Spectral study of the late nitrogen-sequence Wolf-Rayet star FSZ35 in M33

Abstract

We study and analyse the low‐resolution spectra of the unusual late nitrogen‐sequence Wolf–Rayet (WN) star FSZ35 in M33. We classify the object as a hydrogen‐rich WN8 star. Using the radiative transfer code cmfgen, we determine the physical parameters of this object and we compare these to the parameters of other WN8 stars, including the luminous blue variable V532 (also known as Romano’s star) during the minimum of its brightness. Unlike V532, the object is fairly stable, both spectrally and photometrically, which can be attributed to its more advanced evolutionary stage or lower luminosity. FSZ35 is shown to possess a compact nebula that produces a faint but detectable [O iii] emission.

Modeling Hydrogen-Rich Wolf-Rayet Stars in M33

“…FOCAS data were reduced in IDL development environment using procedures similar to those consisting ScoRe but taking into account the specific features of FOCAS. We describe the observational data of V532 and FSZ35 in more detail in Maryeva & Abolmasov [11] and in Maryeva & Abolmasov [20], respectively.…”