Question 1

The Sun's luminosity is 3.83 *1026 watts. By the time this energy reaches Earth, it has spread out so that it provides only 1370 watts to each square meter. The orbit of Mars has a mean radius of 1.53 au. How many watts of the Sun's luminosity are provided to each square meter of the surface of Mars?

Accepted Answer

A)   34
B)   153
C)   585
D)   1578E) C) and D)
F) B) and C)

Question 2

The star Spica is classified as B1 V, which means that it is a

Accepted Answer

A)   hot main-sequence star.
B)   cool giant.
C)   hot supergiant.
D)   cool main-sequence star.E) B) and C)
F) None of the above

Question 3

Use the Hertzsprung-Russell diagram (Figure 12-7)  and the mass-luminosity relation (Figure 12-15)  in the text, to estimate the mass of Vega, an AO V main-sequence star with a surface temperature of about 10,000 K.

Accepted Answer

A)   between 1.5 and 5.0 solar masses
B)   about 10 solar masses
C)   less than 1.0 solar mass
D)   between 5.0 and 10.0 solar massesE) A) and B)
F) A) and C)

Question 4

Stars of spectral type O, the hottest blue-white stars, have spectra characterized by

Accepted Answer

A)   the strongest hydrogen lines of any spectral type.
B)   spectra of complex molecules.
C)   very few spectral lines.
D)   very intense spectral lines all across the spectrum.E) A) and D)
F) A) and C)

Question 5

Which of these stars (each of which is listed with its apparent magnitude)  looks brightest when viewed from Earth?

Accepted Answer

A)   tau Ceti; m = +3.49
B)   alpha Centauri B; m = +1.34
C)   Barnard's star; m = +9.53
D)   61 Cygni A; m = +5.21E) B) and D)
F) B) and C)

Question 6

Which of these sequences of stellar spectral classifications is in the correct order of INCREASING temperature?

Accepted Answer

A)   K, M, G, F, A, B, O
B)   A, B, F, G, K, M, O
C)   M, K, G, F, A, B, O
D)   O, B, A, F, G, K, ME) B) and C)
F) C) and D)

Question 7

As one moves upward and to the left on the H-R diagram, the stars become

Accepted Answer

A)   cooler and redder.
B)   hotter and redder.
C)   cooler and bluer.
D)   hotter and bluer.E) B) and D)
F) All of the above

Question 8

By what standard technique did astronomers in the 1930s originally determine the luminosity class (I, II, III, IV, or V)  of a star?

Accepted Answer

A)   combining the apparent magnitude with the measured distance to the star
B)   observing the diameter of the star on a photographic plate or CCD image
C)   timing how long it takes for the star to be eclipsed by a companion in an eclipsing binary star system
D)   studying the absorption lines in the star's spectrumE) A) and D)
F) B) and D)

Question 9

A particular star appears fainter seen through a blue filter than seen through a yellow filter. Which of these surface temperatures is possible for this star?

Accepted Answer

A)   12,500 K
B)   38,000 K
C)   8800 K
D)   3800 KE) All of the above
F) A) and C)

Question 10

What fraction of the stars surrounding the Sun are main-sequence stars?

Accepted Answer

A)   almost all, about 90%
B)   There are no main-sequence stars close to the Sun.
C)   roughly half, about 55%
D)   very few, about 20%E) A) and B)
F) None of the above

Question 11

An astronomer is observing a binary system with two stars of masses M1 and M2. She determines a, the semimajor axis (also the average distance between the stars)  and P, the period of their motion. Using this information in Kepler's third law she can calculate

Accepted Answer

A)   M1 or M2 but not both.
B)   M1/M2.
C)   M1 + M2.
D)   both M1 and M2.E) A) and D)
F) B) and D)

Question 12

Which of these stars (each of which is listed with its apparent magnitude)  would NOT be visible to the unaided eye on a clear night?

Accepted Answer

A)   tau Ceti; m = +3.49
B)   alpha Centauri B; m = +1.34
C)   Barnard's star; m = +9.53
D)   61 Cygni A; m = +5.21E) B) and C)
F) A) and D)

Question 13

Which of these types of main-sequence stars would have the LARGEST mass?

Accepted Answer

A)   M
B)   A
C)   O
D)   GE) B) and D)
F) B) and C)

Question 14

Spectral classification of a star into the lettered categories, O, B, A, F, G, K, and M is carried out by

Accepted Answer

A)   finding the wavelength of peak emission in the continuum spectrum of the star.
B)   determining the relative mass of the star by the study of binary star motions, in order to place it into its proper mass classification.
C)   determining the total energy emitted at all wavelengths by the star, taking account of the full spread of wavelengths and their distances, in order to place the star into its luminosity class.
D)   examining the relative amounts of absorption caused by various neutral and ionized atoms in a stellar spectrum.E) All of the above
F) C) and D)

Question 15

The star  γ\gammaγ  Phoenicis has an apparent magnitude of +3.4 and an absolute magnitude of -4.6. The North Star (Polaris)  has an apparent magnitude of +2.0 and an absolute magnitude of -4.6. Assuming that no light has been absorbed or scattered by interstellar dust, one can say for sure that Polaris is

Accepted Answer

A)   the same distance as  γ\gammaγ  Phoenicis from Earth.
B)   closer to Earth than  γ\gammaγ  Phoenicis.
C)   farther away from Earth than  γ\gammaγ  Phoenicis.
D)   fainter than  γ\gammaγ  Phoenicis in the Earth's sky. E) All of the above
F) None of the above

Question 16

Which of these four spectral classifications signifies the coolest stellar surface temperature?

Accepted Answer

A)   B
B)   K
C)   G
D)   AE) All of the above
F) B) and C)

Question 17

What observations of a star are necessary to determine the absolute magnitude of a star?

Accepted Answer

A)   distance and temperature
B)   apparent magnitude and temperature
C)   just apparent magnitude since absolute magnitude is simply apparent magnitude + 5
D)   apparent magnitude and distanceE) B) and C)
F) A) and B)

Question 18

The chemical makeup of the Sun's surface can be determined by

Accepted Answer

A)   taking a sample of the star's surface with a space probe.
B)   examining the chemicals present in a meteorite because it is part of the solar system.
C)   measuring the components of the solar wind with Earth-orbiting spacecraft.
D)   solar spectroscopy.E) All of the above
F) B) and C)

Question 19

Which important stellar parameter can be derived from the study of binary stars mutually bound to each other by gravitational forces?

Accepted Answer

A)   stellar masses
B)   distances of the stars from Earth
C)   ages of the stars
D)   surface temperatures of the starsE) All of the above
F) C) and D)

Question 20

The radial velocity curve of a star in a binary star system is a plot against time of the

Accepted Answer

A)   speed of the star in a direction perpendicular to the line of sight to the star.
B)   position of the star in celestial coordinates.
C)   variation of Doppler shift of the star's spectral lines and hence of its speed toward or away from Earth.
D)   temperature of the star as determined from the movement of the peak wavelength of its spectrum.E) All of the above
F) B) and D)

Exam 12: Characterizing Stars

Stars of spectral type O, the hottest blue-white stars, have spectra characterized by

Correct Answer
verified

Spectral classification of a star into the lettered categories, O, B, A, F, G, K, and M is carried out by

Correct Answer
verified

Which of these stars (each of which is listed with its apparent magnitude) looks brightest when viewed from Earth?

Correct Answer
verified

The radial velocity curve of a star in a binary star system is a plot against time of the

Correct Answer
verified

Use the Hertzsprung-Russell diagram (Figure 12-7) and the mass-luminosity relation (Figure 12-15) in the text, to estimate the mass of Vega, an AO V main-sequence star with a surface temperature of about 10,000 K.

Correct Answer
verified

Which of these sequences of stellar spectral classifications is in the correct order of INCREASING temperature?

Correct Answer
verified

By what standard technique did astronomers in the 1930s originally determine the luminosity class (I, II, III, IV, or V) of a star?

Correct Answer
verified

What observations of a star are necessary to determine the absolute magnitude of a star?

Correct Answer
verified

As one moves upward and to the left on the H-R diagram, the stars become

Correct Answer
verified

The chemical makeup of the Sun's surface can be determined by

Correct Answer
verified

Which of these four spectral classifications signifies the coolest stellar surface temperature?

Correct Answer
verified

Correct Answer
verified

Which important stellar parameter can be derived from the study of binary stars mutually bound to each other by gravitational forces?

Correct Answer
verified

An astronomer is observing a binary system with two stars of masses M₁ and M₂. She determines a, the semimajor axis (also the average distance between the stars) and P, the period of their motion. Using this information in Kepler's third law she can calculate

Correct Answer
verified

Which of these types of main-sequence stars would have the LARGEST mass?

Correct Answer
verified

The star Spica is classified as B1 V, which means that it is a

Correct Answer
verified

Which of these stars (each of which is listed with its apparent magnitude) would NOT be visible to the unaided eye on a clear night?

Correct Answer
verified

A particular star appears fainter seen through a blue filter than seen through a yellow filter. Which of these surface temperatures is possible for this star?

Correct Answer
verified

What fraction of the stars surrounding the Sun are main-sequence stars?

Correct Answer
verified

Correct Answer
verified

Exam 12: Characterizing Stars

Stars of spectral type O, the hottest blue-white stars, have spectra characterized by

Correct AnswerverifiedShow Answer

Spectral classification of a star into the lettered categories, O, B, A, F, G, K, and M is carried out by

Correct AnswerverifiedShow Answer

Which of these stars (each of which is listed with its apparent magnitude) looks brightest when viewed from Earth?

Correct AnswerverifiedShow Answer

The radial velocity curve of a star in a binary star system is a plot against time of the

Correct AnswerverifiedShow Answer

Use the Hertzsprung-Russell diagram (Figure 12-7) and the mass-luminosity relation (Figure 12-15) in the text, to estimate the mass of Vega, an AO V main-sequence star with a surface temperature of about 10,000 K.

Correct AnswerverifiedShow Answer

Which of these sequences of stellar spectral classifications is in the correct order of INCREASING temperature?

Correct AnswerverifiedShow Answer

By what standard technique did astronomers in the 1930s originally determine the luminosity class (I, II, III, IV, or V) of a star?

Correct AnswerverifiedShow Answer

What observations of a star are necessary to determine the absolute magnitude of a star?

Correct AnswerverifiedShow Answer

As one moves upward and to the left on the H-R diagram, the stars become

Correct AnswerverifiedShow Answer

The chemical makeup of the Sun's surface can be determined by

Correct AnswerverifiedShow Answer

Which of these four spectral classifications signifies the coolest stellar surface temperature?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which important stellar parameter can be derived from the study of binary stars mutually bound to each other by gravitational forces?

Correct AnswerverifiedShow Answer

An astronomer is observing a binary system with two stars of masses M1 and M2. She determines a, the semimajor axis (also the average distance between the stars) and P, the period of their motion. Using this information in Kepler's third law she can calculate

Correct AnswerverifiedShow Answer

Which of these types of main-sequence stars would have the LARGEST mass?

Correct AnswerverifiedShow Answer

The star Spica is classified as B1 V, which means that it is a

Correct AnswerverifiedShow Answer

Which of these stars (each of which is listed with its apparent magnitude) would NOT be visible to the unaided eye on a clear night?

Correct AnswerverifiedShow Answer

A particular star appears fainter seen through a blue filter than seen through a yellow filter. Which of these surface temperatures is possible for this star?

Correct AnswerverifiedShow Answer

What fraction of the stars surrounding the Sun are main-sequence stars?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

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verified

An astronomer is observing a binary system with two stars of masses M₁ and M₂. She determines a, the semimajor axis (also the average distance between the stars) and P, the period of their motion. Using this information in Kepler's third law she can calculate

Correct Answer
verified

Correct Answer
verified

Correct Answer
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Correct Answer
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Correct Answer
verified

Correct Answer
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Correct Answer
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