Question 1

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 could you go about finding them?

Accepted Answer

You would look for stars that were members of the Milky Way halo.The stars would have highly elliptical orbits,not rotating like other disk stars,and you could identify them by the very high velocities they have as they pass through the solar neighborhood.Also,you could identify halo stars by their low chemical abundance,and main-sequence halo stars by their relatively bluer colors than disk stars.

Question 2

Cosmic rays come mostly from extragalactic sources and contribute little to the overall energy balance in the Milky Way disk.

Accepted Answer

A) True 
 B)False  False

Question 3

The AVERAGE density of the interstellar medium is:

Accepted Answer

A)   1 atom/cm3
B)   1,000 atoms/cm3
C)   106 atoms/cm3
D)   1012 atoms/cm3 A

Question 4

In the figure below,the spectrum of a star is given without being obscured by dust and also being obscured by dust.Explain how the dust affects the light arriving from the star.

Accepted Answer

The answer of In the figure below,the spectrum of a...

Question 5

If you wanted to study regions where star formation is currently happening you could use:

Accepted Answer

A)   Hydrogen emission to look for O and B stars
B)   a radio telescope to search for molecular cloud cores
C)   infrared emission to identify T Tauri stars
D)   all of the above

Question 6

Most of the mass in our galaxy is in the form of:

Accepted Answer

A)   stars
B)   gas
C)   dust
D)   dark matter

Question 7

In a star that has a chemical abundance similar to the Sun,what percentage of its mass is made of heavy elements?

Accepted Answer

A)   0.02 percent
B)   0.2 percent
C)   2 percent
D)   20 percent

Question 8

Halo stars formed before gas in the Milky Way collapsed to form the disk.

Accepted Answer

A) True 
 B)False

Question 9

Stars forming in molecular clouds tend to form first in the low-density periphery.

Accepted Answer

A) True 
 B)False

Question 10

At what wavelength are H II regions most clearly visible,and why do H II regions mark the regions where new stars are currently being formed?

Accepted Answer

The answer of At what wavelength are H II regions...

Question 11

When radiation from an object passes through the interstellar medium:

Accepted Answer

A)   the object appears dimmer
B)   the object appears bluer
C)   the object appears redder and dimmer
D)   the object's apparent velocity changes

Question 12

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 supermassive black hole

Question 13

Explain how a standard candle allows you to determine the distance to an object.What is it that you have to measure or know about the standard candle to derive its distance?

Accepted Answer

The answer of Explain how a standard candle allows you...

Question 14

Where are the most metal-rich stars found in the Milky Way?

Accepted Answer

A)   In the disk near the Sun
B)   At the center
C)   In the halo
D)   In globular clusters

Question 15

The lowest-density gas in the interstellar medium is also the coldest.

Accepted Answer

A) True 
 B)False

Question 16

Our galaxy is classified as an Sd galaxy in the Hubble sequence.

Accepted Answer

A) True 
 B)False

Question 17

Why is the supermassive black hole in the center of our galaxy not an AGN right now? Could it be active in the future? Why or why not?

Accepted Answer

The answer of Why is the supermassive black hole in...

Question 18

Molecular clouds are best observed at __________ wavelengths.

Accepted Answer

A)   ultraviolet
B)   optical
C)   infrared
D)   radio

Question 19

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

Accepted Answer

A)   Globular clusters
B)   Planetary nebulae
C)   RR Lyrae stars
D)   Clouds emitting 21-cm emission

Question 20

Describe the differences between the ages and chemical abundances of globular and open star clusters.

Accepted Answer

The answer of Describe the differences between the ages and...

Exam 16: Our Galaxy: 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 could you go about finding them?

Cosmic rays come mostly from extragalactic sources and contribute little to the overall energy balance in the Milky Way disk.

The AVERAGE density of the interstellar medium is:

In the figure below,the spectrum of a star is given without being obscured by dust and also being obscured by dust.Explain how the dust affects the light arriving from the star.

If you wanted to study regions where star formation is currently happening you could use:

Most of the mass in our galaxy is in the form of:

In a star that has a chemical abundance similar to the Sun,what percentage of its mass is made of heavy elements?

Halo stars formed before gas in the Milky Way collapsed to form the disk.

Stars forming in molecular clouds tend to form first in the low-density periphery.

At what wavelength are H II regions most clearly visible,and why do H II regions mark the regions where new stars are currently being formed?

When radiation from an object passes through the interstellar medium:

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

Explain how a standard candle allows you to determine the distance to an object.What is it that you have to measure or know about the standard candle to derive its distance?

Where are the most metal-rich stars found in the Milky Way?

The lowest-density gas in the interstellar medium is also the coldest.

Our galaxy is classified as an Sd galaxy in the Hubble sequence.

Why is the supermassive black hole in the center of our galaxy not an AGN right now? Could it be active in the future? Why or why not?

Molecular clouds are best observed at __________ wavelengths.

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

Describe the differences between the ages and chemical abundances of globular and open star clusters.