  Recently, surface magnetic field maps had been acquired for a small sample of
active M dwarfs, showing that fully convective stars (spectral types ~M4 and
later) host intense (~kG), mainly axi-symmetrical poloidal fields. In
particular, the rapidly rotating M dwarf V374Peg (M4), believed to lie near the
theoretical full convection threshold, presents a stable magnetic topology on a
time-scale of 1 yr. The rapid rotation of V374Peg (P=0.44 days) along with its
intense magnetic field point toward a magneto-centrifugally acceleration of a
coronal wind. In this work, we aim at investigating the structure of the
coronal magnetic field in the M dwarf V374Peg by means of three-dimensional
magnetohydrodynamical (MHD) numerical simulations of the coronal wind. For the
first time, an observationally derived surface magnetic field map is
implemented in MHD models of stellar winds for a low-mass star. We
self-consistently take into consideration the interaction of the outflowing
wind with the magnetic field and vice versa. Hence, from the interplay between
magnetic forces and wind forces, we are able to determine the configuration of
the magnetic field and the structure of the coronal winds. Our results enable
us to evaluate the angular momentum loss of the rapidly rotating M dwarf
V374Peg.
