Elisa Schösser   (Germany)

elisa.schoesser@uni-heidelberg.de

Spectroscopic analysis of metal-poor massive stars in the Magellanic Bridge

Massive stars play an important role in astrophysics as their strong winds contribute majorly to the chemical enrichment of the interstellar medium. Thus, they influence the formation and evolution of stars and galaxies. To understand the evolution, and impact of massive stars on the structure formation in the early high-redshift Universe, a better understanding in particular of massive stars in low-metallicity environments is crucial. So far, the mass loss rates of massive stars at low metallicity are poorly constrained. A major aim of my PhD project will be to study the mass-loss rates and feedback of massive stars at low metallicity.
With their close distances and their small average metallicities of Z_SMC = 0.2 Z_sun and Z_LMC = 0.5 Z_sun , the Small and Large Magellanic Clouds are excellent laboratories for the study of massive stars in low-metallicity environments. Recently, three O stars and a few early B-type stars were discovered in the Magellanic Bridge, the stream of stars connecting the Magellanic Clouds. Some of these have an even smaller metallicity of Z < 0.1 Z_sun . Using quantitative spectroscopy, I will characterize the winds of the discovered stars and thus constrain the mass-loss-metallicity relation at low metallicity.
To analyze the stars, I will use detailed expanding non-LTE atmosphere models to generate synthetic spectra and compare them to measured optical and UV observations. To fit the synthetic spectra to the measured data and infer the best-fit parameters, I am planning to use Bayesian methods and machine learning algorithms.

Supervisor:    Andreas Sander (ARI)