Astronomy
A BEGINNER’S GUIDE
TO THE UNIVERSE
EIGHTH EDITION
CHAPTER 10
Measuring the Stars
Clickers
© 2017 Pearson Education, Inc.
Question 1
Stellar parallax is used to measure the
a)
b)
c)
d)
e)
sizes of stars.
distances of stars.
temperatures of stars.
radial velocity of stars.
brightness of stars.
© 2017 Pearson Education, Inc.
Question 1
Stellar parallax is used to measure the
a)
b)
c)
d)
e)
sizes of stars.
distances of stars.
temperatures of stars.
radial velocity of stars.
brightness of stars.
Explanation: Parallax can be used to
measure distances to stars accurately
to about 200 parsecs (650 light-years).
© 2017 Pearson Education, Inc.
Question 2
The angle of stellar parallax for a star gets larger as the
a)
b)
c)
d)
e)
distance to the star increases.
size of the star increases.
size of the telescope increases.
length of the baseline increases.
wavelength of light increases.
© 2017 Pearson Education, Inc.
Question 2
The angle of stellar parallax for a star gets larger as the
a)
b)
c)
d)
e)
distance to the star increases.
size of the star increases.
size of the telescope increases.
length of the baseline increases.
wavelength of light increases.
Explanation: Astronomers typically make
observations of nearby stars 6 months
apart, making the baseline distance
equal to 2 AU (astronomical units).
© 2017 Pearson Education, Inc.
Question 3
You can best model the size and distance relationship of
our Sun and the next nearest star using
a)
b)
c)
d)
e)
one tennis ball here and one on the Moon.
two beach balls separated by 100 city blocks.
two grains of sand 100 light-years apart.
two golf balls 100 km apart.
two baseballs 100 yards apart.
© 2017 Pearson Education, Inc.
Question 3
You can best model the size and distance relationship of
our Sun and the next nearest star using
a) one 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.
Explanation: The Sun is about 1 million miles in diameter. The
next nearest star is about 25 million times farther away.
© 2017 Pearson Education, Inc.
Question 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 6 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.
© 2017 Pearson Education, Inc.
Question 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 6 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.
Explanation: A star’s “real space motion” combines its apparent
proper motion with its radial motion toward or away from Earth.
© 2017 Pearson Education, Inc.
Question 5
In the stellar magnitude system invented by Hipparchus, a
smaller magnitude indicates a _____ star.
a)
b)
c)
d)
e)
brighter
hotter
cooler
fainter
more distant
© 2017 Pearson Education, Inc.
Question 5
In the stellar magnitude system invented by Hipparchus, a
smaller magnitude indicates a _____ star.
a)
b)
c)
d)
e)
brighter
hotter
cooler
fainter
more distant
© 2017 Pearson Education, Inc.
Question 6
A star’s apparent magnitude is a number used to describe
how our eyes measure its
a)
b)
c)
d)
e)
distance.
temperature.
brightness.
absolute luminosity.
radial velocity.
© 2017 Pearson Education, Inc.
Question 6
A star’s apparent magnitude is a number used to describe
how our eyes measure its
a)
b)
c)
d)
e)
distance.
temperature.
brightness.
absolute luminosity.
radial velocity.
© 2017 Pearson Education, Inc.
Question 7
The absolute magnitude of a star is its brightness as seen
from a distance of
a)
b)
c)
d)
e)
1 million kilometers.
1 astronomical unit.
1 light-year.
10 parsecs.
10 light-years.
© 2017 Pearson Education, Inc.
Question 7
The absolute magnitude of a star is its brightness as seen
from a distance of
a)
b)
c)
d)
e)
1 million kilometers.
1 astronomical unit.
1 light-year.
10 parsecs.
10 light-years.
Explanation: Astronomers use
a distance of 10 parsecs
(about 32 light-years) as a
standard for specifying and
comparing the brightnesses of stars.
© 2017 Pearson Education, Inc.
Question 8
Which of the following quantities do you need in order to
calculate a star’s luminosity?
a)
b)
c)
d)
e)
Apparent brightness (flux)
Doppler shift of spectral lines
Color of the star
Distance to the star
Both a and d are correct.
© 2017 Pearson Education, Inc.
Question 8
Which of the following quantities do you need in order to
calculate a star’s luminosity?
a)
b)
c)
d)
e)
Apparent brightness (flux)
Doppler shift of spectral lines
Color of the star
Distance to the star
Both a and d are correct.
© 2017 Pearson Education, Inc.
Question 9
What are the two most important intrinsic properties
for classifying stars?
a)
b)
c)
d)
e)
Distance and surface temperature
Luminosity and surface temperature
Distance and luminosity
Mass and age
Distance and color
© 2017 Pearson Education, Inc.
Question 9
What are the two most important intrinsic properties
for classifying stars?
a) Distance and surface
temperature
b) Luminosity and surface
temperature
c) Distance and luminosity
d) Mass and age
e) Distance and color
Explanation: The H–R diagram plots
stars based on their luminosities and
surface temperatures.
© 2017 Pearson Education, Inc.
Question 10
Wien’s law tells us that the hotter an object, the _____ the
peak wavelength of its emitted light.
a)
b)
c)
d)
e)
longer
more green
heavier
shorter
more constant
© 2017 Pearson Education, Inc.
Question 10
Wien’s law tells us that the hotter an object, the _____ the
peak wavelength of its emitted light.
a)
b)
c)
d)
e)
longer
more green
heavier
shorter
more constant
Explanation: Wien’s law
states that hotter stars
appear more blue in color,
and cooler stars appear
more red in color.
© 2017 Pearson Education, Inc.
Question 11
We estimate the surface temperature of a star by using
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.
© 2017 Pearson Education, Inc.
Question 11
We estimate the surface temperature of a star by using
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.
© 2017 Pearson Education, Inc.
Question 12
Which spectral classification type corresponds to a star like
the Sun?
a)
b)
c)
d)
e)
O
A
F
G
M
© 2017 Pearson Education, Inc.
Question 12
Which spectral classification type corresponds to a star like
the Sun?
a)
b)
c)
d)
e)
O
A
F
G
M
Explanation: The OBAFGKM
classification scheme is based
on absorption lines.
© 2017 Pearson Education, Inc.
Question 13
The key difference between the spectra of B stars and
G stars is
a) B stars show strong hydrogen lines; G stars show weaker
hydrogen lines.
b) B stars show few metal lines; G stars show many.
c) B stars have no metal atoms.
d) G stars have no hydrogen atoms.
e) Both a and b are true.
© 2017 Pearson Education, Inc.
Question 13
The key difference between the spectra of B stars and
G stars is
a) B stars show strong hydrogen lines; G stars show
weaker hydrogen lines.
b) B stars show few metal lines; G stars show many.
c) B stars have no
metal atoms.
d) G stars have no
hydrogen atoms.
e) Both a and b are true.
Explanation: The original OBAFGKM sequence was arranged
alphabetically by the strength of hydrogen absorption lines. B
stars had strong hydrogen lines; G stars had weak lines.
© 2017 Pearson Education, Inc.
Question 14
Astronomers can estimate the size of a star using
a)
b)
c)
d)
e)
apparent brightness.
direct observation of diameter.
temperature.
distance to the star.
a, b, and c are all true.
© 2017 Pearson Education, Inc.
Question 14
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.
Explanation: 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.
© 2017 Pearson Education, Inc.
Question 15
Eclipsing binary stars are very useful for determining the
a)
b)
c)
d)
e)
ages of stars.
absolute luminosities of stars.
masses of stars.
distances to stars.
rotation rates of stars.
© 2017 Pearson Education, Inc.
Question 15
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.
Explanation: Analysis of the light curve of an eclipsing binary star
system can reveal the masses of the stars.
© 2017 Pearson Education, Inc.
Question 16
What is the single most important characteristic in
determining the course of a star’s evolution?
a)
b)
c)
d)
e)
Density
Absolute brightness
Distance
Surface temperature
Mass
© 2017 Pearson Education, Inc.
Question 16
What is the single most important characteristic in
determining the course of a star’s evolution?
a)
b)
c)
d)
e)
Density
Absolute brightness
Distance
Surface temperature
Mass
Explanation: A star’s mass
determines how fast it forms,
its luminosity on the main
sequence, how long it will shine,
and its ultimate fate.
© 2017 Pearson Education, Inc.