Limit on the Magnetic Moment of the Neutrino from Supernova 1987A Observations

We consider the possible emission of right-handed neutrinos $v_R$ from SN1987A by neutrinomagnetic-moment interactions. By imposing a bound on the $v_R$ luminosity, we get a limit on the neutrino magnetic moment, ${\mu }_v<(0.2-0.8)\mathrm{}\times {10}^{-11\mathrm{}}{\mu }_B$, depending on the core temperature. It appears that consideration of the number of high-energy ($E\simeq 100-200$ MeV) neutrino events that should have been observed in the underground detectors, after $v_R\to v_L$ rotation in the galactic magnetic field, may lead to a stronger bound, ${\mu }_v<({10}^{-13\mathrm{}}-{10}^{-12\mathrm{}}){\mu }_B$, under specific assumptions.