2 research outputs found
Two-component magnetohydrodynamical outflows around young stellar objects Interplay between stellar magnetospheric winds and disc-driven jets
We present the first-ever simulations of non-ideal magnetohydrodynamical
(MHD) stellar magnetospheric winds coupled with disc-driven jets where the
resistive and viscous accretion disc is self-consistently described. These
innovative MHD simulations are devoted to the study of the interplay between a
stellar wind (having different ejection mass rates) and an MHD disc-driven jet
embedding the stellar wind. The transmagnetosonic, collimated MHD outflows are
investigated numerically using the VAC code. We first investigate the various
angular momentum transports occurring in the magneto-viscous accretion disc. We
then analyze the modifications induced by the interaction between the two
components of the outflow. Our simulations show that the inner outflow is
accelerated from the central object's hot corona thanks to both the thermal
pressure and the Lorentz force. In our framework, the thermal acceleration is
sustained by the heating produced by the dissipated magnetic energy due to the
turbulence. Conversely, the outflow launched from the resistive accretion disc
is mainly accelerated by the magneto-centrifugal force.}{The simulations show
that the MHD disc-driven outflow extracts angular momentum more efficiently
than do viscous effects in near-equipartition, thin-magnetized discs where
turbulence is fully developed. We also show that, when a dense inner stellar
wind occurs, the resulting disc-driven jet has a different structure, namely a
magnetic structure where poloidal magnetic field lines are more inclined
because of the pressure caused by the stellar wind. This modification leads to
both an enhanced mass-ejection rate in the disc-driven jet and a larger radial
extension that is in better agreement with the observations, besides being more
consistent.Comment: 16 pages, Accepted in A&A 04/08/200