Resonance transitions to inert neutrinos in supernovae

Conversions due to magnetic moment or mixing from an electron neutrino into an inert neutrino in supernovae are considered. For supernova densities the matter effect suppresses significantly the conversion rate, but there exist several resonance zones inside the supernova allowing substantial transitions. The effects of the transitions on the observable neutrino spectrum are discussed and it is argued that the magnetic moment of the electron neutrino from the observations of SN 1987 A is limited by μ νe ≤ 2 10 11 μ B which is one order of magnitude less stringent than the previous estimates