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Questions
Chapter 14
The Milky
Way Galaxy
Copyright © 2010 Pearson Education, Inc.
Question 1
The location of the
galactic center was
identified using
Copyright © 2010 Pearson Education, Inc.
a) supernova remnants.
b) white dwarf stars in the spiral arms.
c) red giant variable stars in globular
clusters.
d) bright O and B stars in open clusters.
e) X-ray sources.
Question 1
The location of the
galactic center was
identified using
a) supernova remnants.
b) white dwarf stars in the spiral arms.
c) red giant variable stars in globular
clusters.
d) bright O and B stars in open clusters.
e) X-ray sources.
Harlow Shapley used pulsating RRLyrae variables as distance indicators
to the globular clusters.
He then deduced the distance and
direction of the Milky Way’s center.
Copyright © 2010 Pearson Education, Inc.
Question 2
Our Sun is
located in the
Milky Way
Galaxy
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a) about 30 Kpc from the center in the
halo.
b) 30,000 light-years from the center in
a globular cluster.
c) at the outer edge of the galactic disk,
in the plane.
d) about halfway from the center, in the
spiral arms.
e) in the bulge, near the Orion arm.
Question 2
Our Sun is
located in the
Milky Way
Galaxy
a) about 30 Kpc from the center in the
halo.
b) 30,000 light-years from the center in
a globular cluster.
c) at the outer edge of the galactic disk,
in the plane.
d) about halfway from the center, in the
spiral arms.
e) in the bulge, near the Orion arm.
The Sun orbits the center of
the Galaxy within the disk,
taking about 225 million years
to complete one orbit.
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Question 3
The period –
luminosity
relationship is
a crucial
component of
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a) measuring distances with Cepheid
variable stars.
b) identifying the mass of the Galaxy’s
central black hole.
c) determining the masses of stars in
an eclipsing binary system.
d) using spectroscopic parallax to
measure distances to stars.
Question 3
The period –
luminosity
relationship is
a crucial
component of
a) measuring distances with Cepheid
variable stars.
b) identifying the mass of the Galaxy’s
central black hole.
c) determining the masses of stars in
an eclipsing binary system.
d) using spectroscopic parallax to
measure distances to stars.
Cepheid variable stars with
longer periods have higher
actual luminosities; short-period
Cepheids are dimmer.
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Question 4
High-speed motion
of gas and stars
near the Milky Way
Galaxy’s center is
explained by
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a) tidal forces from the Andromeda Galaxy.
b) accretion disks around neutron stars.
c) gamma-ray bursts.
d) gravitation from globular clusters.
e) a supermassive black hole.
Question 4
High-speed motion
of gas and stars
near the Milky Way
Galaxy’s center is
explained by
a) tidal forces from the Andromeda Galaxy.
b) accretion disks around neutron stars.
c) gamma-ray bursts.
d) gravitation from globular clusters.
e) a supermassive black hole.
Recent observations
estimate the black hole to be
4 million solar masses.
Copyright © 2010 Pearson Education, Inc.
Question 5
Detailed measurements
of the disk suggest that
our Milky Way is
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a) a spiral galaxy.
b) a barred spiral galaxy.
c) an elliptical galaxy.
d) a quasar.
e) an irregular galaxy.
Question 5
Detailed measurements
of the disk suggest that
our Milky Way is
a) a spiral galaxy.
b) a barred spiral galaxy.
c) an elliptical galaxy.
d) a quasar.
e) an irregular galaxy.
Measurements of stellar motion in and near the bulge
imply that it is football shaped, about half as wide as it is
long, characteristic of a barred spiral galaxy.
Copyright © 2010 Pearson Education, Inc.
Question 6
What two
observations
allow us to
estimate the
Galaxy’s mass?
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a) the Sun’s mass and velocity in orbit
around the galactic center
b) the rotation of the bulge and disk
components
c) the Sun’s age and age of globular
cluster stars
d) the motion of spiral arms and the
mass of the central black hole
e) the Sun’s orbital period and distance
from the center
Question 6
What two
observations
allow us to
estimate the
Galaxy’s mass?
a) the Sun’s mass and velocity in orbit
around the galactic center
b) the rotation of the bulge and disk
components
c) the Sun’s age and age of the globular
cluster stars
d) the motion of spiral arms and mass
of the central black hole
e) the Sun’s orbital period and distance
from the center
Use the modified form of Kepler’s law to find the mass:
Total mass = (orbital size)3 / (orbital period)2
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Question 7
In the formation
of our Galaxy
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a) the spiral arms formed first.
b) the globular clusters formed first.
c) the disk component started out thin
and grew.
d) spiral density waves formed first.
e) the bar in the bulge formed first.
Question 7
In the formation
of our Galaxy
a) the spiral arms formed first.
b) the globular clusters formed first.
c) the disk component started out thin
and grew.
d) spiral density waves formed first.
e) the bar in the bulge formed first.
Globular clusters contain
very old stars, no gas or
dust, and orbit around the
center randomly.
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Question 8
21-cm radio
radiation is useful
in studying our
Galaxy because
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a) the waves penetrate dusty cocoons
to reveal star formation.
b) it reflects from the Galaxy’s core.
c) the waves are not absorbed by
galactic black holes.
d) it can be used to map out the cool
hydrogen in spiral arms.
e) radio waves provide a distance
measurement like parallax.
Question 8
21-cm radio
radiation is useful
in studying our
Galaxy because
a) the waves penetrate dusty cocoons
to reveal star formation.
b) it reflects from the Galaxy’s core.
c) the waves are not absorbed by
galactic black holes.
d) it can be used to map out the cool
hydrogen in spiral arms.
e) radio waves provide a distance
measurement like parallax.
The Doppler shifts of 21-cm radiation from
hydrogen in the spiral arms provides
astronomers with a tool to map out the
Galaxy’s structure.
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Question 9
Which of these
is not a typical
part of our
Galaxy’s spiral
arms?
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a) OB associations
b) open clusters
c) giant molecular clouds
d) emission nebulae
e) Population II red giant stars
Question 9
Which of these
is not a typical
part of our
Galaxy’s spiral
arms?
a) OB associations
b) open clusters
c) giant molecular clouds
d) emission nebulae
e) Population II red giant stars
The spiral arms contain gas,
dust, molecular clouds, new
clusters, and Population I stars.
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Question 10
What suggests that
the mass of our
Galaxy extends
farther than its
visible disk?
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a) 21-cm maps of the spiral arms
b) the rotation curve of the outer edges
of the Galaxy
c) orbits of open clusters in the disk
d) infrared observations of new starforming regions
e) X-ray images of other galaxies
Question 10
What suggests that
the mass of our
Galaxy extends
farther than its
visible disk?
a) 21-cm maps of the spiral arms
b) the rotation curve of the outer edges
of the Galaxy
c) orbits of open clusters in the disk
d) infrared observations of new starforming regions
e) X-ray images of other galaxies
The outer edges of the
Galaxy’s disk rotate much
faster than they should.
Most of the mass of the
Galaxy must be dark matter.
Copyright © 2010 Pearson Education, Inc.