Axisymmetric magnetized winds and stellar spin-down

We present 2.5D stationary solar/stellar wind numerical simulation results obtained within the magnetohydrodynamic (MHD) model. This is an extension of earlier work by Keppens & Goedbloed (1999, 2000), where spherically symmetric, isothermal, unmagnetized, non-rotating Parker winds were generalized to axisymmetric, polytropic, magnetized, rotating models containing both a 'wind' and a 'dead' zone. We study the influence of stellar rotation and coronal magnetic field strength on the wind acceleration. Since dynamos in cool stars are thought to operate more efficiently and to produce a stronger coronal magnetic field with increasing stellar rotation rate, we assume this increase is linear. We quantify the stellar angular momentum loss via the magnetized wind with an equatorial dead zone. The obtained spin-down rates are much smaller than values obtained from Weber-Davis wind estimates. The need to invoke a dynamo with magnetic field saturation to lower the spin-down rates for fast rotators is re-evaluated in view of these results.