Wind and nebula of the M 33 variable GR 290 (WR/LBV)

Abstract

Context: GR 290 (M 33 V0532=Romano's star) is a luminous M 33 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 H ii 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 GR 290. Methods: Long-slit spectra of GR 290 were obtained with three slit orientations in the visual and red spectral regions. The emissionline distribution for each slit was analyzed. Results: We confirm the presence of an asymmetric H ii region that extends ∼50 pc to the south; ∼30 pc to the north and southeast; ∼20 pc to the east and northwest and ∼10 pc to the west. We also present the first spectrum to be acquired of a star belonging to the neighboring OB 88 association, J013501.87+304157.3, which we classify as a B-type supergiant with a possible binary companion.

The History Goes On: Century Long Study of Romano’s Star

“…New spectra of GR 290 were obtained with the OSIRIS spectrograph in September 2018 [23]. Detailed analysis of the spectra obtained in 2016 and 2018 did not reveal any changes ( Figure 5).…”

“…Therefore, we retrieved from General observational archive of Special Astrophysical observatory of Russian Academy of Sciences (SAO RAS) 3 all long-slit spectra of GR 290 obtained on Russian 6-m telescope with the Spectral Camera with Optical Reducer for Photometric and Interferometric Observations (SCORPIO) [21] during the years 2005-2016. We also utilised the spectra obtained with the OSIRIS spectrograph on the Gran Telescopio Canarias (GTC) and analysed by Maryeva et al [22] and Maryeva et al [23]. We reduced these spectra in a uniform way using the ScoRe package 4 initially created 5 of 24 for the SCORPIO data reduction, and extracted the spectra of all stars crossed by the slit.…”

“…Due to this, it has been challenging to obtain its spectra with good enough quality for wind speeds to be adequately estimated. In summer of 2016, GR 290 was observed with the Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy (OSIRIS) on the Gran Telescopio Canarias (GTC) [22]. These observations gave the best spectral resolutions and signal-to-noise ratios ever obtained for this object, and allowed to estimate an average radial velocity (RV) of the object, RV(GR 290) = −163 ± 32 km s −1 , which is consistent, within the uncertainties, with the heliocentric velocity −179 ± 3 km s −1 of M 33 galaxy.…”

“…Polcaro et al [10] built nine models for the most representative spectra acquired between 2002 and 2014. The results of calculations from Polcaro et al [10], Clark et al [47] and Maryeva et al [22] are summarised in Table 5, along with the parameters estimated using the spectrum of September 2018. Comparisons of observed spectra with corresponding models are shown in Figure 6.…”

“…The model spectra are convolved with a Gaussian instrumental profile. Description of observational data may be found in [10,22,23]. Notice that "September 2006" spectrum was obtained by P. Massey with WIYN 3.5 m telescope [18].…”