Supernova nucleosynthesis: Models vs. observations

Type II supernovae (SNe II) are linked to massive stars (M>8M.) at the end of their evolution. Gravitational collapse results in a central hot proto-neutron star which cools via neutrino emission. Neutrino opacities and transport determine the neutrino emission luminosity, which is responsible for the heating of outer layers, causing the explosion and ejection of matter. Nucleosynthesis products are effected via two main uncertainties: (i) the locations of the mass cut between the ejects and the remaining neutron star; and (ii) the total explosion energy responsible for explosive nucleosynthesis. Observations of individual supernovae can constrain these quantities. Type Ia supernovae (SNe Ia) are explained by exploding white dwarfs in binary stellar systems. The favored systems are accreting white dwarfs, approaching the (maximum stable) Chandrasekhar mass before contraction and central ignition, Their major uncertainties are related to: (ii) the the accretion rate in the binary system which determines the carbon ignition density; (ii) the flame speed after central ignition; and (iii) a possible transition from a subsonic deflagration to a supersonic detonation. SNe Ia represent the major source of Fe-group nuclei in the Galaxy,