Neutron rich nuclei and astrophysics

In very high density matter(p > 109g/cm3), neutron rich nuclei become stable instead of ordinary nuclei due to the Fermi sea of degenerate electrons. In the present talk, problems of neutron rich nuclei in supernova cores and their roles on supernova explosion are reviewed. In para. 1, a brief summary of stellar evolution and supernova explosion is given as the introduction. In para. 2, electron captures of nuclei and neutrino trapping in supernova cores are discussed, which play important roles on supernova explosion. In para. 3, recent works about nuclei in neutron rich nuclei in supernova cores are reviewed. In particular, existence of ultra heavy nuclei and their geometrical forms, and also the melting of these nuclei with increasing density of the matter are discussed. para. 4 is devoted for summary and remarks. (author)