Question 1

You measure the parallax angle for a star to be 0.5 arcseconds. The distance to this star is

Accepted Answer

A)  5 light- years.
B)  2 parsecs.
C)  5 parsecs.
D)  0) 5 light- year.
E)  0) 5 parsec.

Question 2

How did astronomers discover the relationship between spectral type and mass for main sequence stars?

Accepted Answer

A)  by using computer models of hydrogen fusion and stellar structure
B)  by measuring stellar radii with very powerful telescopes
C)  by measuring the masses and spectral types of main- sequence stars in binary systems
D)  by comparing stars with the same spectral type but different luminosities

Question 3

What is the approximate luminosity of a main- sequence star with weak hydrogen absorption lines and strong absorption lines of ionized calcium?

Accepted Answer

A)  About 10-2 solar
B)  About 0.1 solar
C)  About 3 solar
D)  About 1 solar

Question 4

Assuming that we can measure the apparent brightness of a star, what does the inverse square law for light allow us to do?

Accepted Answer

A)  determine both the star's distance and luminosity from its apparent brightness
B)  calculate the star's surface temperature if we know either its luminosity or its distance
C)  determine the distance to the star from its apparent brightness
D)  calculate the star's luminosity if we know its distance, or calculate its distance if we know its luminosity

Question 5

Two stars, Tom and Jerry, have the same spectral type. Tom is luminosity class V and Jerry is luminosity class I. Which star is bigger? Which star is more luminous? Which star has a hotter surface temperature? Explain your answers.

Accepted Answer

Tom is on the main sequence, while Jerry...

Question 6

If the distance between us and a star is doubled, with everything else remaining the same, its luminosity

Accepted Answer

A)  is decreased by a factor of four, and its apparent brightness is decreased by a factor of four.
B)  is decreased by a factor of two, and its apparent brightness is decreased by a factor of two.
C)  remains the same, but its apparent brightness is decreased by a factor of four.
D)  is decreased by a factor of four, but its apparent brightness remains the same.
E)  remains the same, but its apparent brightness is decreased by a factor of two.

Question 7

What is the spectral type of a main sequence star with a luminosity 100 times greater than the sun?

Accepted Answer

A)  A
B)  G
C)  M
D)  O

Question 8

What is the approximate luminosity of a main- sequence M star?

Accepted Answer

A)  10 solar
B)  1 solar
C)  0) 01 solar
D)  10-6 solar

Question 9

Which of the following stellar properties has the greatest range in values?

Accepted Answer

A)  radius
B)  surface temperature
C)  luminosity
D)  core temperature
E)  mass

Question 10

A main- sequence star's luminosity can directly inform us of

Accepted Answer

A)  the star's mass.
B)  the star's distance from us.
C)  the rate at which it converts hydrogen to helium.
D)  the star's radius.

Question 11

You observe a star cluster with a main- sequence turn- off point at spectral type G2 (the same spectral type as the Sun) . What is the age of this star cluster?

Accepted Answer

A)  10,000 years
B)  100 billion years
C)  4) 6 billion years
D)  10 billion years
E)  You also need to know the luminosity class of the turn- off point to determine the age.

Question 12

What is the spectral type of a star with strong molecular absorption lines?

Accepted Answer

A)  K
B)  M
C)  G
D)  F

Question 13

A 10 solar mass star is about ten times more luminous than a 1 solar mass star.

Accepted Answer

A) True 
 B)False

Question 14

On a Hertzsprung- Russell diagram, where would you find stars that have the largest radii?

Accepted Answer

A)  upper right
B)  lower right
C)  upper left
D)  lower left

Question 15

What is the approximate surface temperature of a star with moderate hydrogen absorption lines and moderate ionized calcium absorption lines?

Accepted Answer

A)  4,500 K
B)  3,500 K
C)  6,500 K
D)  5,500 K

Question 16

A star is observed with a surface temperature of 3,000 K and a luminosity of 105 solar. What is the approximate radius of this star?

Accepted Answer

A)  30 Msun
B)  0) 3 Msun
C)  3 Msun
D)  The radius cannot be determined.

Question 17

What is the common trait of all main- sequence stars?

Accepted Answer

A)  They are in the final stage of their lives.
B)  They are all spectral type G.
C)  They generate energy through hydrogen fusion in their core.
D)  They all have approximately the same mass.

Question 18

The faintest star visible to the naked eye has an apparent magnitude of about

Accepted Answer

A)  - 1.
B)  10.
C)  0) 
D)  6) 
E)  1)

Question 19

What is the approximate surface temperature of a B star?

Accepted Answer

A)  40,000 K
B)  6,000 K
C)  20,000 K
D)  8,000 K

Question 20

The spectral sequence sorts stars according to

Accepted Answer

A)  core temperature.
B)  radius.
C)  mass.
D)  surface temperature.
E)  luminosity.

Exam 12: Surveying the Stars

The spectral sequence sorts stars according to

Correct AnswerverifiedShow Answer

You observe a star cluster with a main- sequence turn- off point at spectral type G2 (the same spectral type as the Sun) . What is the age of this star cluster?

Correct AnswerverifiedShow Answer

What is the common trait of all main- sequence stars?

Correct AnswerverifiedShow Answer

What is the approximate luminosity of a main- sequence M star?

Correct AnswerverifiedShow Answer

A 10 solar mass star is about ten times more luminous than a 1 solar mass star.

Correct AnswerverifiedShow Answer

You measure the parallax angle for a star to be 0.5 arcseconds. The distance to this star is

Correct AnswerverifiedShow Answer

A star is observed with a surface temperature of 3,000 K and a luminosity of 105 solar. What is the approximate radius of this star?

Correct AnswerverifiedShow Answer

On a Hertzsprung- Russell diagram, where would you find stars that have the largest radii?

Correct AnswerverifiedShow Answer

What is the approximate surface temperature of a B star?

Correct AnswerverifiedShow Answer

A main- sequence star's luminosity can directly inform us of

Correct AnswerverifiedShow Answer

If the distance between us and a star is doubled, with everything else remaining the same, its luminosity

Correct AnswerverifiedShow Answer

Assuming that we can measure the apparent brightness of a star, what does the inverse square law for light allow us to do?

Correct AnswerverifiedShow Answer

What is the approximate luminosity of a main- sequence star with weak hydrogen absorption lines and strong absorption lines of ionized calcium?

Correct AnswerverifiedShow Answer

What is the spectral type of a main sequence star with a luminosity 100 times greater than the sun?

Correct AnswerverifiedShow Answer

What is the approximate surface temperature of a star with moderate hydrogen absorption lines and moderate ionized calcium absorption lines?

Correct AnswerverifiedShow Answer

What is the spectral type of a star with strong molecular absorption lines?

Correct AnswerverifiedShow Answer

Which of the following stellar properties has the greatest range in values?

Correct AnswerverifiedShow Answer

How did astronomers discover the relationship between spectral type and mass for main sequence stars?

Correct AnswerverifiedShow Answer

The faintest star visible to the naked eye has an apparent magnitude of about

Correct AnswerverifiedShow Answer

Two stars, Tom and Jerry, have the same spectral type. Tom is luminosity class V and Jerry is luminosity class I. Which star is bigger? Which star is more luminous? Which star has a hotter surface temperature? Explain your answers.

Correct AnswerverifiedTom is on the main sequence, while Jerry...View AnswerShow Answer

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Tom is on the main sequence, while Jerry...
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