After the explosion

During the explosion, the majority of energy left in the form of neutrinos (nearly 99%), 1% in the form of kinetic energy and only 0.01% in the form of rayonement electromagnetic.

The absence of hydrogen for Ib and helium for the Ic is explained by the stellar wind. As for the Ii-p/ii-l distinction, it comes from the thickness of the hydrogen envelope which modifies opacity. As we saw, the progéniteurs objects are massive stars of short lifespan. These stars are present only in the zones of star formation (mainly arms of the spiral galaxies). The elliptic galaxies correspond to older populations stellar, which explains the gravitational absence of supernovæ in their centre.

The supernova 1987A (Figure 4.2 ), which appeared in the large cloud of Magellan during February 1987, was the first and to date the only astronomical source of neutrinos observed except for the sun.

Figure 4.2: SN1987A appeared in the small cloud of Magellan in February 1987. At left is presented the supernova little time after the explosion, on the right, the star progenitor.

This type of mechanism makes it possible to explain all the types of supernovæ except for the supernovæ of the Ia type.

Lastly, it should be noted that the evolution of the luminosity very strongly depends on the mass of the progenitor object. Indeed, the thickness and the composition of the layers external of star have a very significant influence on the opacity and thus on the quantity of emitted light.