Question 1

Stars in the halo are most easily identified passing by the Sun because of their distinctively redder colors.

Accepted Answer

A) True 
 B)False

Question 2

Sagittarius A*, the radio source located at the center of our galaxy, is believed to be:

Accepted Answer

A)  a massive star cluster 
B)  a supernova remnant 
C)  a quasar 
D)  a Seyfert nucleus 
E)  a supermassive black hole 
A)  a massive star cluster 
B)  a supernova remnant 
C)  a quasar 
D)  a Seyfert nucleus 
E)  a supermassive black hole

Question 3

Cosmic rays in our galaxy can produce synchrotron radiation at what wavelengths?

Accepted Answer

A)  gamma-ray 
B)  X-ray 
C)  ultraviolet 
D)  infrared 
E)  radio 
A)  gamma-ray 
B)  X-ray 
C)  ultraviolet 
D)  infrared 
E)  radio

Question 4

There are no known processes that can change the orbits of disk stars over time.

Accepted Answer

A) True 
 B)False

Question 5

If you found a star cluster that was 13 billion years old and whose stars had fractions of heavy elements that were 100 times less than that in the Sun, what type of star cluster would this be and where would it most likely be located?

Accepted Answer

A)  an open cluster that is likely to be in the disk 
B)  an open cluster that is likely to be in the stellar halo 
C)  a globular cluster that is likely to be in the thin disk 
D)  a globular cluster that is likely to be in the stellar halo 
E)  a globular cluster that is likely to be in the central bar 
A)  an open cluster that is likely to be in the disk 
B)  an open cluster that is likely to be in the stellar halo 
C)  a globular cluster that is likely to be in the thin disk 
D)  a globular cluster that is likely to be in the stellar halo 
E)  a globular cluster that is likely to be in the central bar

Question 6

What are the main observational difficulties in observing the shape and spiral arm pattern of the Milky Way?

Accepted Answer

We are seeing it from within,

Question 7

The ratio of the diameter of the galaxy's disk to the thickness of its disk is about:

Accepted Answer

A)  10 to 1 
B)  30 to 1 
C)  100 to 1 
D)  1,000 to 1 
E)  10,000 to 1 
A)  10 to 1 
B)  30 to 1 
C)  100 to 1 
D)  1,000 to 1 
E)  10,000 to 1

Question 8

By comparing globular clusters, you find that Cluster A's RR Lyrae stars are 100 times fainter than Cluster B's RR Lyrae stars. You know that Cluster A's stars are 1.5 times more luminous than Cluster B's stars, because Cluster A is more metal-rich and somewhat younger. How do the clusters' distances compare?

Accepted Answer

A)  Cluster A is 65 times farther away than Cluster B. 
B)  Cluster A is 12 times farther away than Cluster B. 
C)  Cluster A is 10 times farther away than Cluster B. 
D)  Cluster A is seven times farther away than Cluster B. 
E)  Cluster A and Cluster B are at approximately the same distance. 
A)  Cluster A is 65 times farther away than Cluster B. 
B)  Cluster A is 12 times farther away than Cluster B. 
C)  Cluster A is 10 times farther away than Cluster B. 
D)  Cluster A is seven times farther away than Cluster B. 
E)  Cluster A and Cluster B are at approximately the same distance.

Question 9

The Milky Way has lived out its life mainly in isolation and has not experienced many mergers with other galaxies.

Accepted Answer

A) True 
 B)False

Question 10

Describe a scale model of the disk of the Milky Way using a scale in which 1 cm = 1000 light-years. Note that the diameter of the disk is approximately 100,000 light-years, the thickness of young stars is 500 light-years, and the thickness of the older stars is 4,000 light-years.

Accepted Answer

In this model, the disk would be 100 cm

Question 11

A typical globular cluster is composed of 500,000 stars in a sphere whose radius is approximately 5 pc. The distance between stars in a globular cluster is given approximately by d $\approx$ r/N1/3, where r is the radius and N is the number of stars in the cluster. Calculate this distance, and determine how many times smaller it is than the typical distance between stars in the solar neighborhood, which is 3 light-years.

Accepted Answer

The typical distance between stars in a

Question 12

How have astronomers measured the mass of the black hole at the center of our galaxy?

Accepted Answer

A)  using the rotation curve derived from 21-cm emission 
B)  by observing the motions of stars near the center of the galaxy 
C)  by measuring the brightness of the quasar 
D)  by measuring the Doppler shift of Sagittarius A* 
E)  by counting the number of supernova explosions near the black hole during the last century 
A)  using the rotation curve derived from 21-cm emission 
B)  by observing the motions of stars near the center of the galaxy 
C)  by measuring the brightness of the quasar 
D)  by measuring the Doppler shift of Sagittarius A* 
E)  by counting the number of supernova explosions near the black hole during the last century

Question 13

Cosmic rays are:

Accepted Answer

A)  photons with even higher energy than gamma rays 
B)  high-velocity particles produced in novae 
C)  elementary particles with very high energies 
D)  synchrotron emission from strong magnetic fields 
E)  dark-matter particles falling into the galaxy 
A)  photons with even higher energy than gamma rays 
B)  high-velocity particles produced in novae 
C)  elementary particles with very high energies 
D)  synchrotron emission from strong magnetic fields 
E)  dark-matter particles falling into the galaxy

Question 14

How many years does it take the Sun to complete one orbit around the Milky Way? Note that the Sun is traveling at approximately 220 km/s and is 8 kpc from the center of the Milky Way.

Accepted Answer

A)  180 thousand years 
B)  7 million years 
C)  35 million years 
D)  230 million years 
E)  620 million years 
A)  180 thousand years 
B)  7 million years 
C)  35 million years 
D)  230 million years 
E)  620 million years

Question 15

The chemical abundance of a main-sequence star usually reflects how much nuclear burning has gone on inside it.

Accepted Answer

A) True 
 B)False

Question 16

Which of the following are generally NOT found in our galaxy's halo?

Accepted Answer

A)  globular clusters 
B)  planetary nebulae 
C)  RR Lyrae stars 
D)  stars with high percentages of heavy elements 
E)  low-mass main-sequence stars 
A)  globular clusters 
B)  planetary nebulae 
C)  RR Lyrae stars 
D)  stars with high percentages of heavy elements 
E)  low-mass main-sequence stars

Question 17

If you found a halo star that was 13 billion years old and had the same amount of heavy elements as the Sun, would you be surprised?

Accepted Answer

A)  No; many halo stars have high fractions of heavy elements. 
B)  No; this star probably escaped from a globular cluster. 
C)  No; this star has been around a long time, and has created a lot of heavy elements through nuclear fusion. 
D)  Yes, because most halo or globular cluster stars have few heavy elements. 
E)  Yes; halo stars mostly have ages less than 10 billion years. 
A)  No; many halo stars have high fractions of heavy elements. 
B)  No; this star probably escaped from a globular cluster. 
C)  No; this star has been around a long time, and has created a lot of heavy elements through nuclear fusion. 
D)  Yes, because most halo or globular cluster stars have few heavy elements. 
E)  Yes; halo stars mostly have ages less than 10 billion years.

Question 18

Why can the observed chemical abundance of a star tell you something about its age?

Accepted Answer

As a galaxy evolves, gas is converted to

Question 19

Which of these galaxies is most like our own, and what is the name for the type of the galaxy we live in?

Accepted Answer

A)  Galaxy A; giant elliptical 
B)  Galaxy A: nonbarred spiral 
C)  Galaxy B: barred spiral 
D)  Galaxy B: irregular 
E)  Galaxy B: lenticular 
A)  Galaxy A; giant elliptical 
B)  Galaxy A: nonbarred spiral 
C)  Galaxy B: barred spiral 
D)  Galaxy B: irregular 
E)  Galaxy B: lenticular

Question 20

The Sun is located approximately:

Accepted Answer

A)  halfway out in the disk 
B)  one-third of the way out in the halo 
C)  one-quarter of the way out in the bulge 
D)  three-quarters of the way out in the disk 
E)  near the galactic center 
A)  halfway out in the disk 
B)  one-third of the way out in the halo 
C)  one-quarter of the way out in the bulge 
D)  three-quarters of the way out in the disk 
E)  near the galactic center

Exam 21: The Milky Waya Normal Spiral Galaxy

Stars in the halo are most easily identified passing by the Sun because of their distinctively redder colors.

Sagittarius A*, the radio source located at the center of our galaxy, is believed to be:

Cosmic rays in our galaxy can produce synchrotron radiation at what wavelengths?

There are no known processes that can change the orbits of disk stars over time.

If you found a star cluster that was 13 billion years old and whose stars had fractions of heavy elements that were 100 times less than that in the Sun, what type of star cluster would this be and where would it most likely be located?

What are the main observational difficulties in observing the shape and spiral arm pattern of the Milky Way?

The ratio of the diameter of the galaxy's disk to the thickness of its disk is about:

The Milky Way has lived out its life mainly in isolation and has not experienced many mergers with other galaxies.

Describe a scale model of the disk of the Milky Way using a scale in which 1 cm = 1000 light-years. Note that the diameter of the disk is approximately 100,000 light-years, the thickness of young stars is 500 light-years, and the thickness of the older stars is 4,000 light-years.

How have astronomers measured the mass of the black hole at the center of our galaxy?

Cosmic rays are:

How many years does it take the Sun to complete one orbit around the Milky Way? Note that the Sun is traveling at approximately 220 km/s and is 8 kpc from the center of the Milky Way.

The chemical abundance of a main-sequence star usually reflects how much nuclear burning has gone on inside it.

Which of the following are generally NOT found in our galaxy's halo?

If you found a halo star that was 13 billion years old and had the same amount of heavy elements as the Sun, would you be surprised?

Why can the observed chemical abundance of a star tell you something about its age?

Which of these galaxies is most like our own, and what is the name for the type of the galaxy we live in?

The Sun is located approximately:

Why Learn Astronomy

Patterns in the Skymotions of Earth

Motion of Astronomical Bodies

Gravity and Orbits

Light

The Tools of the Astronomer

The Birth and Evolution of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquid the Giant Planets

Planetary Adornmentsmoons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

Star Formation and the Interstellar Medium

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

The Expanding Universe

Galaxies

Modern Cosmology

Large-Scale Structure in the Universe

Life

Filters