When a white dwarf supernova explodes the prime

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When a white dwarf supernova explodes the
prime product of the explosion is radioactive
Nickel-56, which decays into Cobalt-56, then into
Iron-56. (The number of protons plus the number
of neutrons in the nuclei is 56.) Other,
lighter atoms are distributed to interstellar
space too. In a Type II supernova all the heavy
elements up to uranium are produced. All the
gold and silver in your jewelry or in the
fillings in your teeth was produced in Type II
supernova explosions! We are literally
star stuff. The single-star supernova also
produce a huge number of particles called
neutrinos. We detected such particles from the
SN 1987A, which occurred in the Large Magellanic
Cloud, a satellite galaxy of the Milky Way.
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All galaxies in the universe attract each other
by means of the gravitational force. It made
sense to think that the sum total of all this
gravitational attraction would be causing the
expansion of the universe to slow down. However,
when astronomers determined the distances
to faraway Type Ia supernovae, they found that on
average they were too far away for their
velocities of recession. Some mysterious force
was causing an acceleration of the universe. We
now refer to the cause of this acceleration as
Dark Energy. It appears to be a property of the
vacuum of empty space. The universe is not
slowing down. It is speeding up!
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The attraction of the galaxies to each other
caused the universe to be slowing down for a
while, but the Dark Energy eventually took over.
Now the universe is accelerating.
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We have just finished taking 6 seasons of
observations with a 4-m telescope situated at
Cerro Tololo Inter- American Observatory in
northern Chile. We discovered over 200 Type Ia
supernovae, some as far away as 7 billion
light-years. Some of these objects have also
been observed with the Hubble Space Telescope and
the Spitzer Space Telescope.
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The evidence so far indicates that the universe
will expand forever. Many billions of years from
now, when all the gas and dust in the galaxies
has been used up to form stars, and those stars
have become white dwarfs or exploded as Type II
supernovae, the universe will consist of many
faint galaxies that contain nothing but dim
stars. Right now, however, the universe is still
processing its raw material into stars. Some of
those stars end their lives in spectacular
fashion. In one sense these explosions bring
death. In another sense they bring life. All
the heavy atoms such as the calcium in your bones
and the iron in your blood were processed by
stars billions of years ago.