Weak Interaction Rates for Stellar Evolution, Supernovae and r-Process Nucleosynthesis

The role of weak interaction processes in the late stage of evolution of massive stars and during supernova explosions is described. Models for calculating the beta-decay, electron capture and neutrino capture rates on nuclei are reviewed. The neutrinos produced in the sun in the weak interaction reaction processes when detected on earth gave rise to the solar neutrino deficit problem. The resolution of this problem is also mentioned. Roughly half the elements heavier than iron are produced through r-process nucleosynthesis. The methods of calculating the beta-decay rates of very neutron-rich nuclei taking part in the r-process are also presented.