Question 1

Where on the Hertzsprung-Russell diagram do MOST stars near the Sun congregate?

Accepted Answer

A)  white dwarf area 
B)  supergiant area 
C)  giant area 
D)  main sequence 
A)  white dwarf area 
B)  supergiant area 
C)  giant area 
D)  main sequence

Question 2

Two stars are found to have the same luminosity. However, one star has twice the surface temperature of the other. From this information, what can one determine about their radii?

Accepted Answer

A)  The hotter star has half the radius of the cooler star. 
B)  The cooler star has half the radius of the hotter star. 
C)  The hotter star has a quarter the radius of the cooler star. 
D)  Nothing can be determined about the radii from this information. 
A)  The hotter star has half the radius of the cooler star. 
B)  The cooler star has half the radius of the hotter star. 
C)  The hotter star has a quarter the radius of the cooler star. 
D)  Nothing can be determined about the radii from this information.

Question 3

In a particular binary star system, only one star is visible because the other star is too faint to see at that distance. An astronomer measures the size (semimajor axis) and period of the orbit of the visible star. From this information, the astronomer

Accepted Answer

A)  cannot calculate anything about the mass-both stars have to be visible to do so. 
B)  can calculate the mass of each star. 
C)  can calculate the sum of the masses of the two stars but not the mass of each star separately. 
D)  can calculate the mass of the visible star but not that of the unseen star. 
A)  cannot calculate anything about the mass-both stars have to be visible to do so. 
B)  can calculate the mass of each star. 
C)  can calculate the sum of the masses of the two stars but not the mass of each star separately. 
D)  can calculate the mass of the visible star but not that of the unseen star.

Question 4

What is the intensity of sunlight per square meter reaching Venus compared with this intensity at Earth's orbital distance? (Venus's orbit has a semimajor axis of about 0.7 au.)

Accepted Answer

A)  about the same, since this intensity remains constant, following a law of nature 
B)  about 1.4 
C)  about 1.9 
D)  about 0.5 
A)  about the same, since this intensity remains constant, following a law of nature 
B)  about 1.4 
C)  about 1.9 
D)  about 0.5

Question 5

A star of apparent magnitude +5 appears _____ than a star of apparent magnitude +3.

Accepted Answer

A)  fainter 
B)  farther away 
C)  brighter 
D)  either brighter or fainter, depending on the distance to the stars, 
A)  fainter 
B)  farther away 
C)  brighter 
D)  either brighter or fainter, depending on the distance to the stars,

Question 6

How do two unequal-mass stars in a binary star system move around each other, in general?

Accepted Answer

A)  The stars move in a single circular orbit around the same center and always on opposite sides from each other. 
B)  The stars move in straight lines, back and forth past each other. 
C)  The low-mass star moves in a circular orbit around the high-mass star, which remains stationary. 
D)  The stars move in elliptical orbits about a common center of mass. 
A)  The stars move in a single circular orbit around the same center and always on opposite sides from each other. 
B)  The stars move in straight lines, back and forth past each other. 
C)  The low-mass star moves in a circular orbit around the high-mass star, which remains stationary. 
D)  The stars move in elliptical orbits about a common center of mass.

Question 7

Two stars in a binary system orbit around a common point that is

Accepted Answer

A)  exactly midway between the two stars. 
B)  closer to the less massive star. 
C)  closer to the more massive star. 
D)  inside one of the stars. 
A)  exactly midway between the two stars. 
B)  closer to the less massive star. 
C)  closer to the more massive star. 
D)  inside one of the stars.

Question 8

The light curve made of a pair of eclipsing binaries will exhibit dips in intensity. The bottoms of these dips can have different shapes. How do astronomers interpret this?

Accepted Answer

A)  A flat bottom means that one is viewing the system along the long (semimajor) axis. 
B)  A flat bottom means that the stars are experiencing a total eclipse. 
C)  A rounded bottom means that the stars are exhibiting a partial eclipse. 
D)  A V-shaped bottom means that one is viewing the system along the short (semiminor) axis. 
A)  A flat bottom means that one is viewing the system along the long (semimajor) axis. 
B)  A flat bottom means that the stars are experiencing a total eclipse. 
C)  A rounded bottom means that the stars are exhibiting a partial eclipse. 
D)  A V-shaped bottom means that one is viewing the system along the short (semiminor) axis.

Question 9

White dwarfs are NOT included in the luminosity classification because they are

Accepted Answer

A)  not yet active stars; they have not yet begun nuclear reactions. 
B)  no longer producing energy by nuclear reactions. 
C)  no longer radiating energy away. 
D)  too small. 
A)  not yet active stars; they have not yet begun nuclear reactions. 
B)  no longer producing energy by nuclear reactions. 
C)  no longer radiating energy away. 
D)  too small.

Question 10

Some stars are variable, with many properties that change over time. The statement that the apparent magnitude of a variable star has INCREASED indicates that its

Accepted Answer

A)  brightness has increased. 
B)  surface temperature has decreased. 
C)  brightness has decreased. 
D)  surface temperature has increased. 
A)  brightness has increased. 
B)  surface temperature has decreased. 
C)  brightness has decreased. 
D)  surface temperature has increased.

Question 11

A simple relationship exists between mass and luminosity for

Accepted Answer

A)  all stars. 
B)  main-sequence stars. 
C)  giant stars and main-sequence stars. 
D)  white dwarf stars. 
A)  all stars. 
B)  main-sequence stars. 
C)  giant stars and main-sequence stars. 
D)  white dwarf stars.

Question 12

How many times brighter does the Sun appear from Earth than it does from Neptune, which has an orbital radius of approximately 30 au?

Accepted Answer

A)  30 
B)  30 × 2.512 = 75.4 
C)  (30)2 = 900 
D)  4 $\pi$ (30)2 = 1130 
A)  30 
B)  30 × 2.512 = 75.4 
C)  (30)2 = 900 
D)  4 $\pi$ (30)2 = 1130

Question 13

Vega is often used as the star to define an apparent magnitude of 0. Actually, the standard for 0 magnitude is the average of a group of stars including Vega. But the averaging must be done with care. If one takes the combined brightness of one 0.1-magnitude star and one -0.1-magnitude star and divides this brightness by two, the equivalent brightness is

Accepted Answer

A)  one 0-magnitude star. 
B)  one star with a magnitude less than 0. 
C)  one star with a magnitude greater than 0. 
D)  two 0-magnitude stars. 
A)  one 0-magnitude star. 
B)  one star with a magnitude less than 0. 
C)  one star with a magnitude greater than 0. 
D)  two 0-magnitude stars.

Question 14

Suppose astronomers want to measure the distance to a star in astronomical units. They would use the equation d (au) = x/parallax angle (arcsec). What is x?

Accepted Answer

A)  3.26 
B)  360 
C)  206,265 
D)  3.0 × 108 
A)  3.26 
B)  360 
C)  206,265 
D)  3.0 × 108

Question 15

In the spectral classification scheme, what designation is given to a star just a little cooler than a K5 star?

Accepted Answer

A)  K4 
B)  K6 
C)  M0 
D)  K0 
A)  K4 
B)  K6 
C)  M0 
D)  K0

Question 16

The MOST accurate stellar parallax measurements for distances to the majority of stars in Earth's neighborhood in the universe have been made by

Accepted Answer

A)  the Hubble Space Telescope. 
B)  Friedrich Wilhelm Bessel, in 1838; no measurements since then have matched the precision of his measurements. 
C)  the Gaia satellite. 
D)  the Very Long Baseline Array of radio telescopes. 
A)  the Hubble Space Telescope. 
B)  Friedrich Wilhelm Bessel, in 1838; no measurements since then have matched the precision of his measurements. 
C)  the Gaia satellite. 
D)  the Very Long Baseline Array of radio telescopes.

Question 17

The sequence of letters that is used to classify star surface temperatures, as determined by relative spectral absorption line strengths, in order of DECREASING temperature, is

Accepted Answer

A)  A, B, F, G, K, M, O. 
B)  M, O, F, K, G, A, B. 
C)  O, F, M, G, A, B, K. 
D)  O, B, A, F, G, K, M. 
A)  A, B, F, G, K, M, O. 
B)  M, O, F, K, G, A, B. 
C)  O, F, M, G, A, B, K. 
D)  O, B, A, F, G, K, M.

Question 18

The luminosity of a star is

Accepted Answer

A)  its brightness as seen by people on Earth. 
B)  its brightness if it were at a distance of 10 pc (32.6 ly) from Earth. 
C)  its total energy output into all space. 
D)  another name for its color or surface temperature. 
A)  its brightness as seen by people on Earth. 
B)  its brightness if it were at a distance of 10 pc (32.6 ly) from Earth. 
C)  its total energy output into all space. 
D)  another name for its color or surface temperature.

Question 19

A star shows weak hydrogen Balmer lines but strong lines of neutral sodium. What is a likely explanation for this?

Accepted Answer

A)  This particular star contains no hydrogen. 
B)  The hydrogen has been ionized. 
C)  The hydrogen is not receiving enough energy to populate the n = 2 level required for Balmer transitions. 
D)  The sodium lines are masking the hydrogen lines because these occur at the same wavelengths. 
A)  This particular star contains no hydrogen. 
B)  The hydrogen has been ionized. 
C)  The hydrogen is not receiving enough energy to populate the n = 2 level required for Balmer transitions. 
D)  The sodium lines are masking the hydrogen lines because these occur at the same wavelengths.

Question 20

Compared with a star in the middle of the Hertzsprung-Russell diagram, a star in the lower left of the diagram is

Accepted Answer

A)  larger. 
B)  cooler. 
C)  smaller. 
D)  brighter. 
A)  larger. 
B)  cooler. 
C)  smaller. 
D)  brighter.

Where on the Hertzsprung-Russell diagram do MOST stars near the Sun congregate?

Two stars are found to have the same luminosity. However, one star has twice the surface temperature of the other. From this information, what can one determine about their radii?

In a particular binary star system, only one star is visible because the other star is too faint to see at that distance. An astronomer measures the size (semimajor axis) and period of the orbit of the visible star. From this information, the astronomer

What is the intensity of sunlight per square meter reaching Venus compared with this intensity at Earth's orbital distance? (Venus's orbit has a semimajor axis of about 0.7 au.)

A star of apparent magnitude +5 appears _____ than a star of apparent magnitude +3.

How do two unequal-mass stars in a binary star system move around each other, in general?

Two stars in a binary system orbit around a common point that is

The light curve made of a pair of eclipsing binaries will exhibit dips in intensity. The bottoms of these dips can have different shapes. How do astronomers interpret this?

White dwarfs are NOT included in the luminosity classification because they are

Some stars are variable, with many properties that change over time. The statement that the apparent magnitude of a variable star has INCREASED indicates that its

A simple relationship exists between mass and luminosity for

How many times brighter does the Sun appear from Earth than it does from Neptune, which has an orbital radius of approximately 30 au?

Suppose astronomers want to measure the distance to a star in astronomical units. They would use the equation d (au) = x/parallax angle (arcsec). What is x?

In the spectral classification scheme, what designation is given to a star just a little cooler than a K5 star?

The MOST accurate stellar parallax measurements for distances to the majority of stars in Earth's neighborhood in the universe have been made by

The sequence of letters that is used to classify star surface temperatures, as determined by relative spectral absorption line strengths, in order of DECREASING temperature, is

The luminosity of a star is

A star shows weak hydrogen Balmer lines but strong lines of neutral sodium. What is a likely explanation for this?

Compared with a star in the middle of the Hertzsprung-Russell diagram, a star in the lower left of the diagram is

Discovering the Night Sky

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Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

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The Death of Stars

Black Holes: Matters of Gravity

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Exam 12: Characterizing Stars

Where on the Hertzsprung-Russell diagram do MOST stars near the Sun congregate?

Two stars are found to have the same luminosity. However, one star has twice the surface temperature of the other. From this information, what can one determine about their radii?

In a particular binary star system, only one star is visible because the other star is too faint to see at that distance. An astronomer measures the size (semimajor axis) and period of the orbit of the visible star. From this information, the astronomer

What is the intensity of sunlight per square meter reaching Venus compared with this intensity at Earth's orbital distance? (Venus's orbit has a semimajor axis of about 0.7 au.)

A star of apparent magnitude +5 appears _____ than a star of apparent magnitude +3.

How do two unequal-mass stars in a binary star system move around each other, in general?

Two stars in a binary system orbit around a common point that is

The light curve made of a pair of eclipsing binaries will exhibit dips in intensity. The bottoms of these dips can have different shapes. How do astronomers interpret this?

White dwarfs are NOT included in the luminosity classification because they are

Some stars are variable, with many properties that change over time. The statement that the apparent magnitude of a variable star has INCREASED indicates that its

A simple relationship exists between mass and luminosity for

How many times brighter does the Sun appear from Earth than it does from Neptune, which has an orbital radius of approximately 30 au?

Suppose astronomers want to measure the distance to a star in astronomical units. They would use the equation d (au) = x/parallax angle (arcsec). What is x?

In the spectral classification scheme, what designation is given to a star just a little cooler than a K5 star?

The MOST accurate stellar parallax measurements for distances to the majority of stars in Earth's neighborhood in the universe have been made by

The sequence of letters that is used to classify star surface temperatures, as determined by relative spectral absorption line strengths, in order of DECREASING temperature, is

The luminosity of a star is

A star shows weak hydrogen Balmer lines but strong lines of neutral sodium. What is a likely explanation for this?

Compared with a star in the middle of the Hertzsprung-Russell diagram, a star in the lower left of the diagram is

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Atomic Physics and Spectra

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

The Lives of Stars From Birth Through Middle Age

The Death of Stars

Black Holes: Matters of Gravity

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Cosmology

Astrobiology

Filters