Burst Neutrinos from the Nitrogen Flash

Neutrinos provide us with a novel probe in which to explore the deep interior of astrophysical objects that otherwise would not be accessible with optical observations; among the notable examples are solar and supernova neutrinos. We show that there is a new class of strong neutrino emission from helium burning, 14N + α → 18F + γ followed by beta decay 18F → 18O + e+ + νe, that gives a maximum neutrino luminosity of 108 times the solar bolometric luminosity at the helium-core flash of a 1 M☉ star, whereas the flash is not observable by optical means. This means that the neutrino flux, with an average energy of 0.382 MeV, will be 10% the solar CNO neutrino flux on Earth if the star is located at 10 pc.