Question 1

Explain why good distance indicators must be luminous objects. Why must they be unambiguously recognizable?

Accepted Answer

Good distance indicators must be luminou

Question 2

Discuss the observational differences between spiral, elliptical, and irregular galaxies.

Accepted Answer

The answer of Discuss the observational differences between spiral, elliptical,...

Question 3

The hydrogen Balmer line H $\gamma$  has a wavelength of 434.0 nm in the laboratory. It is observed in a quasar at 651.0 nm. In terms of the speed of light, c, what is the recessional velocity of this quasar?

Accepted Answer

A)  217.0c 
B)  2c 
C)  1.5c 
D)  0.67c 
E)  0.5c 
A)  217.0c 
B)  2c 
C)  1.5c 
D)  0.67c 
E)  0.5c

Question 4

The cluster method (motions of galaxies in a cluster of galaxies) can be used to determine the cluster's

Accepted Answer

A)  luminosity. 
B)  distance. 
C)  mass. 
D)  diameter. 
E)  age. 
A)  luminosity. 
B)  distance. 
C)  mass. 
D)  diameter. 
E)  age.

Question 5

The Virgo cluster

Accepted Answer

A)  is the galactic cluster that contains the Milky Way. 
B)  is the oldest known cluster of galaxies. 
C)  is located at the center of the universe. 
D)  contains mostly spiral galaxies and very few elliptical galaxies. 
E)  is a rich cluster and the closest cluster of galaxies outside of the Local Group. 
A)  is the galactic cluster that contains the Milky Way. 
B)  is the oldest known cluster of galaxies. 
C)  is located at the center of the universe. 
D)  contains mostly spiral galaxies and very few elliptical galaxies. 
E)  is a rich cluster and the closest cluster of galaxies outside of the Local Group.

Question 6

What distance method is used to determine the distance to the most distant galaxies?

Accepted Answer

A)  radar echo 
B)  supernova observations 
C)  period-luminosity relationship of variable stars 
D)  parallax 
A)  radar echo 
B)  supernova observations 
C)  period-luminosity relationship of variable stars 
D)  parallax

Question 7

____________________ Seyfert galaxies are very luminous at X-ray and ultraviolet wavelengths and have broad emission lines in their spectra.

Accepted Answer

The answer of ____________________ Seyfert galaxies are very luminous at...

Question 8

The energy from an AGN is produced by

Accepted Answer

A)  the collision of two spiral galaxies. 
B)  the collision of two elliptical galaxies. 
C)  the collision of two radio jets. 
D)  matter flowing into a supermassive black hole. 
E)  supernovae. 
A)  the collision of two spiral galaxies. 
B)  the collision of two elliptical galaxies. 
C)  the collision of two radio jets. 
D)  matter flowing into a supermassive black hole. 
E)  supernovae.

Question 9

____ show(s) that some quasars are further away than distant galaxies and that space time is curved by massive objects.

Accepted Answer

A)  Double-lobed radio galaxies 
B)  Blazars 
C)  The gravitational lens effect 
D)  Head-tail galaxies 
E)  Superluminal expansion 
A)  Double-lobed radio galaxies 
B)  Blazars 
C)  The gravitational lens effect 
D)  Head-tail galaxies 
E)  Superluminal expansion

Question 10

What type of galaxies do astronomers believe to be the most common?

Accepted Answer

A)  elliptical 
B)  spiral 
C)  irregular 
D)  Astronomers have no idea which type of galaxy is most common. 
A)  elliptical 
B)  spiral 
C)  irregular 
D)  Astronomers have no idea which type of galaxy is most common.

Question 11

Statistical evidence

Accepted Answer

A)  can be used to draw conclusions about a specific cases. 
B)  is applicable to classes of objects where only a few objects from the class have been studied. 
C)  allows scientists to determine the mechanism that produces the dust ring in Centaurus A. 
D)  allows scientists to deduce general characteristics about a class of objects with similar properties. 
E)  provides insight into the behavior of an individual object based on careful observations of it. 
A)  can be used to draw conclusions about a specific cases. 
B)  is applicable to classes of objects where only a few objects from the class have been studied. 
C)  allows scientists to determine the mechanism that produces the dust ring in Centaurus A. 
D)  allows scientists to deduce general characteristics about a class of objects with similar properties. 
E)  provides insight into the behavior of an individual object based on careful observations of it.

Question 12

____ are produced when two galaxies pass near each other and pull large streamers of stars, gas, and dust away from the galaxies.

Accepted Answer

A)  Ring galaxies 
B)  Spiral galaxies 
C)  Rotation curves 
D)  Tidal tails 
E)  Irregular galaxies 
A)  Ring galaxies 
B)  Spiral galaxies 
C)  Rotation curves 
D)  Tidal tails 
E)  Irregular galaxies

Question 13

Why are there few quasars at low redshifts and at high redshifts but many at redshifts of about 2?

Accepted Answer

The answer of Why are there few quasars at low...

Question 14

What distance method did Edwin Hubble use to determine the distance to local galaxies?

Accepted Answer

A)  Hubble Law 
B)  supernova observations 
C)  period-luminosity relationship of variable stars 
D)  parallax 
A)  Hubble Law 
B)  supernova observations 
C)  period-luminosity relationship of variable stars 
D)  parallax

Question 15

The hot spots in a double-lobed radio source

Accepted Answer

A)  appear to coincide with the location of the central galaxy responsible for the jets. 
B)  are where hot excited gas interacts with the intergalactic medium. 
C)  are only found near quasars. 
D)  produce enough visible energy to be imaged at visible wavelengths. 
E)  are always perpendicular to each other. 
A)  appear to coincide with the location of the central galaxy responsible for the jets. 
B)  are where hot excited gas interacts with the intergalactic medium. 
C)  are only found near quasars. 
D)  produce enough visible energy to be imaged at visible wavelengths. 
E)  are always perpendicular to each other.

Question 16

A ____ generally contains well over 1000 galaxies and is quite dense. They often contain many giant elliptical galaxies.

Accepted Answer

A)  local group 
B)  poor cluster 
C)  rich cluster 
D)  tidal tail 
E)  quasar 
A)  local group 
B)  poor cluster 
C)  rich cluster 
D)  tidal tail 
E)  quasar

Question 17

What factors are important when trying to classify a spiral galaxy?

Accepted Answer

A)  amount of dust and gas in the galaxy 
B)  structure of the spiral arms 
C)  size of the central region 
D)  All of the these are important. 
A)  amount of dust and gas in the galaxy 
B)  structure of the spiral arms 
C)  size of the central region 
D)  All of the these are important.

Question 18

What distance methods is(are) used to calibrate the Hubble constant?

Accepted Answer

A)  parallax 
B)  supernova observations 
C)  variable stars 
D)  both a and b 
E)  both b and c 
A)  parallax 
B)  supernova observations 
C)  variable stars 
D)  both a and b 
E)  both b and c

Question 19

Many disk galaxies, such as Andromeda and the Milky Way, are thought to have extended halos of dark matter because the disk circular orbital speed is observed to ____________ increasing distances from the disk center.

Accepted Answer

A)  stay constant with 
B)  decrease with 
C)  be totally absent at 
A)  stay constant with 
B)  decrease with 
C)  be totally absent at

Question 20

The hydrogen Balmer line H$\beta$ has a wavelength of 486.1 nm in the laboratory. It is observed in a quasar at 2430.5 nm. What is the change in wavelength (in nm) of this quasar? Is it a "redshift" or "blueshift"?

Accepted Answer

A)  0; no change 
B)  2430.5; redshift 
C)  486.1; blue shift 
D)  1944.4; blueshift 
E)  1944.4; redshift 
A)  0; no change 
B)  2430.5; redshift 
C)  486.1; blue shift 
D)  1944.4; blueshift 
E)  1944.4; redshift

Explain why good distance indicators must be luminous objects. Why must they be unambiguously recognizable?

Discuss the observational differences between spiral, elliptical, and irregular galaxies.

The hydrogen Balmer line H _$\gamma$ has a wavelength of 434.0 nm in the laboratory. It is observed in a quasar at 651.0 nm. In terms of the speed of light, c, what is the recessional velocity of this quasar?

The cluster method (motions of galaxies in a cluster of galaxies) can be used to determine the cluster's

The Virgo cluster

What distance method is used to determine the distance to the most distant galaxies?

____________________ Seyfert galaxies are very luminous at X-ray and ultraviolet wavelengths and have broad emission lines in their spectra.

The energy from an AGN is produced by

____ show(s) that some quasars are further away than distant galaxies and that space time is curved by massive objects.

What type of galaxies do astronomers believe to be the most common?

Statistical evidence

____ are produced when two galaxies pass near each other and pull large streamers of stars, gas, and dust away from the galaxies.

Why are there few quasars at low redshifts and at high redshifts but many at redshifts of about 2?

What distance method did Edwin Hubble use to determine the distance to local galaxies?

The hot spots in a double-lobed radio source

A ____ generally contains well over 1000 galaxies and is quite dense. They often contain many giant elliptical galaxies.

What factors are important when trying to classify a spiral galaxy?

What distance methods is(are) used to calibrate the Hubble constant?

Many disk galaxies, such as Andromeda and the Milky Way, are thought to have extended halos of dark matter because the disk circular orbital speed is observed to ____________ increasing distances from the disk center.

The hydrogen Balmer line H_$\beta$ has a wavelength of 486.1 nm in the laboratory. It is observed in a quasar at 2430.5 nm. What is the change in wavelength (in nm) of this quasar? Is it a "redshift" or "blueshift"?

Here and Now

A Users Guide to the Sky

Cycles of the Sun and Moon

The Origin of Modern Astronomy

Light and Telescopes

Atoms and Spectra

The Sun

The Family of Stars

The Formation and Structure of Stars

The Deaths of Stars

Neutron Stars and Black Holes

The Milky Way Galaxy

Modern Cosmology

The Origin of the Solar System

Earth and Moon: Bases for Comparative Planetology

Mercury, Venus and Mars

The Outer Solar System

Meteorites, Asteroids, and Comets

Astrobiology: Life on Other Worlds

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Exam 13: Galaxies: Normal and Active

Explain why good distance indicators must be luminous objects. Why must they be unambiguously recognizable?

Discuss the observational differences between spiral, elliptical, and irregular galaxies.

The hydrogen Balmer line H γ\gammaγ has a wavelength of 434.0 nm in the laboratory. It is observed in a quasar at 651.0 nm. In terms of the speed of light, c, what is the recessional velocity of this quasar?

The cluster method (motions of galaxies in a cluster of galaxies) can be used to determine the cluster's

The Virgo cluster

What distance method is used to determine the distance to the most distant galaxies?

____________________ Seyfert galaxies are very luminous at X-ray and ultraviolet wavelengths and have broad emission lines in their spectra.

The energy from an AGN is produced by

____ show(s) that some quasars are further away than distant galaxies and that space time is curved by massive objects.

What type of galaxies do astronomers believe to be the most common?

Statistical evidence

____ are produced when two galaxies pass near each other and pull large streamers of stars, gas, and dust away from the galaxies.

Why are there few quasars at low redshifts and at high redshifts but many at redshifts of about 2?

What distance method did Edwin Hubble use to determine the distance to local galaxies?

The hot spots in a double-lobed radio source

A ____ generally contains well over 1000 galaxies and is quite dense. They often contain many giant elliptical galaxies.

What factors are important when trying to classify a spiral galaxy?

What distance methods is(are) used to calibrate the Hubble constant?

Many disk galaxies, such as Andromeda and the Milky Way, are thought to have extended halos of dark matter because the disk circular orbital speed is observed to ____________ increasing distances from the disk center.

The hydrogen Balmer line H β\betaβ has a wavelength of 486.1 nm in the laboratory. It is observed in a quasar at 2430.5 nm. What is the change in wavelength (in nm) of this quasar? Is it a "redshift" or "blueshift"?

Here and Now

A Users Guide to the Sky

Cycles of the Sun and Moon

The Origin of Modern Astronomy

Light and Telescopes

Atoms and Spectra

The Sun

The Family of Stars

The Formation and Structure of Stars

The Deaths of Stars

Neutron Stars and Black Holes

The Milky Way Galaxy

Modern Cosmology

The Origin of the Solar System

Earth and Moon: Bases for Comparative Planetology

Mercury, Venus and Mars

The Outer Solar System

Meteorites, Asteroids, and Comets

Astrobiology: Life on Other Worlds

Filters

The hydrogen Balmer line H _$\gamma$ has a wavelength of 434.0 nm in the laboratory. It is observed in a quasar at 651.0 nm. In terms of the speed of light, c, what is the recessional velocity of this quasar?

The hydrogen Balmer line H_$\beta$ has a wavelength of 486.1 nm in the laboratory. It is observed in a quasar at 2430.5 nm. What is the change in wavelength (in nm) of this quasar? Is it a "redshift" or "blueshift"?