relatively rapid fluctuations in the electromagnetic output of quasars is an indication of
A the rapid rotation of the sources
B objects moving in front of them from our point of view
C the relatively small size of the emitting regions
D their relative closeness to the milky way
which of the following statements poses the greatest challenge to any viable theory of quasars
A the red shifts of quasars tend to increase as their apparent diameters decrease
B quasars have actual brightnesses which are considerably larger than those of galaxies
C quasars vary their energy output significantly over relatively short spans of time
D quasars look like ordinary stars in an optical telescope
we suspect that quasars are the active centers of galaxies because
A quasar fuzz produces stellar spectra.
B a few quasars have large red shifts.
C some quasars fluctuate rapidly.
D none of these.
which observation seems to indicate that quasars are quite small
A large Doppler shift
B variable light output
C brightest in the infrared
D starlike image
how do astronomers find the distances to quasars?
A by measuring their heliocentric parallax.
B by applying Hubble's law to their red shifts.
C by applying the period-luminosity relationship.
D by applying the mass-luminosity relationship.
the most widely-accepted explanation for the large red shifts of quasars is that
A they obey Hubble's law.
B they are ejected from galaxies.
C of a gravitational red shift.
D of a new physics needed to understand the phenomenon.
which of the following is not true of quasars
A the name means "quasi-stellar-source"
B they show marked radio radiation
C they are receding from us at great speeds
D they are extremely large in diameter
in a quasar, which wavelength is brightest
A ultraviolet
B visual
C infrared
D radio
which of the following statements is the best direct evidence that quasars are not part of our galaxy
A the red shifts of quasars tend to increase as their apparent diameters decrease
B quasars have actual brightnesses which are considerably larger than those of galaxies
C quasars vary their energy output significantly over relatively short spans of time
D quasars look like ordinary stars in an optical telescope
it has been suggested that quasars may be giant
A spiral galaxies
B elliptical galaxies
C irregular galaxies
D black holes
which of the following is not a property of quasars
A they are star like in appearance
B they have large red shifts
C they pulsate very regularly in brightness
D much of their emission is at non-visible wavelengths
the size of the quasars is thought to be
A larger than a normal galaxy
B much less than a galaxy but much larger than a star
C about the size of a star
D about the size of the Earth
which of the following objects is brightest in the infrared
A normal galaxy
B colliding galaxies
C radio galaxy
D quasar ("orthodox" interpretation)
if a supermassive black hole drives the activity of an active galaxy, then
A jets can arise from the outflow of material along the spin axis.
B infalling matter forms an accretion disk around it.
C it must be very large, more than 100 light years in diameter.
D (a) and (b).
E (b) and (c).
the great distances of quasars implied by the large red shifts together wit their faint apparent magnitude tells us that quasars are
A highly massive
B very large in diameter
C high temperature objects
D highly luminous
Arp's discordant red shifts refer to groups of galaxies in which
A different galaxies have different red shifts
B some galaxies become quasars
C quasars are emitted from galaxies
D galaxies are still forming
which of the following objects is brightest
A normal galaxy
B exploding galaxy
C radio galaxy
D quasar
which of the following is not a direct observation of quasars
A they emit radio waves
B their light is variable
C they contain a super-massive black hole
D they are star-like in appearance
quasars emit
A less energy than Jupiter
B more energy than our entire galaxy
C as much energy as the sun
D as much energy as the Orion nebula
the evidence for the small size of quasars comes from
A the amount of energy released by them.
B their distance from us.
C the rapidity of their luminosity changes.
D comparison with cepheid variables.
E the magnitude of their blue shift.
all quasars are
A receding from the Earth
B distant stars of exceptional actual brightness
C small brilliant satellites of normal galaxies
D remnants of supernova explosions
quasars appear to be starlike points in the sky. the real size of a quasar can be estimated from
A its emission lines
B its red shift
C its actual brightness
D the period of its fluctuations
it has been suggested in class that quasars may be powered by
A spiral galaxies
B collapsing clouds of gas
C supernovae explosions
D suppermassive black holes
we have observed evidence for a gravitational lens in
A the existence of quasars
B brightness variation of quasars
C the formation of galaxies
D multiple images of a single quasar
the most widely accepted explanation of the red shift of quasars is
A they are nearby but moving quickly
B gravitational
C new physics
D they obey Hubble's law
if a quasar is the hyperactive nucleus of distant, young galaxies, then you would expect
A quasars to be found in distant clusters of galaxies.
B radio jets extending from quasars.
C the surrounding part of the galaxy to be faintly visible.
D all of the above.
E none of the above.
which of the following objects is smallest
A an average cluster of stars
B a galaxy
C a cluster of galaxies
D a quasar
the best evidence that quasars are at cosmological distances is
A their large observed red shift
B their association with clusters of galaxies having the same red shift
C their association with clusters of galaxies having a very different red shift
D their great luminosity
quasars are the ______ and ______ objects in the universe.
A most violent, closest
B most distant, rapidly receding
C youngest, slowest
D coolest, reddest
which of the following is star-like in appearance
A black holes
B super novae
C nebulae
D quasars
a difficult question for the ejection theory of quasars to answer is
A why none are approaching us
B why they are so small
C why they have such high velocities
D why they emit radio waves
by using the Doppler effect to analyze the light of quasars we conclude that they are
A very far away
B very bright
C very small
D moving very rapidly
the largest red shifts are observed in
A distant ordinary galaxies
B seyfert galaxies
C radio galaxies
D quasars
we place a limit on the size of quasars by
A occultation
B interferometry
C time variations
D the red shift
all quasars have emission lines in their spectra. their existence implies that the quasar contains
A a cool, transparent gas.
B a hot, transparent gas.
C a hot, opaque gas.
D many stars like the sun.
we cannot judge quasars' distance by using their absolute luminosity as we do in the case of galaxies because
A they have no absolute luminosity.
B there are no nearby quasars with which to compare distant ones.
C their luminosity is too great.
D their recessional speeds are unknown.
when we see a gravitational lens we can conclude that
A the lensing galaxy is superluminous
B the quasar must be very small
C the quasar and galaxy must be at about the same distance
D the quasar cannot be a local object
if quasars are the most distant objects known, it is difficult to explain
A why they are so large
B why they are receding from us so rapidly
C how anything could be "beyond" the edge of the big bang universe
D how anything so small could be so bright
one possible energy source for quasars may be
A exploding stars.
B electron collisions.
C rapid quasar rotation.
D supermassive black holes.
which of the following is not an observed characteristic of quasars
A emit radio waves
B small in size compared to normal galaxies
C most distant objects in the universe
D move away from us at very high speed
which of the following does not apply to quasars
A they are very far away
B they are very luminous
C they are brightest in the radio part of the spectrum
D their brightness is not constant?
the most remarkable observed feature of quasars is their large
A red shifts in absorption lines.
B red shifts in emission lines.
C blue shifts in emission lines.
D image, as seen through a large telescope.
quasars are believed to be comparatively small because
A objects as large as galaxies do not generate as much energy as quasars
B they appear as small, bluish stars when photographed
C they can change in intensity in a short period of time
D the resemble stars more than galaxies
quasar absorption lines
A have the same red shift as the emission lines
B have greater red shifts than the emission lines
C have smaller red shifts than the emission lines
D are formed in interstellar space
if quasars are relatively nearby, they may be
A formed during supernovae explosions in our own galaxy
B ejected from galaxies
C forming into normal galaxies
D burned out galaxies
what observational evidence do we have that quasars are relatively small in size, the largest being perhaps a few light years across?
A the light output of quasars varies on time scales of days to a few weeks.
B the lines of the quasars' spectra are greatly red-shifted.
C quasars are barely resolved by optical telescopes.
D the radiation output is too intense to be coming from a large object.
quasars are brightest in what part of the spectrum
A x-ray
B radio
C infrared
D visible
which of the following is true about quasars?
A they seem to be extremely large compared to most galaxies.
B they seem to be very small for the energy released.
C if they are as far away as they seem, they are very energetic.
D both (a) and (c) above.
E both (b) and (c) above.
the red shift of quasars can be explained as
A a velocity Doppler shift
B a gravitational red shift
C an affect of the time dependence of the physical constants
D any, all, or none of these
when viewed through a telescope, a quasar appears to be a
A giant irregular galaxy
B spiral galaxy
C cloud of gas
D star
by comparing and contrasting quasars, active galaxies, and the milky way, we might conclude that
A all are essentially the same thing, except that quasars are larger than active galaxies, which in turn are larger than the milky way
B these objects represent an evolutionary sequence, showing that galaxies evolve to become less violent as the universe ages
C galaxies and similar objects were smaller in the distant past than they are today
D objects which are farther away tend to be brighter
quasars appear to be related to
A globular clusters
B galactic clusters
C nuclei of galaxies
D stars
which of the following ideas is the most difficult to understand or explain if quasars are assumed to be very distant?
A the processes which result in a large amount of energy being generated in a small region of space.
B the large red shift in the emission lines.
C the lifetimes of the quasars.
D the chemical composition of the quasars.
quasars were first discovered because of
A the variation in their brightness
B their unusual color
C their radio emission
D their extraordinary brightness
the significance of Arp's groups of galaxies is that
A it is unusual to find galaxies together
B they don't all have the same red shift
C they have the same red shift but are at different distances
D four out of five galaxies are quasars
quasars are known to be very small, compared to galaxies because of
A their small apparent size
B their radio brightness
C their infrared brightness
D the optical variability
the distances to quasars may be determined by
A measuring the size of the quasar.
B measuring the red shift of emission lines.
C measuring the width of the emission lines.
D looking for cepheid variables in the quasar light output.
if quasars are "young" and very far away they could be
A a first phase in the life of galaxies.
B the original big bang.
C a first phase in the life of a single star.
D all of the above.
E none of the above.
which of the following characteristics do at least some AGN's and quasars have in common?
A nuclear radio jet and outer lobes.
B high luminosity (compared to the milky way).
C small region in nucleus producing energy.
D all of the above.
E none of the above.
according to the giant irregular galaxy theory of quasars, they must
A be very large in size
B have very long lifetimes
C have formed immediately following the big bang
D be very far away
the specific characteristics which identify a quasar are
A spiral galaxy appearance, and very high spectral blue shift
B star-like appearance, and very high spectral red shift
C spiral galaxy appearance, but no spectral shift
D star-like appearance, and very high spectral blue shift
the radio emission from quasars is characteristic of
A thermal emission from a hot body
B thermal emission from a cool body
C nonthermal synchrotron emission
D thermal synchrotron emission
the most conspicuous observed property of quasars is their
A high apparent brightness
B high red shift
C high blue shift
D dramatic appearance on photographs
when photographed, quasars appear to be
A black holes surrounded by matter
B stars
C normal giant galaxies
D irregular galaxies
if the red shifts of quasars arise from the expansion of the universe, then
A quasars must be very small.
B quasars must be very luminous.
C quasars must be local.
D all of these.
judging from their Doppler shift, all quasars
A are moving fast relative to us (compared to speeds of most galaxies).
B are moving away from us.
C are very distant.
D all of the above.
E none of the above.
at least some quasars must be small. the evidence for this is
A their small measured angular diameters
B their high luminosity
C their low measured mass
D their rapid fluctuations in luminosity
the active region of a quasar whose light output varies considerably in a month is
A a light-month in size
B a light-year in size
C the size of the milky way
D unknown in size
quasars
A have very large red shifts
B appear star-like in the sky
C are very small compared to galaxies
D all of the above
which of the following locations in our universe has been suggested as the site of a super-massive black hole?
A the center of our quasar
B the center of the universe, as defined by the universal expansion of the observable universe
C the center of the ring nebula in Lyra, an old star
D the center of the crab nebula, an old supernova remnant
why do astronomers believe that quasars' radiation-producing regions must be relatively small?
A the intensity of their synchrotron emission implies that high-speed electrons are confined in a small volume
B their red shifts imply a strong-gravity (and thus much compressed) source
C they change their brightnesses significantly within a few days, and thus t must be only a few "light days" across at most
D they are ejected at high speeds from "peculiar galaxies" and this is possible only for
objects of relatively low mass
quasars must be small, because they
A have high radial velocities
B are very luminous
C are surrounded by quasar fuzz
D fluctuate rapidly in brightness
quasars were discovered because of
A their brightness relative to galaxies
B their variability
C their size
D their radio emission
the light variability of quasars implies they are small because
A only small objects such as stars are observed to vary
B light changes from the far side take longer to reach us if they are larger
C large objects could not rotate rapidly enough
D great compression is needed to produce so much energy as quickly
quasars are known to occur within galaxies because
A they are always found in clusters of galaxies
B their spectra are like those of galaxies
C they look like ordinary galaxies
D a faint fuzz of galaxy light can be detected around them
in a normal photograph, a quasar looks like
A a faint planet
B a star
C a dwarf galaxy
D a planetary nebula
early attempts to explain the spectrum of the first quasar were unsuccessful because the lines in the spectrum were
A produced by elements not usually found in stars
B emission rather than absorption
C produced by elements at higher temperatures than usually found in stars
D red-shifted much more than normal
if the red shifts of quasars arise from the expansion of the universe, the
A quasars must be very small
B quasars must be very luminous
C quasars must be close to us
D all of these
quasar absorption lines are best explained as produced
A by intervening galaxies
B by the general intergalactic medium
C in the outer envelope of the quasar
D by the interstellar medium in the milky way
one possible mechanism for energy production in quasars is
A frequent collisions of galaxies in the early universe
B frequent collisions of densely packed black holes
C matter from an accretion disk falling into a supermassive black hole
D supernovae detonations of supermassive stars
a quasar is now thought to be
A a very active, very distant star
B a long-lived supernova explosion
C the central core of an active galaxy
D a nearby star, ejected with great violence out of a galaxy
astronomers believe that the "powerhouses" (energy-emitting regions) in quasars are very small because
A quasars have high red shifts
B quasars are extremely bright in radio waves
C quasars show variations on the time scales of weeks or months
D quasars do not put out much energy, so they don't need very large energy- producing
regions
astronomers believe that the source of quasars' enormous energy output is
A millions of concurrent supernova explosions
B mater-antimatter mutual annihilation
C matter falling into very massive "black holes"
D shock waves in very hot, compressed interstellar gas
quasars appear to be star-like points in the sky. the real size of a quasar can be estimated from
A its emission lines
B its red shift
C the period of its light fluctuations
D 21-cm radio emission
which of the following typically has the greatest actual brightness
A quasars
B radio galaxies
C giant elliptical galaxies
D seyfert galaxies
an object which we observe to change in brightness must be small(compared to normal galaxies) because
A large objects cannot change their energy output quickly
B large objects do not pulsate
C the universe is not old enough yet
D light from the distant parts of the object take longer to reach us
all quasars appear to be
A moving in random directions, at high speeds
B relatively close, very bright objects
C moving away from Earth at very high speeds
D very distant, with small actual brightnesses
the traditional explanation of the red shift of quasars is
A they are nearby but moving quickly
B gravitational
C new physics
D they obey Hubble's law
the active regions of quasars are
A larger than normal galaxies
B about the same size as normal galaxies, but much brighter
C about the same size as the solar system, but have greater luminosities than the brightest galaxies
D thought to be the longest-lived objects in the universe, since they have traveled so far
away from us
we suspect that quasars are the active centers of galaxies because
A quasar fuzz produces stellar spectra
B a few quasars have large red shifts
C some quasars fluctuate rapidly
D none of these
if a supermassive black hole drives the nuclear activity of active galaxies, then
A infalling matter forms an accretion disk around it.
B jets can arise from outflows along the spin axis.
C the black hole is probably larger than 1,000 ly in radius.
D (a) and (b).
E (b) and (c).
what observational evidence do we have that quasars are relatively small I size?
A the light output of quasars varies on time scales of days to a few years
B the lines of the quasars' spectra are greatly red shifted
C quasars are barely resolved by optical telescopes
D the radiation output is too intense to be coming from a large object
quasars are thought to be:
A mysterious objects that seem to have no connection with more familiar objects.
B nearby objects that have unknown energy sources.
C very old galaxies.
D very young galaxies.
if quasars obey the Hubble law, then they are
A about as bright as a normal star
B about as bright as a normal galaxy
C much brighter than a normal galaxy
D about as bright as all the galaxies together
which of the following statements is the best direct evidence for the small sizes of quasars
A the red shifts of quasars tend to increase as their apparent diameters decrease
B quasars have actual brightnesses which are considerably larger than those of galaxies
C quasars vary their energy output significantly over relatively short spans of time
D quasars look like ordinary stars in an optical telescope
the _______ quasars lead us to conclude that they are far away.
A odd spectra of
B small size of
C intense radio waves from
D dim light received from
E great red shifts of
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