A new outburst in LMC-N66

TL;DR

This paper reports a new outburst in the central star of LMC-N66, revealing its variable nature and spectral evolution, and discusses its implications for understanding the star's true classification and behavior.

Contribution

It presents the first detailed analysis of a recent outburst in LMC-N66, highlighting its spectral features and variability, and compares it with previous episodes.

Findings

The star experienced a new outburst 13 years after the previous one.

Spectral features show similarities and differences with the 1994 outburst.

The star's variable mass-loss rate influences its brightness and spectral appearance.

Abstract

This is the first report on the new outburst presented by the central star of the LMC-N66 nebula. This object was classified as a planetary nebula, however, its true nature is under debate. In the period 1955-1990 the central star was almost undetectable and only nebular emission lines were observed. In 1990, the beginning of an outburst was detected and in few months it became much brighter and developed wide He and N lines, typical of a Wolf Rayet star of the N-sequence. The maximum occurred in 1994 and afterwards the star slowly faded. Analysis of its evolution showed that it has a variable mass-loss rate which occasionally increases enormously, creating a false photosphere at a much larger radius, making it appear a few magnitudes brighter. The present outburst has occurred 13 years after the episode from 1994 to 2000. So far this new event has similar characteristics although there are some significant differences in the spectral features. We present optical and FUSE spectra showing the main properties of this latter event.