Burst Neutrinos from Nitrogen Flash

Neutrinos give a novel probe to explore deep interior of astrophysical objects, which otherwise is not accessible with optical observations; among notable examples are solar and supernova neutrinos. We show that there is a new class of strong neutrino emission from helium burning, N + alpha --> 18F gamma followed by beta decay 18F --> 18O + e+ + nu_e, that gives a maximum neutrino luminosity of 10^8 times the solar bolometric luminosity at the helium-core flash of a 1 M_sun star, whereas the flash is not observable by optical means. This means that the neutrino flux, of average energy of 0.382 MeV, will be 10% the solar CNO neutrino flux on Earth if the star is located at 10pc.