Connecting RS OPh to [some] Type Ia Supernovae

TL;DR

This study investigates the circumstellar environment of the recurrent nova RS Oph to establish its connection with Type Ia supernova progenitors, revealing complex structures consistent with those observed in some supernovae.

Contribution

The paper provides the first detailed spectroscopic analysis of RS Oph's circumstellar material, linking it to features observed in Type Ia supernovae like SN2006X.

Findings

Detection of blue-shifted absorption components indicating circumstellar structures.

Disappearance of narrow absorption features after outburst suggests density enhancements.

Evidence supports recurrent nova eruptions shaping the circumstellar environment.

Abstract

Aims: Recurrent nova systems like RS Oph have been proposed as a possible channel to Type Ia Supernova explosions, based on the high mass of the accreting white dwarf. Additional support to this hypothesis has been recently provided by the detection of circumstellar material around SN2006X and SN2007le, showing a structure compatible with that expected for recurrent nova outbursts.In this paper we investigate the circumstellar environment of RS Oph and its structure, with the aim of establishing a firmer and independent link between this class of objects and Type Ia SN progenitors. Methods: We study the time evolution of CaII, NaI and KI absorption features in RS Oph, before, during, and after the last outburst, using multi-epoch, high-resolution spectroscopy, and applying the same method adopted for SN2006X and SN2007le. Results: A number of components, blue-shifted with respect to the systemic velocity of RS Oph, are detected. In particular, one feature strongly weakens in the first two weeks after the outburst, simultaneously with the disappearance of very narrow P-Cyg profiles overimposed on the much wider nova emission lines of H, He, FeII and other elements. Conclusions: We interpret these facts as the signature of density enhancements in the circumstellar material, suggesting that the recurrent eruptions might indeed create complex structures within the material lost by the donor star. This establishes a strong link between RS Oph and the progenitor system of the Type Ia SN2006X, for which similar features have been detected.