Speaker
Description
Massive stars are stars whose mass (M) is greater than 8 times that of the Sun. While they only live for a mere 3 to 50 Myr, they heavily impact their surroundings. For example, they drive strong stellar winds, which inject kinetic energy and nuclear processed materials into their environment, therefore affecting local star formation. The properties and structure of these stellar winds are not very well understood, however, especially at low metallicity (Z). This low Z regime is of particular interest if one wants to gain insight into the nature of the very first stars in the Universe, as these were composed entirely of hydrogen and helium generated after the Big Bang. Several dwarf galaxies in the Local Group have metal contents that are extremely low. By accurately constraining the wind properties of the massive stars within these galaxies, we will learn more about the evolution of massive stars, as winds can severely impact this, while also learning more about the nature of the first stars. To do this, it is imperative to analyse both the optical and ultraviolet spectra of these stars. In this talk, I will introduce these distant, low Z, massive stars. I will outline the methods we use, namely quantitative spectroscopy, and the genetic algorithm Kiwi-GA, which is used with the stellar atmosphere code FASTWIND to obtain the stellar and wind parameters of these stars. Finally, I will present our results from the lowest Z test to date of the theory of hot star winds, and their implications for our understanding of the first stars in the Universe.
