The adiabatic stability of stars containing magnetic fields. II. Poloidal fields
Abstract
It is shown that, if a star contains a poloidal magnetic field with field lines closed within the star, it is almost certain to suffer from hydromagnetic instabilities with a growth time very much shorter than the thermal time scale of the star. The motions driven by these instabilities are almost entirely parallel to surfaces of constant gravitational potential. The ultimate result of the instabilities is unclear. In the first instance they are likely to become oscillations of finite amplitude. If their wavelengths are short enough they may be damped by resistivity and this could lead to a substantial reduction of magnetic flux in the star.
This simple result will be affected by rotation and the presence of a toroidal component of magnetic field. Neither of these factors is considered in detail in the present paper but it is made plausible that the instabilities might be suppressed if the toroidal magnetic field is comparable in strength with the poloidal field.- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 1973
- DOI:
- 10.1093/mnras/163.1.77
- Bibcode:
- 1973MNRAS.163...77M