V1047 Cen: The First <i>Z</i> And-type Outburst Observed in the Classical Nova Binary

Abstract In 2019, the classical nova V1047 Cen experienced an unusual outburst, the nature of which has not yet been clearly determined. In this paper, we show that the 2019 V1047 Cen outburst is of Z And-type—a type that is characteristic of and has so far been observed only in symbiotic binaries. We support our claim by modeling the near-ultraviolet to near-infrared spectral energy distribution, which revealed a close similarity between the fundamental parameters and the mass-loss rate of the burning white dwarf (WD) during the 2019 V1047 Cen outburst and those measured during Z And-type outbursts in symbiotic stars. All parameters are in good agreement with the theoretical prediction when the accretion rate exceeds the stable burning limit for WDs with masses ≲0.7 M ⊙ . Our analysis showed that after a nova explosion, the Z And-type outburst can occur not only in symbiotic binaries, but also in short-period cataclysmic variables, when the accretion-powered system changes to a nuclear-powered one as a consequence of the donor’s reaction to the nova explosion. Such a development promotes the production of Type Ia supernovae.