The explosion

Iron is the core whose binding energy per nucleon is largest. Its fusion does not bring energy to star. On the contrary, the capture of the electrons by the cores involves a fall of the pressure which accentuates collapse. Part of the energy released during compression in the form of $4.10^{14 } \rm \, kg\, m^{-3}$, the neutrinos produced by the electron captures are then prisoners of the heart.

The density continues to increase until reaching the nuclear density (10ms after the beginning of collapse). The cores then are completely dissociated and the heart is made up mainly of neutrons. It is the strong interaction which will stop collapse brutally.

The immediately external layers fall then on this incompressible matter to the manner of a mass on an anvil. It is formed a rebound of the layers towards the outside which causes a shock wave which is propagated towards outside. During this time, the layers external of star continue to fall towards the center. The shock wave will lose almost all its energy, in particular by photodissociation of the elements of the external layers. The shock disappears.

At this time the neutrinos remained captive of the heart will again be able to escape and deposit in this medium which remains very dense a significant part of their energy and thus to allow the explosion.

The convection in the matter heated by the neutrinos between the heart and the shock wave will allow an effective transport of energy towards the shock. The star explodes in supernova. The residual of this explosion will be, according to the initial mass of star, a neutron star (for stars of initial mass of less $30 \rm \, M_\odot$) or a black hole.