Modeling Hydrogen-Rich Wolf-Rayet Stars in M33

TL;DR

This study analyzes spectral variability and wind parameters of two luminous stars in M33, suggesting they may be runaway stars with significant luminosity changes and detailed atmospheric modeling.

Contribution

It provides the first detailed spectral variability analysis of LBV V532 and late WN star FSZ35 in M33, including atmospheric parameters and wind properties.

Findings

V532's bolometric luminosity varies by a factor of ~1.5.

Wind parameters were derived using CMFGEN modeling.

Stars may be massive runaway stars with velocities around 100 km/s.

Abstract

We present the results of a spectral variability study of two very luminous stars in the M33 galaxy -- LBV V532 and late WN star (possibly, dormant LBV) FSZ35. We studied spectral variability of V532, derived its atmosphere parameters and showed that the bolometric luminosity varies between the two states by a factor of $\sim$1.5. Using the non-LTE radiative transfer code CMFGEN, we determined wind parameters for both objects. Since both stars are located at distances of about 100 pc from the nearest association, we supposed that they may be massive runaway stars with velocities of the order 100 km/s.