Photometric evolution of the 2016 outburst of recurrent Nova LMC 1968: the first three weeks

TL;DR

This study presents detailed optical photometry of the first three weeks of the 2016 outburst of recurrent Nova LMC 1968, revealing a light-curve identical to the 2010 eruption and insights into the nova's ionization and burning phases.

Contribution

It provides the first detailed optical light-curve comparison between the 2016 and 2010 eruptions, confirming their similarity and analyzing the nova's evolution and recurrence period.

Findings

The 2016 I-band light-curve matches the 2010 eruption in detail.

Maximum brightness occurred on Jan 21.2016 at I=11.5 mag.

A ~1 day plateau coincides with super-soft X-ray emission emergence.

Abstract

Optical (BVRI) photometry of the first three weeks of the 2016 outburst of the recurrent Nova LMC 1968 is presented and discussed. The 2016 I-band light-curve is an exact replica, even in the most minute details, of that for the 2010 eruption. The maximum is inferred to have occurred on 2016 Jan 21.2 at I=11.5 mag, corresponding to an absolute magnitude M(I)=-7.15. A ~1 day plateau is present in all bands about six days past optical maximum, simultaneous with the emergence of super-soft X-ray emission in Swift observations, signalling the widespread ionization of the ejecta. The nova entered a much longer plateau about 9 days past maximum, governed by the brightness of the white dwarf, now directly visible and still nuclearly burning on its surface. An outburst recurrence mean period of ~955 days (2.6 yrs) would fit both the OGLE inter-season gaps and the observed intervals between previous outburts.