Resubmission of HST Cycle 31 AR proposal -2007091112 Assigned ID: 5589 ----- Attempting Submission 1 (Tue Mar 26 19:52:15 GMT 2024) ----- An essential ingredient in the composition of galaxies are massive stars. This is highlighted by the fact that features arising directly from, or due to the impact of, massive stars are observed throughout the Universe, from our Local group to nearby star forming galaxies, through cosmic noon to the era of reionisation. Therefore massive stars must be accounted for in observational studies of galactic properties, the gold standard of which focus on spectroscopy. The model galactic spectra required for these investigations are produced through population synthesis approaches, which are built upon libraries of theoretical stellar atmospheres. However, these libraries are limited in their sampling of the upper Hertzsprung-Russell diagram, as well as their coverage in wavelength, metallicity, mass, abundance and their treatment of mass loss. We propose to establish a new spectral library, utilising recent advancements in stellar evolutionary and atmospheric modelling, that will provide improvements in all of these aspects. The spectral templates produced in this project will be made publicly available, with applications in stellar and photoionisation modelling, and will be an essential tool in tackling some of the most pressing open questions in galaxy evolution related to abundances, outflows, star formation rates and the nature of the initial mass function (including the presence of very massive stars). The PI Calum Hawcroft has experience with detailed spectroscopic atmosphere modelling of massive stars and in population synthesis of star forming galaxies. Co-I Claus Leitherer led the development of the population synthesis code STARBURST99 and has been involved in producing regular updates to the code. Dr Leitherer is an expert in the theoretical and observational studies of massive stars and star forming galaxies from the UV to the near-IR. Co-I Andreas Sander is co-developer of the stellar atmosphere modelling code PoWR. Dr Sander is an expert in developing stellar atmosphere models and the interpretation of spectra of hot stars. Galaxies 0 false false false false true false false SUPPORTED