Bounds on exotic-particle interactions from SN1987A

The observation of a neutrino pulse from the supernova SN1987A constrains the production of light exotic particles in the proto neutron star. We derive a new bound on the axion decay constant, ${f}_{a}$\ensuremath{\gtrsim}${10}^{10}$ GeV. If right-handed (RH) neutrinos exist, the ``RH Fermi constant'' is ${G}_{\mathrm{RH}\ensuremath{\lesssim}{10}^{\mathrm{\ensuremath{-}}4}{G}_{\mathrm{F}}}$, 2 orders of magnitude below laboratory bounds. The Dirac mass of ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ can be constrained below laboratory limits.