The Bremsstrahlung Process Nu_Tau ->Nu_e E+ E- Gamma

The bremsstrahlung process ντ → νee eγ is the dominant photon-producing decay of heavy τ neutrinos with mντ > 2me so that this process is instrumental for supernova 1987A constraints on the properties of these particles, notably on their mixing amplitude with νe. We calculate the rate of the bremsstrahlung process as well as the photon spectrum and the angular distribution relative to the spin direction of the parent neutrino. We carefully pay attention to the difference between Dirac and Majorana neutrinos.