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Issue 6.05

The Astrophysics Spectator

March 25, 2009

Neutrino emission by white dwarfs and neutron stars has dominated the discussion of the past two issues of the web site.  This discussion naturally leads to the most intense neutrino emitters in the sky: the supernova.  This issue I add the “Supernovae” topic path to the web site.  On this path I intend to place articles on the core-collapse and the thermonuclear detonation supernovae.  I debated whether to place these articles on the “Degenerate Objects” path, among the articles on neutron stars and white dwarfs, since supernovae are tied to these objects.  Because supernovae are important enough in their own right, and because their physics is very different from the physics of degenerate objects, I decided to given them their own topic path.

Supernovae play critical roles in galactic evolution and in the study of the universe.  All of the elements heavier than iron are created by supernovae;  without them, we would not live, since many of the elements that compose our bodies would not exist.  The shockwaves generated by the debris of a supernova pushing into the interstellar medium is responsible for many of the hot, ionized regions in our Galaxy.  These regions affects the birth of stars within the Galaxy.  The neutron stars that we see as radio pulsars and x-ray binaries are born in supernovae.  The type Ia supernovae, which are caused by the thermonuclear detonations of white dwarfs, are astronomical tools for measuring distance to the most distant galaxies.  Without the supernova, the universe would have appeared quite different, not that we would have been around to see it.

Next Issue:The next issue of the web site is will appear on or shortly after April 8.

Jim Brainerd

Supernovae

Overview.  Theorists divide supernovae into two types: core-collapse supernovae and thermonuclear detonation supernovae.  The first type occurs when a massive star exhausts its thermonuclear fuel.  The second type occurs when a white dwarf experiences a thermonuclear runaway after becoming gravitationally unstable.  These rare but intense explosions can be seen across the universe.  They are responsible for all of the heavy elements in the universe, and are therefore necessary for human life.  (continue)

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