  We analyze the influence of neutrino helicity conversion, $\nu_L \to \nu_R$,
on the neutrino flux from a supernova caused by the interaction of the Dirac
neutrino magnetic moment with a magnetic field. We show that if the neutrino
has a magnetic moment in the interval $10^{-13} \, \mu_{\rm B} < \mu_\nu <
10^{-12} \, \mu_{\rm B}$ and provided that a magnetic field of $\sim 10^{13} -
10^{14}$ G exists in the supernova envelope, a peculiar kind of time evolution
of the neutrino signal from the supernova caused by the resonance transition
$\nu_L \to \nu_R$ in the magnetic field of the envelope can appear. If a
magnetar with a poloidal magnetic field is formed in a supernova explosion,
then the neutrino signal could have a pulsating behavior, i.e., a kind of a
neutrino pulsar could be observed, when it rotates around an axis that does not
coincide with its magnetic moment and when the orientation of its rotation axis
is favourable for our observation.
