Physical and wind properties of hot luminous. stars with ULLYSES

Massive stars are rare, though dominate the radiative, mechanical and chemical feedback in star-forming galaxies. Metal-poor massive stars are especially important since they are believed to be the progenitors of LIGO/VIRGO/KAGRA gravitational wave mergers and can be seen collectively in the rest-frame UV light of distant star-forming galaxies. This project seeks to exploit a major new HST Legacy programme ULLYSES which is obtaining high quality UV spectroscopy of hundreds of metal-poor massive stars, from which physical, chemical and wind properties will be obtained, allowing refinements to mass-loss prescriptions for massive stars, including the role of metallicity in driving winds from comparison with Galactic counterparts, which directly influences their ultimate fate as core collapse supernovae.