Proto-stellar cores

The bounce shock heats up deleptonized matter and rapidly spends most of its kinetic energy to destroy nuclei and produce plenty of free nucleons (n, p). Modified URCA-processes [38] becomes important e + p n + ve, e++n —> p+ue and pair-neutrino annihilation takes place e++e — ve IL-At the typical collapse temperatures T 10 MeV a lot of z/s is produced [168] However, at densities p 1012 g/cm3 the mean free path of 10 MeV neutrinos is by 5-6 orders of magnitude smaller than the size of the proto neutron star (R 50 km) so the opaque neutrinosphere forms. Most of the core collapse neutrinos diffuse out of the neutrinosphere on a time scale 10 seconds. First calculations of v spectra in core collapse SN were performed by D.K. Nadyozhin [108, 109] We should note that subsequent detailed calculations (e.g. [101] and references therein) did not change much these spectra. Thus, the modest 10% fraction of the total neutrino energy released in the core collapse ( 1053 ergs) would be sufficient to unbind the overlying stellar envelope and produce the phenomenon of type II supernova explosion. 

Thermal SN explosion mechanism was proposed by Colgate and White [32], In this picture, part of the neutrino flux liberated in the core collapse is deposited to the stellar mantle to make it unbound ( 1051 ergs is needed). Specific mechanisms include neutrino-driven fluid instabilities, for example convection both above neutrinosphere and inside the proto-NS. Neutrino-driven convection, however, may not be as important as thought before, as follows from recent detailed 2D studies of convection [24], Instead, other fluid instabilities such as newly found double-diffusive instability (the so-called lepto-entropy fingers ) [23], may effectively increase neutrino luminosity to help successful explosion. Note here that process ve -I u(, e1 I e —>7 + 7... 

---