THE STABILITY OF AN ISOTHERMAL MAGNETIZED ACCRETION DISK

The stability of an isothermal magnetized accretion disk is examined b oth analytically and numerically. We find that acoustic instabilities exist not only in purely viscous disks, but also in disks where viscos ity and magnetic field coexist. The inclusion of magnetic field does n ot change the local stability properties very much, apart from alterin g the numerical values of the growth rates. If the growth rate is requ ired to be greater than the escape rate, the acoustic modes are unstab le only in the long wavelength limit and when some viscosity and magne tic field parameters are larger than certain values. These results are unchanged if a different viscosity prescription is adopted.