Towards the ignition of the explosion

We will consider henceforth that the star which explodes is dwarf white made up of carbon and oxygen to the mass of Chandrasekhar. Even by imposing these constraints, the system is not yet completely described. Significant parameters like the chemical composition of the object and in particular the Carbone/Oxygène report/ratio or the thermal structure remain very badly known.

In particular, report/ratio C/O seems to be included/understood in a range of 0.4 to 0.6, value significantly lower than the majority of the models of explosion of supernovæ of the Ia type. Another problem, involved in the thermal structure of dwarf white, is the influence of convectif process URCA . A radiation of neutrinos by successive $^{21}Ne/^{21}F$ for example) can involve either a cooling, or a reheating even an inversion of variation in temperature towards the center. The abundance of these pairs URCA depends mainly on the metalicity. Moreover, these phenomena are dependent on times, not-rooms, very subsonic and must be modelled on great scales of time. It thus seems very difficult to be able to build digital models giving an account of manner realistic of the evolution of dwarf white right before the explosion.

The models of explosion are thus contingent on definite ad hoc structures in a relatively arbitrary way.

Close to the mass of Chandrasekhar, energy is controlled by balance between the losses by the plasmon of neutrinos and the heating by compression.

With $2.10^9 \rm \, g\, cm^{-3}$, the écrantage of the electrons supports fusions and allows a nuclear generation of energy exceeding the energy lost by the neutrinos.

This stage marks the beginning of the racing of the nuclear reactions which will last a thousand of years. During this period, there is competition between the convection (which dilutes heat) and the nuclear reactions. When the temperature reached $1.5.10^9\rm \, K$, the phenomena of convection become much slower than the phenomena of combustion and carbon and oxygen burn then on the spot. A new balance between generation and transport of energy (by thermal conduction of the electrons) is found but on scales much smaller (typically $10^{-4 } \rm \, cm$).

The flame was born.