The aftermath of nova Centauri 2013 (V1369 Centauri)

Context. Classical nova progenitors are cataclysmic variables and very old novae are observed to match systems with high mass transfer rates and (relatively) long orbital periods. However, the aftermath of a classical nova has never been studied in detail. Aims. We intend to probe the aftermath of a classical nova explosion in cataclysmic variables and observe as the binary system relaxes to quiescence. Methods. We used multiwavelength time-resolved optical and near-infrared spectroscopy for a bright, well-studied classical nova five years after outburst. We were able to disentangle the contribution of the ejecta at this late epoch using its previous characterization, separating the ejecta emission from that of the binary system. Results. We determined the binary orbital period ( P = 3.76 h), the system separation, and the mass ratio ( q ≳ 0.17 for an assumed white dwarf mass of 1.2 M ⊙ ). We find evidence of an irradiated secondary star and no unambiguous signature of an accretion disk, although we identify a second emission line source tied to the white dwarf with an impact point. The data are consistent with a bloated white dwarf envelope and the presence of unsettled gas within the white dwarf Roche lobe. Conclusions. At more than 5 years after eruption, it appears that this classical nova has not yet relaxed.