A new outburst in the extraordinary central star of LMC-N66

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 afterward 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.