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Question 9 -s
Test 3
The Sun & the
Stars
Copyright © 2010 Pearson Education, Inc.
Question 9 - 1
The visible light we see
from our Sun comes
from which part?
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a) core
b) corona
c) photosphere
d) chromosphere
e) convection zone
Question 9 - 1
The visible light we see
from our Sun comes
from which part?
a) core
b) corona
c) photosphere
d) chromosphere
e) convection zone
The photosphere is a
relatively narrow layer below
the chromosphere and
corona, with an average
temperature of about 6000 K.
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Question 9 - 2
The density of the
Sun is most
similar to that of
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a) a comet.
b) Jupiter.
c) Earth.
d) interstellar gas.
e) an asteroid.
Question 9 - 2
The density of the
Sun is most
similar to that of
a) a comet.
b) Jupiter.
c) Earth.
d) interstellar gas.
e) an asteroid.
The Sun is a ball of charged
gas, without a solid surface.
Jupiter has a similar
composition, but not
enough mass to be a star.
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Question 9 - 3
The Sun is
stable as a
star because
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a) gravity balances forces from pressure.
b) the rate of fusion equals the rate of fission.
c) radiation and convection balance.
d) mass is converted into energy.
e) fusion doesn’t depend on temperature.
Question 9 - 3
The Sun is
stable as a
star because
a) gravity balances forces from pressure.
b) the rate of fusion equals the rate of fission.
c) radiation and convection balance.
d) mass is converted into energy.
e) fusion doesn’t depend on temperature.
The principle of
hydrostatic equilibrium
explains how stars
maintain their stability.
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Question 9 - 4
The proton–proton cycle
involves what kind of
fusion process?
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a) carbon (C) into oxygen (O)
b) helium (He) into carbon (C)
c) hydrogen (H) into helium (He)
d) neon (Ne) into silicon (Si)
e) oxygen (O) into iron (Fe)
Question 9 - 4
The proton–proton cycle
involves what kind of
fusion process?
a) carbon (C) into oxygen (O)
b) helium (He) into carbon (C)
c) hydrogen (H) into helium (He)
d) neon (Ne) into silicon (Si)
e) oxygen (O) into iron (Fe)
In the P-P cycle, four
hydrogen nuclei
(protons) fuse into one
helium nucleus,
releasing gamma rays
and neutrinos.
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Question 9 - 5
A neutrino can escape
from the solar core
within minutes. How long
does it take a photon to
escape?
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a) minutes
b) hours
c) months
d) hundreds of years
e) about a million years
Question 9 - 5
A neutrino can escape
from the solar core
within minutes. How long
does it take a photon to
escape?
a) minutes
b) hours
c) months
d) hundreds of years
e) about a million years
Gamma ray photons are absorbed
and re-emitted continuously in the
layers above the core.
They gradually shift in spectrum
to visible and infrared light at the
photosphere.
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Question 9 - 6
What is probably
responsible for the
increase in temperature
of the corona far from
the Sun’s surface?
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a) a higher rate of fusion
b) the Sun’s magnetism
c) higher radiation pressures
d) absorption of X rays
e) convection currents
Question 9 - 6
What is probably
responsible for the
increase in temperature
of the corona far from
the Sun’s surface?
a) the higher rate of fusion
b) the Sun’s magnetism
c) higher radiation pressures
d) absorption of X rays
e) convection currents
Apparently the Sun’s
magnetic field acts like a
pump to increase the speeds
of particles in the upper
corona.
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Question 9 - 7
The number of
sunspots and solar
activity in general
peaks
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a) every 27 days, the apparent rotation
period of the Sun’s surface.
b) once a year.
c) every 5½ years.
d) every 11 years.
e) approximately every 100 years.
Question 9 - 7
The number of
sunspots and solar
activity in general
peaks
a) every 27 days, the apparent rotation
period of the Sun’s surface.
b) once a year.
c) every 5 ½ years.
d) every 11 years.
e) approximately every 100 years.
The sunspot cycle shows a consistent 11-year pattern of activity
dating back more than 300 years.
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Question 9 - 8
The solar neutrino
problem refers to
the fact that
astronomers
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a) cannot explain how the Sun is stable.
b) detect only one-third the number of
neutrinos expected by theory.
c) cannot detect neutrinos easily.
d) are unable to explain how neutrinos
oscillate between other types.
e) cannot create controlled fusion
reactions on Earth.
Question 9 - 8
The solar neutrino
problem refers to
the fact that
astronomers
a) cannot explain how the Sun is stable.
b) detect only one-third the number of
neutrinos expected by theory.
c) cannot detect neutrinos easily.
d) are unable to explain how neutrinos
oscillate between other types.
e) cannot create controlled fusion
reactions on Earth.
Further experiments have shown
that solar neutrinos can change
into other types that were not
initially detected.
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Question 10 - 1
Stellar parallax
is used to
measure the
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a) sizes of stars.
b) distances of stars.
c) temperatures of stars.
d) radial velocity of stars.
e) brightness of stars.
Question 10 - 1
Stellar parallax
is used to
measure the
a) sizes of stars.
b) distances of stars.
c) temperatures of stars.
d) radial velocity of stars.
e) brightness of stars.
Parallax can be used to measure
distances to stars accurately to about 200
parsecs (650 light-years).
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Question 10 - 2
The angle of
stellar parallax
for a star gets
larger as the
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a) distance to the star increases.
b) size of the star increases.
c) size of the telescope increases.
d) length of the baseline increases.
e) wavelength of light increases.
Question 10 - 2
The angle of
stellar parallax
for a star gets
larger as the
a) distance to the star increases.
b) size of the star increases.
c) size of the telescope increases.
d) length of the baseline increases.
e) wavelength of light increases.
Astronomers typically make
observations of nearby stars 6 months
apart, making the baseline distance
equal to 2 AU (Astronomical Units).
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Question 10 - 3
You can best model
the size and distance
relationship of our
Sun & the next
nearest star using
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a) a tennis ball here, and one on the
Moon.
b) two beach balls separated by 100
city blocks.
c) two grains of sand 100 light-years
apart.
d) two golf balls 100 km apart.
e) two baseballs 100 yards apart.
Question 10 - 3
You can best model
the size and distance
relationship of our
Sun & the next
nearest star using
a) a tennis ball here, and one on the
Moon.
b) two beach balls separated by 100
city blocks.
c) two grains of sand 100 light- years
apart.
d) two golf balls 100 km apart.
e) two baseballs 100 yards apart.
The Sun is about one million miles
in diameter.
The next nearest star is about 25
million times farther away.
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Question 10 - 4
A star’s proper
motion is its
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a) true motion in space.
b) apparent shift as we view from opposite
sides of Earth’s orbit every six months.
c) annual apparent motion across the sky.
d) motion toward or away from us, revealed by
Doppler shifts.
e) orbital motion around the galaxy.
Question 10 - 4
A star’s proper
motion is its
a) true motion in space.
b) apparent shift as we view from opposite
sides of Earth’s orbit every six months.
c) annual apparent motion across the sky.
d) motion toward or away from us, revealed by
Doppler shifts.
e) orbital motion around the galaxy.
A star’s “real space motion” combines its apparent proper
motion with its radial motion toward or away from Earth.
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Question 10 - 5
In the stellar magnitude
system invented by
Hipparchus, a smaller
magnitude indicates a
_____ star.
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a) brighter
b) hotter
c) cooler
d) fainter
e) more distant
Question 10 - 5
In the stellar magnitude
system invented by
Hipparchus, a smaller
magnitude indicates a
_____ star.
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a) brighter
b) hotter
c) cooler
d) fainter
e) more distant
Question 10 - 6
A star’s apparent
magnitude is a number
used to describe how
our eyes measure its
Copyright © 2010 Pearson Education, Inc.
a) distance.
b) temperature.
c) brightness.
d) absolute luminosity.
e) radial velocity.
Question 10 - 6
A star’s apparent
magnitude is a number
used to describe how
our eyes measure its
Copyright © 2010 Pearson Education, Inc.
a) distance.
b) temperature.
c) brightness.
d) absolute luminosity.
e) radial velocity.
Question 10 - 7
The absolute magnitude
of a star is its brightness
as seen from a distance
of
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a) one million km.
b) one Astronomical Unit.
c) one light-year.
d) ten parsecs.
e) ten light-years.
Question 10 - 7
The absolute magnitude
of a star is its brightness
as seen from a distance
of
a) one million km.
b) one Astronomical Unit.
c) one light-year.
d) ten parsecs.
e) ten light-years.
Astronomers use a distance of 10 parsecs (about
32 light-years) as a standard for specifying and
comparing the brightnesses of stars.
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Question 10 - 8
Which of the following
quantities do you need
in order to calculate a
star’s luminosity?
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a) apparent brightness (flux)
b) Doppler shift of spectral
lines
c) color of the star
d) distance to the star
e) a and d
Question 10 - 8
Which of the following
quantities do you need
in order to calculate a
star’s luminosity?
Copyright © 2010 Pearson Education, Inc.
a) apparent brightness (flux)
b) Doppler shift of spectral
lines
c) color of the star
d) distance to the star
e) a and d
Question 10 - 9
What are the two
important intrinsic
properties for
classifying stars on
an H-R diagram?
Copyright © 2010 Pearson Education, Inc.
a) distance and surface temperature
b) luminosity and surface temperature
c) distance and luminosity
d) mass and age
e) distance and color
Question 10 - 9
What are the two
important intrinsic
properties for
classifying stars on
an H-R diagram?
a) distance and surface temperature
b) luminosity and surface temperature
c) distance and luminosity
d) mass and age
e) distance and color
The H–R diagram plots stars
based on their luminosities and
surface temperatures.
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Question 10 - 10
Wien’s law tells us that the
hotter an object, the _____
the peak wavelength of its
emitted light.
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a) longer
b) more green
c) heavier
d) shorter
e) more constant
Question 10 - 10
Wien’s law tells us that the
hotter an object, the _____
the peak wavelength of its
emitted light.
a) longer
b) more green
c) heavier
d) shorter
e) more constant
Wien’s law states that
hotter stars appear more blue in color,
and
cooler stars appear more red in color.
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Question 10 - 11
We estimate the
surface temperature
of a star by using
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a) its color.
b) the pattern of absorption lines in its
spectrum.
c) Wien’s law.
d) differences in brightness as measured
through red and blue filters.
e) All of the above are used.
Question 10 - 11
We estimate the
surface temperature
of a star by using
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a) its color.
b) the pattern of absorption lines in its
spectrum.
c) Wien’s law.
d) differences in brightness as measured
through red and blue filters.
e) All of the above are used.
Question 10 - 12
Which spectral classification
type corresponds to a star
like the Sun?
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a) O
b) A
c) F
d) G
e) M
Question 10 - 12
Which spectral classification
type corresponds to a star
like the Sun?
a) O
b) A
c) F
d) G
e) M
The OBAFGKM classification scheme is based on absorption lines.
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Question 10 - 13
Astronomers
can estimate
the size of a
star using
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a) apparent brightness.
b) direct observation of diameter.
c) temperature.
d) distance to the star.
e) a, b, and c are all true.
Question 10 - 13
Astronomers
can estimate
the size of a
star using
a) apparent brightness.
b) direct observation of diameter.
c) temperature.
d) distance to the star.
e) a, b, and c are all true.
Brightness and temperature are
used to plot the star on an H–R
diagram, and indicate its
approximate size.
Some stars are large enough to
measure directly.
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Question 10 - 14
Eclipsing binary
stars are very
useful for
determining the
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a) ages of stars.
b) absolute luminosities of stars.
c) masses of stars.
d) distances to stars.
e) rotation rates of stars.
Question 10 - 14
Eclipsing binary
stars are very
useful for
determining the
a) ages of stars.
b) absolute luminosities of stars.
c) masses of stars.
d) distances to stars.
e) rotation rates of stars.
Analysis of the lightcurve of
an eclipsing binary star
system can reveal the
masses of the stars.
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Question 10 - 15
What is the single most
important characteristic
in determining the
course of a star’s
evolution?
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a) density
b) absolute brightness
c) distance
d) surface temperature
e) mass
Question 10 - 15
What is the single most
important characteristic
in determining the
course of a star’s
evolution?
a) density
b) absolute brightness
c) distance
d) surface temperature
e) mass
A star’s mass determines how fast it
forms, its luminosity on the main
sequence, how long it will shine, and
its ultimate fate.
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Question 11 - 1
Some regions of
the Milky Way’s
disk appear dark
because
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a) there are no stars there.
b) stars in that direction are obscured
by interstellar gas.
c) stars in that direction are obscured
by interstellar dust.
d) numerous black holes capture all
the starlight behind them.
Question 11 - 1
Some regions of
the Milky Way’s
disk appear dark
because
a) there are no stars there.
b) stars in that direction are obscured
by interstellar gas.
c) stars in that direction are obscured
by interstellar dust.
d) numerous black holes capture all
the starlight behind them.
Dust grains are about the same size as visible light, and they can
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Inc.
scatter
or block the shorter wavelengths.
Question 11 - 2
When a star’s
visible light
passes through
interstellar dust,
the light we see
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a) is dimmed and reddened.
b) appears to twinkle.
c) is Doppler shifted.
d) turns bluish in color.
e) ionizes the dust and creates
emission lines.
Question 11 - 2
When a star’s
visible light
passes through
interstellar dust,
the light we see
a) is dimmed and reddened.
b) appears to twinkle.
c) is Doppler shifted.
d) turns bluish in color.
e) ionizes the dust and creates
emission lines.
The same process results
in wonderful sunsets, as
dust in the air scatters the
Sun’s blue light, leaving
dimmer, redder light.
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Question 11 - 3
Astronomers use
the term nebula
to refer to
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a) outer envelopes of dying stars that drift
gently into space.
b) remnants of stars that die by supernova.
c) clouds of gas and dust in interstellar space.
d) distant galaxies seen beyond our Milky Way.
e) All of the above are correct.
Question 11 - 3
Astronomers use
the term nebula
to refer to
a) outer envelopes of dying stars that drift
gently into space.
b) remnants of stars that die by supernova.
c) clouds of gas and dust in interstellar space.
d) distant galaxies seen beyond our Milky Way.
e) All of the above are correct.
Nebula refers to any
fuzzy patch – bright or
dark – in the sky.
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Question 11 - 4
Interstellar gas
is composed
primarily of
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a) 90% hydrogen, 9% helium, and 1%
heavier elements.
b) molecules including water and CO2.
c) 50% hydrogen, 50% helium.
d) hydrogen, oxygen, and nitrogen.
e) 99% hydrogen, and 1% heavier elements.
Question 11 - 4
Interstellar gas
is composed
primarily of
a) 90% hydrogen, 9% helium, and 1%
heavier elements.
b) molecules including water and CO2.
c) 50% hydrogen, 50% helium.
d) hydrogen, oxygen, and nitrogen.
e) 99% hydrogen, and 1% heavier elements.
The composition of
interstellar gas mirrors that
of the Sun, stars, and the
jovian planets.
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Question 11 - 5
The reddish color of
emission nebulae
indicates that
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a) gas and dust is moving away
from Earth.
b) hydrogen gas is present.
c) dying stars have recently
exploded.
d) cool red stars are hidden inside.
e) dust is present.
Question 11 - 5
The reddish color of
emission nebulae
indicates that
a) gas and dust is moving away
from Earth.
b) hydrogen gas is present.
c) dying stars have recently
exploded.
d) cool red stars are hidden inside.
e) dust is present.
Glowing
hydrogen gas
emits red light
around the
Horsehead
nebula.
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Question 11 - 6
21-centimeter
radiation is
important
because
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a) its radio waves pass unaffected through
clouds of interstellar dust.
b) it arises from cool helium gas present
throughout space.
c) it can be detected with optical telescopes.
d) it is produced by protostars.
e) it reveals the structure of new stars.
Question 11 - 6
21-centimeter
radiation is
important
because
a) its radio waves pass unaffected through
clouds of interstellar dust.
b) it arises from cool helium gas present
throughout space.
c) it can be detected with optical telescopes.
d) it is produced by protostars.
e) it reveals the structure of new stars.
Cool atomic hydrogen gas
produces 21-cm radio radiation
as its electron “flips” its
direction of spin.
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Question 11 - 7
Complex
molecules in
space are
found
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a) in the photospheres of red giant stars.
b) primarily inside dense dust clouds.
c) in the coronas of stars like our Sun.
d) scattered evenly throughout interstellar
space.
e) surrounding energetic young stars.
Question 11 - 7
Complex
molecules in
space are
found
a) in the photospheres of red giant stars.
b) primarily inside dense dust clouds.
c) in the coronas of stars like our Sun.
d) scattered evenly throughout interstellar
space.
e) surrounding energetic young stars.
A radio telescope image of the outer portion of the Milky Way,
revealing molecular cloud complexes.
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Question 11 - 8
Stars are often born
within groups known as
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a) clans.
b) spiral waves.
c) aggregates.
d) clusters.
e) swarms.
Question 11 - 8
Stars are often born
within groups known as
a) clans.
b) spiral waves.
c) aggregates.
d) clusters.
e) swarms.
The Pleiades – a nearby open
cluster – is a group of relatively
young stars about 400 light-years
from the Sun.
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Question 11 - 9
All stars in a stellar cluster
have roughly the same
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a) temperature.
b) color.
c) distance.
d) mass.
e) luminosity.
Question 11 - 9
All stars in a stellar cluster
have roughly the same
a) temperature.
b) color.
c) distance.
d) mass.
e) luminosity.
Stars in the Pleiades cluster vary in temperature, color, mass,
and luminosity, but all lie about 440 light-years away.
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Question 11 - 10
Globular clusters are
typically observed
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a) in the plane of our Galaxy.
b) above or below the plane of
our Galaxy.
c) near to our Sun.
d) in the hearts of other
galaxies.
Question 11 - 10
Globular clusters are
typically observed
a) in the plane of our Galaxy.
b) above or below the plane of
our Galaxy.
c) near to our Sun.
d) in the hearts of other
galaxies.
Globular clusters orbit the center of the Milky Way, and are usually
seen
aboveInc.or below the galactic plane far from our Sun.
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Pearson Education,
Question 11 - 11
Stars in clusters &
associations have about
the same
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a) age.
b) temperature.
c) mass.
d) color.
e) luminosity.
Question 11 - 11
Stars in clusters &
associations have about
the same
Most of the stars in a cluster
form about the same time.
Stars in the Omega Centauri
globular cluster are
estimated to be about 14
billion years old.
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a) age.
b) temperature.
c) mass.
d) color.
e) luminosity.
Question 11 - 12
Objects more
massive than our
Sun form into
stars
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a) much slower, over billions of years.
b) in about the same time.
c) much faster, over tens of thousands
of years.
d) not at all – they are unstable.
Question 11 - 12
Objects more
massive than our
Sun form into
stars
a) much slower, over billions of years.
b) in about the same time.
c) much faster, over tens of thousands
of years.
d) not at all – they are unstable.
More mass  faster collapse
More mass  faster start of
fusion reactions
More mass  a hotter, more
luminous main sequence star
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Question 11 - 13
How do single
stars form within
huge clouds of
interstellar gas
and dust?
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a) Clouds fragment into smaller objects,
forming many stars at one time.
b) One star forms; other matter goes into
planets, moons, asteroids, & comets.
c) Clouds rotate & throw off mass until only
enough is left to form one star.
Question 11 - 13
How do single
stars form within
huge clouds of
interstellar gas
and dust?
a) Clouds fragment into smaller objects,
forming many stars at one time.
b) One star forms; other matter goes into
planets, moons, asteroids, & comets.
c) Clouds rotate & throw off mass until only
enough is left to form one star.
The theory of star formation predicts stars in a cluster
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Inc.
form about the same time.
Question 11 - 14
What is a TTauri star?
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a) a collapsing cloud of gas about to
become a protostar
b) a dying star
c) a cool main sequence star
d) a star releasing a planetary nebula
e) a protostar about to become a star
Question 11 - 14
What is a TTauri star?
a) a collapsing cloud of gas about to
become a protostar
b) a dying star
c) a cool main sequence star
d) a star releasing a planetary nebula
e) a protostar about to become a star
T-Tauri stars often show jets of
gas emitted in two directions —
“bipolar flow” — suggesting they
are not yet stable.
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Question 11 - 15
A key feature of
globular clusters
is that they have
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a ) very few cool stars.
b) the oldest stars in our Galaxy.
c) lots of massive main sequence stars.
d) stars with very different ages.
e) high concentrations of metals.
Question 11 - 15
A key feature of
globular clusters
is that they have
a ) very few cool stars.
b) the oldest stars in our Galaxy.
c) lots of massive main sequence stars.
d) stars with very different ages.
e) high concentrations of metals.
The H–R diagram of a
globular cluster has a low
“turnoff point” indicating
its extreme age.
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Question 12 - 1
Stars like our
Sun will end
their lives as
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a) red giants.
b) pulsars.
c) black holes.
d) white dwarfs.
e) red dwarfs.
Question 12 - 1
Stars like our
Sun will end
their lives as
a) red giants.
b) pulsars.
c) black holes.
d) white dwarfs.
e) red dwarfs.
Low-mass stars eventually
swell into red giants, and
their cores later contract
into white dwarfs.
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Question 12 - 2
Elements heavier than
hydrogen and Helium
were created
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a) in the Big Bang.
b) by nucleosynthesis in massive stars.
c) in the cores of stars like the Sun.
d) within planetary nebulae.
e) They have always existed.
Question 12 - 2
Elements heavier than
hydrogen and helium
were created
a) in the Big Bang.
b) by nucleosynthesis in massive stars.
c) in the cores of stars like the Sun.
d) within planetary nebula
e) They have always existed.
Massive stars create
enormous core
temperatures as red
supergiants, fusing helium
into carbon, oxygen, and
even heavier elements.
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Question 12 - 3
The Sun will
evolve away
from the main
sequence when
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a) its core begins fusing iron.
b) its supply of hydrogen is used up.
c) the carbon core detonates, and it
explodes as a Type I supernova.
d) helium builds up in the core, while the
hydrogen-burning shell expands.
e) the core loses all of its neutrinos, so all
fusion ceases.
Question 12 - 3
The Sun will
evolve away
from the main
sequence when
a) its core begins fusing iron.
b) its supply of hydrogen is used up.
c) the carbon core detonates, and it
explodes as a Type I supernova.
d) helium builds up in the core, while the
hydrogen-burning shell expands.
e) the core loses all of its neutrinos, so all
fusion ceases.
When the Sun’s core becomes
unstable and contracts,
additional H fusion generates
extra pressure, and the star
will swell into a red giant.
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Question 12 - 4
The helium
flash occurs
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a) when T-Tauri bipolar jets shoot out.
b) in the middle of the main sequence stage.
c) in the red giant stage.
d) during the formation of a neutron star.
e) in the planetary nebula stage.
Question 12 - 4
The helium
flash occurs
a) when T-Tauri bipolar jets shoot out.
b) in the middle of the main sequence stage.
c) in the red giant stage.
d) during the formation of a neutron star.
e) in the planetary nebula stage.
When the collapsing core of
a red giant reaches high
enough temperatures and
densities, helium can fuse
into carbon quickly – a
helium flash.
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Question 12 - 5
Stars gradually lose
mass as they
become white
dwarfs during the
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a) T-Tauri stage.
b) emission nebula stage.
c) supernova stage.
d) nova stage.
e) planetary nebula stage.
Question 12 - 5
Stars gradually lose
mass as they
become white
dwarfs during the
a) T-Tauri stage.
b) emission nebula stage.
c) supernova stage.
d) nova stage.
e) planetary nebula stage.
Low-mass stars forming
white dwarfs slowly lose
their outer atmospheres,
and illuminate these gases
for a relatively short time.
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Question 12 - 6
Astronomers
determine the age
of star clusters by
observing
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a) the number of main sequence stars.
b) the ratio of giants to supergiants.
c) the luminosity of stars at the turnoff
point.
d) the number of white dwarfs.
e) supernova explosions.
Question 12 - 6
Astronomers
determine the age
of star clusters by
observing
a) the number of main sequence stars.
b) the ratio of giants to supergiants.
c) the luminosity of stars at the turnoff
point.
d) the number of white dwarfs.
e) supernova explosions.
The H–R diagram of a cluster can
indicate its approximate age.
Turnoff point from the main
sequence
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Question 12 - 7
The source of
pressure that
makes a white
dwarf stable is
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a) electron degeneracy.
b) neutron degeneracy.
c) thermal pressure from intense core
temperatures.
d) gravitational pressure.
e) helium-carbon fusion.
Question 12 - 7
The source of
pressure that
makes a white
dwarf stable is
a) electron degeneracy.
b) neutron degeneracy.
c) thermal pressure from intense core
temperatures.
d) gravitational pressure.
e) helium-carbon fusion.
Electrons in the core cannot
be squeezed infinitely close,
and prevent a low-mass star
from collapsing further.
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Question 12 - 8
In a white dwarf,
the mass of the
Sun is packed into
the volume of
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a) an asteroid.
b) a planet the size of Earth.
c) a planet the size of Jupiter.
d) an object the size of the Moon.
e) an object the size of a sugar cube.
Question 12 - 8
In a white dwarf,
the mass of the
Sun is packed into
the volume of
a) an asteroid.
b) a planet the size of Earth.
c) a planet the size of Jupiter.
d) an object the size of the Moon.
e) an object the size of a sugar cube.
The density of a white
dwarf is about a million
times greater than normal
solid matter.
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Question 12 - 9
In a young star
cluster, when more
massive stars are
evolving into red
giants, the least
massive stars are
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a) ending their main-sequence stage.
b) also evolving into red giants.
c) forming planetary nebulae.
d) barely starting to fuse hydrogen.
e) starting the nova stage.
Question 12 - 9
In a young star
cluster, when more
massive stars are
evolving into red
giants, the least
massive stars are
a) ending their main-sequence stage.
b) also evolving into red giants.
c) forming planetary nebulae.
d) barely starting to fuse hydrogen.
e) starting the nova stage.
More massive stars form much
faster, and have much shorter
main-sequence lifetimes.
Low-mass stars form more
slowly.
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Question 12 - 10
A star will spend
most of its
“shining” lifetime
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a) as a protostar.
b) as a red giant.
c) as a main-sequence star.
d) as a white dwarf.
e) evolving from type O to type M.
Question 12 - 10
A star will spend
most of its
“shining” lifetime
a) as a protostar.
b) as a red giant.
c) as a main-sequence star.
d) as a white dwarf.
e) evolving from type O to type M.
In the main-sequence stage,
hydrogen fuses to helium.
Pressure from light and
heat pushing out balances
gravitational pressure
pushing inward.
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Question 12 - 11
A nova
involves
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a) mass transfer onto a white dwarf in a binary
star system.
b) repeated helium fusion flashes in red giants.
c) rapid collapse of a protostar into a massive O
star.
d) the explosion of a low-mass star.
e) the birth of a massive star in a new cluster.
Question 12 - 11
A nova
involves
a) mass transfer onto a white dwarf in a binary
star system.
b) repeated helium fusion flashes in red giants.
c) rapid collapse of a protostar into a massive O
star.
d) the explosion of a low-mass star.
e) the birth of a massive star in a new cluster.
Sudden, rapid fusion of new
fuel dumped onto a white
dwarf causes the star to flare
up, and for a short time
become much brighter.
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Question 12 - 12
What type of atomic
nuclei heavier than
helium are most
common, and why?
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a) those heavier than iron, because
of supernovae
b) iron, formed just before massive
stars explode
c) odd-numbered nuclei, built with
hydrogen fusion
d) even-numbered nuclei, built with
helium fusion
Question 12 - 12
What type of atomic
nuclei heavier than
helium are most
common, and why?
a) those heavier than iron, because
of supernovae
b) iron, formed just before massive
stars explode
c) odd-numbered nuclei, built with
hydrogen fusion
d) even-numbered nuclei, built with
helium fusion
Helium nuclei have an atomic
mass of 4; they act as building
blocks in high-temperature
fusion within supergiants.
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Question 12 - 13
A white dwarf
can explode
when
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a) its mass exceeds the Chandrasekhar limit.
b) its electron degeneracy increases
enormously.
c) fusion reactions increase in it’s core.
d) iron in its core collapses.
e) the planetary nebula stage ends.
Question 12 - 13
A white dwarf
can explode
when
a) its mass exceeds the Chandrasekhar limit.
b) its electron degeneracy increases
enormously.
c) fusion reactions increase in it’s core.
d) iron in its core collapses.
e) the planetary nebula stage ends.
If additional mass from a companion star pushes a white dwarf
beyond 1.4 solar masses, it can explode in a Type I supernova.
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Question 12 - 14
A Type II
supernova
occurs when
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a) hydrogen fusion shuts off.
b) uranium decays into lead.
c) iron in the core starts to fuse.
d) helium is exhausted in the outer layers.
e) a white dwarf gains mass.
Question 12 - 14
A Type II
supernova
occurs when
a) hydrogen fusion shuts off.
b) uranium decays into lead.
c) iron in the core starts to fuse.
d) helium is exhausted in the outer layers.
e) a white dwarf gains mass.
Fusion of iron does not produce energy or provide pressure; the
star’s core collapses immediately, triggering a supernova explosion.
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Question 12 - 15
Supernova
1987A was
important
because
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a) its parent star had been studied before
the explosion.
b) its distance was already known.
c) it was observed early, as its light was
still increasing.
d) its evolution was captured with detailed
images from the Hubble Space
Telescope.
e) All of the above are true.
Question 12 - 15
Supernova
1987A was
important
because
a) its parent star had been studied before
the explosion.
b) its distance was already known.
c) it was observed early, as its light was
still increasing.
d) its evolution was captured with detailed
images from the Hubble Space
Telescope.
e) All of the above are true.
Supernovae are important distance
indicators in the study of galaxies
beyond the Milky Way.
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Question 12 - 16
As stars
evolve during
their mainsequence
lifetime
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a) they gradually become cooler and
dimmer (spectral type O to type M).
b) they gradually become hotter and
brighter (spectral type M to type O).
c) they don’t change their spectral type.
Question 12 - 16
As stars
evolve during
their mainsequence
lifetime
a) they gradually become cooler and
dimmer (spectral type O to type M).
b) they gradually become hotter and
brighter (spectral type M to type O).
c) they don’t change their spectral type.
A star’s main-sequence characteristics of surface
temperature and brightness are based on its mass.
Stars of different initial mass become different spectral
types on the main sequence.
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Question 12 - 17
More massive
white dwarfs are
______ compared
with less massive
white dwarfs.
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a) hotter
b) smaller
c) larger
d) cooler
e) identical in size
Question 12 - 17
More massive
white dwarfs are
______ compared
with less massive
white dwarfs.
a) hotter
b) smaller
c) larger
d) cooler
e) identical in size
Chandrasekhar showed that more mass will squeeze a
white dwarf into a smaller volume, due to electron
degeneracy pressure.
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Question 13 - 1
Pulsars usually
show all of the
following EXCEPT
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a) extremely rapid rotation.
b) high-temperature fusion reactions.
c) a narrow regular pulse of radiation.
d) high-speed motion through the galaxy.
e) an intense magnetic field.
Question 13 - 1
Pulsars usually
show all of the
following
EXCEPT
a) extremely rapid rotation.
b) high-temperature fusion reactions.
c) a narrow regular pulse of radiation.
d) high-speed motion through the galaxy.
e) an intense magnetic field.
Pulsars are neutron stars no
longer undergoing fusion in
their cores.
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Question 13 - 2
Many millisecond
pulsars lie within
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a) emission nebulae.
b) giant molecular clouds.
c) globular clusters.
d) planetary nebulae.
e) open clusters.
Question 13 - 2
Many millisecond
pulsars lie within
a) emission nebulae.
b) giant molecular clouds.
c) globular clusters.
d) planetary nebulae.
e) open clusters.
The cores of globular clusters are
densely packed with stars,
suggesting that millisecond pulsars
might result from “spinning up” as a
result of stellar encounters.
The core of globular cluster 47 Tucanae
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