Question 1

The free-fall contraction of a molecular cloud

Accepted Answer

A)  can be initiated by shock waves from supernovae. 
B)  can be initiated by nearby spectral type G stars. 
C)  can be initiated by the rotation of the cloud. 
D)  causes the cloud to become transparent to ultraviolet radiation. 
E)  causes the particles in the cloud to decrease the speed with which they move.

Question 2

The pressure of an interstellar gas cloud depends on the cloud s ____________________ and ____________________.

Accepted Answer

The answer of The pressure of an interstellar gas cloud...

Question 3

Some massive stars only live a few million years.

Accepted Answer

A) True 
 B)False

Question 4

While on the main sequence a star s primary energy source comes from

Accepted Answer

A)  nuclear fusion. 
B)  nuclear fission. 
C)  gravitational potential energy. 
D)  magnetic fields.

Question 5

Star clusters are important to the study the stellar evolution because stars in a given cluster have the same

Accepted Answer

A)  temperature. 
B)  mass. 
C)  age. 
D)  luminosity.

Question 6

Convection is important in stars because it

Accepted Answer

A)  increases the temperature of the star. 
B)  mixes the gases of the star. 
C)  transports energy outward in the star. 
D)  carries the neutrinos to the surface of the star where they can escape. 
E)  b and c

Question 7

Interstellar gas clouds may collapse to form stars if they

Accepted Answer

A)  have very high temperatures. 
B)  encounter a shock wave. 
C)  rotate rapidly. 
D)  are located near main sequence spectral type K and M stars. 
E)  all of the above.

Question 8

Why are distant stars redder than nearby stars of the same spectral type?

Accepted Answer

The answer of Why are distant stars redder than nearby...

Question 9

The sun has a core in which energy travels outward primarily by radiation.

Accepted Answer

A) True 
 B)False

Question 10

The visual pink glow of the Great Nebula in Orion

Accepted Answer

A)  is a Herbig-Haro object. 
B)  is a reflection nebula of dust. 
C)  is an emission nebula of thin gas. 
D)  contains only young low mass stars. 
E)  is believed to be about 5 billion years old.

Question 11

In the proton-proton chain

Accepted Answer

A)  no neutrinos are produced. 
B)  energy is released because a helium nucleus has a greater mass than a hydrogen nucleus. 
C)  no photons are produced. 
D)  carbon serves as a catalyst for the nuclear reaction. 
E)  energy is produced in the form of gamma rays and the velocity of the created nuclei.

Question 12

What must occur for an object to be considered a main sequence star?

Accepted Answer

A)  Hydrostatic equilibrium 
B)  Nuclear fusion reaction in the core 
C)  Protostar life begins 
D)  Both a and b

Question 13

As a star begin to form the initial energy source is from

Accepted Answer

A)  nuclear fusion. 
B)  nuclear fission. 
C)  gravitational potential energy. 
D)  magnetic fields.

Question 14

Emission nebulae are also called ____ because they are composed of ionized hydrogen.

Accepted Answer

A)  HI regions 
B)  HII regions 
C)  Bok globules 
D)  HeI regions 
E)  reflection nebulae

Question 15

Pre-main sequence stars are above and to the right of the main sequence.

Accepted Answer

A) True 
 B)False

Question 16

Why are massive stars more luminous than low mass stars? That is, why is there a mass-luminosity relation?

Accepted Answer

The answer of Why are massive stars more luminous than...

Question 17

A(n) ____________________ is a cool, dense cloud of dust and gas that is undergoing gravitational contraction.

Accepted Answer

The answer of A(n) ____________________ is a cool, dense cloud...

Question 18

High mass stars evolve more slowly to the main sequence than lower mass stars.

Accepted Answer

A) True 
 B)False

Question 19

What force(s) are responsible for the collapse of an interstellar cloud?

Accepted Answer

A)  nuclear 
B)  gravity 
C)  electric 
D)  magnetic 
E)  both c and d

Question 20

Ninety percent of all stars fuse helium to form carbon and lie on the main sequence.

Accepted Answer

A) True 
 B)False

Exam 10: Structure and Formation of Stars

The free-fall contraction of a molecular cloud

The pressure of an interstellar gas cloud depends on the cloud s and .

Some massive stars only live a few million years.

While on the main sequence a star s primary energy source comes from

Star clusters are important to the study the stellar evolution because stars in a given cluster have the same

Convection is important in stars because it

Interstellar gas clouds may collapse to form stars if they

Why are distant stars redder than nearby stars of the same spectral type?

The sun has a core in which energy travels outward primarily by radiation.

The visual pink glow of the Great Nebula in Orion

In the proton-proton chain

What must occur for an object to be considered a main sequence star?

As a star begin to form the initial energy source is from

Emission nebulae are also called ____ because they are composed of ionized hydrogen.

Pre-main sequence stars are above and to the right of the main sequence.

Why are massive stars more luminous than low mass stars? That is, why is there a mass-luminosity relation?

A(n) ____________________ is a cool, dense cloud of dust and gas that is undergoing gravitational contraction.

High mass stars evolve more slowly to the main sequence than lower mass stars.

What force(s) are responsible for the collapse of an interstellar cloud?

Ninety percent of all stars fuse helium to form carbon and lie on the main sequence.