Deck 13: Deaths of Stars

Question 1

White dwarfs are rare objects.

Answer 1

False

Question 2

A star with the mass of our Sun will go through several stages of energy generation through fusion. Which sequence accurately describes these stages in the correct order?

A) hydrogen core → hydrogen shell → helium shell → helium core
B) hydrogen core → helium core → hydrogen shell → helium shell
C) hydrogen core → hydrogen shell → helium core → helium shell → carbon core
D) hydrogen core → hydrogen shell → helium core → helium shell
E) hydrogen shell → hydrogen core → helium shell → helium core

Answer 2

D

Question 3

A white dwarf generates energy through fusion.

Answer 3

False

Question 4

The amount of mass lost in a star's solar wind is generally greatest during its main sequence lifetime.

Question 5

Red dwarf stars ____.

A) never develop a hydrogen-fusion shell
B) create large amounts of carbon and oxygen
C) have much shorter lifetimes than Sun-like stars
D) never begin hydrogen fusion
E) become brown dwarfs after they exhaust their hydrogen core

Question 6

Although neutrino emission is used to detect supernovae, they do not play a role in the supernova explosion itself.

Question 7

The process and result of a star's evolution off of the main sequence are determined primarily by the star's mass.

Question 8

The first steps of evolution off the main sequence are the same for both medium-mass and high-mass stars.

Question 9

All type I supernovae are caused by white dwarfs.

Question 10

Supernovae are triggered because iron releases the most fusion energy of any element.

Question 11

It is possible for a medium-mass star to collapse and form a white dwarf, but no planetary nebula.

Question 12

A "nova" is the event that creates a planetary nebula.

Question 13

Supernovae have little effect on the development of planets such as Earth.

Question 14

Red dwarf stars (stars between 0.08 and 0.5 solar masses) evolve very differently than other stars as they age because ____.

A) they are formed from pure hydrogen
B) they never reach the minimum temperature required to fuse carbon
C) they never form white dwarf as remnants
D) they are always part of a close binary system
E) their interiors are well mixed, through strong convection

Question 15

Supernovae can trigger star formation.

Question 16

Stars larger than about 1.4 solar masses must lose mass in order to become white dwarfs.

Question 17

Almost all stars are in binary systems.

Question 18

All stars ignite helium fusion as part of the aging process.

Question 19

Stars in binary systems can transfer matter from one star to another at a Lagrange point.

Question 20

The collapse of the iron core of an isolated massive star produces a type II supernova.

Question 21

A massive star can fuse more and more massive nuclei, but this process is limited by the fact that, at some point, an element that is produced ____.

A) becomes completely degenerate in the core, changing the pressure-temperature relationship
B) cannot produce energy through fusion
C) will only fuse in the presence of even more massive nuclei
D) is not found in nature
E) decays radioactively before it can undergo fusion

Question 22

Binary systems with pairs of stars orbiting each other are ____.

A) common, and important for some types of stellar evolution
B) common, but not important for stellar evolution
C) uncommon, but important for some types of stellar evolution
D) uncommon, but not important for stellar evolution
E) very rare, but important for some types of stellar evolution

Question 23

A nova is caused by the ignition of ____.

A) hydrogen fusion in material on the surface of a white dwarf
B) carbon fusion in a white dwarf core
C) helium fusion in the core of a massive red giant
D) silicon fusion in the core of a high mass star
E) iron fusion in the core of a high mass star

Question 24

The production of exotic ____ particle pairs in the core of a high-mass star has a significant effect on the fusion of heavy elements.

A) electron-positron
B) electron-proton
C) proton-antiproton
D) neutrino-antineutrino
E) baryon-antibaryon

Question 25

A medium-mass star evolves into a red giant because ____.

A) the core expands as new fusion products collect there
B) the surface of the star becomes cooler
C) energy from hydrogen shell burning and helium fusion forces the outer layer to expand
D) the surface of the star becomes hotter
E) increased stellar winds carry large amounts of material off of the surface of the star

Question 26

The evolution of a medium-mass star like the Sun, when off of the main sequence, is ____.

A) strongly affected by mass absorption from the interstellar medium
B) strongly affected by mass absorption from the corona
C) not affected by mass loss due to increased solar winds
D) strongly affected by mass loss due to increased solar winds
E) strongly affected by mass loss due to hydrogen fusion

Question 27

Stars with a mass of about 0.5 to 8 solar masses evolve differently than other mass ranges because ____.

A) their interior structure is controlled by radiative energy transport
B) they will never reach the temperature needed to ignite carbon fusion
C) their interior structure is controlled by convective energy transport
D) they have strong stellar winds throughout their main-sequence lifetimes
E) they will never reach the temperature required to establish a helium-fusion shell

Question 28

A planetary nebula is visible due to ____.

A) blackbody continuum radiation from the interstellar medium
B) line emission from the interstellar medium
C) scattering from dust grains ejected by a dying star
D) blackbody continuum radiation from a hot gas ejected by a dying star
E) line emission from ionized hydrogen gas ejected by a dying star

Question 29

The Algol paradox is concerned with ____.

A) the difference between spherical and lobed appearance of planetary nebulae
B) production of heavy elements in supernova events
C) stars in close binaries that are lower mass, but more evolved, than their companion
D) the cooling of matter falling into a compact object in an accretion disk
E) the change in stellar winds from normal to superwind conditions

Question 30

A normal white dwarf is approximately the same size as ____.

A) the Sun
B) Jupiter
C) Earth
D) a large asteroid
E) a house

Question 31

During the Sun's main-sequence lifetime, ____.

A) the solar wind will remove about 50% of the Sun's total mass
B) the solar wind will remove about 10% of the Sun's total mass
C) the solar wind will remove 1-2% of the Sun's total mass
D) the solar wind will remove a tiny fraction of the Sun's total mass
E) mass loss from the solar wind will be balanced by material falling onto the surface from the corona

Question 32

The evolution of a "high mass star" is different from the evolution of smaller stars because these stars ____.

A) do not generate strong stellar winds
B) rotate faster
C) have stronger magnetic fields
D) can ignite carbon fusion
E) are never in binary systems

Question 33

A white dwarf will radiate its heat into space and become a black dwarf after a few ____.

A) thousands of years
B) millions of years
C) hundreds of millions of years
D) billions of years
E) hundreds of billions of years

Question 34

As a white dwarf ages, its position on a standard H-R diagram will move ____.

A) upward and to the right
B) upward and to the left
C) downward and to the right
D) straight downward
E) downward and to the left

Question 35

Fusion processes in stellar cores involving heavy elements ____.

A) generate more energy per atom than fusion of lighter elements
B) generate less total energy because less atoms are available
C) generate energy for longer periods of time for heavier elements
D) occur in shells further and further from the center of the core
E) occur in larger and larger volumes of the core

Question 36

A white dwarf stops collapsing and forms a stable structure due to forces arising from ____.

A) rapid rotation
B) magnetic fields
C) gas pressure
D) neutron degeneracy
E) electron degeneracy

Question 37

The Chandrasekhar limit defines the ____.

A) maximum mass of a white dwarf
B) lifetime of a white dwarf
C) temperature for carbon fusion
D) separation between medium- and high-mass stellar evolution
E) stellar surface temperature needed to ionize a planetary nebula

Question 38

A white dwarf generates energy through ____.

A) gravitational contraction
B) hydrogen fusion
C) helium fusion
D) mass loss
E) rapid rotation

Question 39

A planetary nebula is a(n) ____.

A) expanding envelope of ionized gas expelled by a dying medium-mass star
B) expanding envelope of neutral gas and dust expelled by a dying medium-mass star
C) contracting envelope of dusty material from planets destroyed by a dying medium-mass star
D) contracting envelope of ionized interstellar medium absorbed by a dying medium-mass star
E) expanding atmosphere of a medium-mass star as it becomes a red giant

Question 40

A white dwarf is always the remnant of a star that ____.

A) ejected a planetary nebula
B) was a member of a close binary system
C) failed to ignite carbon
D) failed to ignite helium
E) became a red giant has a mass 20 times larger than our Sun

Question 41

The supernova generated by the explosion of a high mass star fades slowly because of energy generated by ____.

A) magnetic fields around the neutron star
B) disintegration of iron in the core of the star
C) radioactive decay of nickel formed in the expanding shell of the supernova
D) fusion of the remaining hydrogen in the star
E) matter-antimatter disintegration around the collapsed core

Question 42

Supernovae are ____.

A) very common: there are thousands of detectable events occurring in our galaxy each year
B) common: a few dozen are detected in our galaxy each year
C) uncommon: there are only one or two detected in our galaxy each year
D) rare: only one or two occur each century in our galaxy
E) extremely rare: only one or two are detected in the Universe each decade

Question 44

What positive effect have supernovae had on the development of life on Earth?

A) Supernovae are the main source of background radiation needed for mutations.
B) Chemical elements necessary for life can only be formed in supernovae.
C) The formation of the Sun was triggered by a supernova event.
D) Planets form by accretion of material in the expanding remnant of a supernova.
E) Neutrino bombardment was necessary to form the first simple proteins.

Question 45

The supernova event for a massive star that has lost a large amount of mass to a close binary companion ____.

A) does not show hydrogen emission lines in the spectrum of the remnant
B) does not produce iron in the core before the explosion
C) is less luminous because the companion star absorbs most of the remnant material
D) is more likely to produce a neutron star than an isolated supernova
E) triggers a supernova in the binary companion

Question 46

What part of the Sun's aging process will disrupt the biosphere and evaporate the oceans of Earth?

A) the fusion of hydrogen in the core
B) an increase in luminosity as the core becomes helium-enriched
C) the expansion of the outer layers of the Sun as a red giant
D) the supernova explosion caused by the collapse of the iron core
E) hydrogen detonation on the white dwarf remnant

Question 47

How have supernovae affected the development of life on Earth?

Question 48

Which event would you expect to be most closely associated with regions of active star formation?

A) Type Ia supernovae
B) Type Ib supernovae
C) Type II supernovae
D) novae
E) planetary nebulae

Question 49

The main observable difference separating Type I and Type II supernovae is ____.

A) neutrino emission
B) iron absorption lines
C) a difference in luminosity of several thousand times
D) the presence or absence of hydrogen absorption lines
E) the presence or absence of hydrogen emission lines

Question 50

A medium-mass star becomes a red giant as the result of _______________ fusion in a shell.

Question 51

What is an accretion disk?

Question 52

____ supernovae are caused by the collapse of an iron core in a high mass star.

A) Only type Ia
B) Only type Ib
C) Only type II
D) type Ia and type II
E) type Ib and type II

Question 53

What part of the Sun's aging process will destroy Earth itself?

A) the fusion of hydrogen in the core
B) an increase in luminosity as the core becomes helium-enriched
C) the expansion of the outer layers of the Sun as a red giant
D) the supernova explosion caused by the collapse of the iron core
E) hydrogen detonation on the white dwarf remnant

Question 54

The main energy source that drives a supernova explosion is ____.

A) a shock wave from the collapse of the iron core
B) a blast of gravitational waves emanating from the creation of a neutron star
C) a burst of neutrinos generated in the core collapse
D) energy from the radioactive decay of heavy elements
E) fusion of the remaining hydrogen in the star through a chain reaction

Question 55

Supernovae are the main source of ____ in the interstellar medium.

A) cosmic rays
B) helium
C) dust
D) carbon
E) synchotron radiation

Question 56

A white dwarf that exceeds the Chandresekhar limit ____.

A) will collapse to form a neutron star
B) will explode as a nova, and may repeat the cycle over time
C) is completely destroyed by carbon deflagration
D) breaks apart and forms an excretion disk
E) becomes a degenerate object

Question 57

Why is the production of iron important for understanding the explosion of massive stars?

Question 58

The Crab Nebula is the remnant of ____.

A) the SN1987a supernova
B) a supernova which triggered a mass extinction on Earth
C) a supernova recorded by Chinese astronomers
D) a supernova which triggered the formation of the Sun
E) a supernova in the Large Magellanic cloud

Question 59

A white dwarf is supported against its own gravity by the inability of its _______________ electrons to pack into a smaller volume.

Question 60

What physical feature of our planet is most dependent on supernova events?

A) oceans of water
B) a breathable atmosphere
C) organic chemicals
D) uranium in Earth's interior
E) a nickel-iron core

Question 61

Fusion of degenerate hydrogen on the surface of a white dwarf causes temperatures to reach millions of degrees and the density tens of thousands the density of water releasing enough energy to blow the surface layers, resulting in a(n) _______________.

Question 62

High-mass stars evolve differently than medium-mass stars because they are able to fuse _______________.

Question 63

What keeps red dwarfs from becoming giant stars?

Question 64

Matter swirling into a compact object forms a(n) _______________ disk.

Question 65

Chinese astronomers observed supernovae, and called them _______________ stars.

Question 66

How common are supernova events in our galaxy?

Question 67

Explain how planetary nebulae and white dwarfs are related to mass loss from an aging medium-mass star.

Question 68

Describe the process that causes a massive star to become a supernova.

Question 69

Many medium-mass stars will expel its outer atomosphere to form a(n) _______________ nebula as they age.

Question 70

Explain the process that creates a nova.

Question 71

Explain the different causes of Type Ia, Type Ib, and Type II supernovae.

Question 72

What is a planetary nebula?

Question 73

The most easily visible supernova remnant is the _______________ Nebula.

Question 74

The gravitational field around close binary stars is defined by _______________ lobes.