Paper detail

Asymmetrical nebula of the M33 variable GR290 (WR/LBV)

Context: GR290 (M33 V0532=Romano's star) is a luminous M33 object undergoing photometric variability typical for luminous blue variable (LBV) stars. It lies inside Wolf-Rayet region in the Hertzsprung-Russell diagram and possesses a WN8 type spectrum at the light minima. Analysis of Gran Telescopio Canarias (GTC) spectra obtained in 2016 led to the conclusion that it is surrounded by an unresolved HII region formed mostly of ejected material from the central star, and disclosed the presence of a second, more extended asymmetrical emission region. Aims: The aim of this paper is to further explore the structure of the nearby environment of GR290. Methods: Long-slit spectra of GR290 were obtained with three slit orientations in the visual and red spectral regions. The emission-line distribution for each slit was analyzed. Results: We confirm the presence of an asymmetric HII region that extends ~50 pc to the south; ~30pc to the north and southeast; ~20 pc to the east and northwest and ~10pc to the west. We also present the first spectrum to be acquired of a star belonging to the neighboring OB88 association, J013501.87+304157.3, which we classify as a B-type supergiant with a possible binary companion.