The wrong-helicity states of a Dirac neutrino can provide an important cooling mechanism for young neutron stars. Based on numerical models of the early cooling of the neutron start associated with SN 1987A which self-consistently incorporate wrong-helicity neutrino emission, we argue that a Dirac neutrino of mass greater than 30 keV (25 keV if it is degenerate) leads to shortening of the neutrino burst that is inconsistent with the Irvine-Michigan-Brookhaven and Kamiokande II data. If pions are as abundant as nucleons in the cores of neutron stars, our limit improves to 15 keV.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)