for B $\geqslant$ 0.6 mG, the magnetic pressure ($P_{B}=B^{2}/8\pi$) was dominating over the thermal pressure ($P_{th}=n_{H}kT$) in the central region ($\simeq$ 6in size or 12000 AU) defined by @Bujarrabal2002. This corresponds to the area mapped by ALMA. Assuming a temperature of 100 K for a region much closer to the central star ($\simeq$0.5or 1000 AU in size, see @SC2018), the lower limit rises to 1 mG.\
Based on the distances where the fields were observed and the strength derived, it is unlikely that a dynamo-like activity would still be at work in OH231.8+4.2 or at least that it would have any dynamical effect in terms of launching, but magnetic fields can still be involved in shaping of the outflows.\
While the main morphology would be defined by the magnetic tower, there is still the possibility that internal shocks or other localised hydrodynamical motions could locally break the symmetry inside the nebula. For example, @Balick2017 using purely hydrodynamical modeling, find that one way to explain the asymmetry in the lobes is to assume that they are created by the interaction of a fast, bipolar wind with an ambient circumstellar envelope, with the former having different speeds, mass-injection rates and opening angles 