Deck 13: To the Graveyard of Stars: the End Points of Stellar Evolution

Question 1

What kind of astronomical object could form from the situation shown in the figure below?

A) globular cluster
B) planetary nebula
C) supernova
D) Herbig-Haro objects

Answer 1

planetary nebula

Question 2

At which evolutionary stage do intermediate mass stars lose most of their outer layers?

A) white dwarf
B) asymptotic giant branch
C) red giant branch
D) main sequence

Answer 2

asymptotic giant branch

Question 3

What supports a white dwarf star against gravity?

A) thermal pressure
B) fusion
C) electron degeneracy pressure
D) the strong nuclear force

Answer 3

electron degeneracy pressure

Question 4

The Sun will end its life as a:

A) neutron star.
B) white dwarf.
C) black hole.
D) red giant.

Question 5

Which of the following pairs of main sequence stars have different endpoints for their lives as stars?

A) O and B stars
B) 25 and 10 solar mass stars
C) 10 and 5 solar mass stars
D) G and M stars

Question 6

Which of the following sets of measurements CANNOT be used to determine a main sequence star's eventual fate?

A) mass
B) color and composition
C) luminosity and temperature
D) color, distance, and brightness

Question 7

Why does a red giant grow in radius?

A) The star's core expands, pushing out its envelope as well.
B) The star's envelope heats up.
C) The opacity in the outer layer increases.
D) The star's gravity decreases because of mass loss during fusion.

Question 8

Which of the following is responsible for electron degeneracy pressure?

A) the Heisenberg uncertainty principle
B) the strong nuclear force
C) the Bohr model
D) the onion model

Question 9

Which of the following determines the rate at which a star generates energy in its core?

A) the star's composition
B) electromagnetism
C) the efficiency of fusion reactions
D) mass

Question 10

What kind of star is shown in the figure below?

A) main sequence
B) red giant
C) horizontal branch
D) asymptotic giant branch

Question 11

Which of the following stellar endpoints has NOT been observed?

A) a white dwarf from a 0.8 M_Sun star
B) a supernova from a 25 M_Sun star
C) a white dwarf from a 1 M_Sun star
D) a white dwarf from a 6 M_Sun star

Question 12

How does a horizontal branch star produce energy?

A) fusion of hydrogen in the core only
B) fusion of hydrogen in the core and helium in a shell
C) fusion of helium in the core only
D) fusion of helium in the core and hydrogen in a shell

Question 13

The figure below shows the evolutionary path of a star on the HR diagram.At which point does helium fusion begin?

A) A
B) B
C) C
D) D

Question 14

Which of the following describes the evolutionary stages of a star with three times the mass of the Sun?

A) horizontal branch, main sequence, red giant, asymptotic giant branch
B) main sequence, asymptotic giant branch, red giant, horizontal branch
C) main sequence, horizontal branch, red giant, asymptotic giant branch
D) main sequence, red giant, horizontal branch, asymptotic giant branch

Question 15

At the tip of the red giant branch,a star is half as hot as it was on the main sequence and 100 times larger.How does its luminosity compare to its value on the main sequence?

A) It is now 10,000 times larger.
B) It is now 600 times larger.
C) It is now 16 times larger.
D) It is now 16 times smaller.

Question 16

An isolated star's eventual fate is ultimately determined by its:

A) environment.
B) composition.
C) mass.
D) distance.

Question 17

Two stars orbit each other as a close binary system.When the system forms,star A has 10 solar masses and star B has 3 solar masses.Which of the following is most likely to happen in the future?

A) Star A will transfer mass to star B.
B) Star B will transfer mass to star A.
C) The stars will merge.
D) Radiation from star B will disrupt star A.

Question 18

The Sun will undergo fusion in its core during which of the following evolutionary phases?

A) main sequence and horizontal branch
B) main sequence and red giant
C) main sequence only
D) main sequence, red giant, horizontal branch, and asymptotic giant branch

Question 19

As a star moves along the red giant branch,how does it move on the HR diagram?

A) It does not move.
B) downward and to the left
C) upward and to the left
D) upward and to the right

Question 20

What causes a planetary nebula?

A) shocks from colliding winds around dying stars
B) planetary collisions
C) supernovae
D) fragmentation of giant molecular clouds

Question 21

In which wavelength regime are the periodic signals from pulsars typically seen?

A) optical
B) radio
C) X-ray
D) gamma ray

Question 22

Why does stellar fusion end with an iron core?

A) The core becomes so hot it expands too much.
B) Iron cannot undergo fusion.
C) Iron does not produce energy when it undergoes fusion.
D) Iron requires such a high temperature for fusion that it does not occur inside stars.

Question 23

The figure below shows the trajectory of a star on the HR diagram as it moves along the red giant branch.How does its radius at point 3 compare to its radius at point 1?

A) It is 100 times larger at point 3.
B) It is 10 times larger at point 3.
C) It is 2 times larger at point 3.
D) It is 10 times smaller at point 3.

Question 24

Which of the following can most efficiently be used to measure the distance to a galaxy?

A) Type Ia supernovas
B) gamma-ray bursts
C) Type II supernovas
D) novas

Question 25

Uranium in the Universe is produced in:

A) the Big Bang.
B) supernova explosions.
C) winds from asymptotic giant branch stars.
D) cosmic ray collisions.

Question 26

Which of the following phases lasts for the shortest time as a massive star evolves?

A) hydrogen burning
B) helium burning
C) oxygen burning
D) silicon burning

Question 27

Why does the duration over which a massive star fuses elements decrease from hydrogen to iron?

A) The core temperature increases.
B) The star produces less energy per fusion reaction.
C) The core density increases.
D) all of the above

Question 28

What is the source of most of the carbon and oxygen in the interstellar medium?

A) the Big Bang
B) nova explosions
C) supernova explosions
D) winds from asymptotic giant branch stars

Question 29

What kind of remnant will a 100 MSᵤn star leave?

A) neutron star
B) white dwarf
C) black hole
D) Such a star does not leave a remnant.

Question 30

Which of the following factors helps explain why planetary nebula are NOT usually spherical?

A) magnetic fields
B) accretion disk
C) binary companion
D) all of the above

Question 31

What happens when a massive star's core becomes iron?

A) The star begins to fuse iron into nickel.
B) The star begins to pulsate as a variable star.
C) The star becomes a planetary nebula.
D) The star can no longer support itself against gravity.

Question 32

What carries the bulk of the energy from the gravitational collapse of a massive star's core during a supernova?

A) neutrinos
B) radioactive nickel
C) gamma rays
D) optical light

Question 33

A white dwarf has a temperature 10 times that of the Sun,but it has a radius 1,000 times smaller than the Sun.What is its luminosity?

A) 10 solar luminosities
B) 0.1 solar luminosities
C) 0.01 solar luminosities
D) 10-4 solar luminosities

Question 34

Why does a red giant fuse hydrogen more rapidly than a main sequence star of the same mass?

A) The star becomes more luminous.
B) The efficiency of energy generation decreases due to helium fusion.
C) The star's interior heats up.
D) The star becomes larger.

Question 35

Why do asymptotic giant branch stars have powerful winds?

A) Dust forming in the star's envelope is opaque to its radiation.
B) Mass is lost during each of the star's pulsations.
C) The loss of fusion energy in the star's core means that the outer layers are no longer gravitationally bound.
D) The outer layers become too hot to be gravitationally bound.

Question 36

Which of the following is closest in radius to a neutron star?

A) Earth
B) the United States
C) a small city
D) a football stadium

Question 37

Which of the following fusion reactions does NOT occur during a massive star's lifetime?

A) oxygen fusing into iron
B) oxygen fusing into silicon
C) carbon fusing into neon
D) the triple alpha reaction

Question 38

The figure below shows three white dwarfs on an HR diagram.Which of these three is oldest?

A) A
B) B
C) C
D) The answer cannot be determined from this HR diagram.

Question 39

Which of the following would increase the electron degeneracy pressure inside an object?

A) adding metallic elements
B) smaller electron velocities
C) compressing the object
D) faster fusion reactions

Question 40

A white dwarf is in a binary system with a red giant with five times the mass of the Sun.This system could result in a:

A) gamma-ray burst.
B) Type II supernova.
C) Type Ia supernova.
D) none of the above.

Question 41

An X-ray burster is most analogous to a(n):

A) gamma-ray burst.
B) nova.
C) active galactic nucleus.
D) Type II supernova.

Question 42

How does a red giant's structure change as it becomes more luminous?

Question 43

How will the Sun generate its energy when it eventually passes up the asymptotic giant branch?

Question 44

When electrons are squeezed closer together,they obtain a wide range of velocities.What physical principle does this reflect?

Question 45

Which of the following effects would stop novas occurring on a white dwarf for a period of tens of millions of years?

A) the white dwarf's interior cooling to low temperatures
B) the white dwarf's companion evolving onto the horizontal branch
C) the white dwarf undergoing a thermonuclear runaway on its surface
D) the white dwarf becoming tidally locked to its companion

Question 46

What produces the two shock waves in the classic picture of spherical planetary nebulae,as shown in the figure below?

Question 47

Why is an intermediate mass star's time on the horizontal branch much shorter than its time on the main sequence?

Question 48

Suppose that a white dwarf accretes mass.How does its radius change?

Question 49

During part of its time as a red giant,a star remains at roughly the same temperature but increases in luminosity by a factor of 1,000.By what factor does its radius increase?

Question 50

How can a binary companion affect a star's evolution?

Question 51

A star begins its time on the main sequence with 10 solar masses.As it enters the red giant phase,it transfers 5 solar masses to a binary companion.How will the star end its life?

Question 52

The period between pulses from a particular pulsar increases slowly with time.This implies that the:

A) pulsar's magnetic axis is shifting with time.
B) pulsar is moving away from the observer.
C) pulsar has a binary companion.
D) pulsar's radiation carries angular momentum.

Question 53

An astronomer observes two Type Ia supernovas in different galaxies.The first is in a galaxy 100 Mpc away.If the second supernova is 10⁶ times fainter than the first but has an identical light curve,how far away is the second supernova's host galaxy?

A) 10³ Mpc
B) 10⁸ Mpc
C) 10⁶ Mpc
D) 10⁵ Mpc

Question 54

According to recent models,supernova explosions are driven by:

A) shock waves from rebounding gas.
B) absorption of light from the collapsing core.
C) neutrino flows.
D) magnetic fields.

Question 55

Suppose that dust could not form in the outer parts of asymptotic giant branch stars.How would that affect the composition of the interstellar medium?

Question 56

According to recent models of supernovas,a massive star's envelope stops collapsing because:

A) the strong nuclear force becomes repulsive.
B) neutrinos push the material outward.
C) jets from a gamma-ray burst push it outward.
D) high-energy gamma rays push it outward.

Question 57

Which of the following does NOT generate its energy through fusion?

A) main sequence star
B) nova
C) Type Ia supernova
D) Type II supernova

Question 58

Astronomers detect a roughly spherical shock wave 50 light-years across in the plane of the Milky Way galaxy.This was most likely caused by:

A) photoionization from a very massive star.
B) the death of a massive star.
C) the death of an intermediate mass star.
D) magnetized jets during star formation.

Question 59

In order from most to least common,what are the possible remnants of stars that run out of fuel for fusion?

A) white dwarf, neutron star, black hole
B) white dwarf, black hole, neutron star
C) neutron star, white dwarf, black hole
D) neutron star, black hole, white dwarf

Question 60

Why are pulsars periodic?

A) Their magnetic fields oscillate.
B) They have hot spots on their surfaces.
C) They are periodically blocked by binary companions.
D) Their radiation sweeps across Earth periodically.

Question 61

What are the resulting particles when protons and electrons are forced together in the core of a massive star during the early stages of a supernova?

Question 62

How is a neutron star supported against its own gravity?

Question 63

Why can massive stars fuse heavier elements than less massive stars?

Question 64

Suppose that the binding energy per nucleon of oxygen was larger than the binding energy per nucleon of silicon.How would this change stellar evolution?

Question 65

A massive star collapses and its core forms a neutron star.What two properties of the core must be amplified during collapse in order to produce a pulsar?

Question 66

What explodes in Type Ia and Type II supernovas?

Question 67

If the initial mass function changed to form more high-mass stars,how would the overall elemental composition of the Universe be different?

Question 68

A neutron star has a radius of 10 km and twice the mass of the Sun.How does the gravitational acceleration of a ball on the surface of a neutron star compare to that on the surface of the Sun? (The Sun has a radius of about 700,000 km.)

Question 69

In order from least to most massive,what are the possible remnants of stars that run out of fuel for fusion?

Question 70

An astronomer detects a Type Ia supernova in a distant galaxy.In order to measure the distance to the galaxy using the supernova,what must the astronomer measure?