1. Supernova

2. Carbon Fusion
At 15 MK carbon can fuse with four hydrogen nuclei to create more helium.
At 100 MK carbon can directly fuse with helium to form oxygen.
Both processes release photons.
photons and neutrinos
carbon-12
carbon-12
oxygen-16

3. Core Fusion High mass stars continue beyond helium and carbon fusion.
Higher temperatures
Higher pressures
Deeper layers
Iron is stable and doesn’t fuse without massive added energy.
Fusion steps
Hydrogen to helium
Helium to carbon
Carbon to oxygen
Oxygen to neon
Neon to silicon
Silicon to iron

4. Degenerate electrons
The nuclei from fusion are separated from their electrons.
Very close degenerate electrons
During core fusion degenerate electrons build up.
Electric charge opposes gravity
Opposing forces create enormous stress
inward force of gravity
outward force of electrons

5. Death of Supergiants
A supergiant changes temperature becoming more luminous.
More than 8 M
Core collapses more
Charge loses to gravity
This becomes a type II supernova.
supernovae
Sun

6. Stellar Explosion
When gravitational force exceeds the electron repulsion, the core collapses immediately.
Energy in photons and neutrinos
The outward energy hits collapsing material and the star explodes.

7. Binary Explosions
A binary can transfer gas from a giant to a white dwarf.
Increases white dwarf size
Gravity exceeds electron repulsion
It will explode into a type I supernova.
Brighter than type II
white dwarf
supernova
giant star
gas pulled to partner

8. Supernova Remnants The supernova core collapse is at 200 billion K.
Photon energies enough to break up iron nuclei
Broken nuclei fuse with iron to create heavy elements.
This matter goes to form new stars and planets.