Question 1

Which one of the following objects does not exhibit differential rotation?

Accepted Answer

A) Mercury 
B) the Sun 
C) the solar system 
D) the disk of the Milky Way Galaxy 
A) Mercury 
B) the Sun 
C) the solar system 
D) the disk of the Milky Way Galaxy A

Question 2

The speed of the Sun in its orbit around the galaxy is deduced from observations of:

Accepted Answer

A) the galactic center, about which the Sun is orbiting. 
B) Cepheid variables between spiral arms, because distances can easily be measured to them. 
C) the orbital motions of stars near the Sun. 
D) globular clusters in the galactic halo and distant galaxies. 
A) the galactic center, about which the Sun is orbiting. 
B) Cepheid variables between spiral arms, because distances can easily be measured to them. 
C) the orbital motions of stars near the Sun. 
D) globular clusters in the galactic halo and distant galaxies. D

Question 3

What is the net electric charge on a single unit of H I?

Accepted Answer

A) -1 
B) 0 
C) +1 
D) +2 
A) -1 
B) 0 
C) +1 
D) +2 B

Question 4

The distance to the globular cluster M55 has been determined to be 6500 pc by analysis of RR Lyrae stars in the cluster. How do the apparent brightnesses of these stars compare with the apparent brightness of the Sun? (Calculate b/bŸe)

Accepted Answer

A) 5.9 × 10-17 
B) 2.5 × 10-7 
C) 2.4 × 10-6 
D) There is no reason to believe all RR Lyrae stars in M55 have the same apparent brightness. 
A) 5.9 × 10-17 
B) 2.5 × 10-7 
C) 2.4 × 10-6 
D) There is no reason to believe all RR Lyrae stars in M55 have the same apparent brightness.

Question 5

Who did early studies of RR Lyrae variable stars?

Accepted Answer

A) Harlow Shapley 
B) Henrietta Leavitt 
C) Edwin Hubble 
D) Sir Isaac Newton 
A) Harlow Shapley 
B) Henrietta Leavitt 
C) Edwin Hubble 
D) Sir Isaac Newton

Question 6

Astronomers are able to study the center of the Milky Way galaxy in all of the following parts of the spectrum EXCEPT ONE. Which one is the EXCEPTION?

Accepted Answer

A) infrared 
B) radio 
C) visible 
D) x ray 
A) infrared 
B) radio 
C) visible 
D) x ray

Question 7

Where in the Milky Way Galaxy would you look for O and B stars?

Accepted Answer

A) only in the disk and spiral arms 
B) everywhere in the galaxy 
C) only in the halo 
D) only in the central bulge 
A) only in the disk and spiral arms 
B) everywhere in the galaxy 
C) only in the halo 
D) only in the central bulge

Question 8

If the Sun were traveling around the galactic center along with companion stars (all in circular orbits), as depicted in Figure 22-17 (Universe, 11th ed.), from which of the stars in that diagram would you measure a Doppler shift of their light? (Hint: Think about relative velocities and orbital velocities at different orbital distances from the galactic center.)
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Accepted Answer

A) stars at the same orbital distance as the Sun 
B) stars in directions at 45° angles from the Sun's direction of motion 
C) stars directly between the Sun and the galactic center 
D) None of them, because they are all moving along with the Sun and have no relative velocity with respect to it. 
A) stars at the same orbital distance as the Sun 
B) stars in directions at 45° angles from the Sun's direction of motion 
C) stars directly between the Sun and the galactic center 
D) None of them, because they are all moving along with the Sun and have no relative velocity with respect to it.

Question 9

If you want to find the distribution of neutral hydrogen in the Milky Way Galaxy, you should observe in which portion of the spectrum?

Accepted Answer

A) x ray 
B) near infrared 
C) far infrared 
D) radio 
A) x ray 
B) near infrared 
C) far infrared 
D) radio

Question 10

In the absence of interstellar dust, a certain A0 star has the same magnitude through a blue filter and through a visual filter. When the light passes through a dust cloud before being observed, the:

Accepted Answer

A) B and V magnitudes remain equal. 
B) B magnitude will be a smaller number than the V magnitude. 
C) V magnitude will be a smaller number than the B magnitude. 
D) size of the dust particles will determine whether B or V is the larger number. 
A) B and V magnitudes remain equal. 
B) B magnitude will be a smaller number than the V magnitude. 
C) V magnitude will be a smaller number than the B magnitude. 
D) size of the dust particles will determine whether B or V is the larger number.

Question 11

Dark matter cannot be seen, but we can detect its presence by its:

Accepted Answer

A) strong radio emissions. 
B) strong emissions in the near infrared. 
C) gravitational influence on visible stars. 
D) accretion disk. 
A) strong radio emissions. 
B) strong emissions in the near infrared. 
C) gravitational influence on visible stars. 
D) accretion disk.

Question 12

The dimensions of the disk of our Milky Way Galaxy are:

Accepted Answer

A) diameter 80,000 ly; thickness 6500 ly. 
B) diameter 6500 ly; thickness 2000 ly. 
C) diameter 2000 ly; thickness 160,000 ly. 
D) diameter 160,000 ly; thickness 2000 ly. 
A) diameter 80,000 ly; thickness 6500 ly. 
B) diameter 6500 ly; thickness 2000 ly. 
C) diameter 2000 ly; thickness 160,000 ly. 
D) diameter 160,000 ly; thickness 2000 ly.

Question 13

Variable stars, such as Cepheid variables and RR Lyrae stars, are used in what important measurement in astronomy?

Accepted Answer

A) rotation speeds of galaxies 
B) surface temperature measurement 
C) distance measurement 
D) the keeping of accurate time 
A) rotation speeds of galaxies 
B) surface temperature measurement 
C) distance measurement 
D) the keeping of accurate time

Question 14

The present estimate for the total mass of our galaxy (including a dark matter halo) is approximately:

Accepted Answer

A) 1011 $M_{\odot}$ 
B) 1010 $M_{\odot}$ 
C) 1012 or more. 
D) 109 or less. 
A) 1011 $M_{\odot}$ 
B) 1010 $M_{\odot}$ 
C) 1012 or more. 
D) 109 or less.

Question 15

The compact radio source Sagittarius A* has a mass of about 4.1 million and a size comparable to:

Accepted Answer

A) the Sun. 
B) the solar system. 
C) a globular cluster. 
D) the galactic central bulge. 
A) the Sun. 
B) the solar system. 
C) a globular cluster. 
D) the galactic central bulge.

Question 16

The most important reason why globular clusters are useful for finding the speed of the Sun in its orbit around the galaxy is that globular clusters:

Accepted Answer

A) on average rotate at the same speed as the Sun around the center of the galaxy. 
B) are bright and easily seen at large distances. 
C) are distributed uniformly around the galaxy. 
D) on average do not rotate like stars in the disk of the galaxy. 
A) on average rotate at the same speed as the Sun around the center of the galaxy. 
B) are bright and easily seen at large distances. 
C) are distributed uniformly around the galaxy. 
D) on average do not rotate like stars in the disk of the galaxy.

Question 17

The diameter of our galaxy is about:

Accepted Answer

A) 50 kpc. 
B) 2 kpc. 
C) 8 kpc. 
D) 160 kpc. 
A) 50 kpc. 
B) 2 kpc. 
C) 8 kpc. 
D) 160 kpc.

Question 18

One proposed source for the energy to sustain density waves is:

Accepted Answer

A) the Kelvin-Helmholtz contraction on a galactic scale. 
B) radioactivity. 
C) gravitational attraction between the bar and the rest of the galaxy. 
D) energy from gamma-ray bursters. 
A) the Kelvin-Helmholtz contraction on a galactic scale. 
B) radioactivity. 
C) gravitational attraction between the bar and the rest of the galaxy. 
D) energy from gamma-ray bursters.

Question 19

If the Milky Way Galaxy were rescaled to the size of the continental United States, the size of an average star would be about the size of a(n):

Accepted Answer

A) automobile. 
B) basketball. 
C) tennis ball. 
D) human cell. 
A) automobile. 
B) basketball. 
C) tennis ball. 
D) human cell.

Question 20

Do we believe the black hole Sagittarius A* is growing?

Accepted Answer

A) We have witnessed the sudden disappearance of several orbiting stars in recent years, suggesting that Sagittarius A* is growing. 
B) The x-ray radiation from Sagittarius is relatively weak, suggesting it is not growing. 
C) The intense gravitational waves coming from Sagittarius A* suggest that it is growing. 
D) While Sagittarius A* is not visible, the accretion disk around it is visible. This disk is growing, so we believe Sagittarius A* is growing. 
A) We have witnessed the sudden disappearance of several orbiting stars in recent years, suggesting that Sagittarius A* is growing. 
B) The x-ray radiation from Sagittarius is relatively weak, suggesting it is not growing. 
C) The intense gravitational waves coming from Sagittarius A* suggest that it is growing. 
D) While Sagittarius A* is not visible, the accretion disk around it is visible. This disk is growing, so we believe Sagittarius A* is growing.

Exam 22: Our Galaxy

Which one of the following objects does not exhibit differential rotation?

The speed of the Sun in its orbit around the galaxy is deduced from observations of:

What is the net electric charge on a single unit of H I?

The distance to the globular cluster M55 has been determined to be 6500 pc by analysis of RR Lyrae stars in the cluster. How do the apparent brightnesses of these stars compare with the apparent brightness of the Sun? (Calculate b/bŸe)

Who did early studies of RR Lyrae variable stars?

Astronomers are able to study the center of the Milky Way galaxy in all of the following parts of the spectrum EXCEPT ONE. Which one is the EXCEPTION?

Where in the Milky Way Galaxy would you look for O and B stars?

If you want to find the distribution of neutral hydrogen in the Milky Way Galaxy, you should observe in which portion of the spectrum?

In the absence of interstellar dust, a certain A0 star has the same magnitude through a blue filter and through a visual filter. When the light passes through a dust cloud before being observed, the:

Dark matter cannot be seen, but we can detect its presence by its:

The dimensions of the disk of our Milky Way Galaxy are:

Variable stars, such as Cepheid variables and RR Lyrae stars, are used in what important measurement in astronomy?

The present estimate for the total mass of our galaxy (including a dark matter halo) is approximately:

The compact radio source Sagittarius A* has a mass of about 4.1 million and a size comparable to:

The most important reason why globular clusters are useful for finding the speed of the Sun in its orbit around the galaxy is that globular clusters:

The diameter of our galaxy is about:

One proposed source for the energy to sustain density waves is:

If the Milky Way Galaxy were rescaled to the size of the continental United States, the size of an average star would be about the size of a(n):

Do we believe the black hole Sagittarius A* is growing?

Astronomy and the Universe

Knowing the Heavens

Eclipses and the Motion of the Moon

Gravitation and the Waltz of the Planets

The Nature of Light

Optics and Telescopes

Comparative Planetology I: Our Solar System

Comparative Planetology II: the Origin of Our Solar System

The Living Earth

Our Barren Moon

Mercury, Venus, and Mars: Terrestrial, yet Unique

Jupiter and Saturn: Lords of the Planets

Jupiter and Saturns Satellites of Fire and Ice

Uranus, Neptune, Pluto, and the Kuiper Belt: Remote Worlds

Asteroids, Comets, and Impacts

Our Star, the Sun

The Nature of the Stars

The Birth of Stars

Stellar Evolution: on and After the Main Sequence

Stellar Evolution: The Death of Stars

Stellar Remnants: Neutron Stars and Black Holes

Galaxies

Quasars and Active Galaxies

Cosmology: The Origin and Evolution of the Universe

Exploring the Early Universe

The Search for Extraterrestrial Life

Filters

The distance to the globular cluster M55 has been determined to be 6500 pc by analysis of RR Lyrae stars in the cluster. How do the apparent brightnesses of these stars compare with the apparent brightness of the Sun? (Calculate b/b_Ÿe)