which of the following best refutes the theory that galactic evolution proceeds from elliptical to spiral form
A elliptical galaxies consist primarily of old, red stars
B spiral galaxies contain large numbers of old, red stars
C elliptical galaxies are not as flattened as are spirals
D spiral galaxies contain arms that have not wound up
astronomers now speculate that a galaxy's shape depends on all the following except for
A the rate of star formation
B the history of past collisions
C the chemical composition
D the mass
as a galaxy ages, most of the visible stars will be red stars because
A blue stars evolve faster
B blue stars are fainter
C blue stars are obscured by the interstellar medium
D as a galaxy ages the hot stars will become too hot to be visible
which of the following processes would tend to resist a proto galaxy's contraction?
A merging with other proto galaxies
B self-gravitation
C random motions of its component atoms and molecules
D close encounters with other clumps
the current rate of spin of a galaxy depends on
A the original mass of the galaxy
B the "amount of rotation" the galaxy was formed with
C the position of the galaxy in its cluster of galaxies
D the number of stars in the galaxy
which of the following is not a major problem with simple models of galaxy formation?
A the existence of different types of galaxies.
B the origin of disturbances that form galaxies.
C the time required for gravity to cause galaxies to form from local disturbances.
D the cosmic abundances of hydrogen and helium.
the milky way's interstellar gas
A is more massive in total than its halo stars
B is less massive in total than its interstellar dust
C is mostly helium
D is mostly hydrogen
rotation leads to
A collapse
B explosion
C irregular shapes
D regular shapes
which of the following galactic types is rotating most rapidly
A elliptical
B dwarf elliptical
C normal spiral
D irregular
irregular galaxies do not collapse to a very small size because
A all the stars have been ejected from a dense nucleus
B their mass is too low for gravity to be strong
C they are too small for rotation to be important
D of the counterbalancing centrifugal force
most objects in the universe are
A rotating
B stationary
C irregular in shape
D moving in irregular patterns
different galactic shapes are thought to be
A different stages in the life cycle of a galaxy
B determined mainly by the amount of mass originally in the proto galaxy
C purely random phenomena
D determined by the efficiency of star formation in the galaxy
as an object contracts, its rate of rotation
A stays the same
B slows down
C speeds up
D may or may not change
rotation is
A a unique property of planets
B impossible to detect for distant stars
C a figment of our imagination
D common to almost all objects in the universe
during the formation of an object, rotation is caused by
A non head-on collisions of elements forming the object
B random motion during collapse
C motion of gas outside the collapsing cloud
D an explosion
stars a and b in the milky way both have the same absolute brightness and surface temperature, and they both have the same wavelength absorption lines in their spectra. however, star a looks orange (as seen from Earth), while star b looks white. which of the following is true?
A star a is probably farther away than star b
B star b is not moving away from us as fast as star a
C star a probably has a lower percentage abundance of heavy elements than do star b
D star a is more likely to be a population I star than is star b
the density wave which is thought to travel through the galaxy is analogous to
A a water wave
B a sound wave
C a light wave
D all of the above
the shape of a galaxy depends upon its
A mass
B age
C size
D amount of rotation
as evidenced by the concentration of gas and dust in the spiral arms, a density wave has its strongest effect on
A stars
B gas and dust
C star clusters
D binary stars
which of the following is not true of any known galaxies
A they are still contracting
B stars are still forming in them
C they are rapidly rotating
D they contain no clouds of gas
which of the following processes would be most likely to cause a proto galaxy to rotate
A merging with other proto galaxies
B self-gravitation
C random motions of its component atoms and molecules
D close encounters with other clumps
the arms of a spiral galaxy
A consist of stars spiraling into the nucleus
B consist of stars spiraling into the nucleus
C are regions in a relatively uniform disk where star formation is favored
D are regions where star formation is favored because of the tremendous enhancement in
the density of gas and dust
the spiral arms in the disk of a spiral galaxy are
A regions of slightly higher gas density where star formation is occurring
B streams of stars being torn from the nucleus by its rapid rotation
C waves of stars collected from the surrounding disk by the rapid rotation of the nucleus
D regions relatively free of obscuring gas and dust where stars are still visible
elliptical galaxies, spiral galaxies, and irregular galaxies are probably
A galaxies that started with different quantities of dust
B galaxies that started with different amounts of rotation
C the same type of galaxy seen from different angles
D different stages in the evolution of a single galaxy
stars in the halo of the galaxy represent stars that
A formed during the early stages of contraction of the galaxy
B have escaped from the main body of the nucleus
C have been trapped by the galaxy after wandering through intergalactic space
D have recently formed from matter left behind by the contraction of the galaxy
the galactic type which is believed to represent the slowest rotation is
A spiral
B irregular
C elliptical
D seyfert
the main physical characteristic that caused some galaxies to become spirals others ellipticals, and others irregulars seems to have been
A total mass
B initial amount of rotation
C initial rate of star formation
D diameter prior to the beginning of contraction
on the average which of the galactic types is rotating most rapidly
A spiral
B elliptical
C irregular
D peculiar
spiral arms are now explained as
A regions in a nearly uniform disk where star formation is favored
B material stripped from the nucleus by rapid rotation
C material being captured by the nucleus
D features of the original proto-galactic cloud
as an isolated rotating object expands, its rate of rotation must
A increase
B decrease
C remain the same
D change in unpredictable ways
the disk-like shape of our galaxy provides evidence that the early galaxy
A was a strong x-ray emitter
B had a high temperature
C had a strong magnetic field
D rotated
stars in our galaxy
A follow Hubble's law
B are all receding from the galactic center
C rotate around the center of the galaxy
D are all moving toward the galactic center
elliptical galaxies are older than spiral galaxies
A true: star formation has finished and there is little gas and dust
B true: spiral arms have wound up, leading to the elliptical shape
C false: both contain very old stars, although ellipticals have more of them
D false: ellipticals have not yet developed spiral arms
a galaxy will form a disk if
A stars form quickly as the galaxy collapses
B if there is a supermassive black hole in its center
C it begins with a great deal of gas and dust
D if star formation is inefficient so that gas remains when the rotation becomes too fast
as a rotating cloud collapses its rate of rotation
A may decrease slowly
B increases
C may change, but not because of the contraction
D always stays the same
if spiral arms form from self sustaining star formation
A each galaxy should have only two (or four) continuous spiral arms
B numerous fragments of spiral arms should be present
C young galaxies should have loosely wound spiral arms
D spiral arms should persist very long in a galaxy
a rapidly rotating cloud of gas becomes flattened because
A material near the axis of rotation of a sphere is closer to the center
B the rotation increases the force of gravity in the cloud
C rotation force partially counteracts the force of gravity for material near the equator but not near the axis of rotation
D rotation force helps to push in material near the axis of rotation
stars in the halo of our galaxy represent stars that
A formed during the early stages of contraction
B have recently formed from matter left behind by the contraction of the galaxy
C have escaped from the main body of the nucleus
D have been trapped by the galaxy after wandering through intergalactic space
the current theory used to explain the different galactic shapes states that
A galaxies evolve from elliptical to spiral
B galaxies evolve from spiral to elliptical
C the shapes are purely random
D the shapes depend in part on the amount of rotation in the galaxy
the predominance of star formation in spiral arms can be explained as the result of
A the compression of gas and dust during the passage of a density wave
B the arms being really large clumps of extra gas and dust rotating as units
C the enhancement of the heavy elements in the spiral arms
D the additional time available for stellar collapse in spiral arms
since globular clusters are distributed in a sphere around spiral galaxies they must represent
A very young objects
B very old objects
C objects gravitationally captured by the galaxy
D objects ejected by the galaxy
why don't galaxies keep collapsing forever?
A electrical repulsion between stars
B the expansion of the universe
C stars orbit around the center of the galaxy after they form
D gravity is too weak to affect stars which are so far apart
which of the following processes would tend to make a forming galaxy shrink?
A merging with other proto galaxies
B internal gravity of the cloud
C random motions of its component atoms and molecules
D close encounters with other clumps
if in the early collapse of a proto galaxy star formation occurs quickly and early, the result will be a(n)
A elliptical galaxy
B normal spiral galaxy
C barred spiral galaxy
D irregular galaxy
the arms of a spiral galaxy may be
A matter being spun out of a rapidly spinning nucleus
B matter being pulled into a rapidly spinning nucleus
C rapidly spinning matter surrounding a more slowly rotating nucleus
D ripples in a nearly uniform medium
an argument against the evolution of galaxies from spiral to elliptical is the fact that
A both types of galaxies show current star formation
B neither type of galaxy shows current star formation
C both types of galaxies contain equally old stars
D the oldest stars in elliptical galaxies are must older than the oldest sta in spiral galaxies
stars in the halo of a galaxy represent stars that
A have escaped from the galaxy
B have been captured by the galaxy
C formed during the early stages of contraction of the galaxy
D have recently formed from matter left behind by the contraction of the galaxy
as a rotating object collapses, its rate of rotation must
A stay the same
B speed up
C slow down
D slowly change direction
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