Discovery of an old nova shell surrounding the cataclysmic variable V1315 Aql

TL;DR

This paper reports the discovery of a nova shell around V1315 Aql, providing evidence for a previous nova event and supporting the hibernation theory of nova-induced mass transfer cycles.

Contribution

First detection of a nova shell around a novalike, confirming predictions of the hibernation theory and expanding understanding of nova remnants.

Findings

Shell's properties match typical nova shells

Shell's velocity aligns with V1315 Aql's systemic velocity

Supports the existence of previous nova eruptions around novalikes

Abstract

Following our tentative discovery of a faint shell around V1315 Aql reported in Sahman et al. (2015), we undertook deep Halpha imaging and intermediate-resolution spectroscopy of the shell. We find that the shell has its geometric centre located on V1315 Aql. The mass, spectral features and density of the shell are consistent with other nova shells, rather than planetary nebulae or supernova remnants. The radial velocity of the shell is consistent with the systemic velocity of V1315 Aql. We believe this evidence strongly suggests that the shell originates from an earlier nova event. This is the first nova shell discovered around a novalike, and supports the theory of nova-induced cycles in mass transfer rates (hibernation theory) first proposed by Shara et al. (1986).