Viscosity Mechanisms in Accretion Disks
Kristen Menou
The self-sustained turbulence that develops in magnetized accretion
disks is suppressed in the weakly ionized, quiescent disks of close
binary stars. Because accretion still proceeds during quiescence,
another viscosity mechanism operates in these systems. An
anticorrelation of the recurrence times of SU UMa dwarf novae with
their mass ratio supports spiral waves or shockwaves tidally induced by
the companion star as the main process responsible for accretion in the
quiescent disks. Other weakly ionized gaseous disks in systems lacking
a massive companion must rely on yet another transport mechanism, or
they could be essentially passive.
Department of Astrophysical Sciences, Princeton University,
Princeton, NJ 08544, USA.