magnetic towers and magneto-centrifugal launch. The main distinction between the two models is the distance up to which the magnetic energy density dominates over the kinetic energy. Based on the magneto-hydrodynamics simulations realised by the authors, magneto-centrifugal launch may dominate below $\simeq$100 R$_{star}$ (inside the Alfvén radius). At larger distances the flow is mostly directed by hydrodynamical motions. Magnetic towers on the contrary can have an effective action at much larger scales. We present in Fig.\[Tower\] a model of a magnetic tower, performed with 3D-MHD numerical simulations (see @Huarte2012), with different spatial layers of magnetic field lines which seems to closely mirror the distribution seen in OH 231.8+4.2. The sketch represents the core of the tower only. Knowing the magnetic field intensity of the stellar engine is therefore a key element to determine first, if the field is strong enough to trigger the magnetic launch and then to discern which magnetic launching mechanism applies. The only available data are the extrapolation given by @Leal2012 indicating a surface magnetic field of $\sim$2.5G. But as this value originates from a single H$_{2}$O maser emission located at $\sim$40 AU it cannot be fully established as representative of the stellar surface. @Sabin2014 deduced that 