Stellar Evolution Review
12-1. Protostars are not seen in
visible light telescopes because:
a) they don’t emit any radiation
b) they are surrounded by clouds of gas and
dust
c) they only emit infrared radiation
d) they are all moving away from Earth so
fast that their visible light is Doppler
shifted into the infrared
12-1. Protostars are not seen in
visible light telescopes because:
a) they don’t emit any radiation
b) they are surrounded by clouds of gas
and dust
c) they only emit infrared radiation
d) they are all moving away from Earth so
fast that their visible light is Doppler
shifted into the infrared
12-2.
A brown dwarf is best
described as:
a) a low mass object that doesn’t fuse
in its core
b) a low mass main sequence star
c) a high mass main sequence star
12-2.
A brown dwarf is best
described as:
a) a low mass object that doesn’t
fuse in its core
b) a low mass main sequence star
c) a high mass main sequence star
12-3. Why are A-type main
sequence stars hotter than G-type
main sequence stars?
a) A-type stars have cores of metal, whereas
G-type stars do not
b) A-type stars have more fusion on their
surface than G-type stars
c) A-type stars have more fusion in their
cores than G-type stars
d) A-type stars fuse in their cores and near
their surfaces, while G-type stars only
fuse in their cores.
12-3. Why are A-type main
sequence stars hotter than G-type
main sequence stars?
a) A-type stars have cores of metal, whereas
G-type stars do not
b) A-type stars have more fusion on their
surface than G-type stars
c) A-type stars have more fusion in their
cores than G-type stars
d) A-type stars fuse in their cores and near
their surfaces, while G-type stars only
fuse in their cores.
12-4. Where on the H-R diagram
are the majority of stars located?
a)
b)
c)
d)
as white dwarves
on the main sequence
as giants
as supergiants
12-4. Where on the H-R diagram
are the majority of stars located?
a)
b)
c)
d)
as white dwarves
on the main sequence
as giants
as supergiants
12-5. Which type of star is
forming iron in its core?
a)
b)
c)
d)
supergiant
giant
main sequence
white dwarf
12-5. Which type of star is
forming iron in its core?
a)
b)
c)
d)
supergiant
giant
main sequence
white dwarf
12-6. The Orion nebula is
a) a reflection nebula illuminated by newly
formed stars.
b) an emission nebula heated by newly
formed stars.
c) a supernova remnant.
d) a dark nebula.
12-6. The Orion nebula is
a) a reflection nebula illuminated by newly
formed stars.
b) an emission nebula heated by newly
formed stars.
c) a supernova remnant.
d) a dark nebula.
12-7. What happens when a
protostar joins the main sequence?
a) Its surface area increases
significantly.
b) Its luminosity increases significantly.
c) Nuclear fusion begins in its core.
d) Nuclear fission begins in its core.
12-7. What happens when a
protostar joins the main sequence?
a) Its surface area increases
significantly.
b) Its luminosity increases significantly.
c) Nuclear fusion begins in its core.
d) Nuclear fission begins in its core.
12-8. An object is found that emits
most of its electromagnetic
radiation in the infrared.
This object could be a
a)
b)
c)
d)
protostar.
G-type star.
B-type star.
cool gas cloud.
12-8. An object is found that emits
most of its electromagnetic
radiation in the infrared.
This object could be a
a)
b)
c)
d)
protostar.
G-type star.
B-type star.
cool gas cloud.
12-9. We see an emission nebula
via
a) reflected blue light from a nearby star.
b) blue light emitted by hot (excited)
hydrogen atoms.
c) red light emitted by hot (excited) hydrogen
atoms.
d) reflected red light from a nearby star.
12-9. We see an emission nebula
via
a) reflected blue light from a nearby star.
b) blue light emitted by hot (excited)
hydrogen atoms.
c) red light emitted by hot (excited)
hydrogen atoms.
d) reflected red light from a nearby star.
12-10. Which of the following are
thought to be mechanisms that
cause a giant molecular cloud to
collapse and form a protostar?
a) The shockwave from a nearby supernova
b) The shockwave from a newly formed
high-mass star that is nearby
c) The shockwave experienced by the cloud
as it passes through a spiral arm
d) All of the above
12-10. Which of the following are
thought to be mechanisms that
cause a giant molecular cloud to
collapse and form a protostar?
a) The shockwave from a nearby supernova
b) The shockwave from a newly formed
high-mass star that is nearby
c) The shockwave experienced by the cloud
as it passes through a spiral arm
d) All of the above
12-12. Red giants burn helium via
nuclear fusion in their core. The
ash (end product) of this nuclear
fusion is
a)
b)
c)
d)
iron.
hydrogen.
lithium and carbon.
carbon and oxygen.
12-12. Red giants burn helium via
nuclear fusion in their core.
The ash (end product) of this
nuclear fusion is
a)
b)
c)
d)
iron.
hydrogen.
lithium and carbon.
carbon and oxygen.
12-13. Where is the Sun located
on this H-R diagram?
a)
b)
c)
d)
e)
A
B
C
D
E
12-13. Where is the Sun located
on this H-R diagram?
a)
b)
c)
d)
e)
A
B
C
D
E
12-14. Which stars on this H-R
diagram are on the main sequence?
a) Vega, Sirius A, &
Mira
b) Stars at letters A & B
& Barnard’s Star
c) Sirius A & Sirius B
d) Rigel & Deneb
e) Pollux & Barnard’s
Star
12-14. Which stars on this H-R
diagram are on the main sequence?
a) Vega, Sirius A, &
Mira
b) Stars at letters A &
B & Barnard’s Star
c) Sirius A & Sirius B
d) Rigel & Deneb
e) Pollux & Barnard’s
Star
13-1. A nova is believed to occur
when which of the following pairs of
stars are in a binary system?
a)
b)
c)
d)
white dwarf, main sequence star
white dwarf, neutron star
neutron star, red giant
a pair of supergiants
13-1. A nova is believed to occur
when which of the following pairs of
stars are in a binary system?
a) white dwarf, main sequence star
(when the main sequence star expands as it
ages…)
b) white dwarf, neutron star
c) neutron star, red giant
d) a pair of supergiants
13-2. What is the most dense
element formed in the cores of any
stars?
a)
b)
c)
d)
helium
lead
iron
carbon
13-2. What is the most dense
element formed in the cores of any
stars?
a)
b)
c)
d)
helium
lead
iron
carbon
13-3. Which type of star is not
fusing anything in its core?
a)
b)
c)
d)
main sequence
giant
supergiant
neutron star
13-3. Which type of star is not
fusing anything in its core?
a)
b)
c)
d)
main sequence
giant
supergiant
neutron star
13-4.
A pulsar is best described
as a:
a) a rapidly rotating white dwarf
b) a rapidly rotating neutron star
c) an expanding and contracting white
dwarf
d) an expanding and contracting
neutron star
13-4.
A pulsar is best described
as a:
a) a rapidly rotating white dwarf
b) a rapidly rotating neutron star
c) an expanding and contracting white
dwarf
d) an expanding and contracting
neutron star
13-5. White dwarves are
composed primarily of:
a)
b)
c)
d)
helium
neutrons
carbon and oxygen
iron
13-5. White dwarves are
composed primarily of:
a)
b)
c)
d)
helium
neutrons
carbon and oxygen
iron
13-6. The diameter of a white
dwarf is closest to which of the
following?
a)
b)
c)
d)
about 1 A.U.
about the diameter of the Sun
about the diameter of the Earth
about 10 kilometers
13-6. The diameter of a white
dwarf is closest to which of the
following?
a)
b)
c)
d)
about 1 A.U.
about the diameter of the Sun
about the diameter of the Earth
about 10 kilometers
13-7.
The Sun will end its “life” as
a(n):
a) supernova.
b) nova.
c) planetary nebula.
13-7.
The Sun will end its “life” as
a(n):
a) supernova.
b) nova.
c) planetary nebula.
13-9. Explosions on the surfaces
of white dwarves in binary star
systems are called:
a)
b)
c)
d)
novas
supernovas
flares
planetary nebulas
13-9. Explosions on the surfaces
of white dwarves in binary star
systems are called:
a)
b)
c)
d)
novas
supernovas
flares
planetary nebulas
13-10. Rotating neutron stars with
off-axis magnetic fields are called:
a)
b)
c)
d)
white dwarves
pulsars
quasars
nebulae
13-10. Rotating neutron stars with
off-axis magnetic fields are called:
a)
b)
c)
d)
white dwarves
pulsars
quasars
nebulae
13-11. A 15 M main sequence
star will eventually shed mass as a:
a)
b)
c)
d)
supernova.
nova.
planetary nebula.
Cepheid
13-11. A 15 M main sequence
star will eventually shed mass as a:
a)
b)
c)
d)
supernova.
nova.
planetary nebula.
Cepheid
13-12. A one solar mass star will
a) go through a red giant phase and
end its life as a white dwarf.
b) not go through a red giant phase and
end its life as a white dwarf.
c) go through a red giant phase and
end its life as a black hole.
d) not go through a red giant phase and
end its life as a black hole.
13-12. A one solar mass star will
a) go through a red giant phase and
end its life as a white dwarf.
b) not go through a red giant phase and
end its life as a white dwarf.
c) go through a red giant phase and
end its life as a black hole.
d) not go through a red giant phase and
end its life as a black hole.
13-13. White dwarfs usually have
surface temperatures well above
10,000 K, yet they have extremely
low luminosity. Why is this?
a) They are very far away.
b) They have a very large surface area.
c) They emit most of their radiation in the far
infrared.
d) They have a very small surface area.
13-13. White dwarfs usually have
surface temperatures well above
10,000 K, yet they have extremely
low luminosity. Why is this?
a) They are very far away.
b) They have a very large surface area.
c) They emit most of their radiation in the far
infrared.
d) They have a very small surface area.
13-15. White dwarfs are not
referred to as stars because
a) they do not produce energy by nuclear
fusion.
b) they are not luminous enough to qualify
as a star.
c) we do not know how they produce their
energy.
d) they do not contain any hydrogen.
13-15. White dwarfs are not
referred to as stars because
a) they do not produce energy by nuclear
fusion.
b) they are not luminous enough to qualify
as a star.
c) we do not know how they produce their
energy.
d) they do not contain any hydrogen.
13-16. Elements heavier than iron
are produced by nuclear reactions
a) in a white dwarf.
b) during a supernova explosion of a
massive star.
c) in the shells around the core of a high
mass star.
d) in the core of a massive star just before it
explodes as a supernova.
13-16. Elements heavier than iron
are produced by nuclear reactions
a) in a white dwarf.
b) during a supernova explosion of a
massive star.
c) in the shells around the core of a high
mass star.
d) in the core of a massive star just before it
explodes as a supernova.
13-17. A neutron star is
a) left behind after a Type I supernova
explosion.
b) created if a star stops burning
hydrogen and contracts.
c) created if a star stops burning helium
and contracts.
d) left behind after a Type II supernova
explosion.
13-17. A neutron star is
a) left behind after a Type I supernova
explosion.
b) created if a star stops burning
hydrogen and contracts.
c) created if a star stops burning helium
and contracts.
d) left behind after a Type II
supernova explosion.
13-18. The rotation rate of neutron
stars
a) is constant.
b) is slowing down in all cases.
c) is slowing down for isolated pulsars,
but can be speeding up for pulsars in
binary systems if mass transfer occurs.
d) is speeding up for all pulsars.
13-18. The rotation rate of neutron
stars
a) is constant.
b) is slowing down in all cases.
c) is slowing down for isolated pulsars,
but can be speeding up for pulsars in
binary systems if mass transfer
occurs.
d) is speeding up for all pulsars.
13-19. Helium fusion takes place
in the core of a red giant star.
These fusion reactions produce
a)
b)
c)
d)
e)
iron.
hydrogen.
lithium and carbon.
carbon and oxygen.
beryllium and carbon.
13-19. Helium fusion takes place
in the core of a red giant star.
These fusion reactions produce
a)
b)
c)
d)
e)
iron.
hydrogen.
lithium and carbon.
carbon and oxygen.
beryllium and carbon.