Flickering returns as RS Oph reestablishes quiescent conditions following its 2021 nova outburst

TL;DR

This study tracks the reemergence of optical flickering in RS Oph after its 2021 nova outburst, revealing the timeline of accretion disk recovery and system brightness returning to quiescent conditions.

Contribution

It provides detailed observational evidence of the flickering reappearance timeline post-outburst, linking it to the reestablishment of accretion processes in RS Oph.

Findings

Flickering reappeared around day +224 after outburst.

System brightness returned to quiescence by day +260.

Flickering amplitude correlated with system brightness recovery.

Abstract

RS Oph has persistently displayed flickering at optical wavelengths when observed away from its repeating nova outbursts. During the 2006 eruption the flickering disappeared, and this repeated during the recent 2021 event. We have been monitoring RS Oph looking for the reappearance of flickering at B-band following the 2021 outburst. The flickering was still absent (sigma(B)<0.002 mag) on day +210 (counted from nova optical maximum), appeared at sigma(B)=0.008 mag on day +224, and raised to sigma(B)=0.029 mag on day +250. On following dates the amplitude remained large, although fluctuating. The recovery of B-band quiescence brightness by RS Oph begun around day +225 and was completed by day +260. The parallel patterns followed by the rise in system brightness and the reappearance of flickering confirm the central role played in RS Oph by the return to pre-outburst conditions of the accretion disk and the refilling by the RG wind of the immediate circumstellar space.