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We study the long term, S Dor-type variability and the present hot phase ofthe LBV star GR290 (Romano's Star) in M33 in order to investigate possiblelinks between the LBV and WNL stages of very massive stars. We use intermediateresolution spectra, obtained with WHT in December 2008, when GR290 was atminimum (V = 18.6), as well as new low resolution spectra and B V R Iphotometry obtained with the Loiano and Cima Ekar telescopes during 2007-2010.We identify more than 80 emission lines in the 3100-10000 A range, belonging todifferent species and to forbidden transitions. Many lines, especially the HeItriplets, show a P Cygni profile with an a-e radial velocity difference from-300 to -500 km/s. The shape of the 4630-4713 A emission blend and of otheremission lines resembles that of WN9 stars; the blend deconvolution shows thatthe HeII 4686 A has a strong broad component with FWHM \simeq 1700 km/s. During2003-2010 the star underwent large spectral variations, best seen in the4630-4686 A emission feature. Using the late-WN spectral types of Crowther &Smith (1997), GR290 apparently varied between the WN11 and WN8-9 spectraltypes, the hotter being the star the fainter its visual magnitude. Thisspectrum-visual luminosity anticorrelation of GR290 is reminiscent of thebehaviour of the best studied LBVs. During the 2008 minimum we find asignificant decrease in bolometric luminosity, which could be attributed toabsorption by newly formed circumstellar matter. We suggest that, presently,the broad 4686 A line and the optical continuum are formed in a central WRregion, while the narrow emission line spectrum originate in an extended,slowly expanding envelope, that is composed by matter ejected during previoushigh luminosity phases, and ionized by the central nucleus. GR290 could havejust entered in a phase preceeding the transition from the LBV state to late WNtype.

The Extreme LBV Star GR290 (Romano's Star) in M33. Optical Spectrophotometric Monitoring