Question 1

High-mass stars differ from low-mass stars in that they burn helium to carbon when on the main sequence.

Accepted Answer

A) True 
 B)False

Question 2

Type I and Type II supernovae are respectively caused by what types of stars?

Accepted Answer

A) white dwarfs,Cepheid variables 
B) white dwarfs,pulsars 
C) massive stars,white dwarfs 
D) massive stars,neutron stars 
E) white dwarfs,massive stars 
A) white dwarfs,Cepheid variables 
B) white dwarfs,pulsars 
C) massive stars,white dwarfs 
D) massive stars,neutron stars 
E) white dwarfs,massive stars

Question 3

What mechanism provides the internal pressure inside a neutron star?

Accepted Answer

A) ordinary pressure from hydrogen and helium gas 
B) degeneracy pressure from neutrons 
C) degeneracy pressure from electrons 
D) rapid rotation 
E) strong magnetic fields 
A) ordinary pressure from hydrogen and helium gas 
B) degeneracy pressure from neutrons 
C) degeneracy pressure from electrons 
D) rapid rotation 
E) strong magnetic fields

Question 4

Each kilogram of hydrogen that fuses into helium releases about 6 × 1014 Joules of energy.How many tons of hydrogen are fused each second to power a massive main-sequence star with a luminosity of 100 L⨀? Note that 1 L⨀ = 4 × 1026 Joule/second and 1 ton = 103 kg.

Accepted Answer

A) 2 × 106 tons 
B) 7 × 107 tons 
C) 2 × 109 tons 
D) 7 × 1010 tons 
E) 2 × 1011 tons 
A) 2 × 106 tons 
B) 7 × 107 tons 
C) 2 × 109 tons 
D) 7 × 1010 tons 
E) 2 × 1011 tons

Question 5

Suppose you observe three star clusters.Cluster 1 has a main-sequence turnoff point at spectral type G,Cluster 2 has a turnoff point at spectral type A,and Cluster 3 has a turnoff point at spectral type B.Which cluster is youngest and which is oldest? Explain why.What is the approximate age of the oldest cluster?

Accepted Answer

Of the three types of main-sequence turn

Question 6

We can determine the age of a star cluster by measuring the color of the reddest red giant stars in the cluster.

Accepted Answer

A) True 
 B)False

Question 7

Essentially all the elements heavier than iron in our Milky Way were formed:

Accepted Answer

A) by supernovae 
B) during the formation of black holes 
C) by fusion in the cores of the most massive main-sequence stars 
D) during the formation of planetary nebulae 
E) during the initial stages of the Big Bang 
A) by supernovae 
B) during the formation of black holes 
C) by fusion in the cores of the most massive main-sequence stars 
D) during the formation of planetary nebulae 
E) during the initial stages of the Big Bang

Question 8

Why does the luminosity of a high-mass star remain nearly constant as the star burns heavy elements in its core,even though it is producing millions of times more energy per second than it did on the main sequence?

Accepted Answer

A) Most of the energy is trapped in the core,increasing the core's temperature. 
B) All of the extra energy goes into heating the shells of fusion surrounding the core. 
C) Most of the energy is absorbed by the outer layers of the star,increasing the star's radius but leaving its luminosity unchanged. 
D) Most of the energy is carried out of the star by escaping neutrinos. 
E) All of the energy goes into breaking apart light elements like helium and carbon. 
A) Most of the energy is trapped in the core,increasing the core's temperature. 
B) All of the extra energy goes into heating the shells of fusion surrounding the core. 
C) Most of the energy is absorbed by the outer layers of the star,increasing the star's radius but leaving its luminosity unchanged. 
D) Most of the energy is carried out of the star by escaping neutrinos. 
E) All of the energy goes into breaking apart light elements like helium and carbon.

Question 9

The CNO cycle is the dominant mechanism for hydrogen fusion only in high-mass main-sequence stars because of the greater __________ their cores.

Accepted Answer

A) concentration of heavy elements like carbon in 
B) turbulence in 
C) abundance of hydrogen in 
D) temperature of 
E) rotation speed of 
A) concentration of heavy elements like carbon in 
B) turbulence in 
C) abundance of hydrogen in 
D) temperature of 
E) rotation speed of

Question 10

The collapse of the core of a high-mass star at the end of its life lasts approximately:

Accepted Answer

A) one second 
B) one minute 
C) one hour 
D) one week 
E) one year 
A) one second 
B) one minute 
C) one hour 
D) one week 
E) one year

Question 11

Massive stars explode soon after fusion to iron begins because:

Accepted Answer

A) iron has the smallest binding energy of all elements 
B) neutrinos emitted during the fusion to iron are captured by the star's lighter elements 
C) fusion of elements heavier than iron requires energy,so the star runs out of fuel and cannot hold itself up against gravity 
D) stars do not contain elements heavier than iron;these are made in supernova explosions 
E) iron nuclei are unstable and rapidly break apart into lighter elements 
A) iron has the smallest binding energy of all elements 
B) neutrinos emitted during the fusion to iron are captured by the star's lighter elements 
C) fusion of elements heavier than iron requires energy,so the star runs out of fuel and cannot hold itself up against gravity 
D) stars do not contain elements heavier than iron;these are made in supernova explosions 
E) iron nuclei are unstable and rapidly break apart into lighter elements

Question 12

What mechanism drives the pulsations in Cepheid variables?

Accepted Answer

A) changes in the rate of core nuclear reactions 
B) the formation and destruction of sunspots 
C) the ionization and recombination of hydrogen 
D) the ionization and recombination of helium 
E) large rates of mass loss 
A) changes in the rate of core nuclear reactions 
B) the formation and destruction of sunspots 
C) the ionization and recombination of hydrogen 
D) the ionization and recombination of helium 
E) large rates of mass loss

Question 13

What might be true about the oldest stars in the Milky Way?

Accepted Answer

A) They would have lots of heavy elements,since they have been around for a long time and have undergone a lot of nucleosynthesis in their cores. 
B) They would be seen as supergiants. 
C) They would have few heavy elements,since there was not much chance for earlier generations of stars to explode as supernovae before these stars were formed. 
D) They would be massive,since they were among the first stars formed. 
E) They would likely be seen as pulsars. 
A) They would have lots of heavy elements,since they have been around for a long time and have undergone a lot of nucleosynthesis in their cores. 
B) They would be seen as supergiants. 
C) They would have few heavy elements,since there was not much chance for earlier generations of stars to explode as supernovae before these stars were formed. 
D) They would be massive,since they were among the first stars formed. 
E) They would likely be seen as pulsars.

Question 14

The evolutionary differences between high- and low-mass stars can be attributed to differences in the amount of mass each star possesses.

Accepted Answer

A) True 
 B)False

Question 15

About 2% of the mass of the Sun is in elements heavier than helium.Where did these elements come from?

Accepted Answer

The sun formed out of a gas cloud in the

Question 16

Do large,high-mass main-sequence stars become red giants?

Accepted Answer

No,they do not.Red giants have a degener

Question 17

Where did the iron in your blood come from?

Accepted Answer

A) nucleosynthesis on the surfaces of neutron stars 
B) nucleosynthesis that took place in supernova explosions 
C) nucleosynthesis in the cores of low-mass stars 
D) nucleosynthesis in the cores of massive stars 
E) nucleosynthesis in red giant and horizontal-branch stars 
A) nucleosynthesis on the surfaces of neutron stars 
B) nucleosynthesis that took place in supernova explosions 
C) nucleosynthesis in the cores of low-mass stars 
D) nucleosynthesis in the cores of massive stars 
E) nucleosynthesis in red giant and horizontal-branch stars

Question 18

The nuclear reaction that produces most of the energy for massive main-sequence stars is called the CNO cycle.

Accepted Answer

A) True 
 B)False

Question 19

Although a Type II supernova shines with a luminosity of 100 billion L⨀ in light,most of the energy in the explosion is emitted in another way.What is it,and how much more energy does it carry compared to the light?

Accepted Answer

The majority of the energy released in a

Question 20

What is the meaning of nuclear binding energy?

Accepted Answer

The binding energy of a nucleus is the e

Exam 17: Evolution of High-Mass Stars

High-mass stars differ from low-mass stars in that they burn helium to carbon when on the main sequence.

Type I and Type II supernovae are respectively caused by what types of stars?

What mechanism provides the internal pressure inside a neutron star?

Each kilogram of hydrogen that fuses into helium releases about 6 × 1014 Joules of energy.How many tons of hydrogen are fused each second to power a massive main-sequence star with a luminosity of 100 L⨀? Note that 1 L⨀ = 4 × 1026 Joule/second and 1 ton = 103 kg.

We can determine the age of a star cluster by measuring the color of the reddest red giant stars in the cluster.

Essentially all the elements heavier than iron in our Milky Way were formed:

Why does the luminosity of a high-mass star remain nearly constant as the star burns heavy elements in its core,even though it is producing millions of times more energy per second than it did on the main sequence?

The CNO cycle is the dominant mechanism for hydrogen fusion only in high-mass main-sequence stars because of the greater __________ their cores.

The collapse of the core of a high-mass star at the end of its life lasts approximately:

Massive stars explode soon after fusion to iron begins because:

What mechanism drives the pulsations in Cepheid variables?

What might be true about the oldest stars in the Milky Way?

The evolutionary differences between high- and low-mass stars can be attributed to differences in the amount of mass each star possesses.

About 2% of the mass of the Sun is in elements heavier than helium.Where did these elements come from?

Do large,high-mass main-sequence stars become red giants?

Where did the iron in your blood come from?

The nuclear reaction that produces most of the energy for massive main-sequence stars is called the CNO cycle.

Although a Type II supernova shines with a luminosity of 100 billion L⨀ in light,most of the energy in the explosion is emitted in another way.What is it,and how much more energy does it carry compared to the light?

What is the meaning of nuclear binding energy?

Why Learn Astronomy

Patterns in the Skymotions of Earth

Motion of Astronomical Bodies

Gravity and Orbits

Light

The Tools of the Astronomer

The Birth and Evolution of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquid the Giant Planets

Planetary Adornments Moons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

Star Formation and the Interstellar Medium

Evolution of Low-Mass Stars

Relativity and Black Holes

The Expanding Universe

Galaxies

The Milky Waya Normal Spiral Galaxy

Modern Cosmology

Large-Scale Structure in the Universe

Life

Filters

Each kilogram of hydrogen that fuses into helium releases about 6 × 10¹⁴ Joules of energy.How many tons of hydrogen are fused each second to power a massive main-sequence star with a luminosity of 100 L_⨀? Note that 1 L_⨀ = 4 × 10²⁶ Joule/second and 1 ton = 10³ kg.

Although a Type II supernova shines with a luminosity of 100 billion L_⨀ in light,most of the energy in the explosion is emitted in another way.What is it,and how much more energy does it carry compared to the light?