Enhanced Mass Transfer in Dwarf Novae of the SU~UMa Type During Their Outbursts and Superoutbursts

Observational data for five dwarf novae of the SU UMa type provide several strong arguments in favor of a significant enhancement in the mass transfer rate during their outbursts and superoutbursts. The mass transfer rates during normal outbursts are estimated from the amount of accreted mass assuming the theoretical mass transfer rate at quiescence, based on models involving gravitational waves. The resulting rates Menh≈0.6-1.8×1017 g/s imply enhancement by a factor of 15-46, which is consistent with observational evidence for VW Hyi and with theoretical predictions. The mass transfer rates during superoutbursts are enhanced to Menh≈3-6×1017 g/s. The corresponding enhancement ratios range from ≈20-60 (when the mass transfer rates at quiescence are obtained under assumption of no enhancement during normal outbursts) up to ≈100 (resulting from the assumption of the theoretical mass transfer rate during quiescence).