatively fleeting because galaxies move so rapidly and thus last only a few million years.
C)   can last hundreds of millions of years.
D)   have little long-term effect on the galaxies involved because gravity is a relatively weak force and the distances over which it must act between galaxies are so great.

Question 5

A spherical cluster of several hundred galaxies is found to contain far more ellipticals than spirals and irregulars.How would you classify this cluster?

Accepted Answer

A)   poor regular
B)   poor irregular
C)   rich regular
D)   rich irregular

Question 6

In the Milky Way Galaxy,young,metal-rich stars are found:

Accepted Answer

A)   everywhere.
B)   only at the galactic center.
C)   in the disk and spiral arms.
D)   in the globular clusters in the galactic halo.

Question 7

Which component of the Milky Way Galaxy outlines the spiral arms of the Galaxy?

Accepted Answer

A)   young O and B stars, dust, and gas
B)   globular clusters
C)   predominantly solar-type stars
D)   white dwarf stars

Question 8

What is the galaxy content of rich,regular clusters like the Coma cluster?

Accepted Answer

A)   a more or less even distribution of spirals, ellipticals, irregulars, and S0 galaxies
B)   mostly ellipticals and S0 galaxies and relatively few spirals and irregulars
C)   entirely elliptical galaxies
D)   mostly spirals and irregulars with relatively few ellipticals and S0 galaxies

Question 9

Which statement about the spiral arms of grand-design spirals is TRUE?

Accepted Answer

A)   The density of matter in the spiral arms is many times the density of the regions in between.
B)   The regions between the spiral arms are cloaked in dust which makes them look dimmer than the spiral arms.
C)   the spiral density waves which move around the galaxy are transverse waves, moving up and down across the direction of the waves motion like light waves.
D)   The spiral arms have almost the same density as the rest of the disk. They are more visible because they contain bright, newly formed stars.

Question 10

Observationally,the biggest difference between quasars and other active galaxies such as Seyfert and radio galaxies appears to be that (see Table 13-2,Comins,Discovering the Essential Universe,6th ed.):

Accepted Answer

A)   quasars appear to be located inside elliptical galaxies, whereas Seyfert and radio galaxies are spirals.
B)   Seyfert and radio galaxies do not have the bright, starlike nuclei of quasars.
C)   the brightness of Seyfert and radio galaxies does not vary with time.
D)   Seyfert and radio galaxies are less powerful energy emitters than quasars.

Question 11

What observational fact convinces astronomers that the source of energy in a typical quasar is physically very small?

Accepted Answer

A)   rapid variation in the energy output of the source
B)   extreme distance of all quasars
C)   starlike appearance of quasars in Earth's sky
D)   narrowness of the emission lines in the spectra of quasars

Question 12

Why are we on Earth able to see only a relatively small part of the Milky Way Galaxy?

Accepted Answer

A)   There are so many stars in the Milky Way that the more distant ones are hidden behind the nearer ones.
B)   Distant stars are obscured by gas in interstellar space.
C)   Expansion of the universe has carried the more distant stars out of our view.
D)   Distant stars are obscured by dust in interstellar space.

Question 13

Interstellar matter obscures our view of the disk of the Milky Way Galaxy:

Accepted Answer

A)   most at radio wavelengths, where hydrogen absorbs radio waves efficiently, and least at optical wavelengths.
B)   more at optical wavelengths and less or not at all at infrared and radio wavelengths.
C)   very little at any wavelength.
D)   more or less equally at all wavelengths, from radio waves to light waves.

Question 14

A quasar is now thought to be a:

Accepted Answer

A)   long-lived supernova explosion.
B)   very luminous object at a very large distance from the Sun.
C)   nearby star, ejected with great violence and velocity from the center of a galaxy.
D)   distant but very luminous and active star in the Milky Way Galaxy.

Question 15

The typical fluctuation time for the brightnesses of quasars can be as short as a:

Accepted Answer

A)   few seconds.
B)   month.
C)   day.
D)   year.

Question 16

You are examining quasars and you happen upon two quasars in the same part of the sky that have identical spectra.You cannot see any massive object in the region between the two quasars.What is a reasonable explanation for this discovery?

Accepted Answer

A)   The discovery is not really a surprise because all quasars are formed by the same processes and all have virtually identical spectra.
B)   The two quasars are part of a binary pair of quasars that were formed together, are at the same stage in their lives, and have the same spectra.
C)   The two quasars cannot be gravitational lensing images because there is no visible lensing object in the space between them.
D)   The two quasars are most likely gravitational lensing images, and the lensing object is mostly dark matter with little visible emission.

Question 17

The designation active galaxy does NOT include:

Accepted Answer

A)   radio galaxies.
B)   double-radio sources.
C)   BL Lacertae objects.
D)   any galaxy containing a black hole.

Question 18

Where do black holes occur in the Milky Way Galaxy?

Accepted Answer

A)   nowhere
B)   only in the galactic center
C)   in the galactic center and within some globular clusters
D)   in the galactic center, within some globular clusters, and in several locations between the spiral arms

Question 19

One curious fact about the Milky Way Galaxy,discovered in the past few years,is that:

Accepted Answer

A)   a significant fraction of its mass is in the form of globular clusters, distributed in a spherical halo centered on the galactic center.
B)   a large black hole is slowly clearing out the mass near the galactic center, leaving a cold, dark void.
C)   enormous amounts of energy are pouring out of a compact but very massive source at its center.
D)   most of its mass is in the spiral arms extending out into space.

Question 20

How does the winding dilemma affect flocculent spirals?

Accepted Answer

A)   The winding dilemma is the basic cause of the chaotic structure in flocculent spirals.
B)   The winding dilemma affects only galaxies with flat rotation curves and constant stellar speeds, as in Figure 16-5 of Discovering the Universe, 10th ed., and this does not include flocculent spirals.
C)   Flocculent spirals are dominated by self-propagating star formation in which groups of stars are formed and then fade as the massive luminous stars complete their life cycles. This transient, spotty star formation pattern is unaffected by the winding dilemma.
D)   Flocculent spirals have a whirlpool structure with several centers of rotation, each affected by the winding dilemma. This results in the overall flocculent pattern.

Exam 13: The Galaxies