Question 1

Name the two primary classes of proposed sources of dark matter.What objects are included in each class,and which one is the most likely source of dark matter?

Accepted Answer

MACHOs: compact stellar remnants (white dwarfs,neutron stars,black holes),cool red (M)or brown dwarfs,and planets.
WIMPS: neutrino-like particles are the most likely as they have been discovered to have some mass and are known to be prolific.

Question 2

The figure below indicates a possible picture of a theoretical universe with two separate observers within it.Which of the following statements describes this universe?

Accepted Answer

A)  This universe is homogeneous but not isotropic. 
B)  This universe is isotropic but not homogeneous. 
C)  This universe is both homogeneous and isotropic. 
D)  This universe is neither homogeneous nor isotropic. 
A)  This universe is homogeneous but not isotropic. 
B)  This universe is isotropic but not homogeneous. 
C)  This universe is both homogeneous and isotropic. 
D)  This universe is neither homogeneous nor isotropic. A

Question 3

Galaxies move away from us in all directions because:

Accepted Answer

A)  the force of gravity strengthens with distance. 
B)  the force of gravity weakens with distance. 
C)  space is expanding. 
D)  our galaxy has expelled all other galaxies. 
A)  the force of gravity strengthens with distance. 
B)  the force of gravity weakens with distance. 
C)  space is expanding. 
D)  our galaxy has expelled all other galaxies. C

Question 4

According to Hubble's law,as the distance of a galaxy ________ its ________ increases.

Accepted Answer

A)  increases; luminosity 
B)  increases; recessional velocity 
C)  decreases; luminosity 
D)  decreases; recessional velocity 
A)  increases; luminosity 
B)  increases; recessional velocity 
C)  decreases; luminosity 
D)  decreases; recessional velocity

Question 5

To be a standard candle,an object must have a constant:

Accepted Answer

A)  lifetime. 
B)  brightness. 
C)  luminosity. 
D)  distance. 
A)  lifetime. 
B)  brightness. 
C)  luminosity. 
D)  distance.

Question 6

The spectrum of a galaxy is observed to have a hydrogen emission line,normally found at 656.3 nm,with a measured wavelength of 928.7 nm.What is its redshift?

Accepted Answer

z = (lₒbs - lᵣₑst)/l

Question 7

If suddenly we find that the distance between Earth and the Sun is now 10 percent larger than we thought it was before,what else will change?

Accepted Answer

A)  the distances of stars 
B)  the size of our galaxy 
C)  the value of H0 
D)  all of the above 
A)  the distances of stars 
B)  the size of our galaxy 
C)  the value of H0 
D)  all of the above

Question 8

A galaxy that is classified as Sc would have:

Accepted Answer

A)  tightly wound spiral arms and a large central bulge. 
B)  loosely wound spiral arms and a large central bulge. 
C)  tightly wound spiral arms and a small central bulge. 
D)  loosely wound spiral arms and a small central bulge. 
A)  tightly wound spiral arms and a large central bulge. 
B)  loosely wound spiral arms and a large central bulge. 
C)  tightly wound spiral arms and a small central bulge. 
D)  loosely wound spiral arms and a small central bulge.

Question 9

Besides shape,what characteristic clearly separates elliptical galaxies from spiral galaxies?

Accepted Answer

A)  size 
B)  shape 
C)  age 
D)  color 
A)  size 
B)  shape 
C)  age 
D)  color

Question 10

The figure below shows the spectrum of a star (top)whose motion compared to our star is nearly stationary within the Milky Way Galaxy.The galaxy spectrum (bottom)indicates that the galaxy is

Accepted Answer

A)  moving toward us. 
B)  moving away from us. 
C)  stationary. 
D)  There is not enough information. 
A)  moving toward us. 
B)  moving away from us. 
C)  stationary. 
D)  There is not enough information.

Question 11

Which of the following does NOT support the existence of dark matter?

Accepted Answer

A)  a super massive black hole at the galactic center 
B)  observed galactic rotation curves 
C)  the distribution of light in a galaxy 
D)  X-ray-emitting gas in elliptical galaxies 
A)  a super massive black hole at the galactic center 
B)  observed galactic rotation curves 
C)  the distribution of light in a galaxy 
D)  X-ray-emitting gas in elliptical galaxies

Question 12

Describe the two assumptions regarding the universe that the cosmological principle makes.

Accepted Answer

The universe is homogeneous (t

Question 13

Which distance indicator can be used to measure the most distant objects?

Accepted Answer

A)  Cepheids 
B)  parallax 
C)  Type Ia supernovae 
D)  main-sequence fitting 
A)  Cepheids 
B)  parallax 
C)  Type Ia supernovae 
D)  main-sequence fitting

Question 14

Why are some galaxies' spectra blueshifted rather than redshifted?

Accepted Answer

A)  Some distant galaxies are gravitationally lensed. 
B)  Some nearby galaxies are attracted to us because of the mass of the Milky Way. 
C)  Some nearby galaxies have vigorous star formation and are much bluer than others. 
D)  Some distant galaxies have an AGN at their centers. 
A)  Some distant galaxies are gravitationally lensed. 
B)  Some nearby galaxies are attracted to us because of the mass of the Milky Way. 
C)  Some nearby galaxies have vigorous star formation and are much bluer than others. 
D)  Some distant galaxies have an AGN at their centers.

Question 15

Examine the figure below.Describe why the distance ladder is so important to the field of cosmology.

Accepted Answer

The distance ladder provides m

Question 16

What does the Hubble tuning fork illustrate?

Accepted Answer

A)  the evolutionary sequence of galaxies 
B)  the locations of galaxies 
C)  the motions of galaxies 
D)  a classification scheme 
A)  the evolutionary sequence of galaxies 
B)  the locations of galaxies 
C)  the motions of galaxies 
D)  a classification scheme

Question 17

Name three "rungs" in the distance ladder that let us estimate the value of H₀.

Accepted Answer

Trigonometric parallax,period-

Question 18

The most likely dark matter candidate seems to be:

Accepted Answer

A)  black holes 
B)  planets 
C)  neutron stars 
D)  neutrino-like particles 
A)  black holes 
B)  planets 
C)  neutron stars 
D)  neutrino-like particles

Question 19

Why can Type Ia supernovae be used to determine a galaxy's distance?

Accepted Answer

A)  Type Ia supernovae occur only in very luminous galaxies. 
B)  Type Ia supernova have approximately the same luminosity. 
C)  Type Ia supernovae have approximately the same size. 
D)  A Type Ia supernova occurs in a typical galaxy about once every 100 years. 
A)  Type Ia supernovae occur only in very luminous galaxies. 
B)  Type Ia supernova have approximately the same luminosity. 
C)  Type Ia supernovae have approximately the same size. 
D)  A Type Ia supernova occurs in a typical galaxy about once every 100 years.

Question 20

If you measured the distances and recessional velocities for a sample of galaxies and plotted the data to get the figure below,what value would you derive for the Hubble constant?

Accepted Answer

A)  10 km/s/Mly 
B)  22 km/s/Mly 
C)  45 km/s/Mly 
D)  100 km/s/Mly 
A)  10 km/s/Mly 
B)  22 km/s/Mly 
C)  45 km/s/Mly 
D)  100 km/s/Mly

Name the two primary classes of proposed sources of dark matter.What objects are included in each class,and which one is the most likely source of dark matter?

The figure below indicates a possible picture of a theoretical universe with two separate observers within it.Which of the following statements describes this universe?

Galaxies move away from us in all directions because:

According to Hubble's law,as the distance of a galaxy its increases.

To be a standard candle,an object must have a constant:

The spectrum of a galaxy is observed to have a hydrogen emission line,normally found at 656.3 nm,with a measured wavelength of 928.7 nm.What is its redshift?

If suddenly we find that the distance between Earth and the Sun is now 10 percent larger than we thought it was before,what else will change?

A galaxy that is classified as Sc would have:

Besides shape,what characteristic clearly separates elliptical galaxies from spiral galaxies?

The figure below shows the spectrum of a star (top)whose motion compared to our star is nearly stationary within the Milky Way Galaxy.The galaxy spectrum (bottom)indicates that the galaxy is

Which of the following does NOT support the existence of dark matter?

Describe the two assumptions regarding the universe that the cosmological principle makes.

Which distance indicator can be used to measure the most distant objects?

Why are some galaxies' spectra blueshifted rather than redshifted?

Examine the figure below.Describe why the distance ladder is so important to the field of cosmology.

What does the Hubble tuning fork illustrate?

Name three "rungs" in the distance ladder that let us estimate the value of H₀.

The most likely dark matter candidate seems to be:

Why can Type Ia supernovae be used to determine a galaxy's distance?

If you measured the distances and recessional velocities for a sample of galaxies and plotted the data to get the figure below,what value would you derive for the Hubble constant?

Thinking Like an Astronomer

Patterns in the Skymotions of Earth and the Moon

Laws of Motion

Light and Telescopes

The Formation of Stars and Planets

Terrestrial Worlds in the Inner Solar System

Atmospheres of Venus, earth, and Mars

The Giant Planets

Small Bodies of the Solar System

Measuring the Stars

Our Star: the Sun

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Our Galaxy: the Milky Way

The Evolution of the Universe

Formation of Structure

Life in the Universe

Filters

Exam 14: Measuring Galaxies

Name the two primary classes of proposed sources of dark matter.What objects are included in each class,and which one is the most likely source of dark matter?

The figure below indicates a possible picture of a theoretical universe with two separate observers within it.Which of the following statements describes this universe?

Galaxies move away from us in all directions because:

According to Hubble's law,as the distance of a galaxy ________ its ________ increases.

To be a standard candle,an object must have a constant:

The spectrum of a galaxy is observed to have a hydrogen emission line,normally found at 656.3 nm,with a measured wavelength of 928.7 nm.What is its redshift?

If suddenly we find that the distance between Earth and the Sun is now 10 percent larger than we thought it was before,what else will change?

A galaxy that is classified as Sc would have:

Besides shape,what characteristic clearly separates elliptical galaxies from spiral galaxies?

The figure below shows the spectrum of a star (top)whose motion compared to our star is nearly stationary within the Milky Way Galaxy.The galaxy spectrum (bottom)indicates that the galaxy is

Which of the following does NOT support the existence of dark matter?

Describe the two assumptions regarding the universe that the cosmological principle makes.

Which distance indicator can be used to measure the most distant objects?

Why are some galaxies' spectra blueshifted rather than redshifted?

Examine the figure below.Describe why the distance ladder is so important to the field of cosmology.

What does the Hubble tuning fork illustrate?

Name three "rungs" in the distance ladder that let us estimate the value of H₀.

The most likely dark matter candidate seems to be:

Why can Type Ia supernovae be used to determine a galaxy's distance?

If you measured the distances and recessional velocities for a sample of galaxies and plotted the data to get the figure below,what value would you derive for the Hubble constant?

Thinking Like an Astronomer

Patterns in the Skymotions of Earth and the Moon

Laws of Motion

Light and Telescopes

The Formation of Stars and Planets

Terrestrial Worlds in the Inner Solar System

Atmospheres of Venus, earth, and Mars

The Giant Planets

Small Bodies of the Solar System

Measuring the Stars

Our Star: the Sun

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Our Galaxy: the Milky Way

The Evolution of the Universe

Formation of Structure

Life in the Universe

Filters

According to Hubble's law,as the distance of a galaxy its increases.