Monochromatic neutrinos from the annihilation of fourth-generation massive stable neutrinos in the Sun and in the Earth

The accumulation of relic fourth-generation heavy neutrinos (of mass 50 GeV) in the Earth and the Sun, which is followed by their annihilation, is considered. The most conservative estimates of the fluxes of monochromatic electron, muon, and tau neutrinos and antineutrinos of energy 50 GeV from the annihilation of heavy neutrinos are 4.1×10^?6 cm^?2 s^?1 from Earth’s core and 1.1×10^?7 cm^?2 s^?1 from Sun’s core, whence it follows that an analysis of data from underground neutrino observatories may furnish additional information about the existence of fourth-generation neutrinos. It is shown that, because of kinetic equilibrium between the arrival of cosmic neutrinos and their annihilation, the existence of new U(1) gauge interaction of fourth-generation neutrinos has virtually no effect on the estimates of the annihilation fluxes of electron, muon, and tau neutrinos.