Related papers: Multiple Major Outbursts from a Restless Luminous …

We have studied the spectral time variations of candidate luminous blue variable stars (cLBV) in two low-metallicity blue compact dwarf galaxies, DDO 68 and PHL 293B. The LBV in DDO 68, located in HII region #3, shows an outburst, with an…

We present the nine-year light curve of the cataclysmic variable 1RXS J140429.5+172352 from 2005 April to 2014 July. We identified four dwarf nova-like outbursts, which typically lasted 3 to 5 days, with an amplitude of 3.1 to 5.3…

We performed spectroscopy of five Luminous Blue Variable (LBV) candidates and two known LBV stars (AE And and Var A-1) in M31. We obtained the same-epoch near-infrared (NIR) and optical spectra of these stars. The NIR spectra were taken…

Very massive stars occasionally expel material in colossal eruptions, driven by continuum radiation pressure rather than blast waves. Some of them rival supernovae in total radiative output, and the mass loss is crucial for subsequent…

(abridged) We present the results of studying the spectral and photometric variability of the luminous blue variable star V532 in M33. The photometric variations are traced from 1960 to 2010, spectral variations - from 1992 to 2009. The…

In this second paper on our variability survey of central stars of planetary nebulae (CSPNe) using ZTF, we report 11 long-timescale variables with variability timescales ranging from months to years. We also present preliminary analyses…

We present a detailed study of McNeil's nebula (V1647 Ori) in its ongoing outburst phase starting from September 2008 to March 2013. Our 124 nights of photometric observations were carried out in optical V, R, I and near-infrared J, H, K…

Based on long-term SWIFT, RXTE, and MAXI observations of the X-ray novae H1743-322 (IGR J17464-3213) and GX339-4, we have investigated the morphology and classified the light curves of their X-ray outbursts. In particular, we have confirmed…

We present a comprehensive analysis of the photometric variability of (presumably single) nitrogen-rich Wolf-Rayet (WN) stars in the Magellanic Clouds, using long-term observations from the OGLE survey. Our sample comprises 47 stars with no…

The light curve of a blue variable in the MACHO LMC database (FTS ID 78.5979.72) appeared nearly unvarying for ~4 years (quasi-flat segment) but then rapidly changed to become periodic with noisy minima for the remaining 4 years (periodic…

In this series of papers we have presented the results of a spectroscopic survey of luminous and variable stars in the nearby spirals M31 and M33. In this paper, we present spectroscopy of 132 additional luminous stars, variables, and…

We report the results of a photometric and spectroscopic follow-up campaign of the unusual interacting supernova (SN) 2022pda. Precursor variability lasting $\sim 100$ days is observed before the explosion. The SN light curve has a double…

During 2001-2002 the optically violent variable (OVV) blazar 3C 279 un- derwent the most intense outburst seen during the entire fourteen year history that this quasar has been studied at Colgate University's Foggy Bottom Obser- vatory…

The luminous blue variable (LBV) RMC143 is located in the outskirts of the 30~Doradus complex, a region rich with interstellar material and hot luminous stars. We report the $3\sigma$ sub-millimetre detection of its circumstellar nebula…

The SMC harbours a class of hot nitrogen-sequence Wolf-Rayet stars (WNE) that display only relatively weak broad emission lines. This indicates low mass-loss rates and makes them also hard to detect. However, such stars are possible…

V347 Aurigae is associated with the small dark cloud L1438 and appears to be an isolated pre-main sequence star located at distance $d\approx$200 pc. Multi-epoch, archival photometry reveals periodic brightness variations with amplitude…

V1647 Ori is a young eruptive variable star, illuminating a reflection nebula (McNeil's Nebula). It underwent an outburst in 2003 before fading back to its pre-outburst brightness in 2006. In 2008, V1647 Ori underwent a new outburst. The…

We present the results of a new epoch of a long-term photometric monitoring of the variable planetary nebula IC~4997. The integral $UBV$ light curves display a continuing brightening of 0.$^{m}15$ in $V$, a slight rise (<0.$^{m}1$) in $B$,…

The VISTA Variables in the Via Lactea (VVV) survey obtained near-infrared photometry toward the Galactic bulge and the southern disc plane for a decade (2010 - 2019). We designed a modified Lomb-Scargle method to search for large-amplitude…

We performed R-band time series observations of the young, metal rich open cluster NGC 2301 for 12 nights in Feb. 2004. B images were also obtained and color magnitude diagrams, having limits of R=19.5 and B=21.5, were produced. Only asmall…