Deck 10: The Deaths of Stars

Question 1

A(n) _________ is a collection of 105 to 106 stars in a region 10 to 30 pc in diameter. The stars in the collection tend to be more than 109 years old and mostly yellow and red stars.

A)Herbig-Haro object
B)globular cluster
C)open cluster
D)giant cluster
E)supernova

Answer 1

globular cluster

Question 2

Stars within a cluster that are at the turnoff point

A)have life expectancies that are equal to the age of the cluster.
B)are stars that are just becoming white dwarfs.
C)are stars that are just entering the main sequence portion of their evolution.
D)are stars that are about to supernova.
E)are stars that are generally spectral type G stars.

Answer 2

have life expectancies that are equal to the age of the cluster.

Question 3

The Crab nebula is

A)a planetary nebula.
B)a Bok globule.
C)an open cluster.
D)an absorption nebula.
E)a supernova remnant.

Answer 3

a supernova remnant.

Question 4

_________ is a form of electromagnetic radiation produced by rapidly moving electrons spiraling through magnetic fields.

A)Lagrangian radiation
B)Accretion
C)Ultraviolet radiation
D)Synchrotron radiation
E)Infrared radiation

Question 5

Helium flash occurs

A)because helium is very explosive and cannot be controlled when the nuclear reactions occur.
B)because degenerate gas does not allow the core to expand as it heats up.
C)in Cepheid variables.
D)in stars with masses less than 0.4 M.
E)None of the other choices are correct.

Question 6

A Sun-like star will experience a helium flash in the core if

A)it is less massive than about 3 solar masses.
B)it has become a red giant star.
C)it has formed a helium core.
D)the material in the core has gradually become degenerate.
E)All of the other choices are correct.

Question 7

In the orbital plane of a binary star system matter can be transferred from one star to the other through the ___________, located directly between the two stars is the point where the Roche lobes meet.

A)turnoff points
B)horizontal branch
C)Lagrangian points
D)synchrotron points
E)radiation belts

Question 8

The _________ stars are giant stars fusing helium in their cores and then in their shells.

A)turnoff-point
B)main-sequence
C)turnon-point
D)hydrogen-flash
E)horizontal-branch

Question 9

In the diagram below, which point indicates the location on the H-R diagram of a one-solar-mass star when it undergoes helium flash

A)1
B)2
C)3
D)4
E)5

Question 10

Star clusters are important to our study of stars because

A)all stars formed in star clusters.
B)the Sun was once a member of a globular cluster.
C)they give us a method to test the our theories and models of stellar evolution.
D)they are the only objects that contain Cepheid variables.
E)All of the other choices are correct.

Question 11

As a Sun-like main-sequence star exhausts hydrogen in its core, it next becomes

A)a protostar.
B)a red giant star.
C)a white dwarf star.

Question 12

If the stars at the turnoff point of a cluster have a mass of 3M, what is the age of the cluster

A)3.0×1010 years
B)3.3×109 years
C)6.4×108 years
D)1.6×1011 years
E)The age of a star cluster cannot be determined from the mass of stars at the turnoff point.

Question 13

The triple-alpha process

A)controls the pulsations in Cepheid variable stars.
B)is the nuclear fusion of hydrogen to helium in massive stars.
C)is the process that produces the neutrinos we receive from the Sun.
D)requires a temperature of about 5,000,000 K to operate.
E)occurs during helium flash.

Question 14

Which of the following nuclear fuels does a one-solar-mass star fuse over the course of its entire evolution

A)hydrogen
B)hydrogen and helium
C)hydrogen, helium and carbon
D)hydrogen, helium, carbon, and neon
E)hydrogen, helium, carbon, neon, and oxygen

Question 15

Mass is transferred from a normal star in a close binary system toward a white dwarf. The material that is transferred to the white dwarf forms a rapidly growing whirlpool of material known around the white dwarf known as a(n)

A)accretion disk.
B)Lagrangian point.
C)Algol paradox.
D)planetary nebula.
E)supernova remnant.

Question 16

Stars in a star cluster

A)all have the same age.
B)all have the same chemical composition.
C)all have the same luminosity.
D)all of the above.
E)all have the same age and all have the same chemical composition.

Question 17

What is the approximate age of the star cluster in the H-R diagram below (Hint: Main-sequence stars of spectral types between A and B have core supplies of hydrogen sufficient to last about 250 million years, between A and F about 2 billion years, type G about 10 billion years, and between K and M about 30 billion years.)

A)200 million years
B)2 billion years
C)10 billion years
D)30 billion years
E)The age of the cluster cannot be estimated from an H-R diagram of the cluster.

Question 18

Giant and supergiant stars are rare because

A)they do not form as often as main-sequence stars.
B)the star blows up before the giant or supergiant stage is reached
C)the giant or supergiant stage is very short.
D)the giant or supergiant stage is very long

Question 19

In degenerate matter

A)pressure depends only on the temperature.
B)temperature depends only on density.
C)pressure does not depend on temperature.
D)pressure does not depend on density.
E)temperature depends only on density and does not depend on temperature.

Question 20

A(n) _________ is a collection of 10 to 1000 stars in a region about 25 pc in diameter. The stars in the collection are typically quite young.

A)Herbig-Haro object
B)globular cluster
C)open cluster
D)giant cluster
E)supernova

Question 21

A planetary nebula is

A)the expelled outer atmosphere of a medium-mass star.
B)produced by a supernova explosion.
C)produced by a nova explosion.
D)a nebula within which planets are forming.
E)a cloud of hot gas surrounding a planet.

Question 22

A planetary nebula has a radius of 0.5 pc and is expanding at 20 km/s. What is the approximate age of this planetary nebula (1 pc is equal to 3×1013 km and 1 year is equal to 3.15×107 seconds.)

A)240 years
B)790,000 years
C)96,000 years
D)960 years
E)24,000 years

Question 23

What are the two longest stages in the life of a one-solar-mass star

A)Protostar, pre-main-sequence
B)Protostar, white dwarf
C)Protostar, main-sequence
D)Main-sequence, white dwarf

Question 24

The Chandrasekhar limit tells us that

A)accretion disks can grow hot through friction.
B)neutron stars of more than 3 solar masses are not stable.
C)white dwarfs more massive than 1.4 solar masses are not stable.
D)stars cannot travel through space too fast.
E)stars with a mass less than 0.5 solar masses will not go through helium flash.

Question 25

Synchrotron radiation is produced

A)in planetary nebulae.
B)by red dwarfs.
C)in massive stars as their iron core collapses.
D)in supernova.
E)by neutrinos.

Question 26

The theory that the collapse of a massive star's iron core produces neutrinos was supported by

A)the size and structure of the Crab nebula.
B)laboratory measurements of the mass of the neutrino.
C)the brightening of supernovae a few days after they are first visible.
D)underground counts from solar neutrinos.
E)the detection of neutrinos from the supernova of 1987.

Question 27

A type II supernova

A)occurs when a white dwarf's mass exceeds the Chandrasekhar limit.
B)is the result of helium flash.
C)is characterized by a spectrum that shows hydrogen lines.
D)occurs when the iron core of a massive star collapses.
E)is characterized by a spectrum that shows hydrogen lines and occurs when the iron core of a massive star collapses.

Question 28

Stars with masses between 0.4- and 4-

A)undergo thermonuclear fusion of hydrogen and helium, but never get hot enough to ignite carbon.
B)undergo thermonuclear fusion of hydrogen, but never get hot enough to ignite helium.
C)produce type I supernovae after they exhaust their nuclear fuels.
D)produce type II supernovae after they exhaust their nuclear fuels.
E)undergo carbon detonation.

Question 29

The diagram below shows a light curve from a supernova. How many days after maximum light did it take for the supernova to decrease in brightness by a factor of 100

A)less than 50
B)50
C)150
D)250
E)more than 250

Question 30

For a star of Sun-like mass, what is the last stage of the nuclear fusion

A)Hydrogen to helium
B)Helium to carbon and oxygen
C)Carbon to magnesium
D)Fusion goes all the way up to iron.

Question 31

A planetary nebula

A)produces an absorption spectrum.
B)produces an emission spectrum.
C)is contracting to form planets.
D)is contracting to form a star.
E)is the result of carbon detonation in a 1- star.

Question 32

A supernova is almost always associated with

A)a very massive star.
B)a very young star.
C)a star undergoing helium flash.
D)a white dwarf in a close binary system.
E)a solar-like star that has exhausted its hydrogen and helium.

Question 33

A white dwarf is composed of

A)hydrogen nuclei and degenerate electrons.
B)helium nuclei and normal electrons.
C)carbon and oxygen nuclei and degenerate electrons.
D)degenerate iron nuclei.
E)a helium burning core and a hydrogen burning shell.

Question 34

A Type Ia supernova is believed to occur when

A)the core of a massive star collapses.
B)hydrogen detonation occurs.
C)a white dwarf exceeds the Chandrasekhar limit.
D)the cores of massive stars collapse.
E)neutrinos in a massive star become degenerate and form a shock wave that explodes the star.

Question 35

As a white dwarf cools its radius will not change because

A)pressure due to nuclear reactions in a shell just below the surface keeps it from collapsing.
B)pressure does not depend on temperature for a white dwarf because the electrons are degenerate.
C)pressure does not depend on temperature because the white dwarf is too hot.
D)pressure does not depend on temperature because the star has exhausted all its nuclear fuels.
E)material accreting onto it from a companion maintains a constant radius.

Question 36

The Algol paradox is explained by considering

A)the degenerate nature of the hydrogen on the surface of the white dwarf.
B)synchrotron radiation.
C)the rate of expansion of the shock wave inside the supernova.
D)the rotation rate of a neutron star.
E)mass transfer between the two stars in a binary system.

Question 37

Synchrotron radiation is produced by

A)objects with temperature below 10,000 K.
B)high-velocity electrons moving through a magnetic field.
C)cold hydrogen atoms in space.
D)the collapsing cores of massive stars.
E)a helium flash.

Question 38

About how long will a 0.5- star spend on the main sequence

A)6 billion years
B)62 billion years
C)620 million years
D)6 million years
E)600 thousand years

Question 39

If the theory that novae occur in close binary systems is correct, then recurrent novae should

A)produce synchrotron radiation.
B)occur in regions of star formation.
C)not occur in old star clusters.
D)all be visual binaries.
E)repeat after some interval.

Question 40

The lowest-mass stars cannot become giants because

A)they do not contain helium.
B)they rotate too slowly.
C)their convective interiors prevent the development of an inert helium core surrounded by unprocessed hydrogen.
D)they contain strong magnetic fields.
E)they never use up their hydrogen.

Question 41

Before it ejects a planetary nebula, a star is a

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

Question 42

After what evolutionary stage does a star become a white dwarf

A)protostar
B)pre-main sequence
C)main sequence
D)giant

Question 43

The central star in a planetary nebula

A)is a main-sequence star.
B)is a pre-main-sequence protostar.
C)is a neutron star.
D)will become a white dwarf.

Question 44

Why do higher-mass stars live shorter lives on the main sequence than lower-mass stars

A)Higher-mass stars burn through their nuclear fuel faster.
B)Lower-mass stars don't get their energy from that same nuclear fusion source as higher-mass stars.
C)Higher-mass stars have less hydrogen fuel to burn.
D)Lower-mass stars spend a longer time evolving to the main sequence.
E)All of the other choices are false.

Question 45

The Helix and Egg nebulae which originated from (what are today) white dwarf stars are

A)supernova remnants.
B)planetary nebulae.
C)the result of uranium detonation.
D)the result of the collapse of the iron core of each star.
E)nebulae associated with protostars.

Question 46

Star clusters are important to our study of the lives of high-mass versus low-mass stars because

A)stars in each cluster all formed at about the same time all with the same mass.
B)the Sun was once a member of a globular cluster.
C)stars in each cluster all formed at about the same time but with differing masses.
D)stars in each cluster all formed at different times with differing masses.
E)All of the other choices are correct.

Question 47

Which of the following nuclear fuels does a twenty-solar-mass star NOT fuse over the course of its entire evolution

A)hydrogen
B)carbon
C)nitrogen
D)oxygen
E)iron

Question 48

In A.D. 1054, Chinese astronomers observed the appearance of a new star, whose location is now occupied by

A)a globular cluster.
B)a planetary nebulae.
C)a white dwarf.
D)a young massive star.
E)a supernova remnant.

Question 49

The explosion of a supernova type II can leave behind

A)a planetary nebula.
B)a shell of hot, expanding gas with a white dwarf at the center.
C)a shell of hot, expanding gas with a neutron star at the center.
D)Nothing is ever left behind.

Question 50

The energy a white dwarf emits into space is

A)replaced by fusion of hydrogen atoms into helium.
B)replaced by fusion of helium atoms into carbon.
C)not replaced.

Question 51

As a star like the Sun exhausts hydrogen in its core, the outer layers of the star

A)become hotter and more luminous.
B)become cooler and more luminous.
C)become hotter and less luminous.
D)become cooler and less luminous.
E)become larger in radius and hotter.

Question 52

Helium fusion is called the triple-alpha process because

A)the helium nucleus is known as an alpha particle.
B)it occurs very rapidly.
C)it requires a temperature three times greater than that of hydrogen fusion.
D)it is the third source of the primary fusion processes.
E)each reaction produces three carbon nuclei.

Question 53

What will eventually happen to a star after its formation is most affected by its initial

A)speed through space.
B)oxygen content.
C)uranium content.
D)anti-matter content.
E)mass.

Question 54

We know that the central object in a planetary nebula has a surface temperature of at least ____ because the nebula contains large amounts of ionized hydrogen.

A)50 K
B)100 K
C)500 K
D)5,000 K
E)25,000 K

Question 55

A white dwarf star is prevented from collapsing by

A)nuclear energy it is generating.
B)its gravitational force.
C)Hubble's law of extragalactic redshifts.
D)degenerate electron gas pressure.
E)degenerate astronomers observing the star.

Question 56

Open clusters tend to be ____ than globular clusters.

A)younger and contain fewer stars
B)younger and contain more stars
C)older and contain fewer stars
D)older and contain more stars
E)more luminous and cooler

Question 57

As material leaves an expanding star and begins to fall into a white dwarf close companion

A)an accretion disk will form around the white dwarf.
B)the material will cool off because it begins to move at high velocities.
C)the material will fall directly straight onto the surface of the white dwarf.
D)the white dwarf will produce a protostar.
E)the white dwarf's iron core will collapse.

Question 58

What nuclear fusion mechanism does an isolated white dwarf use to generate energy

A)proton-proton chain
B)CNO cycle
C)triple alpha process
D)white dwarfs don't generate their own energy.

Question 59

A main-sequence star of 8.5 solar masses can become a white dwarf by

A)exceeding the Chandrasekhar limit.
B)losing mass in a close binary.
C)gaining mass.
D)remaining at 8.5 solar masses.

Question 60

Stars that have ejected a planetary nebula eventually become

A)protostars.
B)brown dwarfs.
C)white dwarfs.
D)red giants.

Question 61

The HST visual wavelength image shown above is an example of a __________, where gaseous material is blown off the surface of a white dwarf.

A)planetary nebula
B)supernova
C)nova
D)None of the other choices are correct.

Question 62

Electrons moving in a strong magnetic field emit ____________________ radiation.

Question 63

The nebula shown above is an example of a _____________ nebula.

A)emission
B)absorption
C)dark
D)planetary

Question 64

The maximum mass of a white dwarf is ____________________ solar masses.

Question 65

A white dwarf converts __________________ energy into _________________ energy.

A)nuclear, gravitational
B)chemical, potential
C)kinetic, potential
D)gravitational, thermal

Question 66

In the visual wavelength image, a/an ______________ cluster is shown.

A)open
B)globular
C)Trapezium
D)Helix nebula

Question 67

The age of a star cluster can be determined from the ____________________ of the cluster.

Question 68

The triple-alpha process involves the fusion of

A)three alpha particles.
B)three neutral helium atoms.
C)three alpha particles or three neutral helium atoms.
D)None of the other choices are correct.

Question 69

A gas in which the pressure no longer depends on the temperature of the gas is said to be ____________________.

Question 70

The SN 1987A event shown above is which type of supernova

A)Type Ia
B)Type Ib
C)Type II
D)None of the other choices are correct.

Question 71

___________ particles were observed coming from supernova 1987A, confirming models and theories of core collapse formation of neutron stars.

Question 72

The electron spirals around a magnetic field line and emits photons in a process called _________________.

A)synchrotron radiation
B)nuclear fusion
C)nuclear fission
D)an accretion disk

Question 73

A(n) ____________________ is the sudden expulsion of the outer layers of a moderate mass star that has a dormant carbon core.

Question 74

Mass can flow from one star in a binary system to its companion through the first ____________________ point.

Question 75

A(n) ____________________ is the expulsion of the outer layers of a moderate-mass star that has a degenerate carbon and oxygen core.

Question 76

A(n) ____________________ supernova is caused by the collapse of a massive star that has lost its outer envelope of hydrogen.

Question 77

The image shows the Crab Nebula. The Crab Nebula is

A)a planetary nebula.
B)a name for the cloud of gas and dust which later became our solar system.
C)an ejected cloud of gas from a supernova.
D)in the constellation Orion, containing many bright young blue stars.

Question 78

The person in the drawing ____________________ in the right panel when compared to the left panel because of conservation of angular momentum.

A)spins faster
B)spins slower
C)spins at the same rate
D)None of the other choices are correct.

Question 79

A white dwarf whose red giant companion dumps hydrogen onto it may

A)show no effect.
B)explode recurrently as a nova.
C)blow up as a type I supernova.
D)explode recurrently as a nova or blow up as a type Ia supernova.

Question 80

Which nuclear fusion processes occur in Sun-like stars

A)triple alpha
B)CNO and triple alpha
C)proton-proton and triple alpha
D)All of the other choices are correct.