Question 1

The bright star named Rigel has a luminosity of 66,000 L and a temperature of 11,000 K.What is its radius? Note that the temperature of the Sun is 5,800 K.

Accepted Answer

A) 5 R☉ 
B) 30 R☉ 
C) 70 R☉ 
D) 135 R☉ 
E) 190 R☉ 
A) 5 R☉ 
B) 30 R☉ 
C) 70 R☉ 
D) 135 R☉ 
E) 190 R☉ C

Question 2

For which type of binary system are astronomers able to resolve each of the two stars individually?

Accepted Answer

A) eclipsing binary 
B) spectroscopic binary 
C) visual binary 
D) binaries where the two stars have the same mass 
E) binaries where the two stars have the same luminosity 
A) eclipsing binary 
B) spectroscopic binary 
C) visual binary 
D) binaries where the two stars have the same mass 
E) binaries where the two stars have the same luminosity C

Question 3

How is the unit of length known as a parsec defined?

Accepted Answer

The parsec is defined such that an object at a distance of 1 parsec has a parallax exactly equal to 1 arcsecond.

Question 4

The fraction of the Sun's mass that is made of heavy elements is:

Accepted Answer

A) 0.5 percent 
B) 2 percent 
C) 10 percent 
D) 20 percent 
E) 50 percent 
A) 0.5 percent 
B) 2 percent 
C) 10 percent 
D) 20 percent 
E) 50 percent

Question 5

If the Hubble space telescope can see stars as faint as magnitude 27,how much fainter are these stars than the faintest ones you can see in a very dark night sky,which have magnitude 6?

Accepted Answer

The Hubble space telescope can

Question 6

Explain how astronomers can use the blue and visual filters to determine the temperatures of stars.

Accepted Answer

Astronomers compare the relati

Question 7

What is the approximate luminosity of a 5 M main-sequence star?

Accepted Answer

A) 50 L☉ 
B) 80 L☉ 
C) 150 L☉ 
D) 280 L☉ 
E) 510 L☉ 
A) 50 L☉ 
B) 80 L☉ 
C) 150 L☉ 
D) 280 L☉ 
E) 510 L☉

Question 8

Binary star systems are extremely useful in studying stars because they allow us to determine stars' masses.

Accepted Answer

A) True 
 B)False

Question 9

A star with a stellar parallax of 0.025 arcseconds has a distance of how many parsecs?

Accepted Answer

The inverse of stellar paralla

Question 10

Why do O- and B-type stars have weaker hydrogen absorption lines than A-type stars?

Accepted Answer

A) O- and B-type stars are cooler than A-type stars. 
B) O- and B-type stars are smaller than A-type stars. 
C) A larger fraction of hydrogen atoms in O- and B-type stars is ionized. 
D) O- and B-type stars have converted much more of their hydrogen into heavier elements. 
E) A-type stars have a higher mass than O- and B-type stars,so they have more hydrogen. 
A) O- and B-type stars are cooler than A-type stars. 
B) O- and B-type stars are smaller than A-type stars. 
C) A larger fraction of hydrogen atoms in O- and B-type stars is ionized. 
D) O- and B-type stars have converted much more of their hydrogen into heavier elements. 
E) A-type stars have a higher mass than O- and B-type stars,so they have more hydrogen.

Question 11

What is the approximate luminosity of a 0.5 M main-sequence star?

Accepted Answer

A) 0.09 L☉ 
B) 0.01 L☉ 
C) 0.2 L☉ 
D) 0.5 L☉ 
E) 0.7 L☉ 
A) 0.09 L☉ 
B) 0.01 L☉ 
C) 0.2 L☉ 
D) 0.5 L☉ 
E) 0.7 L☉

Question 12

Star A is a red star.Star B is a blue star.You are able to determine that both stars are the same size.Which star is more luminous?

Accepted Answer

A) Star A is more luminous. 
B) Star B is more luminous. 
C) They have the same luminosities. 
D) We also need to know the distance of the stars to determine their luminosity. 
E) We cannot tell because color is not related to luminosity. 
A) Star A is more luminous. 
B) Star B is more luminous. 
C) They have the same luminosities. 
D) We also need to know the distance of the stars to determine their luminosity. 
E) We cannot tell because color is not related to luminosity.

Question 13

To measure the parallax of the most distant stars measurable,we would make two measurements of the star's position on the sky separated by:

Accepted Answer

A) 6 hours 
B) 12 hours 
C) 24 hours 
D) 6 months 
E) 12 months 
A) 6 hours 
B) 12 hours 
C) 24 hours 
D) 6 months 
E) 12 months

Question 14

Roughly what percentage of stars in our galaxy are main-sequence stars?

Accepted Answer

A) 10 percent 
B) 25 percent 
C) 50 percent 
D) 75 percent 
E) 90 percent 
A) 10 percent 
B) 25 percent 
C) 50 percent 
D) 75 percent 
E) 90 percent

Question 15

Which of the following properties would not be plotted on the horizontal axis of an H-R diagram?

Accepted Answer

A) Color would not be plotted. 
B) Luminosity would not be plotted. 
C) Temperature would not be plotted. 
D) Spectral class would not be plotted. 
E) All of the above are plotted on the horizontal axis of an H-R diagram. 
A) Color would not be plotted. 
B) Luminosity would not be plotted. 
C) Temperature would not be plotted. 
D) Spectral class would not be plotted. 
E) All of the above are plotted on the horizontal axis of an H-R diagram.

Question 16

Parallax is used to measure a star's:

Accepted Answer

A) distance 
B) velocity 
C) luminosity 
D) mass 
E) radius 
A) distance 
B) velocity 
C) luminosity 
D) mass 
E) radius

Question 17

Which sequence correctly lists the spectral classes of stars in order from hottest to coolest?

Accepted Answer

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

Question 18

What is the spectral type of stars that have the strongest hydrogen absorption lines? Why do stars that are hotter than these have weaker hydrogen lines?

Accepted Answer

A-type stars have the strongest hydrogen

Question 19

In which region of an H-R diagram would you find the main-sequence stars with the widest habitable zones?

Accepted Answer

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

Question 20

If a star's distance is 10 pc,what is its parallax?

Accepted Answer

A) 0.01 arcsec 
B) 0.05 arcsec 
C) 0.1 arcsec 
D) 0.5 arcsec 
E) 1 arcsec 
A) 0.01 arcsec 
B) 0.05 arcsec 
C) 0.1 arcsec 
D) 0.5 arcsec 
E) 1 arcsec

Exam 13: Taking the Measure of Stars

The bright star named Rigel has a luminosity of 66,000 L and a temperature of 11,000 K.What is its radius? Note that the temperature of the Sun is 5,800 K.

For which type of binary system are astronomers able to resolve each of the two stars individually?

How is the unit of length known as a parsec defined?

The fraction of the Sun's mass that is made of heavy elements is:

If the Hubble space telescope can see stars as faint as magnitude 27,how much fainter are these stars than the faintest ones you can see in a very dark night sky,which have magnitude 6?

Explain how astronomers can use the blue and visual filters to determine the temperatures of stars.

What is the approximate luminosity of a 5 M main-sequence star?

Binary star systems are extremely useful in studying stars because they allow us to determine stars' masses.

A star with a stellar parallax of 0.025 arcseconds has a distance of how many parsecs?

Why do O- and B-type stars have weaker hydrogen absorption lines than A-type stars?

What is the approximate luminosity of a 0.5 M main-sequence star?

Star A is a red star.Star B is a blue star.You are able to determine that both stars are the same size.Which star is more luminous?

To measure the parallax of the most distant stars measurable,we would make two measurements of the star's position on the sky separated by:

Roughly what percentage of stars in our galaxy are main-sequence stars?

Which of the following properties would not be plotted on the horizontal axis of an H-R diagram?

Parallax is used to measure a star's:

Which sequence correctly lists the spectral classes of stars in order from hottest to coolest?

What is the spectral type of stars that have the strongest hydrogen absorption lines? Why do stars that are hotter than these have weaker hydrogen lines?

In which region of an H-R diagram would you find the main-sequence stars with the widest habitable zones?

If a star's distance is 10 pc,what is its parallax?

Why Learn Astronomy

Patterns in the Skymotions of Earth

Motion of Astronomical Bodies

Gravity and Orbits

Light

The Tools of the Astronomer

The Birth and Evolution of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquid the Giant Planets

Planetary Adornments Moons and Rings

Dwarf Planets and Small Solar System Bodies

Our Starthe Sun

Star Formation and the Interstellar Medium

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

The Expanding Universe

Galaxies

The Milky Waya Normal Spiral Galaxy

Modern Cosmology

Large-Scale Structure in the Universe

Life

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