Question 1

The bright star named Rigel has a luminosity of 66,000 LSUN and a temperature of 11,000 K.What is its radius? Note that the temperature of the Sun is 5800 K.

Accepted Answer

A)  5 RSUN 
B)  30 RSUN 
C)  70 RSUN 
D)  135 RSUN 
E)  190 RSUN 
A)  5 RSUN 
B)  30 RSUN 
C)  70 RSUN 
D)  135 RSUN 
E)  190 RSUN C

Question 2

You observe two stars in a visual binary system using a blue filter that is centered at a wavelength of 550 nm and a red filter that is centered at a wavelength of 650 nm.Star A has a temperature of 10,000 K, while star B has a temperature of 4000 K, and you know that both stars are the same size.Which star will be brighter in each filter?

Accepted Answer

A)  Star A is brighter in the blue filter, and star B is brighter in the red filter. 
B)  Star B is brighter in the blue filter, and star A is brighter in the red filter. 
C)  Star A is brighter in both filters. 
D)  Star B is brighter in both filters. 
E)  Both stars have the same brightness in each filter. 
A)  Star A is brighter in the blue filter, and star B is brighter in the red filter. 
B)  Star B is brighter in the blue filter, and star A is brighter in the red filter. 
C)  Star A is brighter in both filters. 
D)  Star B is brighter in both filters. 
E)  Both stars have the same brightness in each filter. C

Question 3

Stars are made mostly of

Accepted Answer

A)  helium. 
B)  oxygen. 
C)  hydrogen. 
D)  nitrogen. 
E)  carbon. 
A)  helium. 
B)  oxygen. 
C)  hydrogen. 
D)  nitrogen. 
E)  carbon. C

Question 4

If we measure a star's luminosity and temperature, what other property of the star can we calculate? Explain how.

Accepted Answer

If we measure the luminosity L

Question 5

A star's location on the main sequence is determined entirely by its

Accepted Answer

A)  mass. 
B)  composition. 
C)  distance. 
D)  size. 
E)  radial velocity. 
A)  mass. 
B)  composition. 
C)  distance. 
D)  size. 
E)  radial velocity.

Question 6

A star classified as a K0III star is

Accepted Answer

A)  a giant that is cooler than the Sun. 
B)  a supergiant that is hotter than the Sun. 
C)  a main-sequence star that is hotter than the Sun. 
D)  a subgiant that is cooler than the Sun. 
E)  a dwarf that is hotter than the Sun. 
A)  a giant that is cooler than the Sun. 
B)  a supergiant that is hotter than the Sun. 
C)  a main-sequence star that is hotter than the Sun. 
D)  a subgiant that is cooler than the Sun. 
E)  a dwarf that is hotter than the Sun.

Question 7

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

Question 8

Star A and star B appear equally bright, but star A is twice as far away from us as star B. Which of the following is true?

Accepted Answer

A)  Star A is twice as luminous as star B. 
B)  Star A is four times as luminous as star B. 
C)  Star B is twice as luminous as star A. 
D)  Star B is four times as luminous as star B. 
E)  Star A and star B have the same luminosity because they have the same brightness. 
A)  Star A is twice as luminous as star B. 
B)  Star A is four times as luminous as star B. 
C)  Star B is twice as luminous as star A. 
D)  Star B is four times as luminous as star B. 
E)  Star A and star B have the same luminosity because they have the same brightness.

Question 9

To measure the most accurate parallax possible from Earth's surface, we would make two measurements of a 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 10

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

Accepted Answer

The A-type star has the strongest hydrog

Question 11

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

Accepted Answer

A)  0.2 LSUN 
B)  5.0 LSUN 
C)  30 LSUN 
D)  450 LSUN 
E)  10,000 LSUN 
A)  0.2 LSUN 
B)  5.0 LSUN 
C)  30 LSUN 
D)  450 LSUN 
E)  10,000 LSUN

Question 12

How can a star glow like a blackbody but still have an absorption spectrum, and what does this spectrum tell us about the elements present in the star?

Accepted Answer

A star's surface glows like a blackbody,

Question 13

Suppose you take images of star SBD 1256 in different filters and find that, by comparing the brightness of the star through the different filters, it's an F5 star.You assume the star is on the main sequence (F5V), and then use the H-R diagram and determine that it's at a distance of 120 parsecs.A few months later you take a spectrum of SBD 1256 and notice that its absorption lines are very narrow, indicating that it's not an F5V main-sequence star but rather a giant F5III star.Explain how this now affects the distance estimate and why.

Accepted Answer

Because the star is now found to be a gi

Question 14

Star A is exactly the same color as star B and appears equally bright.Through stellar parallax measurements, we find that star B is twice as far away from us as star A.Determine which star has the larger radius and how much larger it is.

Accepted Answer

For stars of equal brightness,luminosity

Question 15

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 16

Star A and star B both have the same temperature but different sizes and distances.Star A is more luminous than star B, but star B appears brighter than star A in our sky.Which of these statements about the absolute and apparent magnitudes of the two stars is correct?

Accepted Answer

A)  Star A has a larger apparent magnitude and a larger absolute magnitude. 
B)  Star A has a larger apparent magnitude, while star B has a larger absolute magnitude. 
C)  Star B has a larger apparent magnitude and a larger absolute magnitude. 
D)  Star B has a larger apparent magnitude, while star A has a larger absolute magnitude. 
E)  Both stars have the same apparent and absolute magnitudes. 
A)  Star A has a larger apparent magnitude and a larger absolute magnitude. 
B)  Star A has a larger apparent magnitude, while star B has a larger absolute magnitude. 
C)  Star B has a larger apparent magnitude and a larger absolute magnitude. 
D)  Star B has a larger apparent magnitude, while star A has a larger absolute magnitude. 
E)  Both stars have the same apparent and absolute magnitudes.

Question 17

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

Question 18

The Hipparcos satellite was capable of measuring parallaxes to ________ stars.

Accepted Answer

A)  all of the Milky Way galaxy's 400 billion 
B)  200 million 
C)  120,000 
D)  1,500 
E)  116 
A)  all of the Milky Way galaxy's 400 billion 
B)  200 million 
C)  120,000 
D)  1,500 
E)  116

Question 19

What type of star is most common in the solar neighborhood?

Accepted Answer

A)  subgiant 
B)  supergiant 
C)  white dwarf 
D)  giant 
E)  main-sequence 
A)  subgiant 
B)  supergiant 
C)  white dwarf 
D)  giant 
E)  main-sequence

Question 20

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

Exam 13: Taking the Measure of Stars

The bright star named Rigel has a luminosity of 66,000 LSUN and a temperature of 11,000 K.What is its radius? Note that the temperature of the Sun is 5800 K.

Stars are made mostly of

If we measure a star's luminosity and temperature, what other property of the star can we calculate? Explain how.

A star's location on the main sequence is determined entirely by its

A star classified as a K0III star is

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

Star A and star B appear equally bright, but star A is twice as far away from us as star B. Which of the following is true?

To measure the most accurate parallax possible from Earth's surface, we would make two measurements of a star's position on the sky separated by

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

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

How can a star glow like a blackbody but still have an absorption spectrum, and what does this spectrum tell us about the elements present in the star?

Star A is exactly the same color as star B and appears equally bright.Through stellar parallax measurements, we find that star B is twice as far away from us as star A.Determine which star has the larger radius and how much larger it is.

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

Star A and star B both have the same temperature but different sizes and distances.Star A is more luminous than star B, but star B appears brighter than star A in our sky.Which of these statements about the absolute and apparent magnitudes of the two stars is correct?

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

The Hipparcos satellite was capable of measuring parallaxes to ________ stars.

What type of star is most common in the solar neighborhood?

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

Thinking Like an Astronomer

Patterns in the Skymotions of Earth and the Moon

Motion of Astronomical Bodies

Gravity and Orbits

Light

The Tools of the Astronomer

The Formation of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquidthe Giant Planets

Planetary Moons and Rings

Dwarf Planets and Small Solar System Bodies

Our Starthe Sun

The Interstellar Medium and Star Formation

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

Galaxies

The Milky Waya Normal Spiral Galaxy

The Expanding Universe

Cosmology

Large-Scale Structure in the Universe

Life

Filters

The bright star named Rigel has a luminosity of 66,000 L_SUNand a temperature of 11,000 K.What is its radius? Note that the temperature of the Sun is 5800 K.

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