STABILITY OF A HOT 2-TEMPERATURE ACCRETION DISC WITH ADVECTION

The effects of radial advection and thermal diffusion were considered in investigating the linear stability of an optically thin, two-temper ature accretion disc. If the disc has very little advection, we prove that the thermal instability exists when the disc is geometrically thi n. However, it disappears in a geometrically slim disc if the thermal diffusion is considered. Moreover, if the disc is advection-dominated, the thermal instability does not exist. We also found that the instab ilities of inertial-acoustic modes exist only in a geometrically thin disc or an advection-dominated disc with a low Mach number, whereas th e Lightman & Eardley viscous instability always disappears in a two-te mperature disc. A simple comparison also showed that an optically thin , bremsstrahlung cooling-dominated disc is generally more thermally un stable than a two-temperature disc if it is not advection-dominated.