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Context: GR290 (M33/V532=Romano's Star) is a suspected post-LBV star locatedin M33 galaxy that shows a rare Wolf-Rayet spectrum during its minimum lightphase. In spite of many studies, its atmospheric structure, its circumstellarenvironment and its place in the general context of massive stars evolution ispoorly known. Aims: Detailed study of its wind and mass loss, and study of thecircumstellar environment associated to the star. Methods: Long-slit spectra ofGR290 were obtained during its present minimum luminosity phase with the GTCtogether with contemporaneous BVRI photometry. The data were compared withnon-LTE model atmosphere synthetic spectra computed with CMFGEN and with CLOUDYmodels for ionized interstellar medium regions. Results: The current $m_V=18.8$mag, is the faintest at which this source has ever been observed. The non-LTEmodels indicate effective temperature $T_{eff}$=27-30 kK at radius$R_{2/3}$=27-21 Rsun and mass loss rate $\dot{M}=1.5\times10^{-5}$ Msunyr$^{-1}$. The terminal wind speed $V_\infty$=620 ${\rm km~s^{-1}}$ is fasterthan ever before recorded while the current luminosity $L_*=(3.1-3.7)\times10^5$ Lsun is the lowest ever deduced. It is overabundant in He and N andunderabundant in C and O. It is surrounded by an unresolved compact HII regionwith dimensions $\leq$4 pc, from where H-Balmer, HeI lines and [OIII] and [NII]are detected. In addition, we find emission from a more extended interstellarmedium (ISM) region which appears to be asymmetric, with a larger extent to theEast (16-40 pc) than to the West. Conclusions: In the present long lastingvisual minimum, GR290 is in a lower bolometric luminosity state with highermass loss rate. The nearby nebular emission seems to suggest that the star hasundergone significant mass loss over the past $10^4-10^5$ years and is nearingthe end stages of its evolution.

Wind and nebula of the M33 variable GR290 (WR/LBV)