Previous 2-D MHD studies have shown that a region of strong magnetic field develops at the cloud nose as a result of field stretching. This large magnetic pressure was recognized to play an important role in suppressing MHD instabilities. However, in 3-D we shall see that MHD instabilities develop along the third dimension and are considerably enhanced by the magnetic field trapped in surface corrugations. In particular, the presence of a strong backgroung magnetic field seem to drive magnetically enhanced Rayleigh-Taylor like instabilites that grow on a timescale that is about 2 times faster than in the hydrodynamic case. We compare the cloud evolution for the three studied cases of the field intensity.
Time is expressed in units of crushing time.
Because the cloud body is not stiff, magnetic field lines can anchor themselves to the surface corrugations. They subsequently influence the development of the cloud deformations produced by instabilities so that their trapping becomes more efficient.