Related papers: Multiple Major Outbursts from a Restless Luminous …

We present photometric and spectroscopic observations of SN 2000ch, an unusual and extremely luminous variable star located in the galaxy NGC 3432. The object was discovered on 2000 May 3.2 during the course of the Lick Observatory…

We analyse photometric observations of the supernova (SN) impostor SN 2000ch in NGC 3432 covering the time since its discovery. This source was previously observed to have four outbursts in 2000-2010. Observations now reveal at least three…

Some reports of supernova (SN) discoveries turn out not to be true core-collapse explosions. One such case was SN 2009ip, which was recognized to be a luminous blue variable (LBV) eruption. This source had a massive hot progenitor star…

Luminous blue variables (LBVs) exhibit unique variability features, characterized by episodic outbursts ($>$1 mag) accompanied by spectroscopic changes (S Dor variables). It is debated if all massive stars undergo an LBV-like phase during…

Luminous blue variables (LBVs) are evolved massive stars close to the Eddington limit, with a distinct spectroscopic and photometric variability having unsteady mass-loss rates. These stars show a considerable change in their surface…

The short period variable star MG1-688432 has been discovered to exhibit occasional extremely high energy optical outbursts as high as 10^31 joules. Outbursts are typically of several hours duration. These events are often highly…

So far the highly unstable phase of luminous blue variables (LBVs) has not been understood well. It is still uncertain why and which massive stars enter this phase. Investigating the variabilities by looking for a possible regular or even…

We report the fifth confirmed Luminous Blue Variable/S Doradus variable in M31. In 2006, J004526.62+415006.3 had the spectrum of hot Fe II emission line star with strong P Cygni profiles in the Balmer lines. In 2010, its absorption line…

Luminous blue variables (LBVs) are expected to play an important role in massive stellar evolution as well as being the progenitors of some of the most luminous supernovae known. In this paper we provide a multiwavelength study of the…

We present spectra of the supernova (SN) impostor AT 2016blu spanning over a decade. This transient exhibits quasiperiodic outbursts with a $\sim$113 d period, likely triggered by periastron encounters in an eccentric binary system where…

Very massive stars in the final phases of their lives often show unpredictable outbursts that can mimic supernovae, so-called, "SN impostors", but the distinction is not always straigthforward. Here we present observations of a luminous…

I review recent progress on understanding eruptions of unstable massive stars, with particular attention to the diversity of observed behavior in extragalatic optical transient sources that are generally associated with giant eruptions of…

The paradigmatic Luminous Blue Variable R127 in the Large Magellanic Cloud has been found in the intermediate, peculiar early-B state, and substantially fainter in visual light, signaling the final decline from its major outburst that began…

We present spectroscopic and photometric observations of the emission-line star MWC 930 (V446 Sct) during its long-term optical brightening in 2006--2013. Based on our earlier data we suggested that the object has features found in Luminous…

Luminous Blue Variables (LBVs) are a class of massive blue supergiants exhibiting irregular and eruptive instability, sometimes accompanied by extreme mass loss. While they have often been considered to be a brief but very important…

We show that Supernova (SN) 2002kg in NGC 2403, initially classified as Type II-narrow (IIn), has photometric and spectroscopic properties unlike those of normal SNe. Its behavior, instead, is more typical of highly massive stars which…

MCA-1B (also called UIT003) is a luminous hot star in the western outskirts of M33, classified over 20yr ago with a spectral type of Ofpe/WN9 and identified then as a candidate luminous blue variable (LBV). Palomar Transient Factory data…

We present multi-epoch, multi-colour pre-outburst photometry and post-outburst light curves and spectra of the luminous blue variable (LBV) outburst Gaia16cfr discovered by the Gaia satellite on 1 December 2016. We detect Gaia16cfr in 13…

We study the long term, S Dor-type variability and the present hot phase of the LBV star GR290 (Romano's Star) in M33 in order to investigate possible links between the LBV and WNL stages of very massive stars. We use intermediate…

We search for LBV stars in galaxies outside the Local Group. Here we present a study of two bright $H\alpha$ sources in the NGC 247 galaxy. Object j004703.27-204708.4 ($M_V=-9.08 \pm 0.15^m$) shows the spectral lines typical for…