SUPERNOVAE!
At the end of their lives, stars tend to either fade out completely or
they die in one last burst of energy - explosive burning of Carbon and/or
other heavy elements or in a core collapse which compresses the center of
the star and causes ignition. There are two distinct type of supernovae.
Those objects showing Hydrogen at early times in their spectra are known as
Type II objects while those without are called Type I. There are subclasses
in these types which are determined by their spectral signature as well.
The various types of supernovae are shown in the
figure.
This is an image of Type Ia supernova 1995bd found in the galaxy UGC 3151. This
was a white dwarf star which was accreting matter from a companion and when enough
pressure builds on the outside of the star, carbon inside ignites explosively
and completely destroys the star.
MPEG format Movie of type IIb SN 1993J. You may need
to acquire an mpeg player to show this movie on your computer. This was a core collapse
event. The fuel burned in the core of the star is used up and when radiation pressure
from photons can no longer support the star, gravity takes over and the star collapses.
If you take a basketball (representing the central very heavy matter in the core of the
star) and a tennis ball (representing the lighter elements on the outer layers of the
star and drop them together (the tennis ball on top and touching the basketball), you
will see what happens to the light matter on the outer part of the star when the star
collapses. In many cases, a pulsar or neutron star is formed from the core material
which is not burned explosively.
Other Supernovae
sites.
Last updated: December 15, 2000
