Question 1

A particular star has an absolute magnitude of +12 and a spectral class of A5. Using Figures 12-7 and 12-10 from the text, how would this star be classified?

Accepted Answer

A)  A5 I 
B)  A-type white dwarf 
C)  A5 V 
D)  A5 III 
A)  A5 I 
B)  A-type white dwarf 
C)  A5 V 
D)  A5 III

Question 2

The spectral luminosity class of the star Spica is B1 V, and that of the star  $ \tau $ Ceti is G8 V. From this information, one knows that Ceti is _____ Spica.

Accepted Answer

A)  cooler but has the same luminosity as 
B)  cooler and has a lower luminosity than 
C)  hotter but has the same luminosity as 
D)  hotter and has a lower luminosity than 
A)  cooler but has the same luminosity as 
B)  cooler and has a lower luminosity than 
C)  hotter but has the same luminosity as 
D)  hotter and has a lower luminosity than

Question 3

The Sun's absolute magnitude is about +5. The brightest stars in the sky have absolute magnitudes of about -10. What is the luminosity of these stars compared with that of the Sun, assuming that they have similar spectral light distributions?

Accepted Answer

A)  1 million times less 
B)  5 times less 
C)  1 million times greater 
D)  15 times greater 
A)  1 million times less 
B)  5 times less 
C)  1 million times greater 
D)  15 times greater

Question 4

A typical white dwarf has a surface temperature about 4 times that of the Sun and a radius about 1 percent that of the Sun. What can one determine about the luminosity of a typical white dwarf from this information?

Accepted Answer

A)  The white dwarf will be less luminous than the Sun. 
B)  The white dwarf and the Sun will have about the same luminosity. 
C)  The white dwarf will be more luminous than the Sun. 
D)  Nothing can be concluded about the relative luminosities from this information. 
A)  The white dwarf will be less luminous than the Sun. 
B)  The white dwarf and the Sun will have about the same luminosity. 
C)  The white dwarf will be more luminous than the Sun. 
D)  Nothing can be concluded about the relative luminosities from this information.

Question 5

What are the two physical parameters of stars that are plotted on the Hertzsprung-Russell diagram?

Accepted Answer

A)  mass and surface temperature 
B)  luminosity and mass 
C)  radius and mass 
D)  luminosity and surface temperature 
A)  mass and surface temperature 
B)  luminosity and mass 
C)  radius and mass 
D)  luminosity and surface temperature

Question 6

Which of these statements is NOT true about the center of mass of a binary star system?

Accepted Answer

A)  The center of mass is always on the line joining the two stars. 
B)  The center of mass is simultaneously a focus of the ellipse of each star's motion. 
C)  The center of mass is always more distant from the more massive star. 
D)  The center of mass can move with respect to the more distant background stars. 
A)  The center of mass is always on the line joining the two stars. 
B)  The center of mass is simultaneously a focus of the ellipse of each star's motion. 
C)  The center of mass is always more distant from the more massive star. 
D)  The center of mass can move with respect to the more distant background stars.

Question 7

Compared with a star in the middle of the Hertzsprung-Russell diagram, a star in the upper right of the diagram is

Accepted Answer

A)  fainter. 
B)  hotter. 
C)  larger. 
D)  nonexistent because there are no stars that appear in the upper right of the diagram. 
A)  fainter. 
B)  hotter. 
C)  larger. 
D)  nonexistent because there are no stars that appear in the upper right of the diagram.

Question 8

An astronomer is measuring the brightness of a particular star through a telescope, using different filters in the visual (yellow-green), violet, and ultraviolet regions. What is the name of the technique being used by this astronomer?

Accepted Answer

A)  spectroscopy 
B)  geometry 
C)  interferometry 
D)  photometry 
A)  spectroscopy 
B)  geometry 
C)  interferometry 
D)  photometry

Question 9

Which of these is not a type of true binary system, or, in other words, that the stars are NOT physically associated with each other?

Accepted Answer

A)  optical double 
B)  visual binary 
C)  spectroscopic binary 
D)  eclipsing binary 
A)  optical double 
B)  visual binary 
C)  spectroscopic binary 
D)  eclipsing binary

Question 10

When observers look out at the night sky, the number of stars with

Accepted Answer

A)  each magnitude (first, second, etc.) is about the same. 
B)  smaller magnitude numbers is much larger than the number of stars with larger magnitude numbers. 
C)  larger magnitude numbers is much larger than the number of stars with smaller magnitude numbers. 
D)  magnitudes around 3 is larger than either the number with magnitudes around 2 or the number with magnitudes around 4. 
A)  each magnitude (first, second, etc.) is about the same. 
B)  smaller magnitude numbers is much larger than the number of stars with larger magnitude numbers. 
C)  larger magnitude numbers is much larger than the number of stars with smaller magnitude numbers. 
D)  magnitudes around 3 is larger than either the number with magnitudes around 2 or the number with magnitudes around 4.

Question 11

The star Hadar is classified as B1 II, which means that it is a

Accepted Answer

A)  cool supergiant. 
B)  hot dwarf. 
C)  cool giant. 
D)  hot supergiant. 
A)  cool supergiant. 
B)  hot dwarf. 
C)  cool giant. 
D)  hot supergiant.

Question 12

Apparent magnitude is a measure of a star's

Accepted Answer

A)  intrinsic brightness (actual light output). 
B)  size (diameter). 
C)  temperature. 
D)  brightness, as seen from Earth. 
A)  intrinsic brightness (actual light output). 
B)  size (diameter). 
C)  temperature. 
D)  brightness, as seen from Earth.

Question 13

How can astronomers tell that some stars are relatively close to Earth?

Accepted Answer

A)  The stars appear to move periodically back and forth against the background stars because of Earth's movement around the Sun. 
B)  The stars appear to be extremely bright and must therefore be very close to Earth. 
C)  The stars are occasionally occulted or eclipsed by the Moon; hence they must be close. 
D)  The light from these stars shows only a very small redshift caused by the universal expansion of the universe, so they must be close. 
A)  The stars appear to move periodically back and forth against the background stars because of Earth's movement around the Sun. 
B)  The stars appear to be extremely bright and must therefore be very close to Earth. 
C)  The stars are occasionally occulted or eclipsed by the Moon; hence they must be close. 
D)  The light from these stars shows only a very small redshift caused by the universal expansion of the universe, so they must be close.

Question 14

Is there a relationship between the mass of a main-sequence star and its luminosity?

Accepted Answer

A)  No. Large masses can have low luminosities and vice versa. 
B)  Yes. Mass and luminosity are related linearly: A star twice as massive has twice the luminosity. 
C)  Yes. The mass and luminosity are related, but not linearly: A star twice as massive has more than twice the luminosity. 
D)  Yes, but surprisingly there is an anticorrelation: Larger masses have smaller luminosities. 
A)  No. Large masses can have low luminosities and vice versa. 
B)  Yes. Mass and luminosity are related linearly: A star twice as massive has twice the luminosity. 
C)  Yes. The mass and luminosity are related, but not linearly: A star twice as massive has more than twice the luminosity. 
D)  Yes, but surprisingly there is an anticorrelation: Larger masses have smaller luminosities.

Question 15

Where are the MOST massive stars to be found in the main sequence of a Hertzsprung-Russell diagram?

Accepted Answer

A)  upper left end 
B)  Main-sequence stars all have approximately the same mass, by definition. 
C)  center 
D)  lower right end 
A)  upper left end 
B)  Main-sequence stars all have approximately the same mass, by definition. 
C)  center 
D)  lower right end

Question 16

If the surface temperature of a star is very low, which of these atomic or molecular constituents will produce the MOST prominent absorption lines in its spectrum?

Accepted Answer

A)  Fe II 
B)  TiO 
C)  Mg II 
D)  He II 
A)  Fe II 
B)  TiO 
C)  Mg II 
D)  He II

Question 17

As a person drives along a road, trees in the middle distance seem to shift in position relative to faraway hills. What name is given to this phenomenon?

Accepted Answer

A)  parallax 
B)  perspective 
C)  Doppler effect 
D)  inverse-square law 
A)  parallax 
B)  perspective 
C)  Doppler effect 
D)  inverse-square law

Question 18

The star Alphard has an apparent magnitude of 2.0, and the star Megrez has an apparent magnitude of 3.3. The only thing that can be said with certainty about Alphard is that it is _____ than Megrez.

Accepted Answer

A)  brighter, as seen in Earth's sky 
B)  more luminous 
C)  fainter, as seen in Earth's sky 
D)  closer to Earth 
A)  brighter, as seen in Earth's sky 
B)  more luminous 
C)  fainter, as seen in Earth's sky 
D)  closer to Earth

Question 19

What is the fundamental difference between absolute and apparent magnitude of a star?

Accepted Answer

A)  The difference is +5 since absolute and apparent magnitude differ by this value by definition. 
B)  Apparent magnitude depends on the star's temperature, whereas absolute magnitude is independent of temperature. 
C)  Apparent magnitude depends on the size of the star, whereas absolute magnitude is independent of this parameter. 
D)  Absolute magnitude is an intrinsic property of the star, whereas apparent magnitude depends on its distance from Earth. 
A)  The difference is +5 since absolute and apparent magnitude differ by this value by definition. 
B)  Apparent magnitude depends on the star's temperature, whereas absolute magnitude is independent of temperature. 
C)  Apparent magnitude depends on the size of the star, whereas absolute magnitude is independent of this parameter. 
D)  Absolute magnitude is an intrinsic property of the star, whereas apparent magnitude depends on its distance from Earth.

Question 20

Among these spectral types, which signifies the hottest stellar surface temperature?

Accepted Answer

A)  G 
B)  A 
C)  K 
D)  B 
A)  G 
B)  A 
C)  K 
D)  B

A particular star has an absolute magnitude of +12 and a spectral class of A5. Using Figures 12-7 and 12-10 from the text, how would this star be classified?

The spectral luminosity class of the star Spica is B1 V, and that of the star $\tau$ Ceti is G8 V. From this information, one knows that Ceti is _____ Spica.

The Sun's absolute magnitude is about +5. The brightest stars in the sky have absolute magnitudes of about -10. What is the luminosity of these stars compared with that of the Sun, assuming that they have similar spectral light distributions?

A typical white dwarf has a surface temperature about 4 times that of the Sun and a radius about 1 percent that of the Sun. What can one determine about the luminosity of a typical white dwarf from this information?

What are the two physical parameters of stars that are plotted on the Hertzsprung-Russell diagram?

Which of these statements is NOT true about the center of mass of a binary star system?

Compared with a star in the middle of the Hertzsprung-Russell diagram, a star in the upper right of the diagram is

An astronomer is measuring the brightness of a particular star through a telescope, using different filters in the visual (yellow-green), violet, and ultraviolet regions. What is the name of the technique being used by this astronomer?

Which of these is not a type of true binary system, or, in other words, that the stars are NOT physically associated with each other?

When observers look out at the night sky, the number of stars with

The star Hadar is classified as B1 II, which means that it is a

Apparent magnitude is a measure of a star's

How can astronomers tell that some stars are relatively close to Earth?

Is there a relationship between the mass of a main-sequence star and its luminosity?

Where are the MOST massive stars to be found in the main sequence of a Hertzsprung-Russell diagram?

If the surface temperature of a star is very low, which of these atomic or molecular constituents will produce the MOST prominent absorption lines in its spectrum?

As a person drives along a road, trees in the middle distance seem to shift in position relative to faraway hills. What name is given to this phenomenon?

The star Alphard has an apparent magnitude of 2.0, and the star Megrez has an apparent magnitude of 3.3. The only thing that can be said with certainty about Alphard is that it is _____ than Megrez.

What is the fundamental difference between absolute and apparent magnitude of a star?

Among these spectral types, which signifies the hottest stellar surface temperature?

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

Exam 12: Characterizing Stars

A particular star has an absolute magnitude of +12 and a spectral class of A5. Using Figures 12-7 and 12-10 from the text, how would this star be classified?

The spectral luminosity class of the star Spica is B1 V, and that of the star τ \tau τ Ceti is G8 V. From this information, one knows that Ceti is _____ Spica.

The Sun's absolute magnitude is about +5. The brightest stars in the sky have absolute magnitudes of about -10. What is the luminosity of these stars compared with that of the Sun, assuming that they have similar spectral light distributions?

A typical white dwarf has a surface temperature about 4 times that of the Sun and a radius about 1 percent that of the Sun. What can one determine about the luminosity of a typical white dwarf from this information?

What are the two physical parameters of stars that are plotted on the Hertzsprung-Russell diagram?

Which of these statements is NOT true about the center of mass of a binary star system?

Compared with a star in the middle of the Hertzsprung-Russell diagram, a star in the upper right of the diagram is

An astronomer is measuring the brightness of a particular star through a telescope, using different filters in the visual (yellow-green), violet, and ultraviolet regions. What is the name of the technique being used by this astronomer?

Which of these is not a type of true binary system, or, in other words, that the stars are NOT physically associated with each other?

When observers look out at the night sky, the number of stars with

The star Hadar is classified as B1 II, which means that it is a

Apparent magnitude is a measure of a star's

How can astronomers tell that some stars are relatively close to Earth?

Is there a relationship between the mass of a main-sequence star and its luminosity?

Where are the MOST massive stars to be found in the main sequence of a Hertzsprung-Russell diagram?

If the surface temperature of a star is very low, which of these atomic or molecular constituents will produce the MOST prominent absorption lines in its spectrum?

As a person drives along a road, trees in the middle distance seem to shift in position relative to faraway hills. What name is given to this phenomenon?

The star Alphard has an apparent magnitude of 2.0, and the star Megrez has an apparent magnitude of 3.3. The only thing that can be said with certainty about Alphard is that it is _____ than Megrez.

What is the fundamental difference between absolute and apparent magnitude of a star?

Among these spectral types, which signifies the hottest stellar surface temperature?

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

The spectral luminosity class of the star Spica is B1 V, and that of the star $\tau$ Ceti is G8 V. From this information, one knows that Ceti is _____ Spica.