Question 1

The "helium flash" is

Accepted Answer

A) The rapid consumption of core helium when helium fusion first starts in a star 
B) A flash of light as the star encounters a cloud of helium 
C) A bright X-ray flash from a helium accretion disk surrounding a black hole 
D) An infrared burst from helium-rich proto stars 
A) The rapid consumption of core helium when helium fusion first starts in a star 
B) A flash of light as the star encounters a cloud of helium 
C) A bright X-ray flash from a helium accretion disk surrounding a black hole 
D) An infrared burst from helium-rich proto stars A

Question 2

What do all main sequence stars have in common?

Accepted Answer

A) They are all the same age 
B) They are all consuming hydrogen in their cores 
C) They all have the same mass 
D) They all have convective cores. 
A) They are all the same age 
B) They are all consuming hydrogen in their cores 
C) They all have the same mass 
D) They all have convective cores. B

Question 3

Elements heavier than iron are produced

Accepted Answer

A) In stars during hydrogen burning 
B) In interstellar space 
C) During supernova outbursts 
D) During carbon burning in massive stars 
A) In stars during hydrogen burning 
B) In interstellar space 
C) During supernova outbursts 
D) During carbon burning in massive stars C

Question 4

What is the general name for a star that is converting hydrogen into helium in its core?

Accepted Answer

A) Main sequence star 
B) Red giant star 
C) White dwarf star 
D) Protostar 
A) Main sequence star 
B) Red giant star 
C) White dwarf star 
D) Protostar

Question 5

Which of the following occurs just after a star like the Sun exhausts the hydrogen in its core?

Accepted Answer

A) The core contracts,the outer layers contract 
B) The core contracts,the outer layers expand 
C) The core expands,the outer layers contract 
D) The core expands,the outer layers expand 
E) It becomes a supernova 
A) The core contracts,the outer layers contract 
B) The core contracts,the outer layers expand 
C) The core expands,the outer layers contract 
D) The core expands,the outer layers expand 
E) It becomes a supernova

Question 6

All the stars in a cluster are usually assumed to have the same

Accepted Answer

A) Age 
B) Mass 
C) Temperature 
D) Main sequence lifetime 
A) Age 
B) Mass 
C) Temperature 
D) Main sequence lifetime

Question 7

When a superwind strips away the outer layers of a star,the resulting shell of expanding gas becomes visible as

Accepted Answer

A) A planetary nebula 
B) An HII region 
C) A reflection nebula 
D) A dark nebula 
A) A planetary nebula 
B) An HII region 
C) A reflection nebula 
D) A dark nebula

Question 8

The main sequence turnoff of a cluster of stars is a good indicator of which of the following properties of the cluster?

Accepted Answer

A) Age 
B) Number of stars in the cluster 
C) Chemical composition 
D) Distance 
A) Age 
B) Number of stars in the cluster 
C) Chemical composition 
D) Distance

Question 9

What prevents stars of 4 solar masses from exploding as supernovae?

Accepted Answer

A) Winds strip away their outer layers 
B) They become white dwarfs first 
C) They become black holes first 
D) They have such long main sequence lifetimes that this has never happened 
A) Winds strip away their outer layers 
B) They become white dwarfs first 
C) They become black holes first 
D) They have such long main sequence lifetimes that this has never happened

Question 10

What would happen if asymptotic giant branch stars didn't shed their outer layers into interstellar space?

Accepted Answer

A) More of them would become supernovas 
B) They would become black holes more quickly 
C) The mass of the galaxy would be greater 
D) There would be more star formation going on in the galaxy 
A) More of them would become supernovas 
B) They would become black holes more quickly 
C) The mass of the galaxy would be greater 
D) There would be more star formation going on in the galaxy

Question 11

Carbon,hydrogen,and helium can all be used a fuels during the career of a massive star.Which of the following gives these elements in the correct order in which they will be consumed in the star?

Accepted Answer

A) Hydrogen,helium,carbon 
B) Helium,carbon,hydrogen 
C) Carbon,hydrogen,helium 
D) Hydrogen,carbon,helium 
A) Hydrogen,helium,carbon 
B) Helium,carbon,hydrogen 
C) Carbon,hydrogen,helium 
D) Hydrogen,carbon,helium

Question 12

The sequence of reactions by which stars convert helium into carbon is called the

Accepted Answer

A) S-process 
B) Triple alpha reaction 
C) CNO cycle 
D) Proton-proton chain 
A) S-process 
B) Triple alpha reaction 
C) CNO cycle 
D) Proton-proton chain

Question 13

The fusion of iron nuclei does not occur in stable stars.Why not?

Accepted Answer

A) Iron isn't a stable element. 
B) The fusion process skips over iron and goes on to more massive elements. 
C) Iron fusion uses up energy instead of producing energy 
D) Iron is destroyed in stars as soon as it is produced 
A) Iron isn't a stable element. 
B) The fusion process skips over iron and goes on to more massive elements. 
C) Iron fusion uses up energy instead of producing energy 
D) Iron is destroyed in stars as soon as it is produced

Question 14

An evolutionary track describes the career of a star by showing changes in its location in

Accepted Answer

A) Space 
B) An H-R diagram 
C) A mass-luminosity diagram 
D) A mass-radius diagram 
A) Space 
B) An H-R diagram 
C) A mass-luminosity diagram 
D) A mass-radius diagram

Question 15

The least massive stars in which nuclear fusion occurs have masses of about 8% that of the Sun.Why don't less massive objects ever experience nuclear fusion?

Accepted Answer

A) They explode before fusion can begin 
B) They collide with other objects and increase their masses 
C) They never become hot enough for fusion to occur 
D) They become black holes before fusion can begin 
A) They explode before fusion can begin 
B) They collide with other objects and increase their masses 
C) They never become hot enough for fusion to occur 
D) They become black holes before fusion can begin

Question 16

If M is the mass of a star and L is its luminosity,which of the following is proportional to the main sequence lifetime of a star?

Accepted Answer

A) M / L 
B) M * L 
C) M - L 
D) M + L 
A) M / L 
B) M * L 
C) M - L 
D) M + L

Question 17

The most important factor affecting a star's main-sequence lifetime is

Accepted Answer

A) Radius 
B) Mass 
C) Chemical composition 
D) Surface temperature 
A) Radius 
B) Mass 
C) Chemical composition 
D) Surface temperature

Question 18

Which of the following is a key difference between the pressure in a normal gas and in a degenerate gas?

Accepted Answer

A) In a degenerate gas,pressure doesn't depend on temperature 
B) In a degenerate gas,pressure doesn't depend on density 
C) Degenerate pressure exists whether matter is present or not 
D) In a degenerate gas pressure varies rapidly with time 
A) In a degenerate gas,pressure doesn't depend on temperature 
B) In a degenerate gas,pressure doesn't depend on density 
C) Degenerate pressure exists whether matter is present or not 
D) In a degenerate gas pressure varies rapidly with time

Question 19

Massive stars on the upper end of the main sequence generate energy by means of the

Accepted Answer

A) Proton-proton cycle 
B) CNO cycle 
C) Triple alpha reaction 
D) Radiation reaction 
A) Proton-proton cycle 
B) CNO cycle 
C) Triple alpha reaction 
D) Radiation reaction

Question 20

What element is produced by the triple-alpha reaction,in which three helium nuclei are fused together?

Accepted Answer

A) Hydrogen 
B) Carbon 
C) Iron 
D) Uranium 
A) Hydrogen 
B) Carbon 
C) Iron 
D) Uranium

Exam 19: The Evolution of Stars

The "helium flash" is

What do all main sequence stars have in common?

Elements heavier than iron are produced

What is the general name for a star that is converting hydrogen into helium in its core?

Which of the following occurs just after a star like the Sun exhausts the hydrogen in its core?

All the stars in a cluster are usually assumed to have the same

When a superwind strips away the outer layers of a star,the resulting shell of expanding gas becomes visible as

The main sequence turnoff of a cluster of stars is a good indicator of which of the following properties of the cluster?

What prevents stars of 4 solar masses from exploding as supernovae?

What would happen if asymptotic giant branch stars didn't shed their outer layers into interstellar space?

Carbon,hydrogen,and helium can all be used a fuels during the career of a massive star.Which of the following gives these elements in the correct order in which they will be consumed in the star?

The sequence of reactions by which stars convert helium into carbon is called the

The fusion of iron nuclei does not occur in stable stars.Why not?

An evolutionary track describes the career of a star by showing changes in its location in

The least massive stars in which nuclear fusion occurs have masses of about 8% that of the Sun.Why don't less massive objects ever experience nuclear fusion?

If M is the mass of a star and L is its luminosity,which of the following is proportional to the main sequence lifetime of a star?

The most important factor affecting a star's main-sequence lifetime is

Which of the following is a key difference between the pressure in a normal gas and in a degenerate gas?

Massive stars on the upper end of the main sequence generate energy by means of the

What element is produced by the triple-alpha reaction,in which three helium nuclei are fused together?

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