Fermi National Accelerator Laboratory

Previous work has shown that the cooling of SN 1987A excludes a Diracneutrino mass greater than O(20keV) for v_, %, or v,-. We re-examine the emission of wrong-helicity, Dirac neutrinos from SN 1987A, and conclude that due to neutrino degeneracy and additional emission processes (N + N --* N + N + v_, rr+ p _ n + v_) the effect of a Dirac neutrino on the cooling of SN 1987A has been underestimated. We believe that the limit that follows from the cooling of SN 1987A is better--probably much better--than 10 keV. This result is significant in light of the recent evidence for a 17 keV mass eigenstate that mixes with the electron neutrino. (_JASA-Cr_-IBRk4d) GI_AC NEUTRINOS AND SN 19_37A (F_rmi National Accelerator Lab.) 15 p CSCL 20H N91-24865 ...... UncldS G3/72 0019355 ,_ Operated by Universities Research Association Inc. under contract with the United States Department of Energy https://ntrs.nasa.gov/search.jsp?R=19910015551 2019-11-09T23:37:16+00:00Z