Question 1

If you find a halo star that is 13 billion years old and has the same amount of heavy elements as the Sun, should you be surprised?

Accepted Answer

A)  No, because many halo stars have high fractions of heavy elements. 
B)  No, because this star probably escaped from a globular cluster. 
C)  No, because 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, because most halo stars are less than 10 billion years old. 
A)  No, because many halo stars have high fractions of heavy elements. 
B)  No, because this star probably escaped from a globular cluster. 
C)  No, because 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, because most halo stars are less than 10 billion years old.

Question 2

Compared to the Sun's stellar neighborhood, globular clusters have

Accepted Answer

A)  higher heavy-element abundances. 
B)  much higher stellar densities. 
C)  mainly younger stars. 
D)  large amounts of dust present between stars. 
E)  larger amounts of dark matter present. 
A)  higher heavy-element abundances. 
B)  much higher stellar densities. 
C)  mainly younger stars. 
D)  large amounts of dust present between stars. 
E)  larger amounts of dark matter present.

Question 3

The location, motion, and heavy-element enrichment of interstellar gas can be strongly affected by what?

Accepted Answer

A)  dark matter 
B)  low-mass stars 
C)  pulsars 
D)  supernovae 
E)  halo stars 
A)  dark matter 
B)  low-mass stars 
C)  pulsars 
D)  supernovae 
E)  halo stars

Question 4

What is a cosmic ray? Do cosmic rays affect life on Earth?

Accepted Answer

A cosmic ray is a charged particle movin

Question 5

These three barred spirals are the largest members of the Local Group:

Accepted Answer

A)  Andromeda, Milky Way, Sagittarius 
B)  Milky Way, Phoenix, Leo 
C)  Andromeda, Triangulum, Sagittarius 
D)  Andromeda, Milky Way, Triangulum 
E)  Milky Way, Triangulum, Sagittarius 
A)  Andromeda, Milky Way, Sagittarius 
B)  Milky Way, Phoenix, Leo 
C)  Andromeda, Triangulum, Sagittarius 
D)  Andromeda, Milky Way, Triangulum 
E)  Milky Way, Triangulum, Sagittarius

Question 6

Astronomers expect life to be rare (and maybe impossible) in the Milky Way's bulge because

Accepted Answer

A)  there are so many stars that no material is left over to make planets. 
B)  the bulge is too poor in heavy elements. 
C)  the tidal force of the central black hole would strip stars of their planets. 
D)  the lack of green and blue photons from younger stars would make photosynthesis impossible. 
E)  the amount of radiation in the central regions is very high. 
A)  there are so many stars that no material is left over to make planets. 
B)  the bulge is too poor in heavy elements. 
C)  the tidal force of the central black hole would strip stars of their planets. 
D)  the lack of green and blue photons from younger stars would make photosynthesis impossible. 
E)  the amount of radiation in the central regions is very high.

Question 7

Somebody shows you the picture in the figure below and comments that it is the most recent photo of the Milky Way taken with an instrument aboard a spacecraft that has just recently left the boundaries of our home galaxy and is on its way to Andromeda. You would immediately react by saying: "This cannot be the Milky Way because

Accepted Answer

A)  we live in an elliptical galaxy." 
B)  our galaxy does not have a bar." 
C)  the Sun is at the very center of the galaxy." 
D)  the Milky Way is way too big for a spacecraft to go that far." 
E)  all galaxies in the universe are identical and therefore we cannot be so sure this is the Milky Way." 
A)  we live in an elliptical galaxy." 
B)  our galaxy does not have a bar." 
C)  the Sun is at the very center of the galaxy." 
D)  the Milky Way is way too big for a spacecraft to go that far." 
E)  all galaxies in the universe are identical and therefore we cannot be so sure this is the Milky Way."

Question 8

Cosmic rays in the Milky Way are important to study because

Accepted Answer

A)  these energetic photons easily penetrate Earth's atmosphere. 
B)  they can be collected and used to generate electricity. 
C)  they provide information about the most energetic events in the universe. 
D)  they are leftover particles from the formation of the Galaxy. 
E)  they can influence the motion of stars in the halo. 
A)  these energetic photons easily penetrate Earth's atmosphere. 
B)  they can be collected and used to generate electricity. 
C)  they provide information about the most energetic events in the universe. 
D)  they are leftover particles from the formation of the Galaxy. 
E)  they can influence the motion of stars in the halo.

Question 9

What would be the apparent angular size of a 100 light-year-diameter globular cluster in the Andromeda Galaxy (2.5 x106 light-years away), as measured from Earth?

Accepted Answer

The apparent angular size (in radians)wo

Question 10

Why is 21-cm radiation one of the best ways to map the spiral arms of the Milky Way?

Accepted Answer

A)  The molecular hydrogen gas that produces this emission is concentrated in the spiral arms. 
B)  These photons, which are produced by neutral hydrogen, are not blocked by the dense clouds of gas and dust in the disk. 
C)  The emission is produced by supernovae, which are concentrated in the spiral arms. 
D)  Radio telescopes are easier to operate than optical telescopes, and observations can be made even during the daytime. 
E)  Radio photons do not have Doppler shifts, so we can detect clouds of gas without having to worry about the orbital velocities. 
A)  The molecular hydrogen gas that produces this emission is concentrated in the spiral arms. 
B)  These photons, which are produced by neutral hydrogen, are not blocked by the dense clouds of gas and dust in the disk. 
C)  The emission is produced by supernovae, which are concentrated in the spiral arms. 
D)  Radio telescopes are easier to operate than optical telescopes, and observations can be made even during the daytime. 
E)  Radio photons do not have Doppler shifts, so we can detect clouds of gas without having to worry about the orbital velocities.

Question 11

If you wanted to study the properties of nearby stars that were some of the first stars to form in the Milky Way, but were not members of a globular cluster, how would you go about finding them? Name and explain two properties that would allow you to distinguish these stars from others.

Accepted Answer

Some halo stars can pass through the gal

Question 12

If dust is present between Earth and a distant globular cluster, the cluster will appear to be ________ than it is in reality.

Accepted Answer

A)  more distant 
B)  larger 
C)  more massive 
D)  more heavy metal-rich 
E)  smaller 
A)  more distant 
B)  larger 
C)  more massive 
D)  more heavy metal-rich 
E)  smaller

Question 13

Name at least two objects that are best studied at radio or infrared wavelengths, and explain why.

Accepted Answer

The long wavelengths allow us to see thr

Question 14

We find that interstellar gas and the youngest disk stars are found in a very narrow distribution along the galactic plane, but the older disk stars can be found in a thicker disk.What might this mean?

Accepted Answer

A)  Gravitational scattering of molecular clouds changes the orbits of disk stars as they get older. 
B)  The disk is still settling down from a thicker to a thinner state. 
C)  The galaxy has not absorbed any dwarf galaxies in the last several billion years. 
D)  Cosmic rays are responsible for causing star formation to happen in a narrow layer over time. 
E)  Most of the dark matter in the galaxy is in a thin layer along the disk. 
A)  Gravitational scattering of molecular clouds changes the orbits of disk stars as they get older. 
B)  The disk is still settling down from a thicker to a thinner state. 
C)  The galaxy has not absorbed any dwarf galaxies in the last several billion years. 
D)  Cosmic rays are responsible for causing star formation to happen in a narrow layer over time. 
E)  Most of the dark matter in the galaxy is in a thin layer along the disk.

Question 15

Most of the stars near the Sun have

Accepted Answer

A)  element abundances similar to those of the Sun. 
B)  velocities much higher than that of the Sun. 
C)  element abundances that are much higher than those of the Sun. 
D)  velocities much lower than that of the Sun. 
E)  element abundances that are much lower than those of the Sun. 
A)  element abundances similar to those of the Sun. 
B)  velocities much higher than that of the Sun. 
C)  element abundances that are much higher than those of the Sun. 
D)  velocities much lower than that of the Sun. 
E)  element abundances that are much lower than those of the Sun.

Question 16

Why is the Milky Way Galaxy's magnetic field "trapped" in its disk? How does this affect cosmic rays?

Accepted Answer

Magnetic fields are "attracted" to molec

Question 17

Outline the basic scenario of formation and evolution of the Milky Way, including a description of how the halo and disk formed.

Accepted Answer

Within a large clump of dark matter the

Question 18

Globular clusters, when compared with open clusters, generally

Accepted Answer

A)  are located closer to the center of the Milky Way. 
B)  are younger in age. 
C)  have lower fractions of heavy elements. 
D)  are less massive. 
E)  contain more dark matter. 
A)  are located closer to the center of the Milky Way. 
B)  are younger in age. 
C)  have lower fractions of heavy elements. 
D)  are less massive. 
E)  contain more dark matter.

Question 19

Our galaxy is ________ many other galaxies because the dark matter in the Milky Way ________.

Accepted Answer

A)  unlike; makes up a smaller fraction of the total mass than in other galaxies 
B)  unlike; makes up a larger fraction of the total mass than in other galaxies 
C)  like; makes up most of the mass in the galaxy 
D)  like; is made up of black holes and other stellar remnants 
E)  like; is made up of dust and faint objects of planetary mass 
A)  unlike; makes up a smaller fraction of the total mass than in other galaxies 
B)  unlike; makes up a larger fraction of the total mass than in other galaxies 
C)  like; makes up most of the mass in the galaxy 
D)  like; is made up of black holes and other stellar remnants 
E)  like; is made up of dust and faint objects of planetary mass

Question 20

Observations show that the halo of the Milky Way contains

Accepted Answer

A)  globular clusters. 
B)  dwarf galaxies. 
C)  stars orbiting the galaxy by themselves. 
D)  tidally disrupted objects. 
E)  all of these 
A)  globular clusters. 
B)  dwarf galaxies. 
C)  stars orbiting the galaxy by themselves. 
D)  tidally disrupted objects. 
E)  all of these

Exam 20: The Milky Waya Normal Spiral Galaxy

If you find a halo star that is 13 billion years old and has the same amount of heavy elements as the Sun, should you be surprised?

Compared to the Sun's stellar neighborhood, globular clusters have

The location, motion, and heavy-element enrichment of interstellar gas can be strongly affected by what?

What is a cosmic ray? Do cosmic rays affect life on Earth?

These three barred spirals are the largest members of the Local Group:

Astronomers expect life to be rare (and maybe impossible) in the Milky Way's bulge because

Cosmic rays in the Milky Way are important to study because

What would be the apparent angular size of a 100 light-year-diameter globular cluster in the Andromeda Galaxy (2.5 x106 light-years away), as measured from Earth?

Why is 21-cm radiation one of the best ways to map the spiral arms of the Milky Way?

If you wanted to study the properties of nearby stars that were some of the first stars to form in the Milky Way, but were not members of a globular cluster, how would you go about finding them? Name and explain two properties that would allow you to distinguish these stars from others.

If dust is present between Earth and a distant globular cluster, the cluster will appear to be ________ than it is in reality.

Name at least two objects that are best studied at radio or infrared wavelengths, and explain why.

We find that interstellar gas and the youngest disk stars are found in a very narrow distribution along the galactic plane, but the older disk stars can be found in a thicker disk.What might this mean?

Most of the stars near the Sun have

Why is the Milky Way Galaxy's magnetic field "trapped" in its disk? How does this affect cosmic rays?

Outline the basic scenario of formation and evolution of the Milky Way, including a description of how the halo and disk formed.

Globular clusters, when compared with open clusters, generally

Our galaxy is ________ many other galaxies because the dark matter in the Milky Way ________.

Observations show that the halo of the Milky Way contains

Thinking Like an Astronomer

Patterns in the Skymotions of Earth and the Moon

Motion of Astronomical Bodies

Gravity and Orbits

Light

The Tools of the Astronomer

The Formation of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquidthe Giant Planets

Planetary Moons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

The Interstellar Medium and Star Formation

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

Galaxies

The Expanding Universe

Cosmology

Large-Scale Structure in the Universe

Life

Filters

What would be the apparent angular size of a 100 light-year-diameter globular cluster in the Andromeda Galaxy (2.5 x10⁶ light-years away), as measured from Earth?

Our galaxy is many other galaxies because the dark matter in the Milky Way .