  We consider a massive Dirac neutrino electric charge and magnetic moment
within the context of the standard model supplied with SU(2)-singlet
right-handed neutrino in arbitrary R_\xi gauge. Using the
dimensional-regularization scheme we start with calculations of the one-loop
contributions to the neutrino electromagnetic vertex function exactly
accounting for the neutrino and other particles masses. We examine the
decomposition of the massive neutrino electromagnetic vertex function and show
that it contains only the four form factors. Then we get the closed integral
expressions for different contributions to the neutrino electric charge and
magnetic form factors. These calculations enable us to follow the neutrino and
corresponding charged lepton masses and gauge-fixing parameters dependence. For
several one-loop contributions to the neutrino charge and magnetic moment, that
were calculated previously by the other authors with mistakes, we find the
correct results. We show that the neutrino charge for massive neutrino is a
gauge independent and vanishing value in the first two orders of the expansion
over the neutrino mass parameter b. In the particular choice of the 't
Hooft-Feynman gauge we also demonstrate that the neutrino charge is zero for
arbitrary mass of neutrino. For each of the diagrams contributing to the
neutrino magnetic moment, we get expressions accounting for the leading and
next-to-leading order in b with the gauge dependence shown explicitly. Each of
the contributions are finite and the sum of all contributions turns out to be
gauge-independent. Our calculations also enable us to get the magnetic moment
of a heavy neutrino.
