Infrared spectroscopy of the recent outburst in V1047 Cen (Nova Centauri 2005)

TL;DR

This study reports near-infrared spectroscopy of an unusual dwarf nova eruption in V1047 Cen, occurring only 14 years after its classical nova event, challenging standard theories of accretion and outburst timing.

Contribution

It provides the first detailed spectroscopic evidence of a dwarf nova eruption shortly after a classical nova, questioning existing models of accretion disk behavior post-eruption.

Findings

Spectroscopy indicates a dwarf nova eruption in V1047 Cen.

The eruption occurred only 14 years after the classical nova event.

The event challenges standard theories of accretion and outburst timing.

Abstract

Fourteen years after its eruption as a classical nova (CN), V1047 Cen (Nova Cen 2005) began an unusual re-brightening in 2019 April. The amplitude of the brightening suggests that this is a dwarf nova (DN) eruption in a CN system. Very few CNe have had DN eruptions within decades of the main CN outburst. The 14 years separating the CN and DN eruptions of V1047 Cen is the shortest of all instances recorded thus far. Explaining this rapid succession of CN and DN outbursts in V1047 Cen may be challenging within the framework of standard theories for DN outbursts. Following a CN eruption, the mass accretion rate is believed to remain high $(\dot{M}\sim10^{-8}$M$_\odot$yr$^{-1})$ for a few centuries, due to the irradiation of the secondary star by the still-hot surface of the white dwarf. Thus a DN eruption is not expected to occur during this high mass accretion phase as DN outbursts, which result from thermal instabilities in the accretion disk, and arise during a regime of low mass accretion rate $(\dot{M}\sim10^{-10}$M$_\odot$yr$^{-1})$. Here we present near-infrared spectroscopy to show that the present outburst is most likely a DN eruption, and discuss the possible reasons for its early occurrence. Even if the present re-brightening is later shown to be due to a cause other than a DN outburst, the present study provides invaluable documentation of this unusual event.