Question 1

A typical molecular cloud has a temperature of approximately:

Accepted Answer

A)  0.3 K
B)  10 K
C)  80 K
D)  300 K
E)  1000 KF) A) and B)
G) A) and C)

Question 2

"Weather" in the interstellar medium is produced:

Accepted Answer

A)  only by supernovae
B)  by supernovae and strong winds from luminous stars
C)  by supernovae,strong winds from luminous stars,and fast-moving stars
D)  by supernovae,strong winds from luminous stars,fast-moving stars,and exploding planets
E)  by supernovae,strong winds from luminous stars,fast-moving stars,exploding planets,and black holesF) A) and B)
G) A) and C)

Question 3

The H- ion is very important in protostars because it:

Accepted Answer

A)  reacts with oxygen to produce water
B)  undergoes fusion and produces energy
C)  helps make the protostars denser
D)  acts as a temperature regulator
E)  reduces angular momentumF) D) and E)
G) A) and E)

Question 4

The figures below show the spectrum of a star,along with five other spectra labeled A through E.  Which one of the labeled spectra shows what the spectrum of that star would look like if it were viewed through a significant amount of interstellar dust?

Accepted Answer

A)  A
B)  B
C)  C
D)  D
E)  EF) A) and E)
G) A) and D)

Question 5

How are H II regions and the hot intercloud gas heated?

Accepted Answer

Hot intercloud gas is heated b...

Question 6

When a 3 M⨀ protostar forms,it starts out at the top of the Hayashi track with a luminosity of 4,000 L⨀ and a temperature of 3600 K.What is its radius at this point (give the answer in units of R⨀),and how many times larger is it at this stage compared to its radius as a main-sequence star,which is about 2.5 R⨀? For reference,the Sun's temperature is 5800 K.

Accepted Answer

The Stefan-Boltzmann law says ...

Question 7

Magnetic fields inside a molecular cloud act to:

Accepted Answer

A)  inhibit gravitational collapse
B)  fragment the cloud into numerous cores
C)  modulate the temperature of the molecules
D)  increase the formation of dust grains
E)  increase the formation of protostarsF) C) and E)
G) All of the above

Question 8

If a 1 M⨀protostar starts out on the Hayashi track with a temperature of 3300 K and a luminosity of 320 L⨀,what is its approximate radius?

Accepted Answer

A)  25 R⨀
B)  55 R⨀
C)  75 R⨀
D)  105 R⨀
E)  125 R⨀F) A) and E)
G) A) and D)

Question 9

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

H II regions are best seen at H-alpha wi...

Question 10

The coldest molecular clouds in our galaxy have temperatures of approximately 1000 K.

Accepted Answer

A) True 
 B)False

Question 11

Which of the following stars spend the longest time on their Hayashi tracks?

Accepted Answer

A)  100 M⨀ stars
B)  10 M⨀ stars
C)  1 M⨀ stars
D)  0.1 M⨀ stars
E)  0.08 M⨀ starsF) B) and E)
G) All of the above

Question 12

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 bluer and dimmer
D)  the object appears redder and dimmer
E)  the object's apparent velocity changesF) C) and E)
G) A) and C)

Question 13

If you could watch stars forming out of a gas cloud,which stars would form first?

Accepted Answer

A)  low-mass stars
B)  medium-mass stars
C)  high-mass stars
D)  stars with low temperatures
E)  stars with more heavy elementsF) A) and B)
G) A) and C)

Question 14

Why do many stars form from a single molecular cloud?

Accepted Answer

Small density fluctuations in the parent...

Question 15

We detect neutral gas in the interstellar medium by looking for radiation at 21 cm that arises when:

Accepted Answer

A)  an electron moves from the n = 1 to n = 2 state in a hydrogen atom
B)  an electron is ionized from a hydrogen atom
C)  carbon monoxide (CO) gas is excited by stellar radiation
D)  the spin of an electron flips and aligns with the spin of a proton in a hydrogen atom
E)  an electron combines with a proton to make a hydrogen atomF) A) and B)
G) A) and C)

Question 16

The dust in the interstellar medium comes primarily from the stellar winds of main-sequence stars.

Accepted Answer

A) True 
 B)False

Question 17

Why does the surface temperature of a low-mass protostar remain nearly constant as its core contracts?

Accepted Answer

It remains nearly constant bec...

Question 18

The red emission in the photo below is due to: 2)  D) ionized hydrogen (H II region)  E) dust" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  carbon monoxide (CO) 
B)  warm,neutral hydrogen
C)  molecular hydrogen (H2) 
D)  ionized hydrogen (H II region) 
E)  dustF) A) and B)
G) C) and E)

Question 19

The H- atom is important in protostars because it acts as a powerful temperature regulator.

Accepted Answer

A) True 
 B)False

Question 20

Molecular hydrogen atoms are found only inside dense clouds where they are shielded from stellar radiation.

Accepted Answer

A) True 
 B)False

Exam 15: Star Formation and the Interstellar Medium

Molecular hydrogen atoms are found only inside dense clouds where they are shielded from stellar radiation.

Correct Answer
verified

The red emission in the photo below is due to:

Correct Answer
verified

Correct Answer
verified
The Stefan-Boltzmann law says ...
View Answer

"Weather" in the interstellar medium is produced:

Correct Answer
verified

Why do many stars form from a single molecular cloud?

Correct Answer
verified
Small density fluctuations in the parent...
View Answer

The figures below show the spectrum of a star,along with five other spectra labeled A through E. Which one of the labeled spectra shows what the spectrum of that star would look like if it were viewed through a significant amount of interstellar dust?

Correct Answer
verified

If a 1 M_⨀protostar starts out on the Hayashi track with a temperature of 3300 K and a luminosity of 320 L_⨀,what is its approximate radius?

Correct Answer
verified

A typical molecular cloud has a temperature of approximately:

Correct Answer
verified

The dust in the interstellar medium comes primarily from the stellar winds of main-sequence stars.

Correct Answer
verified

Why does the surface temperature of a low-mass protostar remain nearly constant as its core contracts?

Correct Answer
verified
It remains nearly constant bec...
View Answer

We detect neutral gas in the interstellar medium by looking for radiation at 21 cm that arises when:

Correct Answer
verified

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?

Correct Answer
verified
H II regions are best seen at H-alpha wi...
View Answer

When radiation from an object passes through the interstellar medium:

Correct Answer
verified

The coldest molecular clouds in our galaxy have temperatures of approximately 1000 K.

Correct Answer
verified

Which of the following stars spend the longest time on their Hayashi tracks?

Correct Answer
verified

Magnetic fields inside a molecular cloud act to:

Correct Answer
verified

The H^- atom is important in protostars because it acts as a powerful temperature regulator.

Correct Answer
verified

The H^- ion is very important in protostars because it:

Correct Answer
verified

If you could watch stars forming out of a gas cloud,which stars would form first?

Correct Answer
verified

How are H II regions and the hot intercloud gas heated?

Correct Answer
verified
Hot intercloud gas is heated b...
View Answer

Exam 15: Star Formation and the Interstellar Medium

Molecular hydrogen atoms are found only inside dense clouds where they are shielded from stellar radiation.

Correct AnswerverifiedShow Answer

The red emission in the photo below is due to:

Correct AnswerverifiedShow Answer

Correct AnswerverifiedThe Stefan-Boltzmann law says ...View AnswerShow Answer

"Weather" in the interstellar medium is produced:

Correct AnswerverifiedShow Answer

Why do many stars form from a single molecular cloud?

Correct AnswerverifiedSmall density fluctuations in the parent...View AnswerShow Answer

The figures below show the spectrum of a star,along with five other spectra labeled A through E. Which one of the labeled spectra shows what the spectrum of that star would look like if it were viewed through a significant amount of interstellar dust?

Correct AnswerverifiedShow Answer

If a 1 M⨀protostar starts out on the Hayashi track with a temperature of 3300 K and a luminosity of 320 L⨀,what is its approximate radius?

Correct AnswerverifiedShow Answer

A typical molecular cloud has a temperature of approximately:

Correct AnswerverifiedShow Answer

The dust in the interstellar medium comes primarily from the stellar winds of main-sequence stars.

Correct AnswerverifiedShow Answer

Why does the surface temperature of a low-mass protostar remain nearly constant as its core contracts?

Correct AnswerverifiedIt remains nearly constant bec...View AnswerShow Answer

We detect neutral gas in the interstellar medium by looking for radiation at 21 cm that arises when:

Correct AnswerverifiedShow Answer

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?

Correct AnswerverifiedH II regions are best seen at H-alpha wi...View AnswerShow Answer

When radiation from an object passes through the interstellar medium:

Correct AnswerverifiedShow Answer

The coldest molecular clouds in our galaxy have temperatures of approximately 1000 K.

Correct AnswerverifiedShow Answer

Which of the following stars spend the longest time on their Hayashi tracks?

Correct AnswerverifiedShow Answer

Magnetic fields inside a molecular cloud act to:

Correct AnswerverifiedShow Answer

The H- atom is important in protostars because it acts as a powerful temperature regulator.

Correct AnswerverifiedShow Answer

The H- ion is very important in protostars because it:

Correct AnswerverifiedShow Answer

If you could watch stars forming out of a gas cloud,which stars would form first?

Correct AnswerverifiedShow Answer

How are H II regions and the hot intercloud gas heated?

Correct AnswerverifiedHot intercloud gas is heated b...View AnswerShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
The Stefan-Boltzmann law says ...
View Answer

Correct Answer
verified

Correct Answer
verified
Small density fluctuations in the parent...
View Answer

Correct Answer
verified

If a 1 M_⨀protostar starts out on the Hayashi track with a temperature of 3300 K and a luminosity of 320 L_⨀,what is its approximate radius?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
It remains nearly constant bec...
View Answer

Correct Answer
verified

Correct Answer
verified
H II regions are best seen at H-alpha wi...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

The H^- atom is important in protostars because it acts as a powerful temperature regulator.

Correct Answer
verified

The H^- ion is very important in protostars because it:

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
Hot intercloud gas is heated b...
View Answer