The burst from SN1987a

The results of a series of general relativistic stellar evolution calculations of the first 20 seconds in the lives of young neutron stars born in Type II supernovae are presented. For each of these models, the theoretical neutrino burst signatures of SN1987a in both the Kamiokande II and IMB water Cherenkov detectors are calculated. The results are compared to the actual Kamiokande II and IBM SN1987a neutrino data to test the general theory of such bursts and to determine the nature of the residue that now resides inside the LMC supernova. It is concluded that the new neutron star in the LMC has a baryon mass between 1.2 and 1.7 M solar mass and a best-fit gravitational mass between 1.3 and 1.5 m solar mass. The best-fit total energy lost after 20 seconds is ∼ 2.0-2.5x1053 (D/50 kpc)2 ergs. In addition, using all the SN1987a neutrino burst events culled by the Kamiokande II detector and a realistic underlying neutrino source model and spectrum, we have performed a series of Monte Carlo calculations to obtain upper limits with confidence levels for the mass of the electron neutrino (mνe). With conservative assumptions, the upper limits are 14 eV (90%), 16 eV (95%), and 19 eV (99%). These limits are inconsistent with the lower limit quoted by the ITEP collaboration and are lower than all the extant upper limits from tritium decay experiments