  We discuss the production of a class of heavy sterile neutrinos $\nu_h$ in
proto-neutron stars. The neutrinos, of mass around $50$ MeV, have a negligible
mixing with the active species but relatively large dimension-5 electromagnetic
couplings. In particular, a magnetic dipole moment $\mu\approx 10^{-6}$
GeV$^{-1}$ implies that they are thermally produced through $e^+ e^-\to \bar
\nu_h \nu_h$ in the early phase of the core collapse, whereas a heavy--light
transition moment $\mu_{\rm tr}\approx 10^{-8}$ GeV$^{-1}$ allows their decay
$\nu_h\to \nu_i \gamma$ with a lifetime around $10^{-3}$ s. This type of
electromagnetic couplings has been recently proposed to explain the excess of
electron-like events in baseline experiments. We show that the production and
decay of these heavy neutrinos would transport energy from the central regions
of the star to distances $d\approx 400$ km, providing a very efficient
mechanism to enhance the supernova shock front and heat the material behind it.
