Abstract

Contributed Talk - Splinter CloseBinaries

Wednesday, 09 September 2026, 14:00   (MW-0250)

Unveiling the mysteries of WR stars at Low Metallicity: Insights from new spectroscopy from NGC 6822

Robin Trigg
University of Potsdam

WR stars are rare, highly evolved massive stars that stand out as the principal sources of stellar feedback in galaxies. These luminous stars are very hot, and drive strong stellar winds that lead to characteristic strong broad emission lines in their spectra. So far, the SMC is the lowest-Z galaxy where a complete sample of WR stars has been systematically investigated. It was found that the properties of the WR star population in the SMC are substantially different from those in the Galaxy and LMC. This raises important questions: are the evolutionary paths of massive stars culminating in the WR stage different in low metallicity galaxies? What are the realistic stellar parameters of WR stars, such as mass-loss rate, temperature, and luminosity in low metallicity environments? To answer these fundamental questions, we obtained new Hubble Space Telescope and ESO Very Large Telescope spectroscopy of all known WR stars in another low metallicity galaxy, NGC 6822. Analyses of the spectra using the Potsdam Wolf-Rayet (PoWR) model atmosphere allowed us to determine the stellar parameters, which have been compared with new evolutionary tracks to estimate stellar masses and consider possible evolutionary scenarios. In this talk, we will present the results of this analysis and discuss properties, binarity, and evolutionary pathways leading to the formation of WR stars in NGC 6822. We conclude that the comparative analysis of WR stars in SMC and NGC 6822 reveals new facts about low metallicity WR stars and opens a new door for better understanding of final evolutionary stages of massive stars at low metallicity.