the original condensation from which an object forms is created by
A an explosion
B random motion within a cloud
C overall contraction of a cloud
D expansion of the universe
which of the following effects is most important in the initial formation of most celestial objects
B pressure of the gases
C an explosion
D random motion
the contraction of an interstellar cloud to become a star is caused by
A magnetic forces.
B electric forces.
C nuclear forces.
D gravitational forces.
E both (a) and (b) above, for they are closely related.
the formation of a clump depends upon turbulence being overcome by
B magnetic forces
C external forces
D internal pressure
interstellar gas clouds may collapse to form stars if they
A have very high temperatures.
B encounter a shock wave.
C are rich in helium.
D all of these.
the basic property of the molecular cloud that causes its collapse into a star is:
A its own gravitational forces.
B the pressure from surrounding clouds.
C nuclear forces that are as yet not understood.
D gas pressure forces that tend to make such clouds condense.
it is now believed that all objects in the universe formed
A from the collapse of large clouds of gas
B at the same time
C during a universal explosion
D from quasars
star formation takes place in
A interstellar clouds
B intergalactic space
C supernovae remnants
D unknown conditions since it is no longer occurring
the first step in the formation of a star from a cloud of gas is
A local heating in the cloud
B the formation of a local condensation in the cloud
C formation of a local, rapidly rotating vortex in the cloud
D condensation of a few bits of rock in the cloud
during the star formation process the formation of planets depends on
A a strong magnetic field
B a high temperature
C the proper rate of growth of bits of rock as they collect atoms of gas from the cloud
D a close encounter with another star retarding the contraction
which of the following is not considered a possible trigger to begin the collapse of an interstellar gas cloud?
A a shock wave from a supernova.
B a shock wave occurring during the formation of very massive stars.
C a shock wave resulting from radiation from nearby emission nebulae.
D a shock wave passing around the galaxy.
E all of the above are considered likely triggers.
local condensations in clouds are formed of
A gas only
B dust only
C gas and dust
D unknown particles
which of the following does not occur during the formation of stars
A a cloud collapses under its own force of gravity
B a turbulent condensation forms in a large cloud of gas
C a collapsing cloud of gas breaks apart to form a cluster of stars
D planets form within a collapsing cloud of gas
which of the following can trigger star formation
A a heat source
C a supernova explosion
D the passage of a star through a cloud of gas
the formation of a star within a large cloud of gas requires
A gravity to overcome the rotation of the cloud
B gravity to overcome the turbulent motion of the cloud
C a rapidly rotating cloud
D a cloud without any rotation or turbulence
evidence for the general existence of an interstellar medium is
A reddening of the light of distant stars
B radio emission from atoms and molecules in space
C spectral lines in the spectra of stars which don't fit the normal pattern
D all of the above
in which regions of the universe are stars thought to be born?
A in the relatively empty space between the galaxies
B in the centers of globular clusters
C in large clouds of dust and gas
D in the centers of planetary nebulae
the great amount of compression that must take place to form a star is caused by
B the pressure of the surrounding gas pushing in
C nuclear reactions
D collisions with other stars
clouds of gas and dust between stars can be observed by
A reddening of star light
B patches of few stars in regions of many stars
C "unusual" spectral lines in the spectrum
D all of the above
the temperature in an interstellar cloud before star formation is
A a few thousand degrees
B about room temperature
C somewhat below freezing
D only a few degrees above absolute zero
as an object collapses, the force of gravity
A becomes weaker
B eventually disappears
C stays the same
D gets stronger
new stars are formed from
A huge, cool dust and gas clouds
B free space - out of pure energy
C activity in the centers of galaxies
D supernova remnants
the density of gas in a typical interstellar cloud is
A a billion trillion atoms per cubic inch
B a billion atoms per cubic inch
C a thousand atoms per cubic inch
D less than one atom per cubic inch
a fragment of a gas cloud can contract to start star formation
A only if it is less than 80 times as massive as the sun
B unless it is perturbed, as by a supernova explosion which would disrupt it
C if it passes through a spiral arm
D only when its core temperature reaches several million degrees
the formation of a star generally involves
A collapse caused by radiation pressure
B expansion caused by gravity
C collapse under the influence of gravity
D expansion caused by nuclear reactions
star formation begins when
A an entire large cloud begins to collapse
B a small condensation within a cloud begins to collapse
C a light source is created within a cloud
D gravity is turned on in a cloud
the most likely places where stars and planetary systems are forming in the universe are
A in the centers of black holes
B in regions surrounding quasars
C in cool gas and dust clouds
D in the rarified outer space between galaxies
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