Question 1

How do astronomers measure the masses of stars directly?

Accepted Answer

A)  by observing the star's brightness at different wavelengths (colors) 
B)  by observing the motion of two stars in a binary star system 
C)  by measuring the star's brightness, temperature, and distance 
D)  by measuring the star's brightness and obtaining its radius using the H-R diagram 
A)  by observing the star's brightness at different wavelengths (colors) 
B)  by observing the motion of two stars in a binary star system 
C)  by measuring the star's brightness, temperature, and distance 
D)  by measuring the star's brightness and obtaining its radius using the H-R diagram

Question 2

The first accurate measurement of stellar parallax was made in

Accepted Answer

A)  the fourth century B.C. 
B)  1721. 
C)  1838. 
D)  1927. 
A)  the fourth century B.C. 
B)  1721. 
C)  1838. 
D)  1927.

Question 3

Two stars in Earth's sky have the same apparent brightness. If neither of them is hidden behind gas or dust clouds, then one knows that they

Accepted Answer

A)  must be at the same distance from Earth. 
B)  may be at different distances, in which case the nearer one must have the greater luminosity. 
C)  may be at different distances, in which case the farther one must have the greater luminosity. 
D)  must have the same temperature. 
A)  must be at the same distance from Earth. 
B)  may be at different distances, in which case the nearer one must have the greater luminosity. 
C)  may be at different distances, in which case the farther one must have the greater luminosity. 
D)  must have the same temperature.

Question 4

A star whose absolute magnitude M is +2.2 is seen to have an apparent magnitude when viewed from Earth of +5.2. How far away is the star?

Accepted Answer

A)  40 pc 
B)  12.3 pc 
C)  130 pc 
D)  3/5, or 0.6 pc 
A)  40 pc 
B)  12.3 pc 
C)  130 pc 
D)  3/5, or 0.6 pc

Question 5

Parallax of a nearby star is used to estimate its

Accepted Answer

A)  surface temperature. 
B)  distance from Earth. 
C)  apparent magnitude. 
D)  physical size or diameter. 
A)  surface temperature. 
B)  distance from Earth. 
C)  apparent magnitude. 
D)  physical size or diameter.

Question 6

What is the only way to measure directly the mass of a star accurately?

Accepted Answer

A)  Measure its distance using trigonometric parallax and its brightness using photometry. 
B)  It is not possible to measure the mass of a star. 
C)  Measure its spectral type and luminosity class, then use the H-R diagram. 
D)  Measure its gravitational effect on another object. 
A)  Measure its distance using trigonometric parallax and its brightness using photometry. 
B)  It is not possible to measure the mass of a star. 
C)  Measure its spectral type and luminosity class, then use the H-R diagram. 
D)  Measure its gravitational effect on another object.

Question 7

The surface temperature of a nearby star can BEST be determined from spectral classification by examining the

Accepted Answer

A)  pattern of spectral absorption lines from various atoms. 
B)  relative intensities of light measured through different photometric filters. 
C)  peak wavelength of the star's continuous blackbody spectrum. 
D)  pattern of emission lines that are on the star's spectrum. 
A)  pattern of spectral absorption lines from various atoms. 
B)  relative intensities of light measured through different photometric filters. 
C)  peak wavelength of the star's continuous blackbody spectrum. 
D)  pattern of emission lines that are on the star's spectrum.

Question 8

If a distant cluster were to be composed only of stars with apparent magnitude of +3, how many stars would there be in this cluster if its apparent magnitude matched that of a star with apparent magnitude of +1?

Accepted Answer

A)  2 
B)  102, or 100 
C)  about 2.5 
D)  between 6 and 7 
A)  2 
B)  102, or 100 
C)  about 2.5 
D)  between 6 and 7

Question 9

Which of these statements about measuring the mass of an isolated star (a star that is not in a binary star system) is CORRECT?

Accepted Answer

A)  The mass of the star can be measured accurately in several ways. 
B)  The mass of the star can be measured accurately only if its luminosity and temperature can be measured. 
C)  The mass of the star can be measured accurately only if its distance can be found. 
D)  The mass of the star cannot be measured accurately. 
A)  The mass of the star can be measured accurately in several ways. 
B)  The mass of the star can be measured accurately only if its luminosity and temperature can be measured. 
C)  The mass of the star can be measured accurately only if its distance can be found. 
D)  The mass of the star cannot be measured accurately.

Question 10

The intensity of sunlight per square meter reaching Jupiter is approximately what fraction of that at Earth's orbital distance? (Jupiter's orbit has a semimajor axis of about 5 au.)

Accepted Answer

A)  25 times 
B)  about the same 
C)  1/5 
D)  1/25 
A)  25 times 
B)  about the same 
C)  1/5 
D)  1/25

Question 11

The faintest stars observable through the largest telescopes have apparent magnitudes of roughly m = 30. How many of these stars would it take to equal the brightness of Vega, which has m = 0?

Accepted Answer

A)  30 
B)  30 * 2.512 
C)  302.512 
D)  2.51230 
A)  30 
B)  30 * 2.512 
C)  302.512 
D)  2.51230

Question 12

Luminosity is measured in

Accepted Answer

A)  watts. 
B)  watts per second. 
C)  watts per square meter. 
D)  parsecs. 
A)  watts. 
B)  watts per second. 
C)  watts per square meter. 
D)  parsecs.

Question 13

The spectrum of an ordinary main-sequence star is a

Accepted Answer

A)  continuum of colors, crossed by brighter lines caused by emission from the hot atoms and molecules on the star's surface. 
B)  smooth continuum of color, peaking at a specific wavelength whose position depends on the star's surface temperature. 
C)  series of emission lines, mostly from hydrogen, the major constituent of stellar surfaces, that occasionally overlap to produce sections of continuous color. 
D)  continuum of colors crossed by dark absorption lines caused by absorption by cooler atoms and molecules at the star's surface. 
A)  continuum of colors, crossed by brighter lines caused by emission from the hot atoms and molecules on the star's surface. 
B)  smooth continuum of color, peaking at a specific wavelength whose position depends on the star's surface temperature. 
C)  series of emission lines, mostly from hydrogen, the major constituent of stellar surfaces, that occasionally overlap to produce sections of continuous color. 
D)  continuum of colors crossed by dark absorption lines caused by absorption by cooler atoms and molecules at the star's surface.

Question 14

As one moves upward and to the right on the H-R diagram, stars become

Accepted Answer

A)  hotter and brighter. 
B)  hotter and dimmer. 
C)  cooler and dimmer. 
D)  cooler and brighter. 
A)  hotter and brighter. 
B)  hotter and dimmer. 
C)  cooler and dimmer. 
D)  cooler and brighter.

How do astronomers measure the masses of stars directly?

The first accurate measurement of stellar parallax was made in

Two stars in Earth's sky have the same apparent brightness. If neither of them is hidden behind gas or dust clouds, then one knows that they

A star whose absolute magnitude M is +2.2 is seen to have an apparent magnitude when viewed from Earth of +5.2. How far away is the star?

Parallax of a nearby star is used to estimate its

What is the only way to measure directly the mass of a star accurately?

The surface temperature of a nearby star can BEST be determined from spectral classification by examining the

If a distant cluster were to be composed only of stars with apparent magnitude of +3, how many stars would there be in this cluster if its apparent magnitude matched that of a star with apparent magnitude of +1?

Which of these statements about measuring the mass of an isolated star (a star that is not in a binary star system) is CORRECT?

The intensity of sunlight per square meter reaching Jupiter is approximately what fraction of that at Earth's orbital distance? (Jupiter's orbit has a semimajor axis of about 5 au.)

The faintest stars observable through the largest telescopes have apparent magnitudes of roughly m = 30. How many of these stars would it take to equal the brightness of Vega, which has m = 0?

Luminosity is measured in

The spectrum of an ordinary main-sequence star is a

As one moves upward and to the right on the H-R diagram, stars become

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

How do astronomers measure the masses of stars directly?

The first accurate measurement of stellar parallax was made in

Two stars in Earth's sky have the same apparent brightness. If neither of them is hidden behind gas or dust clouds, then one knows that they

A star whose absolute magnitude M is +2.2 is seen to have an apparent magnitude when viewed from Earth of +5.2. How far away is the star?

Parallax of a nearby star is used to estimate its

What is the only way to measure directly the mass of a star accurately?

The surface temperature of a nearby star can BEST be determined from spectral classification by examining the

If a distant cluster were to be composed only of stars with apparent magnitude of +3, how many stars would there be in this cluster if its apparent magnitude matched that of a star with apparent magnitude of +1?

Which of these statements about measuring the mass of an isolated star (a star that is not in a binary star system) is CORRECT?

The intensity of sunlight per square meter reaching Jupiter is approximately what fraction of that at Earth's orbital distance? (Jupiter's orbit has a semimajor axis of about 5 au.)

The faintest stars observable through the largest telescopes have apparent magnitudes of roughly m = 30. How many of these stars would it take to equal the brightness of Vega, which has m = 0?

Luminosity is measured in

The spectrum of an ordinary main-sequence star is a

As one moves upward and to the right on the H-R diagram, stars become

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