Study of the Massive O- and WR-stars and their Associated Winds

Abstract

Massive stars (initial mass > 8M⊙) are important objects within a galaxy, impacting their environments via their intense radiation fields as well as dense, supersonic winds and subsequently via supernova explosions. This thesis aims to explore the massive O-type and Wolf-Rayet (WR) stars and their associated winds in detail using multi-wavelength data sets. These are, more generally, found in binary or higher multiplicity systems with other massive stars having orbital periods from a couple of days up to a few hundred of years. WR stars are the evolved counterparts of O-type objects whose strong stellar winds gradually unravel their deeper layers. While some WRs display enhanced nitrogen and helium abundances (WN stars), others present enhanced carbon and depletion in nitrogen while helium is still highly present (WC stars).