Question 1

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."E) B) and C)
F) A) and B)

Question 2

A star has a surface temperature of 6000K (see Figure 10-4b,Comins,Discovering the Essential Universe,6th ed.) .Its spectrum registers a certain intensity in the green middle of the visible spectrum.Which statement characterizes the rest of the spectrum?

Accepted Answer

A)   The violet is brighter than the green, but the red is less intense.
B)   The violet is less intense than the green, but the red is more intense.
C)   The violet and the red are both less intense than the green.
D)   The violet and the red are both more intense than the green.E) A) and B)
F) A) and D)

Question 3

Which is NOT needed to compute a distance to a star by the spectroscopic parallax method?

Accepted Answer

A)   the mathematical relationship among distance, absolute magnitude, and apparent magnitude
B)   the star's stellar parallax
C)   the star's apparent magnitude
D)   the star's luminosityE) B) and C)
F) B) and D)

Question 4

Two stars of equal mass form a visual binary system.The separation between the two stars is 4 AU and the period of the orbital motion is 8 years.What is the mass of each star relative to the mass of the Sun?

Accepted Answer

A)   1
B)   1/2
C)   1/4
D)   2E) A) and C)
F) A) and D)

Question 5

Optical glass filters are used to select certain portions of a star's light for photometry.Which filter would MOST closely match the sensitivity of our eyes,which have a peak sensitivity at about 550 nm wavelength? (See Figure 3-1,Comins,Discovering the Essential Universe,6th ed.)

Accepted Answer

A)   ultraviolet
B)   red
C)   yellow
D)   blueE) B) and C)
F) A) and B)

Question 6

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.E) All of the above
F) A) and C)

Question 7

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.E) All of the above
F) A) and B)

Question 8

The absolute magnitude of a star is the brightness the star would appear to have if it were placed at what distance from Earth?

Accepted Answer

A)   32.6 ly
B)   distance to the galactic center
C)   10 ly
D)   1 AUE) A) and B)
F) None of the above

Question 9

Two stars have the same spectral classification,say,M2,but one of them is a red giant while the other is a main-sequence star.To determine which is which,we look at their spectra because (see Figure 10-9,Comins,Discovering the Essential Universe,6th ed.) the absorption lines in the giant will be:

Accepted Answer

A)   narrower because of the pressure difference between the atmospheres of the two stars.
B)   broader because of the pressure difference between the atmospheres of the two stars.
C)   narrower because of the temperature difference between the two luminosity classes.
D)   broader because of the temperature difference between the two luminosity classes.E) All of the above
F) B) and D)

Question 10

A star of apparent magnitude +1 appears _____ than a star of apparent magnitude +2.

Accepted Answer

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

Question 11

Use the Hertzsprung-Russell diagram (Figure 10-7) and the mass-luminosity relation (Figure 10-14) in Comins,Discovering the Essential Universe,6th ed.,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 masse
D)   between 5.0 and 10.0 solar massesE) None of the above
F) B) and C)

Question 12

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.E) B) and C)
F) C) and D)

Question 13

By approximately how many magnitudes is the star Sirius fainter than the full Moon in our sky? (See Figure 10-2,Comins,Discovering the Essential Universe,6th ed.)

Accepted Answer

A)   15
B)   2
C)   11
D)   5E) C) and D)
F) B) and D)

Question 14

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

Accepted Answer

A)   mass and surface temperature
B)   luminosity and mass
C)   radius and mass
D)   luminosity and surface temperatureE) B) and D)
F) All of the above

Question 15

Spica (in Virgo) and Hador (in Centaurus) have about the same temperature.However,Hador has roughly four times the luminosity of Spica.What can you determine about the relative radii of these two stars? Spica is about:

Accepted Answer

A)   the same diameter as Hador.
B)   half the diameter of Hador.
C)   one-quarter the diameter of Hador.
D)   twice the diameter of Hador.E) All of the above
F) None of the above

Question 16

A star's absolute magnitude and its apparent magnitude have the same numerical value.How far is this star from Earth?

Accepted Answer

A)   It is not possible for a star to have the same absolute and apparent magnitudes.
B)   The star would have to be an infinite distance away.
C)   10 ly
D)   10 pcE) B) and C)
F) B) and D)

Question 17

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) A) and B)
F) A) and C)

Question 18

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

Accepted Answer

A)   There is no sodium in this particular star.
B)   The sodium atoms have all been completely ionized.
C)   The neutral sodium is receiving so much energy that the energy levels responsible for its usual spectrum are being depopulated.
D)   The neutral sodium is not receiving enough energy to excite its electrons to higher energy levels.E) A) and B)
F) None of the above

Question 19

If we restrict our measurements to a specific band of color or wavelength using an optical filter,what observations of a star are necessary to determine the absolute magnitude of the star at this color?

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 D)
F) A) and B)

Question 20

Stellar parallax appears because:

Accepted Answer

A)   Earth rotates about its own axis.
B)   stars move in space.
C)   stars have finite size (i.e., they are not really just points of light) .
D)   Earth moves in space.E) B) and D)
F) A) and B)

Exam 10: Characterizing Stars

The absolute magnitude of a star is the brightness the star would appear to have if it were placed at what distance from Earth?

Correct Answer
verified

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

Correct Answer
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Stellar parallax appears because:

Correct Answer
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Correct Answer
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Two stars of equal mass form a visual binary system.The separation between the two stars is 4 AU and the period of the orbital motion is 8 years.What is the mass of each star relative to the mass of the Sun?

Correct Answer
verified

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:

Correct Answer
verified

If we restrict our measurements to a specific band of color or wavelength using an optical filter,what observations of a star are necessary to determine the absolute magnitude of the star at this color?

Correct Answer
verified

Optical glass filters are used to select certain portions of a star's light for photometry.Which filter would MOST closely match the sensitivity of our eyes,which have a peak sensitivity at about 550 nm wavelength? (See Figure 3-1,Comins,Discovering the Essential Universe,6th ed.)

Correct Answer
verified

A star's absolute magnitude and its apparent magnitude have the same numerical value.How far is this star from Earth?

Correct Answer
verified

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

Correct Answer
verified

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

Correct Answer
verified

A star has a surface temperature of 6000K (see Figure 10-4b,Comins,Discovering the Essential Universe,6th ed.) .Its spectrum registers a certain intensity in the green middle of the visible spectrum.Which statement characterizes the rest of the spectrum?

Correct Answer
verified

The statement that the apparent magnitude of a variable star has increased indicates that its:

Correct Answer
verified

Two stars have the same spectral classification,say,M2,but one of them is a red giant while the other is a main-sequence star.To determine which is which,we look at their spectra because (see Figure 10-9,Comins,Discovering the Essential Universe,6th ed.) the absorption lines in the giant will be:

Correct Answer
verified

Use the Hertzsprung-Russell diagram (Figure 10-7) and the mass-luminosity relation (Figure 10-14) in Comins,Discovering the Essential Universe,6th ed.,to estimate the mass of Vega,an AO V main-sequence star with a surface temperature of about 10,000 K.

Correct Answer
verified

A star of apparent magnitude +1 appears _____ than a star of apparent magnitude +2.

Correct Answer
verified

By approximately how many magnitudes is the star Sirius fainter than the full Moon in our sky? (See Figure 10-2,Comins,Discovering the Essential Universe,6th ed.)

Correct Answer
verified

Spica (in Virgo) and Hador (in Centaurus) have about the same temperature.However,Hador has roughly four times the luminosity of Spica.What can you determine about the relative radii of these two stars? Spica is about:

Correct Answer
verified

Apparent magnitude is a measure of a star's:

Correct Answer
verified

Which is NOT needed to compute a distance to a star by the spectroscopic parallax method?

Correct Answer
verified

Exam 10: Characterizing Stars

The absolute magnitude of a star is the brightness the star would appear to have if it were placed at what distance from Earth?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Stellar parallax appears because:

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Two stars of equal mass form a visual binary system.The separation between the two stars is 4 AU and the period of the orbital motion is 8 years.What is the mass of each star relative to the mass of the Sun?

Correct AnswerverifiedShow Answer

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:

Correct AnswerverifiedShow Answer

If we restrict our measurements to a specific band of color or wavelength using an optical filter,what observations of a star are necessary to determine the absolute magnitude of the star at this color?

Correct AnswerverifiedShow Answer

Optical glass filters are used to select certain portions of a star's light for photometry.Which filter would MOST closely match the sensitivity of our eyes,which have a peak sensitivity at about 550 nm wavelength? (See Figure 3-1,Comins,Discovering the Essential Universe,6th ed.)

Correct AnswerverifiedShow Answer

A star's absolute magnitude and its apparent magnitude have the same numerical value.How far is this star from Earth?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

A star has a surface temperature of 6000K (see Figure 10-4b,Comins,Discovering the Essential Universe,6th ed.) .Its spectrum registers a certain intensity in the green middle of the visible spectrum.Which statement characterizes the rest of the spectrum?

Correct AnswerverifiedShow Answer

The statement that the apparent magnitude of a variable star has increased indicates that its:

Correct AnswerverifiedShow Answer

Two stars have the same spectral classification,say,M2,but one of them is a red giant while the other is a main-sequence star.To determine which is which,we look at their spectra because (see Figure 10-9,Comins,Discovering the Essential Universe,6th ed.) the absorption lines in the giant will be:

Correct AnswerverifiedShow Answer

Use the Hertzsprung-Russell diagram (Figure 10-7) and the mass-luminosity relation (Figure 10-14) in Comins,Discovering the Essential Universe,6th ed.,to estimate the mass of Vega,an AO V main-sequence star with a surface temperature of about 10,000 K.

Correct AnswerverifiedShow Answer

A star of apparent magnitude +1 appears _____ than a star of apparent magnitude +2.

Correct AnswerverifiedShow Answer

By approximately how many magnitudes is the star Sirius fainter than the full Moon in our sky? (See Figure 10-2,Comins,Discovering the Essential Universe,6th ed.)

Correct AnswerverifiedShow Answer

Spica (in Virgo) and Hador (in Centaurus) have about the same temperature.However,Hador has roughly four times the luminosity of Spica.What can you determine about the relative radii of these two stars? Spica is about:

Correct AnswerverifiedShow Answer

Apparent magnitude is a measure of a star's:

Correct AnswerverifiedShow Answer

Which is NOT needed to compute a distance to a star by the spectroscopic parallax method?

Correct AnswerverifiedShow Answer

Correct Answer
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