Deck 14: Investigating Other Galaxies

Question 1

The Tully-Fisher relation can be used for measuring distance.

Answer 1

True

Question 2

Quasars look like stars and have identical spectra to stars but have a few extra spectral lines in the spectra indicating more chemical elements.

Answer 2

False

Question 3

When two galaxies collide,it is highly likely that the stars in each galaxy will collide.

Answer 3

False

Question 4

An elliptical galaxy has a lot of hot,young,blue stars in its core.

Question 5

The Eddington limit is the maximum diameter that a black hole can have.

Question 6

Rapid fluctuations in the brightness of active galaxies indicate that the region that emits radiation is quite small.

Question 7

Large galaxies in a rich cluster may tend to grow through galactic cannibalism.

Question 8

No known galaxy has its spectra lines shifted toward the blue part of the spectra.

Question 9

The Tully-Fisher relation is mainly used for determining the temperature of a galaxy.

Question 10

The acronym AGN stands for active galactic nuclei.

Question 11

Debates about the nature of so-called "spiral nebulae" were ongoing until about 20 years ago.

Question 12

Gravitational lensing involves using a special type of lens in a telescope to view gravitational waves.

Question 13

Lenticular galaxies are intermediate between spiral and elliptical galaxies.

Question 14

Observations indicate that galaxies arose from the splitting of large gas clouds into smaller gas clouds.

Question 15

Starburst galaxies occur when a rapid and sudden onset of star formation causes it to shine more brightly.

Question 16

A barred spiral galaxy has young,hot,blue stars in its disk.

Question 17

The Milky Way Galaxy is the only large spiral that appears to have the presence of extended halos of dark matter.

Question 18

A rich cluster contains hundreds or even thousands of galaxies,whereas a poor cluster,often called a group,may contain a few dozen.

Question 19

In general,elliptical galaxies are sites of active star formation.

Question 20

As gases spiral in toward a supermassive black hole,some of the gas may be redirected to become two jets of high-speed particles that are aligned perpendicularly to the accretion disk.

Question 21

What assignment is given to a galaxy with a moderately sized nuclear bulge and moderately wound arms starting from a bar through the central part of the galaxy?

A) SBb
B) SBc
C) Sb
D) SBa

Question 22

At the conclusion of the Shapley-Curtis debate in April 1920,the general understanding of the astronomical community toward the "spiral nebulae" was

A) that the "spiral nebulae" were part of the Milky Way Galaxy.
B) that the "spiral nebulae" were distant island universes like the Milky Way Galaxy.
C) still inconclusive.
D) that some "spiral nebulae" were within the Milky Way Galaxy and others were far outside it.

Question 23

Variable stars,such as Cepheid variables and RR Lyrae stars,are used in what important measurement in astronomy?

A) Keeping of accurate time
B) Measurement of the gravitational fields of supermassive black holes by their effect on the star's pulsation rate
C) Measurement of the surface temperatures of stars
D) Measurement of distances to galaxies

Question 24

The method used by Hubble to determine the distance to the Andromeda Galaxy (M31),thereby establishing the concept of separate and individual galaxies throughout the universe,was the

A) measurement of the redshift of the whole galaxy.
B) observation of the apparent brightness of supernovas in M31.
C) measurement of stellar parallax,or apparent motion of stars because of Earth's orbital motion.
D) observation of Cepheid variable stars.

Question 25

In the Hubble classification scheme for spiral galaxies,the tightness of the winding of the spiral arms appears to be directly related to the

A) overall intrinsic size of the galaxy,or the diameter across the spiral arms.
B) number of globular clusters in the halo of the galaxy.
C) age of the galaxy,as determined from the age of its individual stars.
D) size of the central bulge of the galaxy.

Question 26

The results of the 1920 Shapley-Curtis debate on the nature of "spiral nebulae" were inconclusive.What was really needed to provide an answer to the question was

A) a better idea of the size of the Milky Way Galaxy.
B) a better understanding of interstellar extinction.
C) distances to spiral nebulae.
D) a clearer idea of star formation.

Question 27

In determining the distance to a galaxy by using observations of a Cepheid variable star,which of the following is NOT needed?

A) The star's velocity via the Doppler effect
B) The Cepheid's period of variability
C) The type of spectrum of the Cepheid: metal-rich or metal-poor
D) The star's average brightness or apparent magnitude

Question 28

According to the Hubble classification scheme,an Sa galaxy has a(n)

A) round or spherical appearance with a smooth light distribution.
B) large central bulge and broad,smooth,tightly wound spiral arms.
C) irregular shape with no obvious disk or spiral arms.
D) small central bulge and loosely wound spiral arms.

Question 29

Why does the central bulge of a spiral galaxy appear red when compared to the color of the spiral arms?

A) UV light from the very hot stars in the bulge has excited hydrogen gas,which is emitting the red Balmer H_ light as a consequence.
B) There is no star formation there,and the star population is dominated by old,long-lived,low-mass red stars.
C) The light from the stars in this region is not Doppler-shifted by galactic rotation,in contrast to that from spiral arm stars.
D) Dust surrounding the bulge has preferentially scattered the blue light from the bulge stars.

Question 30

The observation by Hubble that demonstrated for the first time that the Andromeda "nebula" was at a very large distance from the Sun,and outside our Galaxy,was that

A) the "nebula" appeared to be rotating night-by-night around a center that was not the center of our Galaxy.
B) Cepheid variable stars appeared to be very faint in the "nebula."
C) stars with characteristics similar to those of our Sun appeared to be absent in this "nebula."
D) globular clusters appeared to be distributed in a halo around the "nebula," a sure sign of a separate galaxy.

Question 31

Distances to a nearby galaxy can be determined most accurately by

A) using pulsating stars as beacons.
B) measuring the chemical compositions of the brightest stars.
C) measuring the shifts of spectral lines from stars in this Galaxy.
D) measuring the total amount of energy received from the galaxy.

Question 32

The Hubble classification for a spiral galaxy with a prominent central bulge and smooth,broad spiral arms is

A) Sc.
B) E0.
C) SBa.
D) Sa.

Question 33

The observational fact about a Cepheid variable star that leads to a measurement of its distance from Earth is that its period of variation is directly related to its

A) absolute magnitude or luminosity.
B) apparent magnitude.
C) speed away from us,using the relativistic effect upon pulsation period.
D) surface temperature.

Question 34

The Andromeda Galaxy (M31)is best described as a(n)

A) extension of the Milky Way.
B) spiral collection of stars,dust,and gas,200,000 light-years across.
C) gaseous nebula,extending for 6° across our sky.
D) vortex surrounding a black hole.

Question 35

A particular galaxy has a nuclear region of more-or-less uniform brightness from which long lanes of stars curve outward.What type of galaxy is this?

A) Lenticular
B) Spiral
C) Elliptical
D) Irregular

Question 36

Which of the following fundamental astronomical questions did Curtis and Shapley debate in 1920 in their famous confrontation?

A) Whether the Sun was at the center of the Milky Way Galaxy
B) Whether the universe was expanding outward in all directions
C) Whether the "spiral nebulae" were part of the Milky Way Galaxy or more distant,separate entities
D) Whether the theory of general relativity could be used to explain the behavior of our universe

Question 37

Who developed the classification system that divides galaxies into spiral,elliptical,and irregular,and classified spirals by the size of their nuclear region and the tightness of winding of their arms?

A) Ejnar Hertzsprung
B) Sir John Herschel
C) Henrietta Leavitt
D) Edwin Hubble

Question 38

An astronomer studying a distant cluster of galaxies finds that several of the galaxies are spiral shaped,with a nuclear region of moderate size and moderately wound arms.How should the astronomer classify these galaxies?

A) Sa
B) Sb
C) SBc
D) Sc

Question 39

What does a spiral galaxy look like when seen edge-on?

A) Round,but without spiral arms because they are hidden
B) A thick line curved into a spiral shape
C) A thick,flat line with a bulge in the center
D) A thick,flat line

Question 40

In the Hubble classification scheme,the four main categories of galaxies include all of the following EXCEPT

A) normal spirals.
B) barred spirals.
C) starbursts.
D) ellipticals.

Question 41

Galaxies are distributed through the universe in

A) clusters,which are grouped into linked superclusters around huge voids (like soap bubbles).
B) isolated clusters containing anywhere from a few dozen galaxies to thousands of galaxies.
C) isolated superclusters,each containing dozens of clusters of galaxies.
D) a random scattering of small clusters of galaxies similar to the Local Group.

Question 42

The largest range of sizes of galaxies is found in which class of galaxies?

A) Barred spiral
B) Elliptical
C) Irregular
D) Spiral

Question 43

The following distance-measuring techniques,arranged in order of the distance for which they are most effective,from smallest to greatest,are

A) Cepheid variables,spectroscopic parallax,Type Ia supernovae,Tully-Fisher relation.
B) Spectroscopic parallax,Tully-Fisher relation,Cepheid variables,Type Ia supernovae.
C) Spectroscopic parallax,Cepheid variables,Tully-Fisher relation,Type Ia supernovae.
D) Cepheid variables,spectroscopic variables,Type Ia supernovae,Tully-Fisher relation.

Question 44

Which of the following statements is NOT characteristic of elliptical galaxies?

A) They are almost devoid of interstellar gas and dust.
B) They stopped forming stars billions of years ago.
C) Different elliptical galaxies appear to be flattened by different amounts.
D) They have a disk and central bulge,but no spiral arms.

Question 45

The largest galaxies in the universe come from which classification group?

A) Giant elliptical galaxies
B) Irregular galaxies
C) Lenticular galaxies
D) Large spiral galaxies like the Milky Way Galaxy

Question 46

Which of the following techniques are NOT used for distance measurement to distant galaxies?

A) Supernova explosions
B) Tully-Fisher relationship
C) Hot white dwarf stars
D) Cepheid variable stars

Question 47

How are galaxies spread throughout the universe?

A) They are grouped into clusters that are spread more-or-less evenly throughout the universe.
B) They are grouped into clusters,which are,in turn,grouped into clusters of clusters (superclusters).
C) Galaxies are densest near the Milky Way Galaxy and become less and less numerous the farther we look out into the universe.
D) Galaxies are spread more-or-less evenly throughout the universe.

Question 48

The Tully-Fisher relationship relies on broadening of the 21-cm radio line in distant spiral galaxies.What causes this broadening?

A) Thermal motion of the gases in the galaxy
B) Random motions of the stars in the galaxy
C) The rotation of the galaxy
D) The general expansion of the universe (Hubble flow)

Question 49

What is the Local Group?

A) A group of about 100 stars within 100 light-years of the Sun,which appears to have been formed in a star cluster at about the same time from similar material
B) The planets Mars,Earth,and Venus,which are similar in physical properties and in orbital positions around the Sun
C) A group of galaxies orbiting around the Andromeda Galaxy M31,all completely separate from the Milky Way
D) A cluster of about 40 galaxies of which the Milky Way is a member

Question 50

Which of the following types of galaxies contains primarily population II,low-mass,long-lived stars?

A) Elliptical
B) Irregular
C) Lenticular
D) Spiral

Question 51

The Tully-Fisher relation provides a method of determining distances to galaxies by estimating the galaxy luminosity from the measurement of what parameter relating to the 21-centimeter atomic hydrogen radio emission line?

A) Its position and Doppler shift
B) The split between its two components
C) Its width
D) Its intensity

Question 52

To an astronomer,what is a "standard candle"?

A) A standard light source that can be placed in a telescope,to which the brightnesses of stars and other objects can be compared
B) Any type of object whose absolute magnitude is known
C) Any galaxy whose redshift has been measured accurately
D) An accurately defined brightness scale for stars and galaxies,such as the magnitude scale

Question 53

Are there types of galaxies in which we can see completely through their centers?

A) No.The intense gravity generated by the central black hole will bend light beams passing through all galaxies,even if they have few stars.
B) Yes.Dwarf galaxies have very few stars that are not closely packed,even near their centers.
C) No.All galaxies have dense central bulges and most contain a central black hole.
D) Yes.Space has been cleared through the centers of some very massive galaxies by their central supermassive black holes,producing a tunnel.

Question 54

Of the following distance measurement techniques,which one can be used to find the farthest distances?

A) RR Lyrae variable star measurement
B) Parallax measurement
C) Cepheid,population I,variable star measurement
D) Type Ia supernova apparent brightness measurement

Question 55

What is an elliptical galaxy?

A) A galaxy with an elliptical outline and a smooth distribution of brightness (no spiral arms)
B) A spiral galaxy seen from an angle (not face-on),giving it an elliptical profile
C) Any galaxy with an elliptical halo when observed at radio wavelengths
D) A spiral galaxy with an elliptical central bulge,and the spiral arms starting from the ends of the ellipse

Question 56

The Hubble classification for a very flat elliptical galaxy is

A) SBc.
B) Sc.
C) E0.
D) E7.

Question 57

What is a rich cluster of galaxies?

A) A cluster with a high-metal content
B) A cluster with more spiral than elliptical galaxies
C) A cluster (like our Local Group)that contains at least two large galaxies
D) A cluster containing thousands of galaxies

Question 58

What is the Tully-Fisher relation?

A) The more distant the galaxy,the fainter it appears.
B) The more distant the galaxy,the greater the recessional velocity.
C) The brighter the Cepheid,the longer the pulsation period.
D) The brighter the galaxy,the wider the 21-cm radio emission line.

Question 59

Which of the following types of galaxies contain little or no interstellar dust or gas?

A) Elliptical
B) Barred spiral
C) Spiral
D) Irregular

Question 60

What is a lenticular (S0)galaxy?

A) A galaxy with a lot of gas and dust and no particular structure
B) A spiral galaxy with fuzzy and poorly formed spiral arms
C) A galaxy with a smooth brightness profile,lacking the central bulge and disk of a spiral galaxy
D) A galaxy with a disk and central bulge like a spiral galaxy,but with no spiral arms

Question 61

A starburst galaxy appears to be a galaxy in which

A) essentially all of the star formation took place in a single,billion-year-long burst early in the life of the galaxy.
B) a central,supermassive black hole is throwing jets of gas and stars out from the nucleus into intergalactic space.
C) most of the energy from the galaxy is being produced by supernovae.
D) a collision with another galaxy has produced a burst of star formation.

Question 62

Which single major problem perhaps concerns astronomers the most as they attempt to interpret the properties and behavior of clusters of galaxies?

A) The presence of star formation in many galaxies,long after it is expected to have died out
B) The problem that at least 10 times more mass is needed for galactic cluster stability than is observed in visible material
C) The structure and motion of spiral arms in galaxies in many clusters
D) The excessive rate of supernova occurrence in galaxies in some clusters

Question 63

The rotation curve of a galaxy is a graph showing the galaxy's speed of rotation at different distances from the center.The observed rotation curve in the outer parts of a typical large spiral galaxy

A) decreases suddenly to zero at the outer edge of the visible galaxy.
B) decreases smoothly with increasing distance from the center,following a Keplerian curve.
C) is quite flat (roughly the same speed at all distances).
D) increases drastically with increasing distance from the center,as shown by the spiral arms.

Question 64

In order for gravitational lensing of a distant quasar to occur,the galaxy producing the lensing must

A) be rotating rapidly in order to produce the requisite curvature of space to bend the light beam.
B) be almost perfectly placed on a line between Earth and the quasar.
C) contain a supermassive black hole at its center.
D) be a dwarf galaxy,otherwise the quasar's light cannot pass through it and reach Earth.

Question 65

The fact that quasars can be detected from distances where even the biggest and most luminous galaxies cannot be seen means that they

A) must be intrinsically far more luminous than the brightest galaxies.
B) must be in directions where intergalactic absorption by dark matter is minimal,allowing us to see them.
C) must be in directions where gravitational focusing by the masses of nearer galaxies makes them visible from Earth.
D) have not been as redshifted by their motion as have galaxies,and hence they can still be seen.

Question 66

In observations of a double-quasar image produced by gravitational lensing,fluctuations on the intensity of one image appear to be delayed compared to equivalent variations on the other image.Why is this?

A) Rotation of the lensing galaxy has delayed the beam of light on one side compared to the other because of the Doppler effect.
B) One beam has had to pass through material with a greater refractive index than the other beam within the lensing galaxy.
C) The gravitational field of the lensing object slows down the light on one beam compared to the other.
D) The optical path through the gravitational lens producing one image is longer than that for the other image.

Question 67

How are clusters of galaxies spread throughout the universe?

A) They are distributed more-or-less evenly (i.e. ,at random)throughout the universe.
B) They are distributed over the surfaces of large voids,making the universe look like a large collection of soap bubbles.
C) They are distributed with increasing density of galaxies toward some point,which must be the original site of the Big Bang.
D) They are distributed into long lines that cover the universe like a gigantic network of strings.

Question 68

The specific characteristics that identify most quasars are

A) star-like appearance,very high redshifts,and hence very large distances,indicating very energetic sources.
B) that they look like elliptical galaxies,but with high spectral redshifts.
C) spiral galaxy appearance and very high spectral blueshift,indicating that they are coming toward the Sun at high speed.
D) star-like appearance,and very high spectral blueshift,indicating that they are approaching the Sun very rapidly.

Question 69

As much as 90% of the matter in the universe may be unseen "dark matter." Where is this dark matter?

A) It seems to be rather uniformly distributed throughout the universe.
B) It is concentrated in the centers of galaxies,and may,in fact,be related to black holes at galactic centers.
C) It is concentrated in the planes of galaxies,but extends far beyond the visible galactic plane.
D) It appears to be concentrated in spherical haloes around galaxies,but extends several times the radius of visible matter.

Question 70

What is the likely fate of our Milky Way Galaxy within about the next 6-8 billion years?

A) It will collide with the Andromeda Galaxy,triggering new star birth in gas and dust clouds.
B) It will continue to move away from its near neighbor galaxy,M31 in Andromeda,allowing its spiral arms to straighten to form a central bar.
C) Its rate of rotation will slow and its spiral arms will dissipate into intergalactic space as the Galaxy becomes an elliptical galaxy.
D) It will slowly condense under the action of the central supermassive black hole,causing its spin rate to increase.

Question 71

What evidence is there for considerable extra mass within galaxies that does not produce visible light,the so-called "dark matter?"

A) The rotation curve of galaxies,showing orbital speeds of material,remains flat to large distances from the galactic centers and does not follow a Keplerian curve.
B) The appearance of many very dark spots within the galaxy,evidence of numerous low-mass black holes scattered throughout the galaxy
C) Widespread evidence for gravitational lensing of background stars in a galaxy by massive,but invisible,objects in the foreground
D) Intense output of X-rays from very hot gas between the stars,originating in otherwise dark regions

Question 72

Dark matter in clusters of galaxies

A) does not appear to exist.
B) is distributed uniformly throughout the volume of the cluster.
C) is distributed mostly in and around the galaxies in the cluster and not in the voids between galaxies.
D) is distributed mostly in the voids between galaxies and not within the galaxies themselves.

Question 73

The extreme redshifts of quasar spectra are caused by

A) very high recession speeds of the sources away from our Galaxy.
B) the high gravitational fields at the surfaces of these quasars (gravitational redshift).
C) absorption of all but the red parts of the quasar spectrum by intergalactic matter.
D) Zeeman effects from the very intense magnetic fields in the vicinity of the source.

Question 74

What would happen if the Andromeda Galaxy (a spiral about the same size as ours)collided with our own Milky Way Galaxy?

A) The two galaxies would pass through each other,the stars sailing past one another unharmed,while the interstellar gas and dust clouds would collide and stop,thereby becoming extremely heated.
B) The two galaxies would pass through each other almost unchanged,with essentially no interactions at all.
C) The supermassive black holes of the two galaxies would collide and explode,the resulting radiation essentially destroying their stars,planets,and any life forms that there may have been (including us).
D) All of the gas and dust clouds and a great many of the stars would collide with each other,stopping both galaxies and creating a galactic merger.

Question 75

Collisions between galaxies

A) do not occur because the distances between galaxies are so vast.
B) are relatively fleeting because galaxies move so rapidly and thus last only a few million years.
C) can last hundreds of millions of years.
D) have little long-term effect on the galaxies involved because gravity is a relatively weak force and the distances over which it must act between galaxies are so great.

Question 76

Which of the following astronomical objects can be described as follows: "Starlike in appearance;a spectrum showing very high redshift;and energy output of about 1000 galaxies from a small region about 1 light-year across"?

A) A giant molecular cloud
B) A quasar
C) The center of our Galaxy
D) A supernova explosion in a neighboring galaxy

Question 77

Which one of the following statements is TRUE about clusters of galaxies?

A) The mass observed in the galaxies of the cluster is about 10 times larger than the amount needed to hold the cluster together,causing the cluster to collapse.
B) The mass observed in the galaxies of the cluster is typically almost exactly equal to that needed to hold the cluster together.
C) The mass observed in the galaxies of the cluster is many thousands of times too small to hold the cluster together.
D) The mass observed in the galaxies of the cluster is about 10 times too small to hold the cluster together.

Question 78

What is believed to be the origin of giant elliptical galaxies?

A) They grew by devouring smaller galaxies in galactic cannibalism.
B) They have grown continuously since their formation,by accreting intergalactic gas.
C) Collisions between galaxies in the cluster produce a smooth distribution of stars throughout the cluster;these sink by gravity to the cluster center and form giant elliptical galaxies.
D) They formed that way and have remained unchanged ever since.

Question 79

What percentage of the mass required by the cluster's observed gravity,as shown by the speeds of galaxies in the cluster,is represented by the mass of the presently observable matter in a typical rich cluster of galaxies?

A) 10%
B) 100%,or all of the galaxy
C) About 1%
D) 90%

Question 80

One of the consequences of the collision of two galaxies appears to be

A) the disappearance of one of the galaxies into the central supermassive black hole of the other.
B) almost nothing because stars are widely separated in each galaxy and the probability of star-to-star collisions is very small.
C) a burst of vigorous star birth.
D) a very large explosion similar to,but much larger than,a supernova.