Question 1

Who was the first person to measure the parallax of a star successfully?

Accepted Answer

A)  Sir George Airy in England 
B)  Henry Norris Russell in the United States 
C)  Tycho Brahe in Denmark 
D)  Friedrich Wilhelm Bessel in Germany 
A)  Sir George Airy in England 
B)  Henry Norris Russell in the United States 
C)  Tycho Brahe in Denmark 
D)  Friedrich Wilhelm Bessel in Germany

Question 2

The Hipparcos satellite was able to measure parallax for stars out to about 150 pc. This distance includes roughly 2.5 million stars. The new Gaia satellite should be able to measure the parallax of roughly a billion stars. Assuming the density of stars is approximately constant, what distance would this correspond to? (Hint: The volume of a sphere is proportional to the cube of the radius.)

Accepted Answer

A)  35 pc 
B)  167 pc 
C)  350 pc 
D)  20 kpc 
A)  35 pc 
B)  167 pc 
C)  350 pc 
D)  20 kpc

Question 3

The Sun's spectrum peaks in the green region (i.e., green is the most intense color in its spectrum). The spectrum of Rigel (the knee of Orion) peaks in the short-wavelength end of the visible spectrum. Compared with the Sun, Rigel is

Accepted Answer

A)  cooler and redder. 
B)  hotter and redder. 
C)  cooler and bluer. 
D)  hotter and bluer. 
A)  cooler and redder. 
B)  hotter and redder. 
C)  cooler and bluer. 
D)  hotter and bluer.

Question 4

When two stars of unequal mass orbit each other under their mutual gravitational attraction, where is the center of mass of the system located?

Accepted Answer

A)  point halfway between the centers of the stars 
B)  point between the stars, closer to the less massive star 
C)  center of the more massive star 
D)  point between the two stars, closer to the more massive star 
A)  point halfway between the centers of the stars 
B)  point between the stars, closer to the less massive star 
C)  center of the more massive star 
D)  point between the two stars, closer to the more massive star

Question 5

A particular star is at a distance of 5 pc from Earth. For this star, the apparent magnitude will have

Accepted Answer

A)  the same value as its absolute magnitude, since magnitude is independent of distance. 
B)  a smaller value than its absolute magnitude. 
C)  a larger or smaller value than its absolute magnitude, depending on the temperature and diameter of the star. 
D)  a larger value than its absolute magnitude. 
A)  the same value as its absolute magnitude, since magnitude is independent of distance. 
B)  a smaller value than its absolute magnitude. 
C)  a larger or smaller value than its absolute magnitude, depending on the temperature and diameter of the star. 
D)  a larger value than its absolute magnitude.

Question 6

For a pair of stars to be classified as a visual binary, which one of these conditions must be true?

Accepted Answer

A)  The stars must be orbiting around each other, and both stars must be visible through telescopes from Earth. 
B)  The stars must be orbiting around each other, and absorption or emission lines from both stars must be visible in the spectrum. 
C)  The stars must be orbiting around each other, and one must periodically cross in front of the other (i.e., it must eclipse the other) as seen from Earth. 
D)  The stars must lie in almost the same direction from Earth but must not be orbiting around each other. 
A)  The stars must be orbiting around each other, and both stars must be visible through telescopes from Earth. 
B)  The stars must be orbiting around each other, and absorption or emission lines from both stars must be visible in the spectrum. 
C)  The stars must be orbiting around each other, and one must periodically cross in front of the other (i.e., it must eclipse the other) as seen from Earth. 
D)  The stars must lie in almost the same direction from Earth but must not be orbiting around each other.

Question 7

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. 
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.

Question 8

For a pair of stars to be classified as an optical double, which one of these conditions must be true?

Accepted Answer

A)  The stars must lie in almost the same direction from Earth but must not be orbiting around each other. 
B)  The stars must be orbiting around each other, and one must periodically cross in front of the other (i.e., it must eclipse the other) as seen from Earth. 
C)  The stars must be orbiting around each other, and absorption or emission lines from both stars must be visible in the spectrum. 
D)  The stars must be orbiting around each other, and both stars must be visible through telescopes from Earth. 
A)  The stars must lie in almost the same direction from Earth but must not be orbiting around each other. 
B)  The stars must be orbiting around each other, and one must periodically cross in front of the other (i.e., it must eclipse the other) as seen from Earth. 
C)  The stars must be orbiting around each other, and absorption or emission lines from both stars must be visible in the spectrum. 
D)  The stars must be orbiting around each other, and both stars must be visible through telescopes from Earth.

Question 9

How many fourth-magnitude stars would a star cluster need to have to appear as bright as a single second-magnitude star?

Accepted Answer

A)  2 
B)  4 
C)  2.512 
D)  6.310 
A)  2 
B)  4 
C)  2.512 
D)  6.310

Question 10

What is the ratio of the light energy that falls on a unit area of Mercury's surface compared to that falling on a unit area of Earth's Moon if Mercury is at 0.4 au and the Moon is at 1.0 au from the Sun?

Accepted Answer

A)  1 
B)  6.25 
C)  2.5 
D)  16 
A)  1 
B)  6.25 
C)  2.5 
D)  16

Question 11

What is the physical reason astronomers can find the luminosity class (I, II, III, IV, or V) of a star using the star's spectrum?

Accepted Answer

A)  The wavelength of maximum emission (given by Wien's law) is affected by the size of the star. 
B)  The relative amounts of hydrogen, helium, and other elements are different for stars of different luminosity classes. 
C)  The absorption lines in the spectrum are affected by the density and pressure of the star's atmosphere. 
D)  The absorption lines in the spectrum are affected by the star's surface temperature. 
A)  The wavelength of maximum emission (given by Wien's law) is affected by the size of the star. 
B)  The relative amounts of hydrogen, helium, and other elements are different for stars of different luminosity classes. 
C)  The absorption lines in the spectrum are affected by the density and pressure of the star's atmosphere. 
D)  The absorption lines in the spectrum are affected by the star's surface temperature.

Question 12

The star Algol in the constellation Perseus has these unusual characteristics. Every 68.75 hours its brightness dims suddenly from apparent magnitude 2.3 to apparent magnitude 3.5 and remains there for a few hours before returning just as suddenly to 2.3. In addition, halfway through this 68.75-hour period, the apparent magnitude becomes slightly dimmer than 2.3 for a few hours and then returns to 2.3. From this information alone it is possible to classify Algol as a(n)

Accepted Answer

A)  optical double. 
B)  eclipsing binary. 
C)  totally eclipsing binary. 
D)  partially eclipsing binary. 
A)  optical double. 
B)  eclipsing binary. 
C)  totally eclipsing binary. 
D)  partially eclipsing binary.

Question 13

A star that has an apparent magnitude of 0 would

Accepted Answer

A)  be fainter than Spica (alpha Virginis), which has an apparent magnitude of +1.0. 
B)  be brighter than Deneb (alpha Cygni), which has an apparent magnitude of +1.2. 
C)  have infinite brightness since 1/0 = infinity. 
D)  not be emitting any light and therefore could not be seen from Earth. 
A)  be fainter than Spica (alpha Virginis), which has an apparent magnitude of +1.0. 
B)  be brighter than Deneb (alpha Cygni), which has an apparent magnitude of +1.2. 
C)  have infinite brightness since 1/0 = infinity. 
D)  not be emitting any light and therefore could not be seen from Earth.

Question 14

One important aspect of the study of binary star systems, as distinct from single stars, is that it provides a

Accepted Answer

A)  measurement of the masses of stars. 
B)  measurement of the surface temperatures of stars. 
C)  verification of the Doppler equation for wavelength shift of light from moving objects. 
D)  measurement of the composition (abundances of elements) inside stars. 
A)  measurement of the masses of stars. 
B)  measurement of the surface temperatures of stars. 
C)  verification of the Doppler equation for wavelength shift of light from moving objects. 
D)  measurement of the composition (abundances of elements) inside stars.

Question 15

Which of these stellar classifications describes a star HOTTER than an F5 star?

Accepted Answer

A)  F9 
B)  K2 
C)  M0 
D)  B2 
A)  F9 
B)  K2 
C)  M0 
D)  B2

Question 16

How bright (in absolute magnitude) are the intrinsically faintest stars in the universe?

Accepted Answer

A)  +1 
B)  +17 
C)  -10 
D)  0 
A)  +1 
B)  +17 
C)  -10 
D)  0

Question 17

Star A has luminosity LA = 100 LSun and it is 1000 pc away. Star B has the same luminosity as the Sun, LSun, and it is 100 pc away. What is true about the brightnesses of these two stars?

Accepted Answer

A)  Star A is brighter than Star B. 
B)  Star B is brighter than Star A. 
C)  Star A and Star B have the same brightness. 
D)  It is not possible to answer the question without knowing LSun, the luminosity of the Sun. 
A)  Star A is brighter than Star B. 
B)  Star B is brighter than Star A. 
C)  Star A and Star B have the same brightness. 
D)  It is not possible to answer the question without knowing LSun, the luminosity of the Sun.

Question 18

The star Proxima Centauri has a parallax of 0.77 arcsec (the largest parallax known). How far is this star system from the Sun in light-years? (Careful with units!)

Accepted Answer

A)  4.24 ly 
B)  0.41 ly 
C)  1.33 ly 
D)  0.75 ly 
A)  4.24 ly 
B)  0.41 ly 
C)  1.33 ly 
D)  0.75 ly

Question 19

The Sun is about 8000 parsecs from the center of the Milky Way Galaxy, while the Hipparcos satellite measured parallaxes to an accuracy of about 0.01 arcseconds. How far toward the galactic center could astronomers see with Hipparcos (ignoring galactic dust and other obstacles)?

Accepted Answer

A)  all the way to the center 
B)  about halfway to the center 
C)  about 1/80 of the way to the center 
D)  about 1/1000 of the way to the center 
A)  all the way to the center 
B)  about halfway to the center 
C)  about 1/80 of the way to the center 
D)  about 1/1000 of the way to the center

Question 20

Using Figures 12-7 and 12-8 from the text, determine which of these lists is the correct sequence of stars in order of INCREASING size or stellar radius.

Accepted Answer

A)  Sirius B, the Sun, Betelgeuse, Mira 
B)  Mira, Betelgeuse, the Sun, Sirius B 
C)  Betelgeuse, Mira, the Sun, Sirius B 
D)  Sirius B, the Sun, Mira, Betelgeuse 
A)  Sirius B, the Sun, Betelgeuse, Mira 
B)  Mira, Betelgeuse, the Sun, Sirius B 
C)  Betelgeuse, Mira, the Sun, Sirius B 
D)  Sirius B, the Sun, Mira, Betelgeuse

Who was the first person to measure the parallax of a star successfully?

The Sun's spectrum peaks in the green region (i.e., green is the most intense color in its spectrum). The spectrum of Rigel (the knee of Orion) peaks in the short-wavelength end of the visible spectrum. Compared with the Sun, Rigel is

When two stars of unequal mass orbit each other under their mutual gravitational attraction, where is the center of mass of the system located?

A particular star is at a distance of 5 pc from Earth. For this star, the apparent magnitude will have

For a pair of stars to be classified as a visual binary, which one of these conditions must be true?

Stellar parallax appears because

For a pair of stars to be classified as an optical double, which one of these conditions must be true?

How many fourth-magnitude stars would a star cluster need to have to appear as bright as a single second-magnitude star?

What is the ratio of the light energy that falls on a unit area of Mercury's surface compared to that falling on a unit area of Earth's Moon if Mercury is at 0.4 au and the Moon is at 1.0 au from the Sun?

What is the physical reason astronomers can find the luminosity class (I, II, III, IV, or V) of a star using the star's spectrum?

A star that has an apparent magnitude of 0 would

One important aspect of the study of binary star systems, as distinct from single stars, is that it provides a

Which of these stellar classifications describes a star HOTTER than an F5 star?

How bright (in absolute magnitude) are the intrinsically faintest stars in the universe?

Star A has luminosity L_A = 100 L_Sun and it is 1000 pc away. Star B has the same luminosity as the Sun, L_Sun, and it is 100 pc away. What is true about the brightnesses of these two stars?

The star Proxima Centauri has a parallax of 0.77 arcsec (the largest parallax known). How far is this star system from the Sun in light-years? (Careful with units!)

The Sun is about 8000 parsecs from the center of the Milky Way Galaxy, while the Hipparcos satellite measured parallaxes to an accuracy of about 0.01 arcseconds. How far toward the galactic center could astronomers see with Hipparcos (ignoring galactic dust and other obstacles)?

Using Figures 12-7 and 12-8 from the text, determine which of these lists is the correct sequence of stars in order of INCREASING size or stellar radius.

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Atomic Physics and Spectra

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

The Lives of Stars From Birth Through Middle Age

The Death of Stars

Black Holes: Matters of Gravity

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Cosmology

Astrobiology

Filters

Exam 12: Characterizing Stars

Who was the first person to measure the parallax of a star successfully?

The Sun's spectrum peaks in the green region (i.e., green is the most intense color in its spectrum). The spectrum of Rigel (the knee of Orion) peaks in the short-wavelength end of the visible spectrum. Compared with the Sun, Rigel is

When two stars of unequal mass orbit each other under their mutual gravitational attraction, where is the center of mass of the system located?

A particular star is at a distance of 5 pc from Earth. For this star, the apparent magnitude will have

For a pair of stars to be classified as a visual binary, which one of these conditions must be true?

Stellar parallax appears because

For a pair of stars to be classified as an optical double, which one of these conditions must be true?

How many fourth-magnitude stars would a star cluster need to have to appear as bright as a single second-magnitude star?

What is the ratio of the light energy that falls on a unit area of Mercury's surface compared to that falling on a unit area of Earth's Moon if Mercury is at 0.4 au and the Moon is at 1.0 au from the Sun?

What is the physical reason astronomers can find the luminosity class (I, II, III, IV, or V) of a star using the star's spectrum?

A star that has an apparent magnitude of 0 would

One important aspect of the study of binary star systems, as distinct from single stars, is that it provides a

Which of these stellar classifications describes a star HOTTER than an F5 star?

How bright (in absolute magnitude) are the intrinsically faintest stars in the universe?

Star A has luminosity LA = 100 LSun and it is 1000 pc away. Star B has the same luminosity as the Sun, LSun, and it is 100 pc away. What is true about the brightnesses of these two stars?

The star Proxima Centauri has a parallax of 0.77 arcsec (the largest parallax known). How far is this star system from the Sun in light-years? (Careful with units!)

The Sun is about 8000 parsecs from the center of the Milky Way Galaxy, while the Hipparcos satellite measured parallaxes to an accuracy of about 0.01 arcseconds. How far toward the galactic center could astronomers see with Hipparcos (ignoring galactic dust and other obstacles)?

Using Figures 12-7 and 12-8 from the text, determine which of these lists is the correct sequence of stars in order of INCREASING size or stellar radius.

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Atomic Physics and Spectra

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

The Lives of Stars From Birth Through Middle Age

The Death of Stars

Black Holes: Matters of Gravity

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Cosmology

Astrobiology

Filters

Star A has luminosity L_A = 100 L_Sun and it is 1000 pc away. Star B has the same luminosity as the Sun, L_Sun, and it is 100 pc away. What is true about the brightnesses of these two stars?