DWARF NOVAE AT LOW-MASS TRANSFER RATES

We show that if the inner regions of accretion discs in quiescent dwar f nova systems are removed by magnetic disruption or evaporated by sip hon flows, the remaining disc is globally stable for mass transfer rat es less than or similar to 10(15) g s(-1). This implies that (super)ou tbursts in these systems have to be triggered by an enhanced mass tran sfer from the companion. We suggest that the lack of normal outbursts in WZ Sge results only from its low mass transfer rate and that the vi scosity in its disc does not have to be few orders of magnitude lower than in other quiescent dwarf novae.