Neutrino mass spectrum and neutrino astrophysics

Neutrino astrophysics, and in particular study of solar and supernova neutrinos, plays an important role in reconstruction of the neutrino mass and mixing spectrum. Observable effects of neutrino mass and mixing are basedon neutrino transformations in matter. The Fermi coupling constant determines immediately the scale of phenomena and applications of the effects. We consider the status the solar neutrino problem. The MSW LMA solution with Δm 2 = (6-7) . 10 - 5 eV 2 and tan 2 0 = 0.35-0.4 gives the best fit of the data. In the case of LMA solution the Earth matter effects allow to explain some features of signals from SN1987A. Future studies of neutrino signals from supernova, and in particular the Earth matter effects on these neutrinos will allow to select or confirm the solution of the solar neutrino problem, identify the type of mass hierarchy (ordering) of the neutrino spectrum and measure or restrict the mixing parameter U e 3 .