as a degenerate gas is heated, it will
A expand
B contract
C neither expand nor contract
D oscillate
a planetary nebula is
A the vastly expanded shell of a dying star.
B a cloud of gas out of which stars form.
C a cloud of cold dust in space.
D the same as a white dwarf.
E a circular ring around a black hole.
inside a white dwarf electrons are stripped from atoms because
A of the high temperature
B of the great density
C the nuclear furnace has turned off
D it is becoming a neutron star
in a degenerate electron gas the outward pressure which keeps the star fro collapsing is
A dependent upon temperature
B dependent upon mass
C independent of temperature
D independent of mass
one of the causes for the phenomenon called a nova is
A the fusion of iron in the core of a massive star.
B the in fall of material onto a neutron star from a white dwarf.
C the transfer of material onto a white dwarf in a double star system.
D the collapse of a proto star.
E the death of a massive star and the formation of a black hole.
a planetary nebula is
A a shell of ejected gases, glowing from light from a central star
B the formation stages of planets around other stars than the sun
C a gas cloud surrounding a planet
D the cloud of gas produced by a supernova explosion
a planetary nebula is
A dust and gas orbiting a planet far from its surface.
B dust and gas orbiting close to a planet's surface.
C gas blown off a dying star.
which of the following is the last stage in the life of a low mass star?
A the crab nebula.
B a cepheid variable.
C a dark nebula.
D a pulsar.
E none of the above.
a nova is associated with
A a giant star with a degenerate core
B a white dwarf in a close binary system
C a white dwarf that exceeds 1.4 solar masses
D a star with an iron core
all novae are thought to involve a
A white dwarf
B main sequence star
C supergiant
D neutron star
when the sun "dies" it will become a
A supernova
B neutron star
C white dwarf
D black hole
according to our present theories, when our sun "dies," what will it become
A a white dwarf
B a black hole
C a supernova
D a red giant
the Pauli exclusion principle says that
A no two stars can be in the same place on the H-R diagram
B a star cannot fuse more than one type of nucleus at a time
C when a perfect gas expands, it has to cool
D two subatomic particles can't occupy the same quantum state
a white dwarf is dense, meaning it has a
A great mass
B solid core
C great mass for its volume
D great opacity
the stellar remnant of a one solar mass star is a
A white dwarf
B neutron star
C pulsar
D black hole
the density of white dwarf stars, compared to the sun's is
A lower
B about the same
C somewhat greater
D much greater
which is not true of white dwarfs:
A they are infrequently seen because stars in the appropriate range of mass are rare in our galaxy
B they are infrequently seen because stars in the appropriate range of massage very slowly
C they are infrequently seen because their actual brightness is very low
D they are roughly the size of the Earth?
all novae we have observed are thought to be
A red stars
B cepheids
C close binaries
D pulsars
why are all known white dwarfs relatively close to the sun.
A white dwarfs are only formed in our neighborhood of the galaxy.
B light from distant white dwarfs has not yet reached the Earth.
C no white dwarfs are bright enough to be seen at great distances.
D light from distant white dwarfs is too red shifted to be seen.
E the statement is false; white dwarfs are seen at all distances from the sun.
a nova explosion could be
A a small-scale supernova explosion
B the source of the "crab nebula"
C a temporary spate of fusion reactions on the surface of a white dwarf star in a binary system
D a temporary spate of fusion reactions on the surface of a solitary white dwarf star
white dwarf stars are extremely faint because they are
A young
B old
C too small to have nuclear reactions
D too hot to emit visible light
when stars less massive than one and a half times the sun die, they become
A supernovae
B novae
C black holes
D white dwarfs
astronomers now believe that a nova is caused by
A the fusion of iron in the core of a massive star
B the in fall of material onto a neutron star
C the transfer of material onto a white dwarf in a double star system
D the death of a massive star and the formation of a black hole
when a star less massive than the sun has consumed all of its nuclear fuel, it becomes a
A white dwarf
B nova
C supernova
D black hole.
whether a star becomes a white dwarf, a neutron star, or a black hole depends on its
A mass
B metal abundance
C helium abundance
D apparent brightness
what is the difference between the sun and a one-solar-mass white dwarf?
A the sun is larger.
B the sun has more hydrogen.
C they have different energy sources.
D all of the above.
E none of the above.
the term "nova" means new. a nova is usually associated with
A proto stars
B main-sequence stars
C older stars in a binary system
D star death
all novae are
A red stars
B cepheids
C sites for the formation of pulsars
D close binaries
a star with a mass of less than 1.4 solar masses will probably end its life as a
A white dwarf.
B neutron star.
C black hole.
D pulsar.
a white dwarf is approximately the same size as
A the sun
B a neutron star
C the Earth
D a large building
a low mass main sequence star will, at death, be a
A black hole
B white dwarf
C neutron star
D supernova
if novas occur in close binary star systems, the source of the nova outburst is
A the collision of the two stars.
B the in fall of matter on the more highly evolved star.
C the explosion of the less highly evolved star.
D the start of helium burning in both stars.
which of the following in not a type of "dead" star
A pulsar
B the sun
C black hole
D white dwarf
novae explosions are caused by
A exploding white dwarfs
B interstellar matter falling onto the surface of a star, usually a white dwarf
C material falling into a black hole
D mass lost from a normal star falling onto a white dwarf companion
the probable fate of our sun is
A to expand as a red giant, undergo a nova outburst and end as a white dwarf
B to expand as a red giant, eventually become a planetary nebula, and end as a white dwarf
C expand, undergo a helium flash, become variable, and eventually to explode as a supernova
D to become a black hole
at some time in its lifetime, the sun will become a
A white dwarf
B blue supergiant
C neutron star
D black hole
immediately after all the hydrogen in the core is used up a 1mo star becomes
A Joan Jett
B a supernova
C a red giant
D a white dwarf
a white dwarf is relatively stable because
A gravity is no longer as strong as it was
B powerful reactions release energy to counterbalance gravity
C the rigid structure of the electrons resists further compression
D matter simply can't be compressed anymore
our sun's destiny is to become
A a supernova
B a white dwarf
C a blue giant
D a neutron star
a white dwarf star is at what stage of its evolution?
A main sequence phase, "middle-aged"
B post-supernova stage, after the explosion of a star
C proto star phase, just after formation
D very late phase of evolution
a white dwarf, compared to a main sequence star of the same mass, would be
A larger in radius
B smaller in radius
C younger
D lower in surface temperature
astronomers believe that our sun will someday become
A a red giant
B the source of a planetary nebula
C a white dwarf
D all of the above
which physical phenomenon keeps a white dwarf star from collapsing inwards upon itself?
A the physical size of the neutrons
B normal gas pressure
C convection currents or updrafts from the nuclear furnace
D electron degeneracy
at which phase of its evolutionary life is a white dwarf star?
A very late for small mass star, in dying phase
B post-supernova phase, the remnant of the explosion
C just at main sequence phase
D early phases, soon after formation
white dwarf stars are generating energy by the
A proton-proton process
B carbon cycle
C triple alpha process
D none of the above
the name "white dwarf" indicates that a star is
A hot and large
B cool and large
C cool and small
D hot and small
white dwarfs cannot be more massive than _____ solar masses
A 0.4
B 1.0
C 1.4
D 2.4
which of the following have diameters of about 10,000 miles
A black holes
B neutron stars
C supernovas
D white dwarfs
stars most frequently die when they
A are unable to sustain high enough temperatures for the next nuclear fuel
B run out of all nuclear fuels
C become so hot they explode
D lose all their matter to slow evaporation into space
at the end of its evolution, our sun will become
A a main sequence star
B a white dwarf
C a pulsar (or neutron star)
D a black hole
the mass of a white dwarf
A is greater than 4 solar masses
B is always much less than the mass of the original star
C is greater than the mass of the original main-sequence star
D is less than 1 solar masses
which of the following is not true of white dwarfs
A they are about the size of the Earth
B they are usually hotter than the sun
C they will eventually explode
D they are much fainter than the sun
white dwarf stars are
A young faint stars on the way to the main sequence
B old dead stars
C small stars whose mass is too low to ever reach the main sequence
D bright, hot stars with most of their radiation falling outside the visible region of the
spectrum
when a star dies, it immediately
A explodes
B expands
C contracts
D stops shining
in degenerate matter
A pressure depends only on temperature
B temperature depends only on density
C pressure does not depend on temperature
D none of these
which is the correct sequence for the following end-points of stellar evolution, in order of increasing mass?
A black hole, neutron star, white dwarf
B neutron star, black hole, white dwarf
C white dwarf, black hole, neutron star
D white dwarf, neutron star, black hole
the collapse of a white dwarf is stopped when
A a new source of energy becomes active
B the electrons become degenerate
C the heat inside the star becomes intense enough
D the electrons combine with the protons to form neutrons
matter ejected by a dying low-mass star is called a
A supernova remnant
B diffuse nebula
C planetary nebula
D herbig-haro objects
a white dwarf star is about the same size as
A new york city
B the sun
C the Earth
D the total solar system
will the sun become a white dwarf?
A yes, but only after it explodes as a supernova
B no, because the sun will remain a red giant star indefinitely
C yes, once it has passed through its red-giant phase
D no, because the sun has too much mass to become a white dwarf
a star was found to have the size of the Earth and the mass of the sun. it was undoubtedly a
A red dwarf
B white dwarf
C super giant
D nova
1.5 solar masses is the upper limit on the masses of
A black holes
B supergiants
C neutron stars
D white dwarfs
a star having a core with less than 1.4 solar masses will end its life as a
A white dwarf.
B black hole.
C neutron star.
D pulsar.
a white dwarf is generating its energy from what source?
A nuclear fusion of hydrogen
B it no longer generates energy, but is just cooling down
C nuclear fission of heavy elements
D gravitational contraction
electron "degeneracy" (in astronomy and physics) is a term used to
A describe conditions during a supernova explosion
B describe conditions within a black hole
C describe matter which is prevented from shrinking due to the rules electrons must obey when packed close together
D describe the outer regions of a red giant star
a star with a mass of less than 1.4 solar masses will probably end its life as a
A white dwarf
B neutron star
C black hole
D pulsar
gravity cannot collapse a white dwarf star because
A the un-ionized atoms of the star are in contact
B fusion prevents any contraction
C electron degeneracy counteracts gravity
D the star's core is too hot
at what stage of its life will our sun become a neutron star?
A right after the main sequence
B right after the red giant stage
C right after it gives off a planetary nebula
D you can't fool me; the sun will never become a neutron star
the fate of an isolated white dwarf is
A to eventually collapse to become a neutron star
B to eject a shell of material and become a planetary nebula
C to explode as a supernova
D to cool until it no longer emits enough light to be seen
a typical white dwarf star:
A has a mass about like that of the sun and is about half the sun's diameter.
B has a mass slightly less than that of the sun and is about the size of the Earth.
C has a mass about a hundredth that of the sun and is about the size of the Earth.
D is so small and insignificant that none will likely ever by observed by astronomers.
white dwarfs are
A cold and heavy
B hot and dense
C luminous and magnetic
D bright and active
in the cores of stars that have ceased their nuclear fusion processes a state can develop where all low energy electron states are filled. then only high velocity, high energy states are available to the remaining electrons. this state is called:
A photo disintegration.
B the chandrasekhar limit.
C the helium flash.
D electron degeneracy.
synchrotron radiation is observed from
A black holes
B pulsars
C supernovae
D ordinary stars.
a star which contracts to one half its original size will be rotating
A at the same rate as before
B at the previous rate
C at 1/4 the previous rate
D at 4 times the previous rate
since the crab nebulae is so young (1000 yrs.) it must be
A small
B expanding rapidly
C very dense
D no choice
the material of a planetary nebulae is
A escaping from the central star
B falling onto the central star
C neither (a) nor (b)
D no choice
to produce detectable synchrotron radiation one must have both high energy free electrons and
A an intense gravitational field
B an intense electrical field
C an intense magnetic field
D superheavy nuclei
the radiation observed from neutron stars is primarily
A x-rays
B infrared
C synchrotron
D gravity waves
the velocity of expansion of the crab nebula is
A about 1000 mi/sec
B too small to be detected
C nearly the speed of light
D randomly different for different parts of the nebula
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