redmondscience.files.wordpress.com · web viewgalaxies. how does the density wave model of spiral...
TRANSCRIPT
Galaxies
how does the density wave model of spiral arms explain that they are brighter than the areas between the arms?
A there are more stars per volume in the arms than between them.
B brighter stars are in the spiral arms because they follow along with the arms as they move.
C brighter stars are in the spiral arms because they are formed there and are short lived.
the bluest galaxies with the highest dust content are
A irregular galaxies
B spiral galaxies
C elliptical galaxies
D barred spiral galaxies
when we see the milky way in the sky, we are looking at
A the center of our galaxy
B stars in the plane of the galaxy
C companion galaxies to our own
D the combined light of distant galaxies
a common problem in interpreting the shape of a galaxy is
A it may be partially obscured by clouds of gas and dust
B our perspective may be distorted because it's tilted relative to our line of sight
C stars in our own galaxy are so numerous as to make photographs confusing
D no acceptable theory for the origin of regular shapes exists
infrared studies of the galactic core indicate:
A expanding rings of hydrogen gas.
B a high concentration of hydrogen.
C explosive events.
D a, b, and c.
galactic halo objects are:
A all population I.
B all population ii.
C a mixture of population I and population ii.
D neither population I nor population ii.
the primary use of observations of 21-cm radiation is to determine
A distances to distant stars
B the chemical composition of the interstellar medium
C the spiral structure of the galaxy
D the distance of the sun from the center of the galaxy
the Magellanic clouds are
A satellites of the milky way
B globular clusters
C clouds of hot gas encircling the milky way
D about 2 million ly distant
the biggest and intrinsically brightest galaxies in the universe are member of which group?
A large spirals
B irregular galaxies
C ellipticals
D barred spirals
a cluster of galaxies can contain from ______ up to ______ of galaxies in total.
A millions, billions.
B thousands, millions.
C hundreds, thousands.
D ten, thousands.
E two, thousands.
the most common type of galaxy in the universe, if our cluster is typical, is
A dwarf elliptical and irregular
B giant spiral and elliptical
C quasar
D radio galaxy
which of the following types of galaxies have a small mass and are shaped like footballs?
A supergiant ellipticals.
B dwarf ellipticals.
C spirals.
D irregulars.
which type of galaxy contains the greatest amount of interstellar material
A elliptical
B spiral
C irregular
D all types contain about the same amount of interstellar material
most of the galaxies in rich clusters are
A normal spirals
B barred spirals
C elliptical
D divided equally among all types
which of the following is not true of elliptical galaxies
A they contain mostly old stars
B they have no distinct nucleus
C they are moderately slowly rotating
D they have some clouds of gas
most of the star birth occurs here.
A disk
B spiral arms
C nuclear bulge
D halo
which of the following is not true of spiral galaxies
A they contain some gas and dust
B they rotate relatively rapidly
C they are probably younger than elliptical galaxies
D stars are still being formed in them
we should expect galaxies to collide with each other more often because
A they are large with respect to their separations
B they occur in clusters
C both of these
D none of these
the Magellanic clouds are
A clouds of gas
B dark nebulae
C galaxies of individual stars
D similar to globular clusters
which of the following is not true of elliptical galaxies?
A they have enormous amounts of interstellar material.
B they have very few (if any) young stars.
C they do not have disks or spiral arms.
D they have globular clusters.
which of the following is true of the order of formation of stars and galaxies?
A stars and galaxies started forming at about the same time.
B stars started forming before galaxies.
C galaxies started forming before stars.
D the order of formation of stars and galaxies is not known.
most of the light of normal galaxies is
A radio waves
B emitted by quasars
C trapped in black holes
D emitted by normal stars
radio observations can tell us things about the galaxy that we cannot learn from observations in visible light because
A radio waves are able to pass through clouds of dust.
B stars emit a greater amount of energy in radio wavelengths than in visible wavelengths.
C the velocity of radio waves is greater than that of light.
D our galaxy is spiral in nature.
as the disk of the galaxy evolves, we expect that the
A interstellar medium will have fewer heavy elements.
B star formation will continue.
C spiral arms will slowly disappear.
D stellar corpses will decrease in number.
in order to find out the spiral arm structure of the galaxy, a radio astronomer needs to
A know the galactic rotation curve.
B measure the Doppler shift of 21-cm lines.
C infer the velocities of clouds along the line of sight.
D (a) and (b)
E (b) and (c)
if viewed from another cluster of galaxies, our cluster of galaxies would appear to have
A very few members
B an average number of members
C very many members
D no observable clustering at all
contains most of the galaxy's gas and dust.
A disk
B spiral arms
C nuclear bulge
D halo
the bulge of an ordinary spiral galaxy is similar in characteristics to
A an elliptical galaxy
B an irregular galaxy
C a seyfert galaxy
D a radio galaxy
motions of the components of the galaxy indicate:
A all parts formed at the same time.
B the disk formed before the halo.
C the halo formed before the halo.
D globular and open clusters formed first.
stars in elliptical galaxies are most like stars in
A galactic clusters
B spiral arms
C globular clusters
D the Orion nebula
which of the following types of galaxies have the largest percentage of gas and dust?
A supergiant ellipticals.
B dwarf ellipticals.
C spirals.
D irregulars.
recent observations indicate that superclusters have what kind of overall structure?
A spherical.
B flat.
C elliptical.
D filamentary.
E no shape at all.
the "local group" refers to
A the group of globular clusters surrounding our galaxy
B the stars in the halo of our galaxy
C the group of galaxies to which our galaxy belongs
D no choice
radio maps of our galaxy show spiral arms because
A the arms have high Doppler shifts
B the gas in the spiral arms is hot enough to emit photons
C the dust is denser in spiral arms
D the gas is denser in spiral arms
elliptical galaxies are
A heavily concentrated in a nucleus
B irregular in shape
C older than most other galaxies
D composed mostly of old, red stars
of all the galaxies in our cluster of galaxies, the most common shape is
A spiral
B elliptical
C irregular
D peculiar
which of the following is not true of elliptical galaxies
A they contain some clouds of gas and dust
B they are composed mostly of red stars
C the distribution of light is very uniform
D they may by large or small
which of the following is true of spiral galaxies?
A they have dust lanes in their disks.
B they tend to be bright.
C they have large numbers of young stars.
D a, b, and c are all true of spirals.
the local cluster has more of which type of galaxy?
A elliptical.
B spiral.
C barred spiral.
D irregular.
astronomers now speculate that the galaxy's shape depends on all of the following except for
A the rate of star formation.
B the history of past collisions.
C the chemical composition.
D the mass.
s0 galaxies seem to be
A intermediate between ellipticals and spirals
B intermediate between spirals and irregulars
C intermediate between ellipticals and irregulars
D galactic cannibals
in terms of the number of normal, giant galaxies, our local cluster of galaxies has
A very few
B an average number
C very many
D not enough is known about other clusters
which of the following is not true of irregular galaxies?
A they have little or no interstellar gas and dust.
B they have hot young stars.
C they have h II regions.
D they have globular clusters.
the milky way is which of the following?
A an enormous luminous cloud of gas and dust in the interstellar space.
B a collection of planets with a parent star similar to the solar system.
C a collection of hundreds of billions of stars sometimes called a galaxy.
D a figment of the imagination of early astronomers like, the "seas" of the moon.
when the light of the Andromeda galaxy, our sister galaxy, is analyzed it is characteristic of
A young, massive stars
B low mass stars
C middle aged stars
D old dead stars
the energy source at the center of our galaxy
A is not visible at optical wavelengths
B produces gamma rays
C must be less than a light year in diameter
D all of these
the most common type of galaxy in the local group is
A dwarf
B giant
C peculiar
D giant irregular
which type of galaxy is most common among observable galaxies
A dwarf elliptical and irregulars
B giant spirals
C giant ellipticals
D quasars
when we look at the milky way, we are looking
A at the spiral arm which contains our sun
B at the spiral arm which is on the opposite side of the galaxy to our sun
C along the plane of our galaxy
D at the remnants of a supernova explosion
which of the following is currently occurring in our galaxy: the formation of
A stars
B clusters of stars
C planets
D all of these
the amount of mass in a large cluster of galaxies
A often turns out to be ten or twenty times less than the estimated mass of the galaxies themselves
B cannot be estimated with precision, since we cannot be sure how many galaxies the cluster contains
C often turns out to be greater than the mass we estimate from studying the motions of galaxies within the cluster
D does not suffice to keep the cluster together for more than one or two billion years
if we compare the completion of star formation in various galaxies, the ranking from most complete to least complete star formation is
A spiral, elliptical, irregular
B spiral, irregular, elliptical
C elliptical, spiral, irregular
D irregular, spiral, elliptical
one problem faced by astronomers in trying to figure out the structure of the galaxy is that
A there is no way to measure distances greater than 12,000 ly.
B the galaxy looks the same in all directions from Earth.
C we can only see a small region of the galaxy with optical telescopes because of interstellar dust.
D the galaxy is always changing, so it's hard to pin down a single picture.
observations of matter between clusters of galaxies indicate that this matter appears to be
A nearly nonexistent.
B composed of hot hydrogen.
C composed of intergalactic dust.
D a source of large molecules.
according to the density wave theory of the spiral arms,
A there are about the same number of stars per volume between the spiral arms as in them.
B the number of stars per volume is much greater between the spiral arms than in them.
C the number of stars per volume is much less between the spiral arms than in them.
D the theory predicts nothing about the number of stars per volume of space.
the milky way is
A an irregular galaxy
B an elliptical galaxy
C a spiral galaxy
D a barred spiral galaxy
which galaxy type consists mostly of young, population I stars?
A spiral
B elliptical
C irregular
which of the following statements is most likely to be true, when discussing galactic motions and interactions?
A galaxies occasionally collide with one another, particularly within cluster of galaxies
B galaxies are so closely packed in the universe that they are always interacting with one another
C galaxies are so widely separated that they never interact or collide
D the universe is composed of one giant galaxy of which all observed stars a members, thus, the question of interaction between galaxies is irrelevant
the present density-wave model for spiral structure fails to account for
A the two-arm spiral pattern.
B the origin of the density waves.
C the persistence of spiral arms.
D the content of spiral arms.
the galaxies containing the most dust are
A the irregular galaxies
B the elliptical galaxies
C the spiral galaxies
D the s0 galaxies
astronomers confront the following problems in working out the structure of the galaxy.
A dust cutting out visible light.
B the sun lying in the plane of the galaxy.
C the natural invisibility of spiral arms.
D (a) and (b)
E (b) and (c)
in our galaxy star formation
A is occurring now
B has ceased
C never occurred since the stars had formed before the galaxy condensed
D never occurred since stars survive forever
which of the following galactic types would have no gas or dust
A spiral
B elliptical
C irregular
D peculiar
why can we not be sure we have discovered all the members of the local gro
A some may lie behind the milky way and be obscured from us
B some may be too distant for us to detect
C it is not easy to determine if a galaxy is a member of the local group, or some other cluster
D observations must be carried out from outside the Earth's atmosphere
the largest known galaxies are
A giant ellipticals
B large spirals
C large irregulars
D no choice
what type of galaxy is our milky way?
A elliptical
B spiral
C irregular
D no choice
the Magellanic clouds are
A irregular galaxies
B spiral galaxies
C elliptical galaxies
D distant globular cluster
in finding the bulk physical properties of galaxies, which of these does not require a knowledge of the distance to a galaxy?
A luminosity.
B mass.
C mass-luminosity ratio.
D size (diameter).
E color.
the sun's orbit around the galaxy
A is a random orbit, much like those of the globular clusters.
B is nearly a circular orbit lying in the plane of the galaxy's disk.
C follows along one of the spiral arms.
D slowly moves toward the galactic center as the spiral arms wind tighter around the nucleus.
the sun's galactic motion is toward the center of the galaxy
A correct
B wrong: the sun is moving away from the galactic center
C wrong: the sun's motion is an elongated ellipse
D wrong: the sun moves in a circular orbit
21-cm radiation is produced by hydrogen when
A the electron changes from one orbit to another
B hydrogen is ionized
C the electron in a hydrogen atom changes its direction of spin
D two hydrogen atoms combine to form a hydrogen molecule
the most rapidly rotating type of galaxy is
A spiral
B elliptical
C irregular
D peculiar
as our galaxy ages over the next few billion years it will
A not change at all
B get smaller and become an elliptical galaxy
C get fainter till it fades from view
D contain new generations of stars which are enriched in elements heavier than hydrogen and helium
any galaxy can be defined to be
A any collection of stars
B a collection of millions of stars and gas and dust
C a collection of millions of stars or more
D a spiral collection of millions of stars
which of these might be a photograph of a spiral galaxy?
A one which shows a circular disk containing only old stars
B one which shows a line of stars, gas, and dust passing through a bulbous c
C one which shows a cigar-like distribution of yellow, orange, and red stars only
D an amorphous concentration of young stars and glowing interstellar gas
the local group of galaxies is a group which
A is near to ours by chance
B is the only confirmed cluster of galaxies
C includes our galaxy in a gravitationally bound group
D are not physically associated with each other, but appear together in the sky
from the rotation curve of the galaxy, we infer that its total mass is roughly, in solar masses.
A one million.
B ten million.
C one billion.
D one hundred billion.
E one thousand billion.
which of the following is not evidence of violent activity in the milky way and other galaxies?
A nonthermal radiation from the nucleus.
B large amounts of infrared radiation coming from the center of the galaxy.
C matter being ejected from the nucleus.
D the nuclei of galaxies spin very rapidly.
which of the following have no large clouds of gas
A irregular
B spiral
C elliptical
D our galaxy
which of the following types do not occur as normal sized galaxies
A spiral
B barred spiral
C elliptical
D irregular
the best evidence of the shape of the milky way galaxy comes from the stud of
A o and b type stars
B 21-cm radio signal of neutral hydrogen
C distribution of globular clusters
D Doppler effect
a galaxy composed mostly of old, red stars is probably a
A spiral
B elliptical
C irregular
D peculiar
observation of nearby galaxies indicates that
A all galaxies are spiral in shape
B all galaxies are about the same size
C many galaxies do not occur in clusters
D both giant and dwarf galaxies exist
of all the galaxies that we can see, the most common shape is
A spiral
B elliptical
C irregular
D peculiar
collisions between stars in our galaxy are
A very rare
B common
C undetectable
D impossible
the local group consists of
A one star, nine major planets,, and at least 35 moons
B Vega, Deneb, and Altair
C about 400 billion stars (and their planets if they have any)
D about twenty nearby galaxies including our own
where is the process of galactic cannibalism most likely to be at work?
A in a rich cluster of galaxies
B in intergalactic space, far from clusters
C in barred spirals
D in dwarf ellipticals
density wave model and self-propagating star formation are models for explaining:
A the differential rotation of the galaxy.
B the spiral structure of the galaxy.
C why globular clusters are not found in the galactic disk.
D away the motion that cannot be explained with the known mass of the galaxy.
the light from the nucleus of a spiral galaxy comes mostly from
A red stars
B blue stars
C clouds of gas
D black holes
which of the following is typical of spiral galaxies
A a nucleus which contains young stars
B a halo of very young stars
C large quantities of dust and gas
D none of the above
which one of the following is evidence that the milky way has an active (violent) nucleus?
A observations of some globular clusters ejected from the nucleus with high velocity
B expanding arm at 3 kpc from the nucleus
C the presence of an observed jet of high energy material traveling near the velocity of light near the nucleus
D indications of a massive galactic halo
the conclusion that most galaxies are dwarf galaxies depends directly upon the proper interpretation of
A Hubble's law
B Einstein's theory of relativity
C the uniformity principle of all laws of nature
D the bias introduced by observational selection
some astronomers believe that giant elliptical galaxies are formed from
A the collapse of a small cluster of galaxies into one giant galaxy
B the collisional merging of galaxies in an irregular cluster of galaxies
C stars pulled from nearby galaxies in a cluster by a larger-than-normal elliptical galaxies
D gas ripped from galaxies in compact clusters by tidal forces
which of the following is not a characteristic of elliptical galaxies
A contain mostly old stars
B even distribution of light
C energy primarily from stars
D some gas clouds?
superclusters of galaxies can extend over distances as large as
A hundreds of light years.
B thousands of light years.
C millions of light years.
D hundreds of millions of light years.
it is thought that a black hole is at the center of the galaxy because
A no light comes from that area of the galaxy.
B large amounts of energy come from a small source there.
C motions of objects near the center indicate a large mass there.
D both (a) and (c) above.
E both (b) and (c) above.
if our cluster of galaxies is typical of the universe, which type of galaxy is most common
A dwarf elliptical and irregulars
B giant spirals
C giant ellipticals
D quasars
Edwin Hubble thought perhaps there was an evolution from one galactic type to another. which of the following do modern astronomers believe to be true?
A elliptical galaxies are the oldest and irregular galaxies are the youngest.
B irregular galaxies are the oldest and elliptical galaxies are the youngest.
C spirals are the youngest and ellipticals are the oldest.
D all galaxies are about the same age.
an s0 galaxy looks like
A a large globular cluster
B an irregular galaxy, but they are all the same general shape
C an elliptical galaxy, but shows rudimentary arms
D a spiral galaxy, but lacks arms
objects in the galactic halo:
A have nearly circular orbits and orbit the center in the same direction as the sun.
B have nearly circular orbits that are randomly oriented.
C have nearly circular orbits with retrograde motion.
D have highly elliptical orbits that are randomly oriented.
why is observation of distant parts of the galaxy limited in the visible region?
A interstellar dust blocks visible light.
B the red shift of distant stars makes them difficult to detect.
C opacity of the atmosphere blocks visible light.
D relative motion of the spiral arms makes them difficult to detect.
which galaxy type contains the lowest percentage of gas and dust?
A spiral
B elliptical
C irregular
which of the following is not a characteristic of spiral galaxies?
A a nuclear bulge.
B a flat disk.
C a halo of old stars.
D a, b, and c are all characteristics of spiral galaxies.
the objects you would not expect to find in a spiral arm are
A stars like the sun.
B hot, young o- and b-stars.
C dust clouds.
D galactic or open clusters.
E globular clusters.
the most common type of galaxy visible in a telescope is
A normal sized elliptical and spiral
B dwarf elliptical
C irregular
D quasar
the most common type of galaxy in the universe is believed to be
A spiral
B quasar
C dwarf
D peculiar
in our galaxy
A star creation has come to an end
B the small red dwarfs become white dwarfs within a few million years
C the hot, massive blue supergiants live the shortest lives
D there can't be more than 5,000 white dwarfs in existence
which of the following types of galaxies have the greatest masses?
A supergiant ellipticals.
B dwarf ellipticals.
C spirals.
D irregulars.
in a spiral galaxy with loosely wound arms
A most of the matter is in the nucleus
B the matter is evenly divided between spiral arms and nucleus
C most of the matter is in the spiral arms
D no clear pattern of division exists
what is the distance of the sun from the center of the galaxy?
A 300 light years.
B 3000 light years.
C 30,000 light years.
D 300,000 light years.
E 3 million light years.
in the local group of galaxies, the most common galaxies are
A spiral galaxies.
B irregular galaxies.
C dwarf elliptical galaxies.
D giant elliptical galaxies.
what type galaxy is the milky way?
A elliptical.
B irregular.
C spherical.
D radio.
E spiral.
recent observations show that superclusters have a ______ structure with ______ voids surrounding them.
A spherical, filamentary
B spherical, spherical
C filamentary, spherical
D filamentary, filamentary
in determining the galaxy's spiral arm structure, the main advantage that a radio astronomer has over an optical astronomer is that
A he/she can sleep at night.
B radio telescopes are generally larger than optical telescopes.
C radio waves penetrate interstellar dust more readily than light.
D hydrogen can only be seen with a radio telescope.
the disk nature of our galaxy can be proven by
A the existence of the milky way in our sky
B observations of the rotation of the galaxy
C the existence of young, blue stars in our neighborhood
D observation of a distinct nucleus in our galaxy
which region of the galaxy contains mostly old population II stars?
A core.
B nuclear bulge.
C spiral arms.
D halo.
which type of galaxy may be either giant or dwarf
A spiral
B irregular
C elliptical
D radio
the spectra of stars in distant galaxies appear to be almost identical to the spectra of stars in our own galaxy. why is this important?
A we can measure Doppler shifts in these spectra to determine motions of the galaxies
B the laws of physics governing the formation of these galaxies are similar to the laws of physics governing the formation of our own galaxy
C the relative abundances of chemical elements in these galaxies may be assumed to be fairly similar to the relative abundances measured in our galaxy
D all of the above
which of the following is not a characteristic of elliptical galaxies
A little or no gas and dust
B may be either giant or dwarf
C no young stars
D has a distinct nucleus
the milky way is an example of which type of galaxy?
A barred spiral
B spiral
C elliptical
D irregular
the Magellanic clouds seen from the southern hemisphere are examples of which type of objects?
A irregular galaxies
B supernova remnants
C planetary nebulae
D spiral galaxies
the distribution of blue stars in the galactic plane shows a spiral arm pattern because
A such luminous objects do not live long enough to move out of the arms
B their great masses do not let them overcome the attraction of the arms
C they continue to accumulate new material from the clouds in the arms
D none of the above: the distribution of stars does not show a spiral patter
the solar system is located within
A the galactic halo
B the galactic disc
C the galactic nucleus
D none of the above; the solar system is not located within a galaxy
the galaxies containing the least dust are
A the irregular galaxies
B the elliptical galaxies
C the spiral galaxies
D the barred spiral galaxies
at the center of a rich cluster of galaxies is often a
A barred spiral galaxy
B normal spiral galaxy
C giant elliptical galaxy
D galaxy of randomly determined type
most galaxies occur
A individually
B in pairs
C in clusters of galaxies
D in groups with one ordinary giant galaxy and several dwarf galaxies
which statement is more typical of the stars in the milky way galaxy?
A all going away from each other
B all moving toward the same center
C revolving around a common center
D none of these
the fuzzy band we call the milky way, in the night sky, is actually
A a band of gases
B millions of stars in the flattened part of the galaxy
C simply an illusion
D none of these
the spiral arms in a spiral galaxy
A have about the same density of stars as the regions between the spiral arm
B contain most of the stars in its disk
C are marked by the hot, bright population II stars in the disk
D contain all of its old stars
we believe that little star formation takes place in elliptical galaxies because
A we rarely see any supernova explosions in these galaxies
B they are so small that all of their mass has already been used to form sta
C we do not observe much gas and dust in these galaxies
D all of the above
the type of galaxy that exhibits the largest range of mass and size is the
A barred spiral
B elliptical galaxy
C normal spiral
D irregular galaxy
spiral arm formation in a galaxy may be the result of
A a whirlpool effect as stars spiral into the center of the galaxy
B supernovae explosions blowing stars out of the galaxy as it rotates
C rigid rotation of the galactic disk
D supernovae triggering star formation in the rotating disk of the galaxy
what part of the milky way is the sun located in?
A the halo
B the disk
C the nucleus
D no choice
the milky way in which the sun resides is an example of which type of gala
A elliptical galaxy
B irregular galaxy
C normal spiral galaxy
D it is not a galaxy at all, but a large cluster of stars
the most commonly observed type of galaxy is
A elliptical
B spiral
C irregular
D no choice
which galactic type has a completely uniform appearance without any patchiness
A spiral
B peculiar
C irregular
D elliptical
in which of the following types of galaxy is there very little, if any, dust and gas?
A spirals
B ellipticals
C irregulars
D barred spirals
the sun is presently on the edge of a spiral arm of the galaxy. it will
A remain in the same place relative to the spiral arm for the rest of its life
B orbit the galaxy and repeatedly pass through spiral arms
C move in towards the center of the galaxy along the spiral arm
D none of the above
galactic cannibalism refers to
A binary galaxies
B the merging of galaxies
C galaxies drawing in gas from the intergalactic medium
D none of these
the Andromeda galaxy and the milky way galaxy are both members of
A the Pleiades
B the coma cluster
C a class known as elliptical galaxies
D the local group
the distance to a nearby galaxy could be about
A 8,000 light years
B 27,000 light years
C 1.5 million light years
D 2 billion light years
the type or group of galaxies which contains both the largest and smallest galaxies in the universe is
A spiral galaxies
B irregulars
C barred spirals
D ellipticals
astronomers now know that the most common galaxies are
A globular clusters
B ordinary spirals
C barred spirals
D ellipticals
an elliptical galaxy contains mostly
A lower-main-sequence stars and giants
B upper-main-sequence stars and giants
C upper-main-sequence stars and gas and dust
D roughly equal numbers of upper- and lower-main-sequence stars
spiral galaxies contain
A very little interstellar gas and dust
B mostly old, red stars
C some young, blue stars
D young, blue stars in the nucleus and old, red stars in the spiral arms
emissions from the center of our galaxy
A can be explained as the ordinary emissions of ordinary stars
B can be explained only if an unusual number of very massive stars is present
C must come in part from sources other than stars
D requires the existence of many black holes in the center of the galaxy
21-cm radiation is produced by
A dust
B oxygen
C nitrogen
D hydrogen
we suspect that our galaxy is surrounded by a galactic halo because the disk of the galaxy
A rotates faster than expected in its outer region
B rotates more slowly than expected in its outer region
C rotates faster than expected in its inner region
D rotates more slowly than expected in its inner region
compared with the sun, stars located in the galactic halo are expected to have
A low metal abundances
B metal abundances similar to those in the sun
C metal abundances higher than those in the sun
D none of the above; we have no idea what the metal abundance should be
what type of galaxy has little or no gas or dust
A ellipticals
B spirals
C irregulars
D no choice
large portions of the spiral arms in our galaxy have been traced
A from observations of x-ray sources
B by means of optical telescopes
C from magnitude determinations
D from observations of the 21-cm line of neutral atomic hydrogen
the center of our milky way galaxy can be observed most easily at which of the following wavelengths?
A ultraviolet
B infrared and radio
C visible light
D you can't fool me; we can't see the center of our galaxy at all
the "missing mass" problem refers to
A unseen mass implied to exist by galactic rotation curves
B the mass astronomers believe has been "gobbled up" by enormous black holes in the middle of certain galactic clusters
C the main supporting evidence for the existence of black holes
D the disappearance of mass that was inadvertently left in the open
what technique do astronomers use to see how a galaxy is rotating
A Doppler shift
B measuring the periods of cepheid variables
C measuring the radio luminosity
D we do not know how to measure the rotation of galaxies
the local group is
A the nearest group of stars to the solar system
B the nearest open cluster
C the Andromeda galaxy and its companions
D the cluster of galaxies in which the milky way galaxy is located
the general shape of our galaxy is nearest to that of a(n)
A pear
B egg
C ball
D fried egg
in contrast to spiral galaxies, elliptical galaxies are
A composed of old population I stars
B composed of older stars, and have little dust
C very dusty
D composed of young population I stars
in the milky way galaxy, our solar system is located
A very close to the center
B high above the disk, in the region of the globular clusters
C in the disk, about two-thirds of the way from the center
D no one knows where we are located in the galaxy because all the dust in the disk obscures our view
the spiral arms of our galaxy
A are composed of stars; very few stars are found between the arms
B are the location of the brightest and youngest stars
C are gradually winding up as the galaxy evolves into an elliptical galaxy
D all of the above
elliptical galaxies
A are extremely rare; more than 90 percent of all galaxies are spirals
B are all significantly smaller and less massive than spirals
C generally show much less gas and dust than spirals
D are never seen in clusters of galaxies
the Magellanic clouds are
A galaxies
B h II regions
C spiral arms in the milky way
D a nearby cluster of galaxies
which of the following types of galaxies have star birth taking place now in their disks?
A supergiant ellipticals.
B dwarf ellipticals.
C spirals.
D irregulars.
in a cluster of galaxies, the most common type(s) of galaxy is (are)
A spirals.
B giant ellipticals.
C dwarf ellipticals and irregulars.
D none of these.
we suspect that our galaxy is surrounded by a massive halo because the disk of the galaxy
A rotates faster than expected in its outer region.
B rotates more slowly than expected in its outer region.
C rotates faster than expected in its inner region.
D rotates more slowly than expected in its inner region.
the center of the galaxy is not visible optically because
A it does not emit light.
B it is obscured by intervening dust.
C the galaxy has no center.
D it takes too long for the light to reach us.
according to the density-wave model of spiral structure, the galaxy's spiral arms
A are solid entities, held together by gravity.
B have strong magnetic fields holding them together.
C regions of slightly enhanced density of gas and dust
D are created by shock waves from the galaxy's nucleus.
by studying the rotation curves of distant spiral galaxies, astronomers can measure which property of them?
A age.
B red shift.
C mass distribution.
D distance.
E types of stars.
which part of the galaxy contains most of the milky way's gas and dust?
A core.
B nuclear bulge.
C disk.
D halo.
clusters of galaxies represent
A chance encounters of galaxies passing by each other.
B groups of galaxies held together by gravity.
C chance alignment of galaxies along our line of sight.
D none of the above.
irregular galaxies are
A patches of stars and gas without any form or pattern
B small spiral galaxies.
C small elliptical galaxies.
D galaxies whose original shape has been distorted by a collision
younger stars have more heavy elements because
A old stars destroy heavy elements as they age.
B young stars burn their nuclear fuels faster.
C heavy atoms were made in previous generations of stars.
D all of these.
an "irregular" galaxy
A may be either spiral or elliptical in overall shape
B has neither a flattened nor an ellipsoidal distribution of stars
C is a special type of barred spiral galaxy
D is a galaxy in which star formation has been entirely completed
the rotation curve of a galaxy is a graph showing which parameter plotted against distance from the galactic center?
A thickness of the galactic disk
B the mass of matter inside the distance from the galactic center
C velocity of stars orbiting the galactic center
D mass of cool hydrogen gas
spiral arms appear to be prominent in spiral galaxies because
A all the stars are distributed in a spiral pattern
B cool stars are distributed in a spiral pattern while the hot stars are spread more uniformly
C hot stars are distributed in a spiral pattern while the cool stars are spread more uniformly
D globular clusters are distributed in a spiral pattern around the galaxy
superclusters are ______ characterized by ______ and ______
A small groups of galaxies, spiral, irregular galaxies.
B large groups of galaxies, dust, gas.
C nice looking clusters, shape, color.
D clusters of clusters of galaxies, voids, filaments.
the local group refers to the
A cluster of stars within 100 ly of the sun.
B Virgo and coma clusters plus our galaxy.
C milky way and m 31 plus 20-odd nearby galaxies.
D local region of the largest supercluster yet found.
E new wave band playing at a nearby dance hall.
which of the following would you not expect to find in a spiral arm of the galaxy?
A gas clouds.
B hot stars.
C molecular clouds.
D globular clusters.
a galaxy whose color is reddish compared to a spiral galaxy would be
A barred spiral
B elliptical
C irregular
D indeterminate; color has nothing to do with galaxy type
it is difficult to obtain a clear picture of the spiral structure of our galaxy because
A the interstellar medium obscures the distant stars
B our position in the galaxy gives us poor perspective
C the structure has many irregularities
D all of these
in our galaxy, collisions between stars are
A common
B no longer observed since most stars are now dead
C never observed
D not very violent
our knowledge of the structure of our galaxy is limited partly because
A the structure is too complex to understand
B our perspective is very poor
C very little effort has been expended so far
D our galaxy is too young to have a fixed structure
all of the stars in our galaxy are
A moving in different orbits around the center of the galaxy
B moving away from us
C moving toward us
D moving in completely random directions in space
in spiral galaxies, as the arms become less tightly wound the nucleus becomes
A larger
B smaller
C variable in intensity
D barred
as seen from the Earth, the milky way appears as
A a uniformly bright cloud of glowing gas stretching across the sky
B a spiral arm of our galaxy
C an irregular band of millions of faint stars
D a faint ball of light in the direction of the center of our galaxy
the "zone of avoidance" refers to objects near
A the sun's position in the sky
B the galactic plane
C the galactic pole
D no choice
our view of the galaxy is poor because
A the more distant stars are obscured by the nearby stars
B the more distant stars are obscured by the interstellar medium
C telescopes are not effective instruments for viewing galaxies
D more interesting objects always take priority over observations of our galaxy
the relatively flattened shape of our galaxy can most easily be detected by
A analyzing radio maps of our galaxy
B by observing the milky way
C observing other galaxies
D observing the distribution of stars around the sun.
the spiral structure of our galaxy is most easily demonstrated by
A studying the H-R diagram of globular clusters
B drawing a radio map of interstellar clouds
C studying the velocities of stars around the sun
D direct observations of the nucleus of the galaxy
the most detailed map of our galaxy is obtained by observing
A the position of galactic clusters
B the position of globular clusters
C the positions of all the stars around us
D the Doppler shifts of radio frequency spectral lines