Post-Outburst Accretion Resumption in RS Ophiuchi

The latest outburst of the recurrent nova RS Oph occurred in 2006 February. Photometric data presented here show evidence of the resumption of optical flickering, indicating re-establishment of accretion by day 241 of the outburst. Magnitude variations of up to 0.32 mag in the V-band and 0.14 mag in B on time-scales of 600-7000 s are detected. Over the two week observational period we also detect a 0.5 mag decline in the mean brightness, from V ≈ 11.4 to V ≈ 11.9, and record B ≈ 12.9 mag. Limits on the mass accretion rate of ∼ 10−10 ≤ dM/dtacc ≤ 10−9M⊙yr−1 are calculated, which span the range of accretion rates modelled for direct wind accretion and Roche lobe overflow mechanisms. The current accretion rate presents difficulties in explaining the observed recurrence interval by thermonuclear runaway, implying low average accretion rates immediately post–outburst.