The stability of magnetic fields in massive stars

The stability of magnetic fields in massive stars is a topic of great interest for its astrophysical implications. The combined role of rotation, stable stratification and heat transport in determining the stability of a predominant toroidal field in radiation zones is briefly reviewed. It is shown that, depending on the basic state, rotation can suppress the instability. Moreover stable stratification strongly inhibit the occurrence of instabilities produced by the toroidal field, thus rendering the possibility of dynamo action in radiative zones rather remote. On the other hand, if thermal conductivity is considered, no stable toroidal field configurations are possible, although the growth time of the instability is comparable with the star evolutionary time-scale.