Question 1

What is a spectroscopic binary?

Accepted Answer

A)  an instrument for taking spectra of two sources simultaneously 
B)  a binary system detected through the shifting spectral lines of its stars 
C)  a binary system in which one star moves directly in front of the other 
D)  a pair of stars that are very close to each other on the sky but are not physically related 
A)  an instrument for taking spectra of two sources simultaneously 
B)  a binary system detected through the shifting spectral lines of its stars 
C)  a binary system in which one star moves directly in front of the other 
D)  a pair of stars that are very close to each other on the sky but are not physically related

Question 2

Light leaving a point source spreads out so that the apparent brightness I of light per unit area varies with distance d according to which of these laws ($\infty$ means "proportional to")?

Accepted Answer

A)  I = constant 
B)  I $\infty$ 1/d2 
C)  I $\infty$ d2 
D)  I $\infty$ 1/d 
A)  I = constant 
B)  I $\infty$ 1/d2 
C)  I $\infty$ d2 
D)  I $\infty$ 1/d

Question 3

For Balmer series lines to show up strongly in absorption in stellar spectra, significant numbers of hydrogen atoms must have electrons in the n = 2 energy level. What then does the appearance of these lines in a stellar spectrum describe about the temperature of the star's surface?

Accepted Answer

A)  The appearance of the lines describes very little about the temperature because hydrogen gas will show significant Balmer absorption, whatever the surface temperature. 
B)  The temperature must be high enough to ionize the hydrogen atoms by collision so that they can absorb from this level. 
C)  The temperature must be reasonably low so that no atoms will have electrons excited beyond this energy level . 
D)  The temperature must be reasonably high to excite the electrons to this level by collisions but not high enough to ionize the atoms. 
A)  The appearance of the lines describes very little about the temperature because hydrogen gas will show significant Balmer absorption, whatever the surface temperature. 
B)  The temperature must be high enough to ionize the hydrogen atoms by collision so that they can absorb from this level. 
C)  The temperature must be reasonably low so that no atoms will have electrons excited beyond this energy level . 
D)  The temperature must be reasonably high to excite the electrons to this level by collisions but not high enough to ionize the atoms.

Question 4

Very hot stars have weak hydrogen spectral lines. Why is this?

Accepted Answer

A)  These stars contain very little hydrogen. 
B)  The hydrogen in the atmospheres of these stars is combined into molecules, and these have different spectra. 
C)  The electrons in the hydrogen atoms in these stars are all in their lowest energy levels, and they cannot radiate from these levels. 
D)  The hydrogen atoms in these stars are mostly ionized and hence cannot radiate. 
A)  These stars contain very little hydrogen. 
B)  The hydrogen in the atmospheres of these stars is combined into molecules, and these have different spectra. 
C)  The electrons in the hydrogen atoms in these stars are all in their lowest energy levels, and they cannot radiate from these levels. 
D)  The hydrogen atoms in these stars are mostly ionized and hence cannot radiate.

Question 5

Which of these spectral luminosity classes corresponds to a red supergiant?

Accepted Answer

A)  M2 I 
B)  B7 I 
C)  M3 V 
D)  G2 III 
A)  M2 I 
B)  B7 I 
C)  M3 V 
D)  G2 III

Question 6

Aristotle (fourth century B.C.) rejected the idea that Earth moves because he knew stellar parallax motion would result, and he was unable to measure any. About how long after Aristotle was stellar parallax actually measured?

Accepted Answer

A)  two centuries 
B)  10 centuries 
C)  22 centuries 
D)  29 centuries 
A)  two centuries 
B)  10 centuries 
C)  22 centuries 
D)  29 centuries

Question 7

The European Space Agency recently launched the Gaia mission, which will measure parallax angles down to 10-5 arcseconds. What distance does this correspond to?

Accepted Answer

A)  10-5 pc 
B)  105 light-years 
C)  10 kpc 
D)  100 kpc 
A)  10-5 pc 
B)  105 light-years 
C)  10 kpc 
D)  100 kpc

Question 8

Which of these atoms or ions produces the strongest absorption lines in the spectra of stars with the highest surface temperatures?

Accepted Answer

A)  He II, ionized helium 
B)  Fe I, neutral iron 
C)  Ca II, singly ionized calcium 
D)  H I, neutral hydrogen 
A)  He II, ionized helium 
B)  Fe I, neutral iron 
C)  Ca II, singly ionized calcium 
D)  H I, neutral hydrogen

Question 9

A star of apparent magnitude -1.5 appears _____ than a star of apparent magnitude +2.0.

Accepted Answer

A)  farther away 
B)  fainter 
C)  brighter 
D)  either brighter or fainter, depending on the distance to the stars, 
A)  farther away 
B)  fainter 
C)  brighter 
D)  either brighter or fainter, depending on the distance to the stars,

Question 10

Which of these atoms or ions produces strong absorption lines in the spectra of stars with relatively cool surface temperatures?

Accepted Answer

A)  TiO, molecules of titanium oxide 
B)  Mg II, ionized magnesium 
C)  Ca II, ionized calcium 
D)  He I, neutral helium 
A)  TiO, molecules of titanium oxide 
B)  Mg II, ionized magnesium 
C)  Ca II, ionized calcium 
D)  He I, neutral helium

Question 11

The Hertzsprung-Russell diagram is a plot of

Accepted Answer

A)  apparent brightness against intrinsic brightness of a group of stars. 
B)  apparent brightness against distance for stars near the Sun. 
C)  luminosity against mass of a group of stars. 
D)  absolute magnitude (or luminosity) against temperature of a group of stars. 
A)  apparent brightness against intrinsic brightness of a group of stars. 
B)  apparent brightness against distance for stars near the Sun. 
C)  luminosity against mass of a group of stars. 
D)  absolute magnitude (or luminosity) against temperature of a group of stars.

Question 12

The Sun's classification in terms of its surface temperature, as determined from absorption lines in its spectrum, is

Accepted Answer

A)  M9. 
B)  G2. 
C)  O1. 
D)  B2. 
A)  M9. 
B)  G2. 
C)  O1. 
D)  B2.

Question 13

Which of these could plausibly be the mass of a main-sequence star that has a luminosity 1000 times greater than that of the Sun?

Accepted Answer

A)  105 solar masses 
B)  5 solar masses 
C)  0.1 solar mass 
D)  1000 solar masses 
A)  105 solar masses 
B)  5 solar masses 
C)  0.1 solar mass 
D)  1000 solar masses

Question 14

The modern system of apparent magnitudes uses the star Vega as its basis. In this scheme Vega is defined to have an apparent magnitude of

Accepted Answer

A)  10. 
B)  1.0. 
C)  0.0. 
D)  -1.0. 
A)  10. 
B)  1.0. 
C)  0.0. 
D)  -1.0.

Question 15

How far away is the nearest star beyond the Sun?

Accepted Answer

A)  about 1/4 ly away 
B)  about 1/10 ly away 
C)  about 4 ly away 
D)  between 1 and 2 ly away 
A)  about 1/4 ly away 
B)  about 1/10 ly away 
C)  about 4 ly away 
D)  between 1 and 2 ly away

Question 16

The technique called photometry in stellar astronomy is the measurement of the

Accepted Answer

A)  arrival times of photons from variable and pulsating stars to determine accurately the pulsation or rotation periods of these stars. 
B)  intensity of light from stars through several limited-bandpass filters from which surface temperature, variability, luminosity, and so on of stars can be determined. 
C)  relative absorption of light by different atoms and molecules in high-resolution spectra of starlight, from which stellar temperatures can be estimated. 
D)  precise positions and relative motions of stars in the Galaxy, from which galactic structure and overall rotation can be determined. 
A)  arrival times of photons from variable and pulsating stars to determine accurately the pulsation or rotation periods of these stars. 
B)  intensity of light from stars through several limited-bandpass filters from which surface temperature, variability, luminosity, and so on of stars can be determined. 
C)  relative absorption of light by different atoms and molecules in high-resolution spectra of starlight, from which stellar temperatures can be estimated. 
D)  precise positions and relative motions of stars in the Galaxy, from which galactic structure and overall rotation can be determined.

Question 17

If the surface temperatures of white dwarf stars are 4 times that of the Sun, and energy output per unit area of a star depends on the fourth power of the temperature by the Stefan-Boltzmann relation, why are white dwarfs intrinsically so faint?

Accepted Answer

A)  White dwarfs are very small. 
B)  White dwarfs have very thin atmospheres that do not emit continuum radiation but only line emissions, like a low-density gas. 
C)  White dwarfs are shrouded in very thick atmospheres. 
D)  White dwarfs are moving rapidly away from the Sun and their spectra are extremely redshifted, hence they appear faint at visible wavelengths. 
A)  White dwarfs are very small. 
B)  White dwarfs have very thin atmospheres that do not emit continuum radiation but only line emissions, like a low-density gas. 
C)  White dwarfs are shrouded in very thick atmospheres. 
D)  White dwarfs are moving rapidly away from the Sun and their spectra are extremely redshifted, hence they appear faint at visible wavelengths.

Question 18

See Figure 12-8 in the text. A white dwarf star whose temperature is the same as that of the Sun will have a radius that is

Accepted Answer

A)  10 times smaller than that of the Sun. 
B)  the same size as the Sun's. 
C)  2 times smaller than that of the Sun. 
D)  100 times smaller than that of the Sun. 
A)  10 times smaller than that of the Sun. 
B)  the same size as the Sun's. 
C)  2 times smaller than that of the Sun. 
D)  100 times smaller than that of the Sun.

Question 19

In the Hertzsprung-Russell diagram in Figure 12-7 in the text, which of these lists is the correct sequence of stars in order of DECREASING absolute magnitude?

Accepted Answer

A)  Deneb, the Sun, Sirius B, Procyon B 
B)  Sirius B, Deneb, Procyon B, the Sun 
C)  Sun, Procyon B, Deneb, Sirius B 
D)  Procyon B, Sirius B, the Sun, Deneb 
A)  Deneb, the Sun, Sirius B, Procyon B 
B)  Sirius B, Deneb, Procyon B, the Sun 
C)  Sun, Procyon B, Deneb, Sirius B 
D)  Procyon B, Sirius B, the Sun, Deneb

Question 20

What is the relationship between stellar parallax (p) measured in seconds of arc and distance (d) measured in parsecs?

Accepted Answer

A)  d = 1/p2 
B)  d = 1/p 
C)  d = p 
D)  d = p2 
A)  d = 1/p2 
B)  d = 1/p 
C)  d = p 
D)  d = p2

What is a spectroscopic binary?

Light leaving a point source spreads out so that the apparent brightness I of light per unit area varies with distance d according to which of these laws ( $\infty$ means "proportional to")?

For Balmer series lines to show up strongly in absorption in stellar spectra, significant numbers of hydrogen atoms must have electrons in the n = 2 energy level. What then does the appearance of these lines in a stellar spectrum describe about the temperature of the star's surface?

Very hot stars have weak hydrogen spectral lines. Why is this?

Which of these spectral luminosity classes corresponds to a red supergiant?

Aristotle (fourth century B.C.) rejected the idea that Earth moves because he knew stellar parallax motion would result, and he was unable to measure any. About how long after Aristotle was stellar parallax actually measured?

The European Space Agency recently launched the Gaia mission, which will measure parallax angles down to 10^-5 arcseconds. What distance does this correspond to?

Which of these atoms or ions produces the strongest absorption lines in the spectra of stars with the highest surface temperatures?

A star of apparent magnitude -1.5 appears _____ than a star of apparent magnitude +2.0.

Which of these atoms or ions produces strong absorption lines in the spectra of stars with relatively cool surface temperatures?

The Hertzsprung-Russell diagram is a plot of

The Sun's classification in terms of its surface temperature, as determined from absorption lines in its spectrum, is

Which of these could plausibly be the mass of a main-sequence star that has a luminosity 1000 times greater than that of the Sun?

The modern system of apparent magnitudes uses the star Vega as its basis. In this scheme Vega is defined to have an apparent magnitude of

How far away is the nearest star beyond the Sun?

The technique called photometry in stellar astronomy is the measurement of the

If the surface temperatures of white dwarf stars are 4 times that of the Sun, and energy output per unit area of a star depends on the fourth power of the temperature by the Stefan-Boltzmann relation, why are white dwarfs intrinsically so faint?

See Figure 12-8 in the text. A white dwarf star whose temperature is the same as that of the Sun will have a radius that is

In the Hertzsprung-Russell diagram in Figure 12-7 in the text, which of these lists is the correct sequence of stars in order of DECREASING absolute magnitude?

What is the relationship between stellar parallax (p) measured in seconds of arc and distance (d) measured in parsecs?

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

What is a spectroscopic binary?

Light leaving a point source spreads out so that the apparent brightness I of light per unit area varies with distance d according to which of these laws ( ∞\infty∞ means "proportional to")?

For Balmer series lines to show up strongly in absorption in stellar spectra, significant numbers of hydrogen atoms must have electrons in the n = 2 energy level. What then does the appearance of these lines in a stellar spectrum describe about the temperature of the star's surface?

Very hot stars have weak hydrogen spectral lines. Why is this?

Which of these spectral luminosity classes corresponds to a red supergiant?

Aristotle (fourth century B.C.) rejected the idea that Earth moves because he knew stellar parallax motion would result, and he was unable to measure any. About how long after Aristotle was stellar parallax actually measured?

The European Space Agency recently launched the Gaia mission, which will measure parallax angles down to 10-5 arcseconds. What distance does this correspond to?

Which of these atoms or ions produces the strongest absorption lines in the spectra of stars with the highest surface temperatures?

A star of apparent magnitude -1.5 appears _____ than a star of apparent magnitude +2.0.

Which of these atoms or ions produces strong absorption lines in the spectra of stars with relatively cool surface temperatures?

The Hertzsprung-Russell diagram is a plot of

The Sun's classification in terms of its surface temperature, as determined from absorption lines in its spectrum, is

Which of these could plausibly be the mass of a main-sequence star that has a luminosity 1000 times greater than that of the Sun?

The modern system of apparent magnitudes uses the star Vega as its basis. In this scheme Vega is defined to have an apparent magnitude of

How far away is the nearest star beyond the Sun?

The technique called photometry in stellar astronomy is the measurement of the

If the surface temperatures of white dwarf stars are 4 times that of the Sun, and energy output per unit area of a star depends on the fourth power of the temperature by the Stefan-Boltzmann relation, why are white dwarfs intrinsically so faint?

See Figure 12-8 in the text. A white dwarf star whose temperature is the same as that of the Sun will have a radius that is

In the Hertzsprung-Russell diagram in Figure 12-7 in the text, which of these lists is the correct sequence of stars in order of DECREASING absolute magnitude?

What is the relationship between stellar parallax (p) measured in seconds of arc and distance (d) measured in parsecs?

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

Light leaving a point source spreads out so that the apparent brightness I of light per unit area varies with distance d according to which of these laws ( $\infty$ means "proportional to")?

The European Space Agency recently launched the Gaia mission, which will measure parallax angles down to 10^-5 arcseconds. What distance does this correspond to?