If you take pictures of a galaxy night after night (or better yet
take pictures of lots and lots of galaxies night after night) you
will find that now and then there is a new, very bright light
source in the galaxy. The new source can often be as bright
as a small galaxy (nearly a billion times as luminous as the
Sun). These spectacular explosions are Supernovae
and one particular type, SNI, have the following properties:
What is going on? Remember the equilibrium of a RGB core or
a WD. degeneracy is balancing gravity.
- SNI - No hydrogen seen in their spectra
- Found in All types of galaxies including ellipticals
- Seen everywhere within galaxies (Halo and Disk)
- Maximum brightness: (!!)
- Supernove searches find per year in other galaxies
Remember the Chandrasekar Limit for WD masses.
The idea is, mass accretion onto a WD in a binary adds enough
mass to the WD to push it over the Chandrasekar Limit. Because of the
funny way degeneracy works, for the same reason the Helium Flash
happens, now in the a-little-bit WD the temperature
shoots up and within second a fusion chain triggers that fuses elements
all the way up to radioactive Nickel.
The WD had a runaway thermonuclear catastrophe! This star
What is RIGHT about this theory?
- Would expect to see these objects in ``old'' populations
(Elliptical galaxies and the halos of Spiral galaxies)
- Models of what happens when you add a little mass to a
WD give the right total luminosity for the explosion
- The prediction of the models that lots of Ni will be produced
in the explosion fit the Light Curves perfectly
Mon Feb 23 18:16:20 PST 1998