Earth is made mostly of metals and rocks. Where did this material come from?
It was produced by nuclear fusion in stars
A stars luminosity is the
total amount of light that the star radiates each second
on a Hertzsprung-Russell diagram, where would we find stars that are cool and luminous
if the distance between us and a star is doubled, with everything else remaining the same, the luminosity
remains the same, but the apparent brightness is decreased by a factor of four
which of the following statements about spectral types of stars is true?
all of the above
what prevents the pressure from increasing as a cloud contracts due to its gravity
thermal energy is converted to radiative energy viz molecular collisions and released as photons
what happens to the rotation of a molecular cloud as it collapses to form a star?
the rotation rate increases and results in a disk of material around a protostar
Which of the following statements about degeneracy pressure is not true?
degeneracy pressure caries with the temperature of the star
What happens when a star exausts its core hydrogen supply?
Its core contracts, but its outer layers expand and the star becomes bigger and brighter
Why does the star grow larger after it exhausts its core hydrogen
hydrogen fusion in a shell outside the core generates enough thermal pressure to push the upper layers outward
What is the diameter of the disk of the Milky Way?
which of the folowing gives the two main assumptions of theoretical models of galaxy evolution?
hydrogen and helium filled all of space and certain regions of the universe were slightly denser than others
what kinds of objects lie in the halo of our galaxy?
what kind sof objects lie in the disk of our galaxy
all the above
where are most heavy elements made?
in stars and supernovae
how are interstellar bubbles made?
by winds of massive stars and supernovae
what can cause a galactic fountain?
multiple supernovae occuring together
What is the upper limit to the mass of a neutron star?
There is an upper limit less than 3 solar masses...
Each of the following is a prediciton of the theory of relativity...
In relativity two people share the same fram of reference only if
they are not moving relative to eachother
Bob is coming at you at a speed of 75 kn...
he sees the ball coming at him 150km/hr
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