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We investigate a suspected very massive star in one of the most metal-poordwarf galaxies, PHL~293B. Excitingly, we find the sudden disappearance of thestellar signatures from our 2019 spectra, in particular the broad H lines withP~Cygni profiles that have been associated with a massive luminous bluevariable (LBV) star. Such features are absent from our spectra obtained in 2019with the ESPRESSO and X-shooter instruments of the ESO's VLT. We computeradiative transfer models using CMFGEN that fit the observed spectrum of theLBV and are consistent with ground-based and archival Hubble Space Telescopephotometry. Our models show that during 2001--2011 the LBV had a luminosity$L_* = 2.5-3.5 \times 10^6 ~L_{\odot}$, a mass-loss rate $\dot{M} = 0.005-0.020~M_{\odot}$~yr$^{-1}$, a wind velocity of 1000~km~s$^{-1}$, and effective andstellar temperatures of $T_\mathrm{eff} = 6000-6800$~K and$T_\mathrm{*}=9500-15000$~K. These stellar properties indicate an eruptivestate. We consider two main hypotheses for the absence of the broad emissioncomponents from the spectra obtained since 2011. One possibility is that we areseeing the end of an LBV eruption of a surviving star, with a mild drop inluminosity, a shift to hotter effective temperatures, and some dustobscuration. Alternatively, the LBV could have collapsed to a massive blackhole without the production of a bright supernova.

The possible disappearance of a massive star in the low metallicity galaxy PHL 293B