2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/47321We show that in a supernova core the longitudinal photon (plasmon) has a space-like dispersion and Cerenkov absorption and emission of such photons is kinematically allowed. If the neutrino has a non-zero magnetic moment, then helicity flipping Cerenkov absorption of a plasmon $ν_L+γ\toν_R$ is the most efficient cooling mechanism of the supernova core, and this allows us to put a restrictive bound on the neutrino magnetic moment $μ_ν~<~0.7\times 10^{-13}μ_B$.2 pages, latex, 2 figuresHigh Energy Physics - Phenomenologytext