Thermomagnetic instability in hot discs

A linear stability analysis of ionized discs with a temperature gradient and an external axial magnetic field is presented. It is shown that both hydromagnetic and thermomagnetic effects can lead to the amplification of waves and make discs unstable. The conditions under which the instabilities grow are found and the characteristic growth rate is calculated. The regimes at which both the thermomagnetic and magnetorotational instabilities can operate are discussed.