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  • Magnetic field amplificatio...
    Dyda, S; Lovelace, R V E; Ustyugova, G V; Koldoba, A V; Wasserman, I

    Monthly notices of the Royal Astronomical Society, 06/2018, Volume: 477, Issue: 1
    Journal Article

    Abstract We numerically investigate the generation of a magnetic field in a protostellar disc via an αΩ-dynamo and the resulting magnetohydrodynamic (MHD) driven outflows. We find that for small values of the dimensionless dynamo parameter αd, the poloidal field grows exponentially at a rate $\sigma \propto \Omega _{\rm K} \sqrt{\alpha _{\rm d}}$, before saturating to a value $\propto \sqrt{\alpha _{\rm d}}$. The dynamo excites dipole and octupole modes, but quadrupole modes are suppressed, because of the symmetries of the seed field. Initial seed fields too weak to launch MHD outflows are found to grow sufficiently to launch winds with observationally relevant mass fluxes of the order of $10^{-9} \,\mathrm{M}_{{\odot }}\,\rm {yr}^{-1}$ for T Tauri stars. This suggests that αΩ-dynamos may be responsible for generating magnetic fields strong enough to launch observed outflows.